THE BULLETIN

of the

UNITED STATES GOLF ASSOCIATION GREEN SECTION

Vol. 13 

Washington, D. C., December, 1933 

No. 6

Contents

Page

Use of Sodium Chlorate and Other Chemicals in Controlling Turf Weeds. 
By Fred V. Grau.......................................................................................... 154
Weeding Bermuda Grass Out of Creeping Bent Turf. By Thornton 
Conover ........................................................................................................  179
Fertilization of Fairways: Some Experimental Results. By Kenneth 
Welton ..........................................................................................................  183
Annual Report of the Green Section for 1933. By Ganson Depew..............  200
Questions and Answers..............................................................................................  203

EXECUTIVE

COMMITTEE

Ganson Depew, Chairman, Marine Trust Bldg., 

H. Kendall Read, Vice-Chairman, Philadel­

Buffalo, N. Y.

phia, Pa.

Eberhard Anhbuser, St. Louis, Mo.
Robert F. Arnott, Upper Montclair, N. J.

Frederick Snare,

H. Chandler Eagan, Medford, Oreg. 
Walter S. Harban, Washington, D. C. 
K. F. Kellerman, Washington, D. C. 
Norman Macbeth, Los Angeles, Calif. 
John Monteith, Jr., Washington, D. C. 
Guy M. Peters, Chicago, Ill.
Havana. Cuba.

RESEARCH COMMITTEE 
United States Department of Agriculture 
K. F. Kellerman. Chairman; Associate Chief. Bureau of Plant Industry. 
F. H. Hillman. Botanist, Seed Investigations.
A. J. Pieters, Principal Agronomist in Charge, Forage Crops and Diseases.
Oswald Schreiner, Principal Biochemist in Charge, Soil Fertility.
W. R. Walton, Senior Entomologist, Cereal and Forage Insects.
Harvey L. Westover, Senior Agronomist, Forage Crops and Diseases.

United States Golf Association Green Section 
John Monteith, Jr. 
Kenneth Welton

ADVISORY COMMITTEE

William H. Aston, Detroit, Mich. 
Douglas Call, Richmond, Va. 
Paul N. Coates, St. Paul, Minn. 
W. C. Fownes, Jr., Pittsburgh, Pa. 
A. J. Goetz, Webster Groves, Mo. 
William Harig, Cincinnati, Ohio. 
Jas. E. MacCloskey, Jr., Pittsburgh, Pa. 
John Morley, Youngstown, Ohio. 
Alex Pirie, Fort Sheridan, Ill. 
George Sargent, Atlanta, Ga.

C. A. Sawyer, Jr., Boston, Mass.
John Shanahan, West Newton, Mass. 
Stanley B. Sherman, Cleveland, Ohio. 
Harrison Smith, Oklahoma City, Okla. 
Henry P. Smith, Waco, Tex.
Raymond Tower, Tampa, Fla.
C. A. Tregillus, Everett, Ill.
Joseph Valentine, Haverford, Pa. 
Alan D. Wilson, Philadelphia, Pa. 
Frank H. Wilson, Newton Centre, Mass.

The Bulletin is published in January, February, May, August, October, and December by the 
United States Golf Association Green Section, at Room 7207, Building F, Constitution Ave. and 7th 
St., Washington, D. C.

Address all MAIL to P. O. Box 313, Benjamin Franklin Station, Washington, D. C.
Send TELEGRAMS to Room 7207, Building F, Constitution Ave. and 7th St., Washington, D. C.
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a year.

Entered as second-class matter, April 21, 1926, at the post office at Washington, D. C.. under 
the Act of March 3, 1879. Copyrighted, 1933, by the United States Golf Association Green Section.

154 

Vol. 13, No. 6

Use of Sodium Chlorate and Other Chemicals in Controlling 
Turf Weeds
By Fred V. Grau

In the Bulletin for May, 1933 (page 47), a resume was presented 
of observations made on the control of crabgrass and other turf 
weeds with certain chemicals in the first season’s experiments in 
this problem, as conducted in 1932 simultaneously at the University 
of Maryland, College Park, Md., and the Arlington turf garden, near 
Washington, D. C. The continuation of this same experimental work 
during 1933 at these two stations supplemented by its expansion at 
a few additional stations, affords opportunity now to present fur­
ther observations on the same subject. During this second season 
of our work the data accumulated have been considerably increased 
and their value in connection with golf course problems, it is hoped, 
accordingly enhanced. It is our purpose here to describe in greater 
detail the character of the experimental work thus conducted and 
to present the additional data that have accumulated.

The selective control of weeds in fine turf constitutes one of 
the most outstanding and important problems of turf research to­
day. This control of turf weeds by the selective action of chemicals 
is a phase of the problem which has heretofore been only touched 
on, but with some encouraging results. Most of the experimental 
work conducted by the Green Section in 1932 was on crabgrass in 
fairway turf, using a few chemicals which, by preliminary experi­
ments and through a review of the literature, had been selected 
from a great many and which showed the greatest promise for ef­
fective, cheap, selective control. This group of chemicals included 
the chlorates, arsenical compounds, ammonium thiocyanate, and the 
sulphates of iron and ammonia, each of which showed more or less 
specificity for certain types of weeds and attendant conditions. Of 
these sodium chlorate was reported as having given the best results 
on crabgrass and milk purslane, and gave promise for successfully 
controlling chickweeds. Ammonium thiocyanate compared favor­
ably with sodium chlorate in some respects. The arsenical compounds 
failed to show satisfactory results on crabgrass but showed a great 
deal of promise for the control of legumes, plantains, chickweeds, 
ground ivy, knotweed and pennywort. Iron and ammonium sulphates 
gave little or no promise for crabgrass control.

During 1933 most of these same compounds, as well as others, 
were used in amplified and extended tests, which yielded informa­
tion as to the times, rates and methods of application under different 
conditions of environment, soil type, moisture, and fertility.

Chemical weed control is not new, but its adaptation and ap­
plication to turf, where freedom from weeds is above all desired, 
open up an entirely new field of investigation, which, at the outset, 
appears to be of tremendous importance. The benefits of such inves­
tigations will be shared by all who have occasion to enjoy fine lawns, 
golf courses, parks, polo fields, or other fine turf areas. A great 
deal has been written concerning the advantages of this and that 
fertilizer material or mixture for keeping turf free from weeds. 
Under many conditions some of these materials have been success­
ful, but unfortunately they are not effective against certain weeds 
and under all soil and climatic conditions. Chemical weed control 

December, 1933

155

presents the possibility of attaining this result with a minimum of 
labor, materials, expenditure, and disturbance of the existing turf.
Let it be understood at the beginning that this article lays no 
claim that the ideal weedkiller for turf has been discovered, nor that 
by the use of the materials reported weed-free turf can be main­
tained with no other care. Reported here are the efforts of two years’ 
work, which represent an endeavor to facilitate the removal of turf 
weeds which persist in spite of the best care that can be given. 
The importance of proper soil conditions, seed-bed preparation, fer­
tilizer practices, clipping, and other factors is in no way to be under­
estimated. With this thought in mind the ensuing discussion of the 
experimental results should gain added significance.

The results obtained in 1932 indicated that certain rates of appli­
cation of chemicals were more desirable than others at different 
seasons and at different stages of development of the turf and the 
weeds. The rates at which the various materials were used in the 
1933 experiments are indicated in table 1. This series, in addition, 
yielded valuable information as to the time of year when a single 
application of any given material gave the most favorable results 
under the existing conditions.

Table 1.—Chemicals Used and Methods and Rates of Application, Accord­
ing to Plot Numbers, in Each of Six Series Treated in 1933 at the 
Arlington Turf Garden and Maryland University

Rates of application in 
pounds to 1,000 sq. ft. on 
each of four 4-by-4-ft.
Roiv Chemical used Method of application jdots within each 8-by-8- 

Spray 
Sprinkle
Dry with fertilizer*
Dry with hydrated limef 1

A Sodium chlorate 
B Sodium chlorate
C Sodium chlorate
D Sodium chlorate
E Ammonium thiocyanate Spray
F Ammonium thiocyanate Sprinkle
G Arsenic pentoxide
H Arsenic pentoxide
I Arsenic pentoxide
J Fertilizer (6-12-4 inor­

Spray
Dry with sand
Dry with fertilizer*
Dry

ft. plot
No. 1 No. 2 No. 3 No. 4
IX 
Check
1

Check
1
Check

2
4
4
4
2
4

1
2
2
Check 2
14
1
Check 2
z8
Check 1
1
y*
Check 33% 66/3

2
2

zz4

14

Check
1
Check
i/>
Check
16%

K Fertilizer (6-12-4 or­

ganic)

ganic)

L Calcium cyanamid 

(powder)
M Lead arsenate

Dry

Dry with soilf

Dry with soil!

Check

16% 33% 66/3

4%

5

Check 9% 18%

Check 10

20

* The fertilizer used was 6-12-1 inorganic in amount equivalent to a rate of 16~i pounds,

which yielded 1 pound of nitrogen in readily available form to each 1,000 square feet of area, 

t Hydrated lime was mixed pound for pound with the chemical.
± Finely-sifted dry compost soil.

Experimental Conditions

The greater part of the 1933 work was conducted at the Arling­
ton Turf Garden. Duplicate tests were conducted at the University 
of Maryland and supplementary tests were carried on in the Chicago 
District. Additional tests were made on some golf courses around 
Washington, in New Jersey, and at Indianapolis.

156

Vol. 13, No. 6

At the Arlington turf garden the natural soil is of the sassafras 
silt-loam type, light in color, has a pH of from 5.4 to 5.6, is generally 
low in phosphorus and potash and high in iron, but possesses a high 
potential fertility. When wet it puddles easily and when dry it be­
comes baked and cracked. In most respects the soil at Maryland 
University, where the tests were located, is identical with that at 
Arlington. The Chicago soils on which tests were made were gen­
erally of the black or dark brown silt-loam type, sometimes almost 
mucky in character, fertile and well-drained, and have a pH of about 
6.5 to 7.0. The Indiana soils where the tests were located were of the 
clay-loam type, fine textured in nature, testing about pH 6.0 to 6.5, 
and rather deficient in phosphorus and potash. The New Jersey soils 
were generally sandy in character, well-drained but infertile, with 
a low organic matter content and possessed a rather high degree of 
acidity, about pH 5.0 to 5.2.

In these experiments the plot sizes ranged from 16 square feet 
to 1,000 square feet, depending upon the area available for tests 
and the character of the experiment, as well as the distribution of 
the vegetation. The amount of chemical applied, in no matter what 
manner, was calculated on the basis of pounds, or fractions of pounds, 
to 1,000 square feet. In the ensuing discussion, for the sake of uni­
formity and ease in interpreting results, the amount of chemical 
used on a given plot, regardless of area, will be expressed in pounds 
or ounces to 1,000 square feet (one pound to 1,000 square feet is 
roughly equivalent to 45 pounds to the acre).

The site selected at the Arlington turf garden was a portion of 
neglected, unfertilized lawn at the crest of a slight, well-drained 
slope exposed to the west. The rather fine-textured, infertile soil 
supported a profuse growth of crabgrass (Digitaris sanguinalis), a 
scanty growth of Kentucky bluegrass (Poo, pratensis), great num­
bers of narrow-leaf plantain (Plantago lanceolata), a few major or 
broad-leaf plantain (P. major'), considerable white clover (Trifolium 
repens), much field sorrel (Rumex acetosella), a goodly variety of 
chickweeds, largely the common or smooth chickweed (Stellaria 
media) with some mouse-ear chickweed (Cerastium vulgatum), and 
some milk purslane (Euphorbia maculata). Heal-all or carpenter 
weed (Prunella vulgaris) occurred in isolated patches, as did cinque­
foil (Pontentilla spp.) and thyme-leaved speedwell (Veronica ser- 
pyllifolia). The poverty of the soil was indicated further by the 
presence of considerable wire grass (Aristida spp.). Yellow or wood 
sorrel (Oxalis stricta) was quite generally though thinly distributed, 
as was wild garlic (Allium vineale).

The ground cover at Maryland was quite similar to that at 
Arlington with a few exceptions. The site on the Maryland campus 
was not so well drained as that at Arlington. The slope was slightly 
to the east. A better stand of bluegrass was in evidence at all times, 
there was somewhat more white clover, no field sorrel, and few chick- 
weeds. Wild garlic was quite profuse on all plots and there was 
more of the major plantain present. Fairy rings unequally distrib­
uted through the plots, which were not in evidence at the time the 
site was selected, introduced a considerable error in the turf read­
ings by stimulating the turf as if fertilizer had been applied. Dande­
lions (Taraxacum officinale) were universally present, but accurate 
counts were not made due to the extreme difficulty in counting them.
In addition to the weeds named, observations were made at other 

December, 1933 

157

places on goose grass (Eleusine indica), ladies-bedstraw {Galium 
sp.), annual bluegrass (Poa annua), and winter cress (Barbarea 
so.).
Methods of Application
1 ' 

Apparent discrepancies have been observed among some of the 
previous investigators concerning the efficiency and applicability of 
the various methods of applying chemicals. It has been reported 
that for comparable results the dry application of sodium chlorate 
required five to six times as much material than when applied as a 
spray, cognizance being taken of the influence of the vegetation to 
be treated. In order to thoroughly test this point with respect to 
the treatment of turf with chemicals, over 600 4-by-4-foot plots were 
treated with a single application of materials during 1933 over a 
period of seven months by three methods, as shown in table 1: first, 
the dry method, in which the chemical is mixed with an inert carrier, 
such as soil, sand, lime, or superphosphate, and broadcast over the 
turf using only a sufficient amount of the carrier to insure uniform 
distribution; second, the spray method, where a quantity of stock 
solution of a chemical is diluted with water and delivered to the turf 
in the form of a fine, misty spray at the rate of 150 to 200 gallons 
to the acre or five gallons to 1,000 square feet, using a brass hand 
spray gun which delivers a continual spray, the spray being allowed 
to remain on the vegetation; third, the sprinkling method, whereby 
the chemical is dissolved in water and applied with a sprinkling can, 
barrel cart, or similar device, which delivers the solution to the turf 
as a coarse rain in large drops. In the sprinkling method the chemical 
is immediately brought into contact with the soil, sufficient water 
being used to insure this, with a minimum amount remaining on the 
leaves of the vegetation. The amount of water used in these experi­
ments was at the rate of approximately 25 to 30 gallons to 1,000 
square feet which, it was found, represented a minimum amount for 
obtaining uniform distribution in connection with the use of a garden 
sprinkling can. __ 
Methods of Evaluating Results

n

Before treating any plot, the condition and adundance of the 
various components of the ground cover were determined by a tech­
nique developed during the preliminary experiments. Rosette weeds 
and those with upright stems (determinate) were counted. The rela­
tive abundance of the prostrate and spreading types (indeterminate) 
was estimated on the basis of 10 as a maximum, as was also the ex­
cellence of turf produced by the amount of turf grasses present. For 
example, a plot consisting of pure clover was given a rating of 10 
for clover and 0 for all other components; one with a scattering of 
clover but with a fair turf of grasses would receive the rating “trace” 
for clover and 4 to 5 for turf, and so on. Obviously the method is 
inexact and lacks precision, but it is relative, and inasmuch as all 
plot readings, aside from actual counts, were made by a single ob­
server, the inherent errors may, for the most part, be considered to 
be compensating. In the final check-up at the end of the season, 
duplicate readings were made at different times of the day and the 
results weighted. Most of the comparisons will be drawn from the 
late-season readings on a relative basis. Obviously the natural sea­
sonal variation in vegetation would influence considerably any attempt 
to correlate the results of readings on spring-type vegetation and fall­
type vegetation.

158

Vol. 13, No. 6

Comparison of Methods of Application

This comparison is based principally upon the efficiency of the 
chemicals applied by different methods, at equal rates of application, 
upon the reduction of lance-leaf plantain, with a single application of 
material. This permits of a rather accurate measurement, since the 
plantains were carefully counted in all plots on the first of November. 
The condition of the turf likewise serves as a means of evaluating 
any differences among the methods, although this is not so accurate 
a method, since the values for the condition of the turf are only rela­
tive and susceptible to the error of judgment. Since all notes were 
taken by one observer, in a single day, however, and taken in dupli­
cate after a two-hour interval and averaged, this factor may be con­
sidered to be compensating among the different plots. The error 
due to initial unequal distribution of plants affects the results some­
what, so that small differences must not be considered too seriously.

Table 2.—Percentage Reduction of Plantain and Percentage Increase of 
Turf Grasses, Averaged for Over 600 Plots at Arlington Turf Garden 
and Maryland University Treated with Single Applications Only, 
throughout a Six-Months Period in 1933

Chemical

Rate 
(pounds 
to 1,000 
sq. ft.)

chlorate, 
Sodium 
chlorate, 
Sodium 
Sodium 
chlorate, 
chlorate.
Sodium 
Ammonium thiocyanate.
Ammonium thiocyanate. 
Ammonium thiocyanate. 
Ammonium thiocyanate. 
Arsenic pentoxide. 
Arsenic pentoxide.
Arsenic
pentoxide.
Arsenic pentoxide.
Arsenic pentoxide.
6-12-4 inorganic.* 
6-12-4 
inorganic.* 
6-12-4 
inorganic.* 
6-12-4 
organic.* 
6-12-4 
organic.* 
6-12-4
organic.*
Calcium cyanamid
Calcium cyanamid
Calcium cyanamid

1
2
4

1

4

1
2
4
1

4
1
2
4

Percentage reduction of plantain (first column) 
and percentage increase of grass (second col­
umn). Five methods of application.
Dry with 
Spray Sprinkle 6-12-4., 
inorganic

D ry 
with 
sand

Dry 
with 
lime

41
65
95

8
20
55

5.5
4.5
8.5

0
4
0

23
35
56

0
7
8

17
22

8
7
7.5

1.5
2.5
3

2.5 
4
3.5

77
92
95

60
80
90

6.5
8.5
6.5

o3
68
90

5
6.5

9
13

56
60
70
14
60
87
20

84
17
34
48

11
12
8
10

5
7.5
9.5

4

* Rates for fertilizers

represent pounds

of nitrogen.

Table 2 presents the data on plantain reduction and turf increase 
writh three chemicals and three fertilizer materials at different rates 
and methods of application. Some slight variances occurred in the 
results obtained at Maryland and at Arlington, but in general the 
figures represent the same order of magnitude at both places and 
have been averaged in table 2. Each figure in the table represents 
the average reduction or increase of plants in six plots, one from each 

December, 1933

159

of the six series. By a tabulation such as this any variations due to 
effect of season are smoothed out and> become compensating.

In table 2 it is seen that the greatest reduction of plantain oc­
curred in the use of sodium chlorate at the 4-pound rate, and that 
with sodium chlorate the greatest increase in turf grasses occurred 
when sprinkled at the 4-pound rate, and when applied dry at the 
2-pound rate mixed with inorganic fertilizer; also that arsenic pen­
toxide was most effective when applied at rates of Vi pound or greater. 
This is to be expected when the reduction of plantain by fertilizer 
alone is studied. At the rate corresponding to 1 pound of nitrogen 
to 1,000 square feet, the 6-12-4 inorganic shows a 14-per-cent decrease 
of plantain, the 6-12-4 organic shows a 20-per-cent decrease, and 
calcium cyanamid, 17-per-cent. At the higher rates, the difference 
is in favor of the inorganic form.

Between spraying and sprinkling in the sodium chlorate treat­
ments, there seems to be a slight difference in favor of the sprinkling 
method. This may well be due to the fact that in the spraying method 
a part of the material is lost on the bare ground and does not reach 
the plant in an effective form. The dry-lime method seems to be 
slightly better than either of the wet methods from the standpoint 
of plantain reduction. The single comparison between spray and 
dry applications with arsenic pentoxide shows the balance in favor 
of the dry methods. If the added effect of fertilizer is disregarded, 
the difference in turf increase is negligible.

The spray method depends principally upon leaf absorption and 
the destruction of the aerial organs. It is to this end that sprays 
are finely divided so as to enhance the possibility of the maximum 
amount of material being intercepted by the leaves of plants as it 
falls to the ground. In the four other methods the mode of absorp­
tion by the plant is principally by the roots from the soil solution. 
This is entirely true of the sprinkling method. With the three other 
methods, however, there is a dual effect of root absorption and de­
struction of aerial organs. As the material is broadcast, part of it 
is intercepted by, and rests upon, the broad-leaved plants such as 
plantain and dandelion. The chemical itself, as well as accompanying 
corrosive salts that are present in the fertilizer used, acts upon the 
leaves. The material which sifts through the leaves and reaches the 
soil soon goes into solution and enters the soil. The plants are thus 
attacked both above ground and below ground, which probably ac­
counts for the higher value of plantain reduction for the methods 
where this dual point of attack obtains.

This evidence quite conclusively refutes the results of earlier 
experimental work which has pointed out that about five times the 
quantity of material, sodium chlorate in particular, was required 
for satisfactory weed kill when applied as a diy salt to the soil as 
against its application in the form of a finely divided spray. The 
weed species or the soil type and moisture may affect these results 
but hardly to such an extent. It is to be noticed that these findings 
in table 2 with all three chemicals bear out the validity of this state­
ment. No research has been carried on up to this time to ascertain 
why this is true, yet it presents an interesting problem and one which 
may well engage the early attention of investigators in this particular 
phase of research.

Table 2 does not represent the true picture concerning the increase 

160

Vol. 13, No. 6

of turf, but only a general trend which in itself is sufficiently accu­
rate. With any one treatment the condition of the plots of all six 
series was averaged. The best turf occurred in series 4, 5, and 6. 
Single applications, particularly of sodium chlorate, applied after 
June 1 notably increased the amount and vigor of the turf. Regrowth 
of crabgrass in all series prior to June 1, after the effectiveness of 
the chemical had been lost, smothered the grasses and presented 
nothing but a solid mat of crabgrass at the end of the season. Crab­
grass which was able to germinate in the plots treated June 1, two 
to three weeks later, seemed unable to disturb the growth of the turf 
grasses which, by fall, had formed nearly a solid turf.

The effect of the lime, in conjunction with sodium chlorate, was 
apparently to somewhat increase the length of time the chlorate was 
effective, to retard its killing action, and to add vigor to the remain­
ing turf grasses.

While the 4-pound rate of chlorate applied as a sprinkle and dry 
with lime shows an actual greater percentage kill of plantain, the 
increase in turf is to be regarded with caution, since at this rate a 
second application kills the turf completely. A single application 
causes heavy damage and, when the supply of soil moisture is insuf­
ficient, kills it entirely.

At equivalent rates the sodium chlorate has proved superior to 
ammonium thiocyanate, both in weed kill and in turf improvement, 
in spite of the high nitrogen content of the latter. A very significant 
feature of the thiocyanate-treated plots was the large attendant 
increase in the numbers of dandelion plants, which showed a decrease 
in vigor and numbers in the chlorate-treated plots.

A comparison between sodium chlorate and arsenic pentoxide, at 
the 3/->-pound rate and by the spray method of application, shows a 
slight increase in plantain kill in favor of the arsenic but a lower 
percentage increase in turf grasses. This situation is reversed, how­
ever, at the 1- and 2-pound rates applied dry with fertilizer. The 
comparison can not be made directly, since the effectiveness of the 
two compounds depends upon somewhat different conditions and 
again upon the specific nature of the materials involved.

Of the three fertilizer materials used, the 6-12-4 inorganic gave 
consistently the best results. Burns resulted from the two heavier 
applications but they were not so serious as to permanently impair 
the turf. The reduction in plantain is significant, indicating that by 
proper fertilizer practices at least a part of the weed population can 
be materially reduced. The crabgrass, however, responded entirely 
differently and, with the exception of the last two series of applica­
tions, flourished remarkably under the heavy feeding and virtually 
extinguished the existing turf grasses. The late-season applications, 
however, severely affected the crabgrass and encouraged the turf 
grasses, from which the major portion of the turf increases in table 
2 are derived. This indicates that the time of application of fer­
tilizers for most effective weed control and for the best results on 
turf is extremely important.

Calcium cyanamid applied on an equal nitrogen basis with the 
regular mixtures, yielded results far inferior, both in plantain de­
crease and in turf increase. The cyanamid was applied as a powder 
so that it would cling to the leaves of the vegetation. The recovery 
of the turf was notably slow for several weeks after application until 
the toxic decomposition products had disappeared.

December, 1933

161

Results of Successive Applications of Sodium Chlorate

Adjacent to the experiment outlined in table 1 a second experi­
ment was conducted by which the effects of successive treatments of 
chlorate on different dates and at three rates might be determined. 
Plots 10 by 10 feet in size were so arranged that on any one date four 
successive plots were treated simultaneously at each of the three 
rates 1, 2, and 4 pounds to 1,000 square feet. Subsequent applica­
tions were made so that each time one previously untreated plot 
received a first application, whereas one of the previously treated 
plots received none. Applications were made on April 24, May 29, 
July 11, and August 29. By this plan a variety of combinations of 
rates and times of application were obtained. Half of the plots re­
ceived 6-12-4 inorganic complete mixed fertilizer on June 21 and 
October 14 at the rate of 700 pounds to the acre. Natural conditions 
prevailed throughout the season, no artificial watering being resorted 
to.

Crabgrass began to germinate in this location about April 10. At 
the stage of growth represented on April 24, about the 2-leaf stage, 
a very satisfactory kill was obtained with the ^-pound application 
of chlorate. At this rate the grass was only slightly affected, whereas 
at the 2-pound rate there was considerable turf injury with a com­
plete crabgrass kill and about a 75-per-cent kill of plantain. At the 
time of the second application on May 29 the 2-pound rate still showed 
some chlorate injury whereas the turf treated at the lower rates had 
completely recovered. At this date crabgrass was again repopulating 
all treated areas with newly germinated seedlings but to a somewhat 
less extent at the 2-pound rate.

On the basis of 100 per cent, as nearly as could be estimated, the 
maximum percentages of discoloration due to chlorate after the first 
application were, at rates of Jz4, 1, and 2 pounds, respectively about 
40, 50, and 75.

In this experiment the best plot was that which received the 
2-pound rate on April 24, May 29, and July 11. The fertilized por­
tion was far superior to the unfertilized portion. Standing second 
was the plot receiving the 1-pound rate in 4 successive applications 
on August 29 in addition to the dates named for the 2-pound rate. 
Three applications at the 2-pound rate effected virtually complete 
eradication of crabgrass, plantain, and all other weeds except wild 
garlic. The decrease in numbers and vigor of dandelions was very 
marked. Coverage due to turf grasses increased from about 10 or 
15 per cent in April to 95 per cent in October. There was less than 
5 per cent increase in the control plots.

A duplicate of this experiment conducted at the University of 
Maryland yielded entirely comparable results. An examination of 
the root systems at the end of the season showed that the production 
of rhizomes in the plots receiving the heaviest treatment was superior 
to that in the control plots.

Development of Tolerance for Chlorate

Soon after the second application of chlorate on May 29 it became 
strikingly evident that the discoloration and turf injury was much 
less than it had been following the first application. This became 
evident again following the next successive treatment and was one 
of the outstanding features of interest. Apparently a development 
of the same tolerance was not shared by the weedy plants, particu­

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Vol. 13, No. 6

larly the crabgrass. Observations indicated that in the fertilized 
areas the turf grasses were less affected by the chlorate and that 
recovery was much more rapid.

From this experiment it becomes apparent that the addition of 
a fertilizer in conjunction with the chlorate treatment is advisable, 
particularly in badly run-down weedy turf. It seems that, inasmuch 
as the V2- and 1-pound rates efficiently eliminated the very young 
crabgrass at the beginning of the season, and since the bluegrass quite 
evidently acquires a toleranace to the action of chlorate, a gradual 
increase in the rate of successive applications might well be used. 
By doing this the rather severe injury resulting from the first appli­
cation at the 2-pound rate may be greatly diminished, with the final 
results as good as those obtained with 3 successive full-rate appli­
cations.

Figure 1.—Sodium chlorate treatment of Kentucky bluegrass infested with crab­
grass. Treated plot on the left; check plot, untreated, on the right. Two 2-pound 
applications had been made to the treated plot, 6 weeks apart. Although the 
turf that remains in the treated plot is thin, it is in about the same condition as 
would have resulted from hand weeding.

Figure 1 shows how completely the crabgrass has been eliminated 
from the treated plot, which on July 1, when the picture was taken, 
had received two 2-pound treatments of chlorate.

Figure 2 shows the condition of the plot which received three 
2-pound applications. At the top the normal condition is shown; at 
the bottom, the condition after the plots had been raked to raise the 
crabgrass. The fluffy appearance of the check plot on the left indi­

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163

cates a very heavy mat of crabgrass which virtually choked all the 
turf grasses. The almost complete absence of crabgrass in the treated 
plot is clearly indicated.

The results of a similar experiment on a different location with 
sodium chlorate yielded quite as striking results, as may be seen in 
figure 3. An 8-by-8-foot plot was quartered and 3 of the sections 
treated with chlorate at V2- 1- and 2-pound rates on May 12, June 16, 
July 11, and August 11. One section remained untreated as a check. 
Sulphate of ammonia at the rate of 2^ pounds to 1,000 square feet 
was applied simultaneously with the chlorate in solution and the mix­
ture watered into the soil with a sprinkling can.

Figure 2__ Sodium chlorate treatment of Kentucky bluegrass infested with crab­
grass. Treated plot on the right; check plot, untreated, on the left. Three 
2-pound applications had been made to the treated plot, resulting in an almost 
complete elimination of the crabgrass. Both plots had been raked to lift the 
stolons of the crabgrass for photographing.

On October 7 pictures and color plates were made of this plot 
(figure 3) and at that time the final notes were taken. The ratio of 
turf-crabgrass at that time was 9, 30, 80, and 7 for the Yz-, 1-, 2-pound 
rates and the check plot respectively, indicating practically complete 
freedom from crabgrass in the plot receiving 2 pounds at 4 successive 
times. The excellence of the turf in this plot as compared with that 
in the check plot was striking, both from the standpoint of density 
and color.

Effect of Continued Treatment With Chlorate and Thiocyanate

During 1932 two plots of 250 square feet each were treated twice 
for crabgrass control. On August 1 plot A received sodium chlorate 
and plot B received ammonium thiocyanate each at the 2-pound rate. 
On September 1 each received the 1-pound rate of the respective 
chemicals. No crabgrass seed matured in plot A but in plot B the 
control was much less marked.

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Treatment was continued during 1933, and on June 21, July 15, 
and September 1 plot A received chlorate at the V2-, l-> and 2-pound 
rates respectively. The rates of thiocyanate applied to plot B were 
1, 2, and 2 on the respective dates. Nitrogen as sulphate of ammonia 
was added to plot A at each application in sufficient amount to equal 
the nitrogen applied to plot B in the thiocyanate. On October 10 one- 
half of plot A received 6-12-4 inorganic fertilizer at the rate of 700 
pounds to the acre.

Figure 3—Sodium chlorate treatment of 3 plots of Kentucky bluegrass infested 
with crabgrass, at 3 different rates of application with sulphate of ammonia 
added. Four applications had been made at V2-pound (lower right), 1-pound 
(upper right) and 2-pounds (lower left). The 2-pound rate showed almost com­
plete control and excellent turf condition.

Later observations showed that the turf-crabgrass ratio in plot 
A was about 80 whereas the ratio in plot B was but 20. In plot A 
the turf consisted principally of Kentucky bluegrass, bents, and red- 
top. In plot B the turf was mainly annual bluegrass with scattering 
Kentucky bluegrass plants. Plantain and chickweed had virtually 
disappeared in plot A but were still plentiful in plot B.

One observation of note is that during late fall all chlorate-treated 
turf which had not received fertilizer showed bronzed leaf tips which 
persisted until the end of the growing season and in the early spring 
were evident as dead tips. Where fertilizer had been applied as a 
fall dressing no such tip-bronzing was apparent. No explanation has 
been attempted for this phenomenon, but it is possible that the resid­
ual chlorine in the plant sap has contributed toward this, and that 
by the addition of a complete fertilizer the subsequent growth has 
been sufficient to mask the effect of the chlorate.

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165

The increase of annual bluegrass under the ammonium thiocya­
nate treatment and its decrease with sodium chlorate further show 
the specificity of these chemicals for certain types of plants. It in­
dicates also that where annual bluegrass is desired it may be en­
couraged by small, frequent treatments with thiocyanate.

An examination of the soil in plots A and B at the end of the 
season showed pH values of 5.2 and 5.3 respectively with practically 
no differences in the amount of soluble constituents.

Additional Tests With Sodium Chlorate on Crabgrass

Crabgrass-infested turf on aprons, banks, and approaches of the 
putting greens at Bannockburn, and, in some cases, on the greens 
as well, wras treated with potassium chlorate at two different times. 
The first treatment was made about June 20 and the second about 
the last of July. The results were gratifying. When observations 
were made on the first of September no crabgrass remained in the 
treated areas either on the greens or on the turf outside the greens. 
The turf grasses had begun to fill in the denuded areas and had a 
good, healthy appearance. On the greens the treatment was some­
what drastic but the bent grasses recovered from the shock and made 
good growth all the rest of the season.

Sodium Chlorate Tests at Indianapolis

The crabgrass-infested bluegrass and bent tees at the Highland 
Golf and Country Club at Indianapolis were treated with sodium 
chlorate shortly after the middle of August, 1933. The 2-pound rate 
was applied with a power sprayer and watered into the soil. Ken­
tucky bluegrass and seaside creeping bent seed were sown at the 
time of treatment. Fertilizer was applied after September 1, water­
ing being carried on as usual to keep the soil in good condition. At 
the time of treatment crabgrass had begun to develop seed heads 
where its normal development had not been retarded by cultural 
practices.

Later in the season it was reported that the treatment was highly 
successful. No crabgrass seed matured and the turf grasses filled 
in the area occupied by the crabgrass. The newly-seeded grasses 
developed normally and made good growth.

Experiments in the Chicago District

Tests were conducted at the Mid-West turf garden and on several 
golf courses in the Chicago District from July 22 until November 1. 
Treatments were made chiefly on fairway turf consisting principally 
of Kentucky bluegrass, bent, and fescue. The weed population con­
sisted principally, in the order named, of dandelions, crabgrass, clover, 
major plantain, lance-leaf plantain, and chickweeds. Comparisons 
were made between the sodium and the potassium chlorates, arsenic 
pentoxide and potassium arsenate, and ammonium and potassium 
perchlorates, at rates ranging from 4 ounces to 4 pounds to 1,000 
square feet for a single application. Subsequent applications were 
made as quickly as possible after the recovery of the turf grasses 
from the initial injury. Plots 4 feet square were used throughout.
The varying moisture conditions prevailing over the various loca­
tions had a profound effect on the results. The soil type was fairly 
constant at all locations.

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It is not to be expected that tests covering only a 4-month period 
or less should be regarded as conclusive. The information gathered, 
however, in connection with previous data, indicates what might be 
expected over a longer period of time as well as which chemicals 
appear to be the most effective under the conditions of the tests.

Sodium chlorate here, as elsewhere, has yielded results comparable 
to potassium chlorate when applied at rates yielding an equal amount 
by weight of chlorate (C1O3). Arsenic pentoxide consistently yielded 
better results than potassium arsenate, at rates yielding an equiva­
lent of equal quantities of the elemental arsenic.

The perchlorates (NH4C104, and KC104) proved to be undesir­
able and were alike in every respect. Their action on vegetation 
was rather unusual and merits some consideration. Since both salts 
are but slightly soluble they were mixed with soil and broadcast. At 
the Vo-pound rate they were almost without effect. At the 1-pound 
rate, however, the results were striking. No apparent change in 
vegetation resulted for the first 2 weeks after application, at which 
time the crabgrass first began to show the effects. The fully devel­
oped blades assumed a coppery hue first on the edges and later all 
over, and apparently ceased development. All new shoots emerged 
as stunted, pale, tightly rolled, twisted, and deformed proliferated 
growths. Seed heads were unable to develop normally and practi­
cally no seed was produced even with a single application. Other 
vegetation appeared to be unharmed, but after 3 to 4 weeks the grass 
plants present began to show ill effects and gradually disappeared, 
simultaneously with an increased growth and population of dande­
lions, plantain, chickweeds, clover, and oxalis. This identical phe­
nomenon had been observed at the Arlington turf garden on several 
plots earlier in the season. The high specificity of the perchlorates 
for crabgrass at first appeared to be of great value, but the later 
developments within 2 or 3 months unquestionably rule them out as 
desirable selective weedkilling agents.

Sodium chlorate at 1- and 2-pound rates effectively controlled 
chickweeds and plantain. Goose grass to some extent, and dandelions 
were in a large measure controlled by 3 successive applications. Here, 
as well as at the Arlington turf garden and at Bannockburn Golf 
Club, an interesting observation was made in connection with the 
treatment of goose grass with chlorate. Goose grass, as is well 
known, grows in flat bunches with the seed stalks lying flat, making 
it very difficult to cut the seed heads off with the ordinary mower. A 
few days after the initial treatment with chlorate the seed stalks 
raised up to a nearly vertical position, making it a simple matter to 
clip them off with a mowing machine. In this way seed production 
was almost entirely controlled even though the outright killing action 
was not marked.

During the progress of the experiments at Old Elm Club in the 
Chicago District there was noticed a weed growing on the bank of one 
of the greens which completely choked all the grass into which it was 
rapidly spreading. It closely resembled the common smooth chick- 
weed in habits and appearance but the leaves were much finer and 
were whorled. It was identified as a species of Galium, and appar­
ently was the late summer form of one of the perennial species.

Two plots were marked out where this weed had almost completely 
possessed the turf and were treated with potassium chlorate (plot 1) 
and with arsenic pentoxide (plot 2) both at the ^-pound rate in an 

December, 1933 

167

effort to determine the effect of these chemicals on it. The first 
application was made August 8 by the sprinkle method. Four days 
later the weed was 95 per cent killed in plot 2 whereas no effects 
were noticeable in plot 1. The bent and bluegrass were entirely 
uninjured in both plots. On August 18 a second treatment was made 
on both plots at the initial rates. Ten days later the kill of the weed 
was virtually complete in plot 2 but still there was no apparent effect 
on plot 1. The grasses increased in plot 2 and none of the weed was 
again found although it grew vigorously in the untreated areas until 
frost.

Experiments on Sandy Soil in New Jersey

Chlorates of sodium, potassium, and calcium, as well as several 
of the arsenic compounds, were tested on three golf courses in New 
Jersey. The more extensive tests were conducted on fairway and 
putting turf at Pine Valley Golf Club, where one of the demonstra­
tion gardens has been located. Tests on tees and putting greens were 
conducted at Seaview Golf Club and at the Country Club of Atlantic 
City.

At Pine Valley the soil is largely pure white sand. It was found 
that the rates at which the chemicals could be safely applied on more 
finely textured soils caused such heavy injury to the turf on sand 
that they were impracticable. At the 1-pound rate the chlorates 
seriously injured the turf; above this rate the turf was largely 
killed. Wherever arsenic compounds at rates yielding the equivalent 
of V2 to % pound of elemental arsenic to 1,000 square feet could be 
safely applied on fairway turf on finer soils, here less than half that 
amount represented the upper limit.

The best treatment on putting greens at the Country Club of 
Atlantic City for water pennywort in 1932 was arsenic pentoxide at 
the i/j-pound rate. Two successive applications at this rate in July 
and August yielded 70 per cent control of pennywort and permitted 
normal development of velvet and other bent grasses.

Tests with arsenic compounds and sodium chlorate at the Seaview 
Golf Club have been inconclusive. Fairway tests on white clover 
with arsenic pentoxide are still in progress.

The inconclusiveness of the effects of chemicals on sandy soils 
indicates the necessity for further, more complete investigations. It 
is apparent that the rates and times, and perhaps the frequency of 
applications, require modifications from those applicable to the finer- 
textured types of soils.

Sodium Chlorate on Milk Purslane

Repeated tests have proved the efficacy of chlorates for selectively 
controlling milk purslane. Treatments on a large scale have yielded 
highly satisfactory results on coarse-textured, sandy soil in Florida 
as well as on the finer-textured loams and clay loams. Complete con­
trol has been effected by two applications made either by the dry 
method or the wet method. The 14-POund rate is sufficient for the 
first application made when the weed is just beginning to appear— 
usually around the middle of June at Washington, D. C. A second 
application three or four weeks later at the same rate and up to 
1 pound has effected complete control. If the weed attains consider­
able size, however, it has been found better to treate initially at the 
1-pound rate, followed by a second application at the same rate when 
regrowth occurs.

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Effect of Sulphate of Ammonia and Sulphate of Iron Treatments

Several 8-by-8-foot plots uniform in vegetation were selected from 
an experimental area of a bluegrass-redtop-clover lawn and treated 
April 13. One plot which had been previously limed (No. 1) and an 
unlimed adjoining plot (No. 2) were treated four times during 1933 
(April 13, May 27, June 21, and August 11), each time with sulphate 
of ammonia and sulphate of iron at the rate of 3 and 1.5 pounds to 
1,000 square feet, respectively. The third adjoining unlimed plot 
(No. 3) received calcium cyanamid on the same dates at the rate of 
2.8 pounds to 1,000 square feet. This rate yielded .6 pounds of 
nitrogen to 1,000 square feet, which was equivalent to that applied 
in the sulphate of ammonia on the first two plots.

The materials were broadcast as a dry mixture with compost and 
sand with no subsequent treatment. The mixture of sulphate of 
ammonia and sulphate of iron was prepared and applied after the 
methods employed in the British Isles. Notes were taken frequently 
throughout the season. The varied condition of the three plots at 
the end of the season was striking. Plot 1 had the best turf and 
color and showed no increase in the quantity of plantain. Plot 2 was 
the worst of the three; it had the thinnest turf, showed the highest 
increase in quantity of plantain, and the heaviest crabgrass. Plot 3 
was intermediate.

An examination of the clay loam soil to a depth of 4 inches at 
the end of the season showed pH values of 7.0, 6.0, and 6.2, respec­
tively, for plots 1, 2, and 3. The turf-crabgrass ratio calculated for 
October 1, 1933, varied as 40, 20, and 30, respectively, the variations 
closely corresponding to the variations in the pH values. While 
crabgrass on all three plots was greatly increased over similar adja­
cent untreated plots, the least increase occurred in plot 1, as shown 
by the ratio above.

While we attempt to draw no conclusions from this study, it is 
indicated that the treatment with sulphate of ammonia and sulphate 
of iron in eastern United States, particularly under the conditions 
surrounding Washington, D. C., becomes more successful under 
neutral to alkaline soil conditions. Much has been written concerning 
the advantages of the treatment with sulphate of ammonia and sul­
phate of iron for turf both here and abroad, particularly in the 
British Isles, and in South Africa where the practice originated and 
became general under the direction of Dr. Murray. (Bulletin refer­
ence December, 1927, pages 226 and 227.) Experiments have been 
made here from time to time, but the success of the treatment has 
been lacking. It is apparent that the subject merits consideration 
but that it requires further extensive testing.

Sulphate of Iron as a Spray

Spraying of sulphate of iron during 1932 as a control for crab­
grass was reported in the Bulletin for May, 1933, as unsuccessful. 
Sulphate of iron, alone and in combination with sulphate of ammonia, 
had been sprayed at rates of 3.5 and 7 pounds to 1,000 square feet 
on July 13 and August 24. Greater damage occurred on the turf 
grasses than on crabgrass and other weeds, and at the end of the 
season there could be observed no improvement in turf nor a reduc­
tion in weeds. Crabgrass had increased. It was thought that the 
attendant conditions may have affected the results adversely.

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169

During 1933 an 8-by-8-foot plot was quartered and three of the 
4-by-4-foot plots sprayed with sulphate of iron at IV2-, 3-, and 
6-pound rates on June 27, July 11, and August 29. On the latter 
date half of each plot was bruised with a heavy wooden instrument 
to ascertain if the effects corresponded with the claims made for this 
supplementary treatment.

This experiment in 1933 further substantiated the findings of the 
previous season, so that little need be said further concerning this 
treatment. The turf-crabgrass ratio for the three rates were, respec­
tively, 15, 12, and 6, while that of the untreated plot was 26. It was 
further shown that bruising had little or no effect upon the results 
even at the heaviest rate, which corresponds to spraying 100 gallons 
of solution to one acre in which 230 pounds of sulphate of iron have 
been dissolved. All vegetation became blackened and injured, but 
eventually all recovered. From these experiments, then, it is indi­
cated that a spray of sulphate of iron, either alone or in combination 
with sulphate of ammonia, has slight value as a selective eradicant 
for crabgrass or plantain.

Isolated tests in which the fused ground mixture, as reported in 
the Bulletin for December, 1927, was dusted on the leaves of clover, 
speedwell, oxalis, and heal-all show a great deal more promise than 
anything heretofore reported for sulphate of ammonia, sulphate of 
iron, or a combination of the two. Single applications made while 
the dew was still on the leaves gave quite satisfactory results, and 
were made on putting green turf of mixed bents and creeping bents 
with only slight injury to the grasses. Although further testing is 
necessary, it is indicated that the use of this mixture, or of a mechan­
ical mixture made up of two parts of sulphate of iron and one part 
of sulphate of ammonia, will be more satisfactory for the control of 
clover and other weeds on putting greens than straight sulphate of 
ammonia.

Experiments with Compounds of Arsenic

Results of the preliminary experiments in 1932 indicated that 
arsenic had little or no value as a selective eradicant for crabgrass 
but that it showed promise for clover, chickweed, speedwell, and other 
low-growing weeds. The 1933 tests have shown that the time of 
application is an important factor, and that the failure to obtain 
favorable results in the 1932 tests may be traced in part to the time 
of year at which the applications were made.

Four plots of lawn turf treated with arsenic pe.n.toxide in 1932 
with amounts up to 4 pounds to 1,000 square feet in single and suc­
cessive applications successfully discourage white clover and, to a 
large extent, narrow-leaved plantain. These plots, with no further 
treatment, are still clover-free, although plantain has reestablished 
itself to some extent. There has been no deterioration of the turf, 
and the response to fertilizer has been marked. Figure 4 shows this 
control of clover with arsenic pentoxide.

Arsenic pentoxide has, in several tests, shown considerable value 
for the treatment of weeds in putting greens. The best results have 
been obtained with rates of application yielding the equivalent of 
14 to pound of elemental arsenic, successive applications at the 
same or slightly lower rates following as soon as it is practicable. 
Probably the best method for applying it has been to dissolve it in 
water and use a sprinkling outfit. In this way it immediately be­

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comes effective in the soil with a minimum of injury to the surface 
vegetation.

Of the arsenic compounds tested, the most effective at the lowest 
rates and the most toxic has been sodium arsenite. Its toxicity is 
such that, when applied at rates yielding V2 pound of elemental 
arsenic to 1,000 square feet, the entire treated area is denuded and 
rendered sterile for an indefinite period of time. Weedy species are 
more quickly reestablished in the bare areas than grass species. 
Chief among these has been species of Euphorbia. Potassium, sodium, 
and ammonium arsenates seem to be somewhat less effective than
arsenic pentoxide, but are desirable in that they are dry crystalline 
salts which may be handled conveniently in a number of ways. At 
rates yielding pound of arsenic to 1,000 square feet, all three salts 
have been successfully used on colonial bent. Three successive appli­
cations at this rate have not caused an undesirable condition, and 
clover has largely disappeared.

Figure 4—Control of clover on a lawn at Arlington Farm, Va., with arsenic 
pentoxide. Both the untreated check plot on the left and the treated plot on the 
right were heavily infested with white clover. The treated plot received three 
applications of arsenic pentoxide in 1932, but no further treatment was given in 
1933. The photograph was taken June 28, 1933, and shows the clover controlled 
in the treated plot.

Too heavy an initial application invariably is disastrous, but 
repeated small applications are apparently slightly beneficial to the 
turf. A tolerance is also apparently acquired by the turf grasses 
much as was observed with the use of successive treatments with 
sodium chlorate.

It has been reported by other investigators that any soluble com­

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171

pound of arsenic applied to the soil is quickly fixed in the surface in 
an insoluble form. This has been further substantiated by soluble­
nutrient tests on arsenic-treated clay-loam soils. Sampled and tested 
at 1 inch, 2 to 3, 4 to 5, and at 6 inches, the only portion in which an 
increase in arsenic was detected was in the 1-inch surface layer. In 
this layer there was a general lower pH trend, up to as much as .3 of 
a pH, where a total of 5 pounds of arsenic pentoxide to 1,000 square 
feet had been applied in successive *4-pound applications over a period 
of two years. This is but to be expected, since arsenic pentoxide in 
water solution is an acid corresponding in strength to phosphoric 
acid. There was no apparent difference in the solubility of other 
soil constituents tested for, indicating that, with certain restrictions, 
soluble arsenicals may be applied to soil without destroying its pro­
ductive power. This may appear as a directly opposite view from 
the standpoint of the experience with decreased yields in connection 
with the use of calcium arsenate in the cotton belt. There, however, 
arsenic is applied in greater amount than indicated here and as an 
insoluble powder which is not at once “fixed” but gradually comes 
into solution through the action of processes within the soil. Once 
in solution, it is again fixed in a different form, but crop yields are 
reduced due to the action of the soluble stage, in which form it is 
absorbed by plant roots.

In New Zealand it is a regular practice to spray the banks and 
green surroundings with arsenic pentoxide in June, July, and August 
at the rate of 2 ounces to the gallon. Six gallons cover 1,000 square 
feet—a rate of % pound. Similar treatments in the 1933 experi­
ments here at the corresponding season have yielded comparable 
results. In our experiments the best results have been obtained 
through applying arsenic directly to the soil, either in solution as a 
coarse rain or mixed with dry compost or with fertilizer, broadcast, 
and watered in immediately. This procedure permits the shallow- 
rooted species to absorb the poison, whereas the deeper-rooted grasses 
are largely unaffected, due to the arsenic being held in the surface 
layers of the soil. This may be one of the influencing factors in the 
failure of arsenic compounds to successfully control crabgrass when 
applied after the crabgrass has become established. A further sub­
stantiation of the holding of arsenic in the surface is illustrated by 
the following experiment.

Plots were treated in January of 1933 with the following arsenical 
compounds, each at three rates yielding the equivalent of from Vi to 
1 pound of elemental arsenic and each as a dry mixture with compost: 
sodium arsenate, sodium arsenite, potassium arsenate, ammonium 
arsenate, arsenic acid, arsenious acid, and lead arsenate. The last 
was applied at 10-, 20-, and 40-pound rates. All vegetation except 
chickweeds was largely dormant at the time. No further treatment 
was made throughout the year.

Chickweeds were largely eliminated in all plots where more than 
pound of arsenic in the soluble form was applied. This same ob­
servation was made on the 20- and 40-pound rates of lead arsenate.
The most striking observation of this early-season application of 
arsenic, however, was the fact that as crabgrass and other summer 
weeds began to appear in the check plots, there was no indication of 
establishment in the heavily treated plots. The bluegrass, redtop, and 
bents, however, flourished and largely occupied the otherwise sparsely 
covered soil. Later, however, as the effect of the arsenic had largely 

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disappeared, encroachment of the more hardy seedlings occurred, and 
by mid-season these plots were again infested with crabgrass, but 
to a much less extent than the check plots (see figure 5). At all 
times the turf on these treated plots was superior to that in the check 
plots, and this effect is still apparent.

Figure 5.—Reduction of crabgrass and other summer weeds with lead arsenate 
in a lawn of bluegrass, redtop, and bent grass at Arlington Farm, Va. The check 
plot on the right received no treatment. The plot on the left had received one 
application of lead arsenate in dry mixture with compost at the rate of 40 pounds 
to 1,000 square feet March 21, 1933. Only a few' weeds were present in the 
treated plot at the time this photograph was taken, June 28, 1933.

On the basis of this experiment and to further investigate re­
ported control of crabgrass with lead arsenate, several test plots were 
treated. Lead arsenate was applied at 5-, 10-, 20-, and 40-pound 
rates in single and successive applications throughout the season. 
First applications were made on May 10 and subsequent applications 
at one-month intervals until September 10. Crabgrass had become 
established prior to the first treatment. At no time could there be 
detected any noticeable decrease in the amount of crabgrass present. 
This indicated that the presence of soluble arsenic in the soil at the 
time of germination either prevented germination or caused the 
young seedlings to die before they could push their roots beyond the 
zone of accumulated arsenic. It further throws light on the apparent 
specificity of arsenic for certain species, indicating that the depth 
of the effective feeding roots may have considerable influence on the 
resistance of plants to the poison.

In direct contrast to the results obtained by a January treatment 
of arsenic are results obtained on turf treated at that time with 
chlorate and thiocyanate. Treatment of turf with watery solutions 
of these chemicals as well as dry-compost mixtures gave no such 
desirable indications of toxic effects on germinating seeds of the sum­
mer weeds but, on the contrary, apparently stimulated germination. 
Chlorate at 1-pound rates and higher quite effectively controlled chick- 
weeds, but crabgrass plants appeared first on the treated plots and 
most quickly covered the surface of the soil. Thiocyanate did not 
control chickweed at rates up to 2 pounds; above that rate both grass 
and weeds were killed. With thiocyanate there seemed to have been 

December, 1933

173

little further effect on germination except that annual bluegrass was 
more encouraged than in any other plots. In the chlorate and arsenic 
plots annual bluegrass made very poor growth.

Knotweed has been most effectively controlled with arsenic pen­
toxide when applied as a spray. The best results have been obtained 
when the first application was made shortly after the germination 
of the seeds and before much growth has been made. Two to three 
successive treatments at the J/2-Pound rate have largely controlled 
this weed, which heretofore has successfully resisted all attempts at 
eradication with chemicals.

Sodium Chlorate

Sodium chlorate (NaC10:.) is a dry granular crystalline salt very 
similar to coarse common table salt in color and appearance. It 
may be obtained in quantities with a purity as high as 99 per cent. 
Since it is a dry salt which may be reduced to any desired fineness it 
is admirably adapted to distribution in combination with any common 
dry inert carrier of an inorganic nature. Its high solubility in water 
also permits it to be applied in water solution as a spray with any 
type of sprinkler.

For farm weeds in general, sodium chlorate has found wide appli­
cation, and in comparison with a great many other chemicals it has 
been found to be most efficient and economical on a cost basis. This 
chemical has likewise been found to be the most efficient of a large 
number of chemical agents in the control of weeds of turf. So far 
as the investigations have been pursued it has been found applicable 
to the control of crabgrass, lance-leaf plantain, major plantain, milk 
purslane, goosegrass, chickweeds, speedwell, sour dock, and heal-all. 
Dandelions and clover have, to a large extent, been diminished and, 
with continued treatment, practically controlled with this chemical. 
Wild garlic, oxalis, knotweed, and some few other fairway and lawn 
weeds have not been found to be greatly affected by sodium chlorate 
according to the methods used.

Sodium chlorate has a temporary retarding effect upon the or­
ganic life in the soil which is concerned with transformations of 
nutritive elements. The extent and duration of this effect is depend­
ent upon the rate and method of application, the soil type, the amount 
of effective rainfall whether natural or artificial, the temperature of 
the soil and of the surrounding air (i. e., the season of the year), 
and, to an undetermined extent, the reaction (pH value) of the soil.
The duration of the temporary retarding effect of equal amounts 
of sodium chlorate per unit area on soil is less prolonged when applied 
as a spray than when applied as a solution which enters the soil at 
once and becomes a part of the soil solution. This is due to the reduc­
ing effect of the organic matter on the surface of the soil, which 
quickly transforms the chemical from an active oxidizing and lethal 
agent to a less reactive and less harmful compound. The absorption 
of the chemical by surface vegetation likewise renders that part of it 
inoperative so far as soil organisms are concerned. Since the air 
temperatures during that part of the year when weeds are most 
troublesome, which is the time when the chemical is most used, are 
usually higher than the soil temperatures, it follows that the speed 
of the chemical reactions taking place will be increased.

When the chemical enters the soil it remains active over a longer 
period of time, due to the general lower temperatures and to the gen­

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erally low percentage of reducing materials, since soil constituents 
are ordinarily in a more or less highly oxidized state. The distribu­
tion of organic matter in the soil, however, will affect this relation to 
some extent, so that soils high in organic matter will more quickly 
recover from the effects of an application of sodium chlorate.

Most of the experimental work to date has been conducted on 
soils of a fine-textured nature (clays, clay loams, and silt loams), 
which have in general a high absorptive capacity. A limited amount 
of work on soils of a coarser texture (sands and sandy loams) indi­
cates that the temporary damaging effect of equal amounts of the 
chemical is greater on the coarser-textured soils. The duration of 
the effect on the lighter soils is less, however, due to the lower absorp­
tive capacity and to the greater rapidity of percolation by means of 
which the chemical is carried out of the effective range. But, since 
the initial damage is greater, a longer time is required for regrowth 
of the remaining vegetation, due in part to the lower initial fertility 
of the coarse-textured soils. Hence it must be borne in mind that 
the recommendations given herewith are for soils belonging to the 
finer-textured types. They will be applicable to sandy soils only in 
part, and then with caution.

Sodium chlorate is soluble, and since it must be in solution in 
order that it may be readily absorbed by the plant roots, an optimum 
soil moisture content at the time of application is to be desired. This 
applies also to a large extent to spray applications, since the meta­
bolic processes of the plant are greatest when the soil moisture is at 
an optimum, and since the chemical is readily absorbed by aerial 
organs and carried about in the transpiration stream it will be car­
ried more effectively through the plant. Low soil moisture causes 
a more prolonged sterilization of the soil, greater injury to the desir­
able plants, and other undesirable results. Thus the selective treat­
ment of turf weeds with sodium chlorate in sections which are sub­
ject to prolonged periods of drought where artificial watering is not 
available is liable to produce more or less unfavorable and undesirable 
results.

The duration of the effect of sodium chlorate on the soil, as evi­
denced particularly by the growth of grass, is, in addition to the fac­
tors named, dependent upon the rate of application. At the rate of 
i/2-pound to 1,000 square feet, applied during the summer months, 
the effect on bluegrass under normal conditions entirely disappeared 
within 2 weeks. The 1-pound rate required approximately 3 weeks 
for normal grass growth to recur. At the 2-pound rate the time 
period increased to 4 or 5 weeks. These time-periods represent the 
relative duration of the effects under a given set of conditions approxi­
mating what might be called “normal” for moisture and tempera­
ture. Variations would occur, depending upon the difference in these 
and other influencing factors.

The first noticeable effect of sodium chlorate appears in 24 to 48 
hours after application. It is evidenced by a grayish cast on the vege­
tation. Closer examination shows white streaks in the leaves parallel 
to the venation, indicating a disintegration of the chloroplasts. Later 
the entire plant takes on a whitish, sickly hue, and a little later still 
begins to turn brown and curl. Rather extensive discoloration may 
occur from applications at rates above 1 pound to 1,000 square feet.
In the event that sodium chlorate is distributed as a dry mixture 
with an inert inorganic carrier attention must be given to the nature 

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175

of the carrier. Dry, finely screened soil may be used in any amount. 
The only effect of this carrier will be beneficial as a topdressing by 
smoothing irregularities in the surface. A mixture with limestone 
would be beneficial, not only from the standpoint of increasing the 
effectiveness of the chlorate, but also due to the desirable effects it 
has upon the production of sturdier plant growth and subsequent 
recuperation from the temporary undesirable effects. A mixture 
with a wholly inorganic fertilizer, such as the 6-12-4 used in these 
experiments which was made up of 3 ingredients, namely, sulphate 
of ammonia, superphosphate, and muriate of potash, may be used 
but with reservations. This fertilizer is physiologically acid and 
tends to increase the duration of the effects of the chlorate. This 
may be attributed in part to the additional corrosive effects of the 
fertilizer salts upon the vegetation with consequently a longer period 
of time elapsing before normal growth is resumed. This is greatly 
influenced by the rates of each used in the mixture, since at the 
1-pound rate of chlorate the recovery of the turf was greatly en­
hanced due to the stimulating effects of the nutritive elements.

Certain precautions must always be observed in handling chlo­
rates. Since they are active oxidizing agents they tend to promote 
combustion. For this reason a mixture of chlorate with organic 
materials such as clothing, wood, charcoal, dried vegetation and the 
like is highly inflammable. Clothing upon which chlorate spray has 
fallen and dried may be ignited by friction alone. Vegetation, sprayed 
with chlorate and dried, may ignite spontaneously under the action of 
the sun’s rays. Matches and fires have strictly no place where chlo­
rates are being used or stored. Metal containers should at all times 
be used and the material should be stored away from wooden build­
ings. The salt by itself or mixed with soil or sand is entirely harm­
less and noncombustible.

Potassium Chlorate
Everything that has been here written about sodium chlorate 
applies strictly to potassium chlorate (KC103) with only a few minor 
exceptions of detail. Potassium chlorate is slightly less effective, 
pound for pound, than the sodium salt. Likewise it is slightly more 
expensive. To offset these slight differences the potassium salt is to 
be preferred, especially in sections where potassium is deficient in 
the soil, since the beneficial effects based on cost comparisons offset 
the slightly lower effectiveness. The lower solubility of the potassium 
salt seems only to increase its effectiveness since it is not so readily 
leached from the soil. This characteristic of the potassium salt makes 
it especially adapted to dry mixtures with inorganic carriers, since 
it is yielded to the roots of plants more gradually and thus its effec­
tiveness is increased by its being available over a longer period of 
time?

How' Chlorates Kill

The killing action of chlorates has been discussed by other investi­
gators from time to time. As oxidizing agents, the C1O3 radicle being 
the active lethal ion, they are active in breaking down and destroying 
organic matter. Their chief effect within the plant has been shown 
by Latshaw and Zahnley, of Kansas, to be the disintegration and 
decomposition of starch granules as well as the chloroplasts and pro­
toplasm generally. Without chloroplasts no food is manufactured; 
without starch there can be no production of soluble sugars. As a 

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result the plant starves to death. Chlorates produce this same effect 
whether they are absorbed by the roots from the soil solution or 
absorbed by the aerial organs. Chlorates are not corrosive in any 
way and kill only upon being absorbed into the plant system.

Ammonium Thiocyanate

Ammonium thiocyanate (NHjCNS) is a by-product of the coke- 
oven industry and, according to some investigators, has found con­
siderable application in the destruction of certain weeds of agricul­
tural lands. It has been tested upon turf and has elsewhere been 
reported to have yielded favorable results. During the present in­
vestigations it has been found to be less effective than sodium chlo­
rate and more expensive.

In the pure form ammonium thiocyanate is a colorless salt, coarsely 
granular, which, upon exposure to the air, absorbs moisture so freely 
(deliquescent) that it soon becomes liquid. This characteristic limits 
its use solely to water solutions as a sprinkle or a spray. The com­
mercial product is reddish-brown in color, coarsely crystalline, the 
color being due to certain coal-tar impurities. It contains approxi­
mately 35 per cent of nitrogen which becomes available to plants upon 
being applied to the soil.

The weeds upon which ammonium thiocyanate has yielded the 
best results are crabgrass and plantain. Dandelions have been little 
or not at all discouraged by its use and, in fact, have in some cases 
greatly increased where it has been used. In spite of the nitrogen 
contained in this chemical the growth of the turf grasses following 
its use has been discouraging to its further applications in extensive 
tests as compared with sodium chlorate.

As with the chlorates, this salt has a temporary retarding effect 
upon the soil organisms, which is largely due to the CNS radicle, 
particularly the CN part of it, which is quite poisonous. The effects 
at equal rates are somewhat more quickly dissipated than with the 
chlorates and are influenced in much the same ways by identical 
factors.

Ammonium thiocyanate is a noncorrosive material as applied to 
plants. Its killing action depends first upon its absorption into the 
plant system, where it retards the normal metabolic processes and 
brings about derangements which lead to the death of the plant. It 
is taken into the plant apparently equally well as a spray through the 
aerial organs or as a part of the soil solution through the roots. It 
is somewhat more effective by the root-absorption method, particu­
larly at the lower rates.

When ammonium thiocyanate is applied to turf the first notice­
able effects, which occur after about 10 or 12 hours, are a whitening 
of the tips of the grass blades, and a slight yellowing of the weedy 
grasses, followed by a pronounced bleaching effect over the entire 
treated area. The more resistant weeds become tinged slightly yel­
low, depending upon the rate of application, and at rates of more 
than 3 pounds the entire area is usually bleached completely to a 
whitish cast. This usually persists, at this rate, for about 3 or 4 
weeks. The white-bleached grass blades turn a more pronounced 
yellow after a few days. Those weeds which have not been killed 
outright by the initial application of the material make a very rapid 
growth following recovery from the initial effects, due to the release 
of available nitrogen by the soil organisms. It has been very difficult 

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177

in this respect to determine a satisfactory rate at which this chemi­
cal might be used, since a balance must be found between the amount 
necessary to kill the weeds and the amount which will permit the 
desired grass plants to successfully and most rapidly recover.

Few precautions need be observed in the handling of ammonium 
thiocyanate, except that the material should be kept in a tight con­
tainer so as to preserve it from the deteriorating action of the air. 
The salty taste of the chemical seems to have a certain attraction for 
animals, particularly those that may have been deprived of salt. The 
effect on animals is not definitely known; so it is best to take the 
necessary precautions to prevent injury.

Arsenicals

Comparisons have been made among the several common easily 
obtainable compounds of arsenic. Most of the experimental results 
have been obtained, however, with the arsenic pentoxide, for several 
reasons. Although it is difficult to obtain and is high-priced at 
present, it represents the maximum content of the element arsenic 
obtainable. It adapts itself well to experimental procedure, is highly 
soluble, and, with care, may be used as a dry mixture. The other 
compounds of arsenic are applicable, but with some variations in 
procedure and rates of application.

Arsenic pentoxide (As2O5) is obtained as a white amorphous 
powder which easily takes up moisture from the air (deliquescent), 
so that as far as large-scale use is concerned it can not well be em­
ployed as a dry mixture. In combination with water, it forms the 
orthoarsenic acid, which is similar in practically every respect to the 
corresponding acid of phosphorus. Since it is extremely poisonous, 
as are all compounds of arsenic, it must be handled with extreme 
care, so that it may not be taken into the body or be allowed to come 
within the reach of children or animals.

Due to the rapid fixing of arsenic in the surface layer of soil, it 
is best adapted to the control of the shallow-rooted, low-growing 
forms of turf weeds, such as chickweeds, speedwell, white clover, 
and the like.

The killing action of arsenic depends upon its absorption into 
the circulatory system of the plant, where its toxic effect is particu­
larly effective in preventing the formation of the products of photo­
synthesis. Its absorption into the plant depends upon a number of 
factors, chief among which are soil moisture and the moisture deficit 
within the plant. The value of the moisture deficit within the plant 
as an aid in the absorption of arsenic when applied as a spray is 
apparent as a result of the California investigations, where it was 
found that the best results were obtained by spraying in the early 
evening and up until midnight. This phase of the problem has not 
received consideration in these experiments.

There have been indications that the continued use of soluble 
arsenicals for weed control has a profound effect upon turf pests, 
such as worms, beetles, and grubs. The effects with small applica­
tions are scarcely noticeable, but actual counts of earthworm casts 
made on arsenic-treated plots after two years of light successive 
applications of arsenic pentoxide show a reduction of from 75 to 80 
per cent in earthworm infestation. While this phase of the problem 
merits attention, it has received little consideration in this series of 
experiments aside from incidental observations. The opportunities 

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of the problem are manifold, inasmuch as it reveals an opportunity 
for obtaining weed and grub control with a single chemical, thus 
reducing operating costs.

Summary

The data and observations obtained from two years of experi­
mentation yield certain information which may be summarized as 
follows:

Most of the common turf weeds may be selectively controlled by 
proper cultural treatments and, where these fail, by the judicious 
use of certain chemical compounds.

Of the chemicals tested, the best results, in the order named, have 
been obtained with the following: sodium chlorate, arsenic pentoxide 
as representative of the arsenicals, ammonium thiocyanate, sulphate 
of iron, and sulphate of ammonia.

With sodium chlorate, crabgrass has been best controlled with 
three successive application at the 2-pound rate. Satisfactory con­
trol with lighter first and second applications has been indicated, and 
suggestions have been made as to rates and times of treatment.

Under the treatment as suggested for crabgrass, practically all 
other common turf weeds, such as plantain, field sorrel, chickweeds, 
milk purslane, ground ivy, heal-all, and speedwell, disappear within 
a single season. Dandelion and goose grass are discouraged. Wild 
garlic is little affected.

With any of the chemicals used there is a discoloration of the 
turf, the duration and intensity of which varies with the rate and 
time of application as well as with the attendant conditions of mois­
ture and temperature.

Potassium chlorate, calcium chlorate, and magnesium chlorate 
may be substituted for sodium chlorate. The potassium salt has been 
mentioned as superior particularly where the soil is low in potassium.
The dry method of applying chlorates has been found to be en­
tirely satisfactory. In addition, the fire hazard, which is always 
present when chlorates are used in solution, is virtually eliminated 
with the dry method.

Sodium chlorate has been tested on a large scale on golf courses 

as a result of these experiments and has been found satisfactory.

Ammonium thiocyanate has yielded results inferior to those ob­
tained through the use of chlorates. In these tests its use tended 
to encourage certain types of weeds, principally annual bluegrass 
and dandelion.

Compounds of arsenic, notably arsenic pentoxide, have been used 
most successfully on fairway, lawn, and putting turf to selectively 
control clover, pennywort, ground ivy, Galium sp., knotweed, chick- 
weeds, and heal-all.

Arsenic pentoxide apparently yields the best results when applied 
in successive treatments as a sprinkle at rates not to exceed *4 to % 
pound to 1,000 square feet in successive treatments.

There have been indications that earthworms and grubs may be 

controlled through the use of soluble arsenicals for weed control.

Early-season treatments with arsenicals affect markedly the es­
tablishment of crabgrass but have little effect when applied after 
the plants have become established.

Over a period of two years, there apparently has been no perma­
nently injurious effect on soil treated with any of the chemicals used.

December, 1933

179

With the judicious use of the chemicals, there may be expected 

an improvement in the turf over a period of time.

Certain precautions against poisoning and fire must be observed 

where any of the chemicals are used.

Sulphate of iron and sulphate of ammonia, alone or in combina­
tions, gave no indications of satisfactory crabgrass control but proved 
applicable to the control of broad-leaved, low-growing weeds, particu­
larly those in putting greens.

Calcium cyanamid yielded no favorable results when applied as 

a dust at the rate of 780 pounds to the acre.

The perchlorates of ammonium and potassium proved unsatis­

factory as weedkillers.

The experiments have not been carried out to a sufficient extent 
on sandy soils to permit of definite conclusions. The greater part 
of the data has been gathered from results obtained on loams, silt 
loams, and clay loams.

Results with chemicals are affected by a number of factors to an 
undetermined extent, indicating the necessity for more extensive 
investigations of the problem.

Weeding Bermuda Grass Out of Creeping Bent Turf

By Thornton Conover,

Valley Club of Montecito, Santa Barbara, Calif.

The Valley Club of Montecito was opened for play in the fall of 
1928. The putting greens had been sown with seaside creeping bent 
and the fairways with Bermuda grass. Both got a good start, and 
the season of 1929 opened auspiciously.

In the summer of 1930 the greens began to show a considerable 
amount of Bermuda grass. In spite of some surface weeding and 
patching, this grass continued to increase in the putting greens 
through this season and also in 1931. We then tried the method of 
turning back the sod and weeding the Bermuda from underneath. 
This method proved to be much more effective even though it was 
more costly than the other methods. Since the putting greens were 
so badly infested with the Bermuda grass, it was necessary to devote 
the entire services of one man to this work.

A careful workman was selected, and the first week he was 
assigned to the turf nursery to practice the technique. The second 
■week he was moved to the croquet court, which was seldom used and 
not kept up as carefully as the putting greens. By then he had 
acquired proficiency and was ready to start on the regular greens. 
He worked five 8-hour days a week, turning back an average of 25 
sods a day. From May to July it was a struggle to hold his own 
with new patches showing up constantly; but it was a cool summer 
and the Bermuda grass was a little late in sprouting. I decided to 
put on another man on July 1, and by the first of August we had it 
pretty well under control and one man finished the season. By the 
first of November the greens were practically free from Bermuda 
grass. How successfully the method worked out has been proved 
this season. Only a few scattered patches of Bermuda grass appeared 
in 1933. Of the many thousand sods turned back, only a small 
number had to be replaced. At no time during the season were any 
of the greens marred or their putting surfaces disturbed.

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With the accompanying photographs, the method of weeding can 

be easily understood.

The first photograph shows the workman about to lift the sod 
after having cut three sides around the measuring board with a 
revolving-disc edger. We tried a number of different sized boards 
but finally decided on one 9 by 18 inches. Cutting larger sods might 
have saved a little time, but 9 by 18 inches was a size so handy to 
work with that we used it exclusively. On some soils it might be 
practical to use a somewhat larger measuring board. The workman, 

Starting to lift the bent sod.

Sod turned, disclosing a Bermuda 

» rhizome.

after cutting three sides of the sod, two long and one short, lifts the 
board and places it at the narrow, cut end. He uses it for leverage 
and to protect the turf by the edge of the measured turf when he 
lifts it with a spade. We tried different lifting tools but found an 
ordinary spade was the best. Lifting the turf is a very important 
part of the work. If it is cut an even thickness, there is much less 
danger of finding a hollow or bump after the turf is replaced. It 
takes continued care, but it is not difficult to cut it evenly after some 
practice.

It is hard to advise a definite thickness to cut the turf. That has 
to be gauged by the density of the Bermuda roots. It is best to cut 
it as thin as is practical; but if it is cut too thin, tearing out the roots 
would weaken the turf too much. On the other hand, if it is cut 
thicker than necessary it is difficult to find all of the Bermuda roots, 
and in taking them out so much soil is removed that it is hard to 
avoid soft spots when the turf is replaced. Soft spots will eventually 
become depressions. The larger proportion of sods are cut from 
114 to 1% inches in thickness.

The second photograph shows the sod turned back; a heavy 
Bermuda rhizome can be plainly seen. It will be noted that the sod 

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181

is turned back in the shade of an umbrella. In the hot sun that is 
important. Before we began to use the umbrella we noticed that 
sods turned back in the hot sun were slightly brown after replacing 
even though we used plenty of water. After we began to use the 
umbrella we had no more trouble that way.

The workman first clears the soil beneath. For that work a small 
trowel is a handy tool. If the rhizomes run beyond the soil exposed 
it will be necessary to lift another piece of turf. Though Bermuda 
grass sometimes grows to prodigious depths it seldom goes down far 
under a green unless it is left to develop year after year. We had 
little trouble in clearing the exposed soil.

Weeding the sod turned back is 
the most difficult part of the process. 
We found the handiest tool for that 
work was a 10-inch length of stiff 
wire with a loop in the middle for a 
grip and one or both ends turned back 
to make approximately a ^-inch 
hook. The wire must be stiff enough 
to stand substantial leverage, as some 
of the heavy rhizomes require it. 
Nothing but patience and care will 
achieve good results. It is most im­
portant to get out all of the rhizomes. 
Any left will mean further growth 
and labor wasted. When the rhi­
zomes are all cleared from the bot­
tom it is easy to pull out the surface 
growths from the top.

Extracting the rhizome. The work 
should be done under an umbrella 
to shade the sod.

When the sod has been thor­
oughly weeded the low spots should 
be filled with moist soil. We found 
the best way to do this wras to have 
the soil the consistency that would 
make a good mud pie, and handle it with a trowel the way a bricklayer 
would handle cement. Next to the actual weeding, this is the most 
difficult part of the process, as the soil must not only be spread evenly 
but the depressions must be filled so that when the sod is turned 
back it will lie smoothly and with a uniform consistency.

If the work is expertly done the marks of cutting will disappear 
within a few days. We have found it better to cut the sod at a slight 
angle so as to make it a shade wider at the top. When the sod is 
replaced the line of the cut should be hardly perceptible.

There are no especial precautions to advise except to keep the sod 
in the shade while it is turned back and to use plenty of water on 
hot days.

There will occasionally be a patch of Bermuda grass so thick 
that there is little soil left in the turf after weeding. In such a case 
it would be necessary to fit a new piece of sod. It is surprising 
though how’ few times that is necessary. We used not more than 20 
to 25 new’ sods throughout the season; and our greens were certainly 

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thick with Bermuda grass. On one green during the first thorough 
weeding we took out nearly 7 buckets of rhizomes and shoots from 
the sods lifted and from the soil beneath.

It might seem as if too much labor was involved in this process 
of weeding Bermuda grass from bent greens; but it must be borne 
in mind that our greens were so badly infested that with only surface 
weeding it would have meant a steady increase year after year and 
more and more labor required for weeding, with the highly unsatis­
factory knowledge that we were losing ground and eventually would 
have to perform some major operation to the greens. By that time 
the rhizomes would have penetrated so deep that nothing but new 
construction would be practical. The winters here are not severe 
enough to kill Bermuda grass. It just lies dormant for a few months.
On golf courses which have Bermuda fairways and bent greens 
there will always be a problem of keeping the Bermuda grass out of 
the greens. A certain amount of surface weeding will be necessary 
every year. That is usually all that is done, but it is not enough. If 
the rhizomes are allowed to develop, it will certainly mean trouble in 
the future. The only sure methods of treatment are to patch if it 
can be done successfully or else to weed by turning back the sod as 
I have described. In either case it should be done as soon as the 
Bermuda grass appears. There is danger in neglecting to weed 
promptly and in allowing the rhizomes to develop.

It has been estimated that American agriculture suffers annual 
losses reaching hundreds of millions of dollars from ground squirrels, 
prairie dogs, jack rabbits, pocket gophers, woodchucks, bobcats, stray 
domestic cats, moles, porcupines, mice, and rats. That golf courses 
share to some extent in these losses is evident to anyone who has 
observed turf uprooted or killed from tunneling or who has seen half­
eaten carcasses of birds strewn on a fairway or in the rough. Though 
it is true that certain of the rodent pests destroy quantities of grubs 
working beneath the surface, it is considered that on the whole they 
are more of a detriment than a benefit to a golf course. No general 
program can be outlined for the control of pests of this kind. Some 
can be controlled only by poisoning, others by trapping. Each case 
must be handled individually. In one year over 100,000 farmers took 
advantage of opportunities offered them to wage cooperative warfare 
on these pests under trained leadership.

Don’t place any faith in rain-making devices. As long ago as 1880 
Daniel Ruggles obtained a patent on a rain-making device consisting 
of balloons equipped with explosive cartridges and torpedoes to be 
set off by an electric wire trailing on the ground. In 1891 Louis 
Gathmann obtained a patent on a device for spraying liquid carbon 
dioxide gas high up in the air, the evaporation of which was to cool 
the air sufficiently to cause rain. Since then other rain-making de­
vices have been patented. The science of meteorology is still, how­
ever, in its infancy, and the growers of plants are as much at the 
mercy of the elements for their rain as were their ancestors thousands 
of years ago. Numerous devices are still being offered to farmers by 
professional rain-makers. Fortunately most golf courses are not so 
extensive but that they can equip themselves with reliable means of 
watering fairways and therefore offer little appeal to rain fakers.

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183

Fertilization of Fairways: Some Experimental Results 
By Kenneth Welton

The most common cause of poor fairway turf is undoubtedly 
starvation, although turf may become poor due to a variety of other 
causes. Grass plants require an abundance of nitrogen for the pro­
duction of their highly prized leaves or foliage; but it happens that 
this element is not available in most soils in amounts required for 
good fairway turf. Grass plants also require a number of minerals, 
such as phosphorus, potash, and calcium, and the lack of sufficient 
quantities of any one of these may prevent grass from making ade­
quate turf. If the soil is sufficiently fertile and the other require­
ments are supplied, turf grasses are capable of providing a solid, 
dense, and pure turf year after year.

Starved turf gradually becomes thin and bunchy, and with starva­
tion comes a gradual decrease in depth and size of root system, which 
allows fine-textured soils to pack and makes it difficult for roots to 
forage for food. Foreign grasses and weeds, including clover, which 
can better adapt themselves to such conditions, soon appear and 
crowd the grass. Thin turf, weedy turf, or a combination of the two 
does not come up to the requirements of good golf clubs; and if this 
condition exists for long, clubs often find their members seeking 
better fairways. Clubs can not afford to lose members these days, 
and, if for no other reason, should be interested in any means by 
which poor fairways may be improved.

Not so many years have passed since the popular method of thick­
ening turf, particularly fairway turf, was by sowing seed. The more 
seed sown the thicker the resulting turf was supposed to be. This 
procedure was costly, not only because of the actual outlay for seed, 
but also because of the time and effort lost, since seldom, if ever, did 
the mere act of reseeding effect any permanent improvement. Seed 
is often sown on the theory that the plants have died of old age and 
must be replaced by new plants from seed. This theory is not founded 
on fact however, since most desirable fairway grasses, such as Ken­
tucky bluegrass, fescue, bent, Bermuda, and carpet grass, are peren­
nials and are capable of producing solid pure turf almost endlessly 
without being allowed to seed, or without seed being supplied. It is 
not intended to argue that there are no instances where reseeding 
will bring a marked improvement in old fairways. There are cases 
where the introduction of a new species of grass may solve the prob­
lems, and it is often necessary to introduce new plants into areas that 
have become so patchy that they can not be thickened in a reasonable 
time by the spread of old plants. Except for special cases, such as 
the sowing of seed on southern fairways for temporary improvement 
and coloring of winter turf, it has been shown frequently that it is 
extremely unlikely that a good catch will be procured on old turf 
unless a seed bed be prepared by raking, spiking, straight-discing, 
topdressing, or other methods.

Old grass plants are able to increase and spread by root division 
and from buds formed on rootstocks. The young plants coming from 
the roots of the old plants are planted already in the soil and are 
protected by the old plants, so that plants so produced have a much 
better chance of surviving than plants produced from seed. Con­
sidering the above, it is evident that one should not expect seedling 
plants to produce good turf where old plants have failed. It is 

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unreasonable to expect tender seedlings to grow and spread in an 
area where old plants with established root systems have failed to 
make any increase or have died. This has been proved time and time 
again on the golf courses of the country, and greenkeepers now 
recognize that it is useless to sow seed where turf has failed, unless 
the conditions which have caused the poor turf are first corrected; 
and it has been found frequently that where there is a reasonable 
number of old plants, an improvement in the conditions has enabled 
the old plants to develop new plants, to fill in the area, and to form a 
dense turf without the aid of any reseeding.

Responsibility for the poor quality of the turf on some fairways 
is often laid to lack of water. Water is necessary for plant growth, 
but perennial grasses can survive long periods of drought and then 
make remarkable growth if the soil is fertile. Without plant food, 
however, no amount of moisture will make grass grow. Poor fair­
ways are sometimes blamed also upon poor soil. If lack of plant 
food is meant, fertilizing will solve the problem. Poor soil structure 
may be a factor, inasmuch as it limits root growth; but poor structure 
under turf is more often the result of than the cause of poor turf. 
Many fine fairways have been produced on packed, hard soils and 
have been maintained in excellent condition by adequate fertilizing. 
Such heavy turf eventually greatly improved the structure of the 
soil by increasing its humus content. Sometimes also poor turf is 
supposed to be due to poisons in the soil, but this condition is rare 
and is usually found only in arid or semi-arid areas. There are cases, 
such as in poorly drained areas, where grass will not grow even if 
abundantly fertilized, but in most cases on golf courses the real 
factor in fairway maintenance is fertility, and the problem is hence 
one of how much and what kind of fertilizers to use and the best 
time to apply them.

An experiment was planned and carried out by the Green Section 
to learn how much fertilizer is needed to produce a dense Kentucky 
bluegrass turf on a poor bluegrass fairway. Complete mixed fer­
tilizers were used in order that there would be no deficiency in any 
of the three elements most needed by fine turf. The fertilizers were 
made up in both the inorganic and organic forms in order that a com­
parison could be made between the effects of the two forms. It was 
recognized that information on several phases of fairway culture 
could be gained through such an experiment, and data on the follow­
ing points were also procured: whether the development and spread 
of turf could be gained in proportion to the amount of fertilizer 
applied; the quantities of fertilizer which under these conditions 
would injure the turf; the effect of heavy fertilizing on certain weeds; 
the difference in availability to the plant of inorganic and organic 
fertilizers; the improvement of the soil as measured by the increase 
in amount of organic matter and certain minerals; and whether the 
use of organic fertilizer makes an appreciable increase in soil organic 
matter over the use of inorganic fertilizer.

Kinds of Fertilizers Used in the Experiment

A 6-12-4 fertilizer was made up in both the inorganic and organic 
forms. In other words, the fertilizers contained 6 per cent of nitro­
gen, 12 per cent of available phosphoric acid, and 4 per cent of potash. 
This formula was chosen since there are several popular fairway 
fertilizers on the market which contain approximately 6 per cent of

December, 1933

185

nitrogen. Nitrogen is the element most needed by grass plants for 
turf production, and fertilizers for this purpose should be compared 
on a nitrogen basis. Hence the rates used in these experiments may 
be easily compared with fertilizers commonly used. The soil upon 
which the tests were made was found to be deficient in available 
phosphorus. Ample phosphorus is necessary in increasing growth of 
the stiffer plant structures, such as roots, rootstocks, and stems; and 
as it is necessary to increase the growth of these parts in thickening 
turf, a fairly high percentage of phosphorus was used in the fertilizer 
mixtures. Few soils show potash deficiencies in turf culture, but 
since it was expected that a very heavy growth would be produced 
by the heavier fertilizer rates it was thought that 4 per cent of potash 
in the fertilizer would more than supply any demand made by the 
plants for this element.

General view of the fairway fertilizer experiment at the Bannockburn Golf Club, 
Glen Echo. Md. The four dark areas are the four pairs of fertilized plots; the 
light areas between and at the end are the unfertilized check plots. Each of the 
four pairs of fertilized plots is divided equally into an area fertilized with inor­
ganic fertilizer and an area fertilized with organic fertilizer. Reading from left 
to right, the four fertilized plots represent the 700-pound rate up to the 5,600- 
pound rate at the right. The dark color of the fertilized plots is caused by a 
heavy growth of Kentucky bluegrass.

The composition of the 6-12-4 inorganic fertilizer was 30 pounds 
of sulphate of ammonia, 62 pounds of 20-per-cent superphosphate, 
and 8 pounds of muriate of potash. The composition of the 6-12-4 
organic fertilizer was 45 pounds of sewage sludge, 44 pounds of 3.6- 
per-cent-nitrogen steamed bone meal, 3 pounds of urea, and 8 pounds 
of muriate of potash. Muriate of potash is not an organic material, 
but it was necessary to use a small amount of this material in the 
organic fertilizer to bring up the potash content to 4 per cent.

The plots were laid out running across the No. 16 fairway of the 

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Vol. 13, No. 6

Bannockburn Golf Course at Glen Echo, Md. The area chosen was 
high, well drained, fairly flat, and had a gentle slope in one direction. 
It was particularly suitable for such a test, as it was of uniform 
topography, soil, and turf. The soil was a poor reddish clay loam of 
the Louisa series. The dark layer of topsoil was from 1 to 2 inches 
in depth. This area of fairway had been in play for 12 years and 
had received no fertilizer during that time. It had been given one 
application of ground limestone at the rate of one ton to the acre 
a year before the experiment was started, with no apparent effect on 
the turf. The soil was about neutral in reaction. This area was
Check.

Inorganic fertilizer at rate of 700 pounds per acre.
“ 

“ “ 

“ 

“

66 

66

Plot No.

U 

66 

66 

66 

6 6 

66 

66 

66 

66 

66 

66

66

66

66

6 6

66

66

66

66

66

1
2 Organic 
3
4
5 Organic 
6
7
8 Organic 
9
10
11 Organic 

“ 
Check.

“ 
Check.

“ 
‘ Check.

Inorganic fertilizer at rate of 1400 pounds per acre.
“ 

“ 

“ 

“ 

“

66 

66

Inorganic fertilizer at rate of 2800 pounds per acre.
“ 

“ 

“ 

“ 

“

66

Inorganic fertilizer at rate of 5600 pounds per acre.
“ 

“ 

“ 

“ 

“ 

“

66 

66

Check.
Plan of the fairway fertilizer experiment. Each plot is 10 by 100 feet in size

chosen also for its uniformly poor turf made up of a sparse but even 
distribution of Kentucky bluegrass, a thin scattering of white or 
Dutch clover, chickweeds, plantains, and dandelion. During the sum­
mer common crabgrass (Digitaria sp.) became more or less plentiful. 
There was no provision for watering the fairways on this course, and 
the experimental area received no artificial watering.

Rates and Methods of Application

The method in which the plots were arranged is shown in the 
accompanying diagram. Each fertilizer or check strip was 10 feet 
wide and 100 feet long. The check plots, Nos. 3, 6 and 9, and the 
area surrounding the experimental area, were left unfertilized. In 
plots Nos. 1 and 2, 43.5 pounds of nitrogen to the acre was applied. 
This amounts to about 700 pounds of 6-12-4, and is about the normal 
rate for fairway fertilizing with fertilizers of that formula. Plots 
Nos. 4 and 5 received twice this much, or 1,400 pounds of fertilizer 
to the acre. Plots Nos. 7 and 8 received four times the normal, or 
2,800 pounds to the acre, and plots Nos. 10 and 11 received eight 
times the normal, or 5,600 pounds to the acre.

The fertilizers were broadcast without mixing with any inert 
material and were not watered, brushed, spiked, or raked into the 
soil. The first application was made somewhat late in the season, on 
October 21, 1931. At that time 700 pounds to the acre were applied 
to plots Nos. 1 and 2, and 1,400 pounds to the acre to plots Nos. 4, 5, 
7, 8, 10, and 11. There was a 2/3-inch of rainfall on October 27, and 
a second application of fertilizer, of 1,400 pounds to the acre, was 
made on October 29 to plots Nos. 7, 8, 10, and 11. After another 

December, 1933 

187

rain an application of 2,800 pounds to the acre was made on Novem­
ber 10 to plots Nos. 10 and 11.

As described above, the 700-pound-per-acre plots received a 700- 
pounds-per-acre application on October 21. The 1,400-pounds-per- 
acre plots received a 1,400-pounds-per-acre application on October 21. 
The 2,800-pounds-per-acre plots received a 1,400-pound applica­
tion on October 21, and a similar application on October 29. The 
5,600-pounds-per-acre plots received a 1,400-pounds-per-acre appli­
cation on October 21, a similar application on October 29, and a 2,800- 
pounds-per-acre-application on November 10. Therefore all the plots 
with the exception of those fertilized at the 5,600-pounds-per-acre 
rate got all their fertilizer in nine days with a rainstorm between ap­
plications. The 5,600-pounds-per-acre plot received one-half of its 
total in that time and the other half 12 days later. The fertilizers 
were applied in a similar manner commencing on October 12 in 1932, 
and again in a similar manner commencing March 30, 1933.

The winter of 1931-1932 was a comparatively mild winter in 
Maryland. There was little snow, but there was sufficient rainfall for 
any growth of grass the temperature permitted. The early spring 
was cool and damp and favored the growth of clover. The summer 
of 1932 was a hot, dry summer, and the plots received no artificial 
watering. Due to the dry summer the crabgrass was below normal.
The fertilizers were applied in the fall of 1932 in the same manner 
as in the fall of 1931. The first application was made on October 12. 
Final applications were made a week later. The late fall and early 
winter were mild, and there was an abundant growth of bluegrass 
until December on well fertilized plots. There was practically no 
change in the turf from December, 1932, until late in March, 1933.

It was decided to add an application of fertilizer in the spring of 
1933, and the fertilizers were applied in March at the same rates as 
in the two previous falls. The spring of 1933 was a very wet one 
and the summer was the wettest for more than ten years. The high 
rainfall, aided by summer temperatures that were mostly higher than 
normal, caused a very heavy growth of crabgrass throughout the 
section in which the experiments were being conducted. In Septem­
ber, crabgrass on fairways and check plots commenced to ripen, and 
after October 16, when the first heavy frost occurred, it died and 
turned brown. Resu]ts of Various Rates of Application

700 pounds per acre.—There was no burning during the experi­
ment from any application of the fertilizers used at the rate of 700 
pounds per acre. Practically no results were noticed within a month 
from the first application, except that the inorganic fertilizer pro­
duced a somewhat darker color in the turf. Although the winter was 
mild and moist there was not a great deal of improvement in either 
the inorganic or organic plots. In fact, the inorganic plot became 
worse from a golf standpoint on account of the considerable increase 
of clover in this plot. By early June there was an increase’in the 
growth of grass in the inorganic plot, although the increased per­
centage of clover also persisted. The organic plot had not changed 
and was no different from the check plots, which indicated the slow­
ness of the organic nitrogen to become available during a compara­
tively cool and wet spring. During the late spring and summer of 
1932 a certain amount of crabgrass came into the 700-pounds-per- 
acre plots. The excellence of turf and percentage of crabgrass in 

188

Vol. 13, No. 6

plots at the end of the first year after fertilizer had been applied may 
be seen in table 1.

Table 1.—Condition of the Turf at the End of the Crab­
grass Season (Fall, 1932)

Excellence of turf is based on a maximum of 10 as representing ideal 

fairway condition.

Kind of 
fertilizer 

Rate of

application Excellence Percentage of

(lbs. per acre) of turf crabgrass

Check.............................................................. 2 
Inorganic........................................................  700 
5 
Organic ........................................................... 700 
2 
Check............................................................... 2 
Inorganic........................................................  1400 
6 
Organic ..........................................................  1400 
5 
Check............................................................... 2 
Inorganic......................................................... 2800 
8 
Organic ..........................................................  2800 
8 
Check............................................................... 2 
Inorganic......................................................... 5600 
5 
Organic ........................................................... 5600 
8 
Check............................................................... 2 

50
10
40
50
25
45
50
40
35
50
5
10
50

The fertilizers were applied again in the fall of 1932; and by 
winter, after the bluegrass had made all its fall growth and had 
recovered from the crabgrass, the inorganic plot showed only 2 per 
cent more clover than the average of the check plots, 8 per cent less 
plantain, 13 per cent less bare ground, and an increase of 20 per cent 
in grass coverage. The organic plot showed a 3 per cent decrease in 
clover, 6 per cent less plantain, 8 per cent less bare ground, and an 
increase of 18 per cent in grass coverage. See table 2.

Table 2.—Condition of the Turf at the End of One Year 
(1932) After Being Fertilized for Two Falls

Excellence of turf is based on a 

way condition.

Kind of 
fertilizer 

Rate of
application
(lbs. per acre

Check ........................................
Inorganic....................  700
Organic ................  700
Check ........................................
Inorganic................................... 1400
Organic ..................................... 1400
Check ........................................
Inorganic..................................  2800
Organic ..................................... 2800
Check........................................
Inorganic..................................  5600
Organic ..................................... 5600
Check ........................................

maximum of 10 as representing ideal fair-

Excellence 

of turf Clovo• Plantain

)

2
7
6
2
10
6
2
10
10
2
6
10
2

10
10
5
10

</<
10
3
5
10
1 Trace.
5
10
5
12
0
0
2
io
0
i
5

15
0
3
10

Bare 
ground 
(/c

20
5
10
20
5
5
20
5
2
15
20
5
15

Grass 
cover 
%
60
82
. 80
60
94
80
63
95
93
60
80
91
70

In the spring of 1933 the fertilizers were again applied, and the 
grass was vigorous in both plots until the end of May, when crab­
grass commenced to appear. In September the crabgrass began to 
ripen, and the bluegrass commenced to make excellent fall growth 
in these plots. In October the plots were inspected and showed re­

December, 1933

189

suits indicated in table 3. The 700-pounds-per-acre plots had re­
ceived three applications of fertilizer in two years and had, as the 
table shows, improved greatly and showed decided clover or perennial 
weed control. The turf was however little, if any, better than some 
plots which received heavier applications after one application and 
one growing season.

Table 3.—Condition of the Turf at the End of Two Years 
(1933) After Being Fertilized for Two Falls and One Spring 

Excellence of turf is based on a maximum of 10 as representing ideal 

fairway condition.

Kind of 
fertilizer

Rate of Excellence 

application 
(lbs. per acre)

of turf Clover 

(/c

....................  700
..................... 700

Check ..................
Inorganic............
. .
Organic 
.. • •
Check 
Inorganic............ ....................  1400
....................  1400
Organic ..............
Check ..................
................  2800
Inorganic............
Organic .............. ....................  2800
Check ..................
Inorganic............
Organic ..............
Check ..................

................  5600
....................  5600

2
8
8
2
8
8

2
1
2
0
0
2

15
6
10
15
0
4
10
0
0
15
0
0
15

Plantain 
7c

Bare Grass
cover 
ground
7c

10
0
2
10
0
2
15
0
0
15
0
0
15

25
8
2
25
15
6
25
50
65
20
100
100
20

50
86
86
50
85
88
50
50
35
50
0
0
50

1,400 pounds per acre.—The fertilizers were applied in October, 
1931, in one application of 1,400 pounds per acre. Within a few days 
it was noticed that the inorganic plot was severely burned. No burn­
ing was noticed on the organic plot at any time during the experiment. 
The grass commenced to take on a dark green appearance on the 
organic plot a few days after the first rain following the application. 
Within three weeks the inorganic plot was recovering from the burn­
ing and the bluegrass was putting out leaves in small patches. By 
March, 1932, the inorganic plot had completely recovered and was 
making better growth than the organic plot. The bluegrass was 
making good growth in both plots, but the inorganic plot was grow­
ing the faster and showed a reduction in clover, which the organic 
plot did not.

By early June of 1932 both plots were holding their own against 
any increase in clover, but crabgrass was commencing to appear. In 
September the plots were inspected again before being fertilized and 
showed improvements as indicated in table 1. By October the blue­
grass in these plots had pushed above the crabgrass enough to hide 
the brown color of the dead plants.

The fertilizers were applied in October, 1932, the same as in 1931, 
and the inorganic plot was only slightly burned and the growth of 
the grass was not retarded to any extent. In December, 1932, the 
plots were examined (see table 2), and the inorganic plot showed 
almost complete control of clover and plantain. The coverage of blue­
grass in the inorganic plot had increased from about 62 per cent to 
94 per cent. This increase was made by replacing almost 19 per cent 
of weedy turf and covering about 13 per cent of bare ground. This 
was done in one year with two applications of fertilizer and without 
any seeding, topdressing with soil, or artificial watering. The grass 

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Vol. 13, No. 6

was also greatly increased in the organic plot, but there was less 
clover and plantain control. Since the inorganic plot was hardly 
burned by the fertilizer applied in the fall of 1932, it appears that the 
nature of the fertilizer rather than the effect of burning caused the 
weed control.

In March, 1933, the third application of fertilizer was made and 
a fairly bad burn was noted on the inorganic plot. The grass quickly 
recovered, however, and the bluegrass was in vigorous condition be­
fore the commencement of the crabgrass season. By July 15 it was 
evident that crabgrass was crowding out the bluegrass in these plots. 
During October the crabgrass died and the bluegrass was making 
excellent growth in the plots. The condition of the plots as observed 
at that time is outlined in tables 3 and 4. It will be noted that these 
plots show more bare ground than at the end of the 1932 season. 
This bare ground is almost entirely due to the fact that in some small 
areas the bluegrass was entirely smothered by the heavy growth of 
crabgrass during the summer of 1933.

Table 4.—Count of Plants and Shoots on the Best Plots 
in the Experiment at the End of Two Years (1933)

Kind of 
fertilizer 

Rate of 

Approximate

application Shoots per plants per Shoots

per acre square foot square foot per plant

Inorganic..............................  1400 pounds 
Organic ................................  1400 pounds 
Average of checks..............  

2160 
2000 
256 

240 
400 
80 

8
5
3

Table 4 shows approximately 1,000 per cent increase in Kentucky 
bluegrass shoots in the fertilized plots over the unfertilized or check 
plots.

2,800 pounds per acre.—The first application was made in October, 
1931, and was put on both the organic and inorganic fertilizer plots 
in two parts; that is, 1,400 pounds was applied first and a second 1,400 
pounds following the first rain, which occurred in eight days after 
the first application, to complete the 2,800 pounds. There was no 
burning at any time from the applications of organic fertilizer, and 
the organic plot was growing rapidly within three weeks from the 
first application. The inorganic plot was severely burned by the 
first part (1,400 pounds) of the application, but the second 1,400 
pounds was applied nevertheless, and within two weeks from the last 
application the Kentucky bluegrass was commencing to recover.

The winter of 1931-1932 was mild and there was considerable 
growth on these plots. By March the inorganic plot had completely 
recovered and was making better growth than the organic. Both 
inorganic and organic fertilizers had forced the Kentucky bluegrass 
remarkably, and the extent to which the bluegrass had spread and 
thickened the turf in such a short time (October 31 to April 1) was 
almost unbelievable. There was almost complete clover and partial 
plantain control in the inorganic, and partial control of both in the 
organic plot. By early June the bluegrass was still improving but 
crabgrass was commencing to appear. In September the plots were 
inspected and the percentage of crabgrass estimated. See table 1.
These plots were among the three most highly rated plots of the 
series and showed a crabgrass content of 40 per cent for inorganic 
and 35 per cent for organic fertilizer. The remaining vegetation 

December, 1933

191

(about 55 per cent) on these plots was almost entirely bluegrass. The 
check plots contained 50 per cent of crabgrass and the remaining turf 
was made up of about 18 per cent of bare ground, 7 per cent of clover, 
12 per cent of plantain, and about 13 per cent of Kentucky bluegrass. 
Crabgrass, though undesirable chiefly because of its seasonal nature, 
makes good summer turf when mixed with bluegrass, and this ex­
plains why turf received high ratings in table 1, even though it con­
tained 30 to 40 per cent of crabgrass. In these cases the turf was 
solid and thick, due to the density of the bluegrass plants, whereas 
check plots were rated low because the turf was thin and patchy and 
apart from the crabgrass was principally clover and various weeds. 
By October the crabgrass was dead in these plots fertilized at the 
2,800-pound rate, and the bluegrass was quickly pushing above the 
crabgrass remains.

The 2,800-pounds-per-acre plot at the Bannockburn Golf Club as it appeared 4 
months after receiving the first application of fertilizer. The light areas are not 
fertilized. The dark, fertilized area shows late fall and winter growth. The growth 
in fall, winter, and early spring is most important in getting bluegrass well 
established before the severe summer weather arrives.

The fertilizers were applied in the fall of 1932 in the same manner 
as in 1931. The first part of the application (1,400 pounds) was 
made on October 12 and the second part (1,400 pounds) was made 
after a rain a week later. The inorganic plot was only slightly burned 
after these applications and was not set back as in 1931. Table 2 
gives the condition of the turf during the winter of 1932-1933. These 
results indicate the condition of the turf after it had thrown off the 
effect of the 1932 crabgrass. The increase in Kentucky bluegrass 

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Vol. 13, No. 6

was found to be higher in the inorganic plot than in any other plot 
in the series. It showed a bluegrass covering of 95 per cent as against 
an average of 62 per cent in check plots. This makes an increase of 
33 per cent in bluegrass coverage after two applications of 2,800 
pounds per acre of inorganic fertilizer in a little over one year. The 
results in the organic plot were not far behind those in the inorganic, 
as its covering was 93 per cent for Kentucky bluegrass; it had 3 per 
cent less bare ground than this inorganic plot and 5 per cent more 
clover and plantain.

The fertilizer was again applied in the spring of 1933 and a bad 
burn was noted on the inorganic plot a few days after the first 1,400- 
pound application. The bluegrass recovered, however, and was grow­
ing well at the commencement of the crabgrass season at the end of 
May. The summer of 1933 was very much suited to the growth of 
crabgrass, and the growth in these plots was tremendous. By August 
15 it was difficult to find any bluegrass in these plots, so completely 
had they been taken over by crabgrass. During September crabgrass 
commenced to ripen in the check plots and died after October 16 
when the first heavy frost occurred. In the 2,800-pound-per-acre 
plots, however, the crabgrass did not ripen until several weeks after 
the crabgrass in the checks ripened, and it continued to make vigorous 
growth until the first heavy frost. The Kentucky bluegrass in check 
plots and plots more lightly fertilized commenced to make good growth 
by the end of September and to overcome the crabgrass. The Ken­
tucky bluegrass on these 2,800-pounds-per-acre plots, however, made 
slow recovery, and when table 3 was made it was found that a great 
deal of the bluegrass was dead. Apparently the excessively heavy and 
prolonged growth of crabgrass in these plots killed all clover and 
weeds as well as a large percentage of the bluegrass by smothering.
5,600 pounds per acre.—These plots received the 5,600-pounds- 
per-acre applications in two lots of 2,800 pounds per acre each. There 
was always a severe burn on the inorganic plot when the first half 
(2,800 pounds per acre) was applied, but the second half was applied 
even though the turf was badly burned. The inorganic plot was 
severely burned at each season the fertilizer was applied—that is, 
fall of 1931, fall of 1932, and spring of 1933; but in every case the 
Kentucky bluegrass recovered. The results of the inorganic fertilizer 
at this rate were not as good as those of the 2,800-pounds-per-acre 
rate. The clover and weeds were practically eradicated with the first 
application, but later in the experiment the percentage of bare 
ground still remained high and it was thought that the continued 
severe burning with each application may have prevented some of 
the bare areas from filling in. There was 20 per cent of bare ground 
in the fall of 1932, as shown by table 2, as against 5 per cent of bare 
ground with the 2,800-pounds inorganic plot. Since the 2,800-pound 
inorganic rate also eliminated clover and weeds and at the same time 
reduced the bare ground in the plot from 18 to 5 per cent it is ap­
parent that there was no need of applying more than the 2,800-pound 
rate of inorganic fertilizer.

The organic fertilizer application was also applied in two parts 
at 2,800 pounds per acre per application and at no time was there 
any burning. The results by the fall of 1932 (see table 2), however, 
were not as good as with the 2,800 organic rate, so that there seems 
no reason to apply more than 2,800 pounds per acre of such fertilizer.
With both inorganic and organic plots the final results were even 

December, 1933

193

worse than with the 2,800-pounds-per-acre rates. The Kentucky 
bluegrass in both these plots failed to survive the prolific crabgrass 
growth of the summer of 1933, and the plots were left bare when the 
experiment ended (see table 3).

It is not known how much the 1933 spring fertilizing influenced 
the tremendous growth of crabgrass which crowded out so much 
bluegrass on the 2,800- and 5,600-pounds-per-acre plots during the 
summer of 1933. There are too many factors to consider to enable 
one to draw definite conclusions. The summer of 1933 wras more ideal 
for crabgrass growth than the summers of 1931 and 1932. The crab­
grass injured the bluegrass less the lower the fertilizer rates, which 
indicates that it was the excess fertility in the soil over and above 
what the spring growth of bluegrass used that fertilized the crab­
grass. If such is the case it is much more likely that an excess of 
fertilizer will remain in the soil after spring fertilizing to feed the 
crabgrass during the late spring and summer, than after fall 
fertilizing.

The 5,600-pounds-per-acre plot at the Bannockburn Golf Club as it appeared 
5’/i months after having been fertilized in October, 1931. at the 5,600-pound rate. 
The fertilized area on the left shows a remarkable growth of Kentucky bluegrass. 
Adjoining it on the right is the thin, weedy growth of the unfertilized check plot. 
This growth took place before the first spring mowing on the course.

There was a thin scattering of spots of Chewings fescue and 
colonial bent in the area chosen for this test. These spots were so 
small that they were not considered in describing the turf. However, 
it has been noted that the spots of both the fescue and the bent have 
developed with the bluegrass and have held their own. Since there 

194

Vol. 13, No. 6

was a great preponderance in the proportion of bluegrass to fescue 
and bent, it therefore seems that if the heavy fertilizing had been 
detrimental to these grasses they would have almost if not totally 
disappeared.

In describing the experiment mention was made that the turf ex­
perimented with was made up of Kentucky bluegrass, clover, plan­
tains, dandelion, chickweeds, and crabgrass in season. Later in the 
article the dandelions and chickweeds were not mentioned. There 
was a comparatively small percentage of dandelions in these plots 
and their control was practically the same as the plantain control 
which is indicated throughout the article and in the tables. Chick- 
weed made up a comparatively small amount of the turf treated, and 
its control was proportionately the same as the clover control.

Application of Results

This experiment is being continued in order to get further data 
on the subject; but in the meantime, due to the fact that the observa­
tions reported to date tend to substantiate other experimental work 
and observations, there seems to be no reason why some of the results 
described here can not be applied in a practical way elsewhere. The 
700-pounds-per-acre plots which have received two fall and one spring 
applications have improved greatly, but the turf is not yet as dense 
as the plots receiving heavier applications after only one or two 
previous applications. It therefore seems that a club wishing to get 
thick turf and freedom from clover and certain weeds had better 
fertilize heavily for one or two falls rather than fertilize lightly for 
a number of years without gaining the results desired.

In order to get maximum results the following spring, it is indi­
cated that as much as 2,800 pounds per acre of fertilizer similar to 
what was used in the experiment should be applied in the fall. If 
other fertilizers are used than the 6-12-4 fertilizer used in the experi­
ment the rates should be on a similar nitrogen basis. The experiment 
indicates also that it is possible to gain dense Kentucky bluegrass 
turf which is practically free of clover and perennial weeds if as 
much as 1,400 pounds of an inorganic, or 2,800 pounds of an organic 
fertilizer, analyzing as high as 6-12-4 is used two successive falls. 
When an application of 1,400 pounds of organic fertilizer is applied 
for two falls and one spring, as in this experiment, the results should 
be about the same as with 1,400 pounds of inorganic fertilizer applied 
for two falls only. If the organic fertilizer were applied for three 
falls instead of two falls and one spring the results would probably 
be as good or better. The fall fertilizers were not applied until 
October, but in sections of the country which have earlier and more 
severe winters than Washington it is likely that the fertilizer treat­
ments should start late in September.

Inorganic fertilizer burned when 1,400 pounds per acre were ap­

plied at one time, but the Kentucky bluegrass soon recovered.

Organic fertilizer did not burn when 2,800 pounds per acre 
were applied at one time. The burning effect of the soluble nitrogen 
fertilizers, such as sulphate of ammonia, ammo-phos, and urea, and 
the potassium carriers, such as muriate or sulphate of potash, must 
be taken into account when considering the power of fertilizers to 
burn turf.

This experiment bore out the fact which many previous experi­
ments have demonstrated, namely, that organic fertilizer is slower- 

December, 1933

195

acting than inorganic. Hence in the comparison of inorganic and 
organic fertilizers, the organic fertilizers might give as good results 
as the inorganic when applied at the same rates; but due to the 
nature of the material, the organic fertilizer would take longer to 
produce these results. Also once the desired results have been 
obtained, the organic fertilizer may be expected to have a more last­
ing effect than inorganic fertilizers.

Effect of Fertilizers on Crabgrass

In October, 1933, the series was inspected and results observed as 
shown in table 3. From that table it will be seen that during the 
summer of 1933 considerable bluegrass was lost in plots 7 and 8, and 
no bluegrass remained in plots 10 and 11. These plots were the 2,800 
and 5,600-pounds-per-acre applications of both inorganic and organic. 
Apparently there was such a heavy and prolonged growth of crab­
grass in these plots that Kentucky bluegrass was smothered. When 
the crabgrass eventually died in October, there was no life left in 
the injured Kentucky bluegrass rootstocks and nothing took the place 
of the crabgrass. It is quite significant, however, that in plots 4 and 5, 
which received 1,400-pounds-per-acre fertilizer, the Kentucky blue­
grass survived the heavy crabgrass growth of the 1933 season, and 
when the crabgrass weakened in the fall the bluegrass recovered 
rapidly and almost completely replaced the crabgrass. This might be 
taken to indicate that there is a point where the soil is built up to 
such a high state of fertility that there is a growth of crabgrass suf­
ficiently dense and prolonged to completely smother the bluegrass. 
The possibility that burning at the time of application might have 
been a factor apparently need not be considered. There was no 
burning in plots 8 and 11, which received organic fertilizers, and 
yet the bluegrass died in these two plots the same as it did in the two 
plots which received similar rates of inorganic fertilizer and which 
were badly burned.

The crabgrass factor must be considered when analyzing fairway 
fertilizer results in this part of the country. When the experiment 
was started it was calculated that the check areas were made up of 
about 8 per cent of clover, 11 per cent of plantains, 18 per cent of 
bare ground, and 62 per cent of Kentucky bluegrass. After the heavy 
crabgrass growth during the summer of 1933 the fairways were found 
to be made up of approximately 14 per cent of clover, 13 per cent 
of plantains, 23 per cent of bare ground, and 50 per cent of Kentucky 
bluegrass. It therefore shows that the summers of heavy crabgrass 
growth materially set back bluegrass fairways. In this case the 
percentage of clover, weeds, and bare ground was increased and the 
coverage of bluegrass decreased by 12 per cent. The decrease in 
weeds and bare ground and the large increase in the percentage of 
bluegrass coverage in some of the fertilized plots were all the more 
remarkable when one considers the setback the checks or untreated 
fairway received due to the luxuriant crabgrass growth during 1933.
It seems likely that in the crabgrass districts a combination of 
chemical control and heavy fertilizing will be necessary in order to 
remove this pest from competition with bluegrass and other turf 
grasses. Suggestions for the control of crabgrass with chemicals 
is contained elsewhere in this number of the Bulletin in the article 
describing experiments on the control of various turf weeds with 
sodium chlorate and other chemicals.

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Vol. 13, No. 6

Change in Soil Reaction

The soil in these experiments showed a neutral (pH 7) reaction 
before the fertilizers were applied. By comparing the average of 
the reactions found at each inch depth of the top four inches of the 
various plots after the fertilizer had been applied it was found that 
the soil reaction was scarcely changed in the plots receiving the 
organic fertilizer even when as much as four tons to the acre was 
applied.

In the plots receiving the inorganic fertilizer there was an in­
crease in acidity. Assuming that the increased acidity was due 
largely to the sulphate of ammonia in this fertilizer it may be cal­
culated from the amount of sulphate of ammonia applied in the com­
plete fertilizer, that it required approximately one ton of sulphate of 
ammonia to the acre to increase the acidity 1.2 degrees (from pH 7 
to pH 5.8). From these results it may be seen that it requires a 
large amount of sulphate of ammonia to increase soil acidity to any 
extent in certain soils. Usually fine soils, such as clay and silt loams, 
resist change in acidity more than sandy soils. A fine soil which is 
alkaline or neutral may be subjected to prolonged or severe acidify­
ing influences before showing acid reactions.

Increase of Available Phosphorus

It is known how much phosphoric acid has been applied to each 
plot during the course of the experiment. In August, 1933, soil 
samples were taken at depths of 1 inch or less, 1 to 2 inches, 2 to 3 
inches, and 3 to 4 inches, from each plot and from the check plots. 
Determinations of the pounds of available phosphorus to the acre 
were made by the Truog method, and the increase due to the fer­
tilizer applications is given in table 5.

Table 5.—Increase of Available Phosphorus from a 6-12-4 Fertilizer at 
Various Rates of Application

Increase 
Application (pounds 
(pounds per acre) per acre)

Check plots ........................................................................................
Inorganic—700-pound rate (3 applications)..............  
2,100
Organic—700-pound rate (3 applications)..................  2,100
Inorganic—1,400-pound rate (3  applications).............  
4,200 
Organic—1,400-pound rate (3 applications)................  4,200 
Inorganic—2,800-pound rate (3  applications)............. 
8,400 
Organic—2,800-pound rate (3  applications)............. 
8,400 
Inorganic—5,600-pound rate (3  applications)............. 16,800 
Organic—5,600-pound rate (3  applications)............. 16,800 

39
22
89
73
93
105

From these results it may be seen that a total application amount­
ing to over one ton of 6-12-4 fertilizer to an acre failed to show an 
increase in the amount of available phosphorus in the soil when the 
tests were made four months after the fertilizer had been applied. 
Higher rates however showed decided increases. Due to the fact 
that considerable nitrogen was applied there was a large growth of 
leaves, stems, and roots in the turf, and no doubt a great deal of 
phosphorus was used by the plant in producing this growth. If phos­
phoric acid had been applied in a higher proportion to the nitrogen, 
or if some material containing phosphoric acid but no nitrogen had 
been applied alone, it is possible that the soil would have shown a 
higher increase in available phosphoric acid.

December, 1933

197

Table 6 shows a number of points regarding the penetration of 
phosphoric acid in the soil when applied in inorganic and organic 
forms. The fertilizers and rates used have been described elsewhere 
in this article. Table 6 shows 23.7 pounds greater accumulation in 
the top inch of phosphoric acid from the organic source than from 
the inorganic. There is an accumulation of 138.7 pounds of phos­
phoric acid in the top inch in the plots receiving organic fertilizer 
and 115 pounds in the plots receiving inorganic fertilizer. This dif­
ference is due probably to the fact that the phosphoric acid from the 
organic source is less soluble. This fact is further borne out in the 
table by comparing the total accumulation below a one-inch depth. 
The increase of phosphoric acid below the top inch is about 47 per 
cent greater in the inorganic fertilizer plots than in the organic. The 
increase below the top inch with the inorganic fertilizer was 37.5 
pounds to the acre and with the organic only 17.9 pounds to the 
acre. The penetration of the phosphoric acid to depths where the 
roots may come in contact with it is of importance in supplying ade­
quate quantities of this material to the plant.

Table 6.—Penetration of Available Phosphoric Acid to Different Depths 
as Evidenced by Its Increase in the Soil of Fertilized Plots Over Its 
Presence in the Soil of Unfertilized Check Plots. The Figures for 
Each Depth Shown Are Averages for Four Plots Fertilized Respec­
tively at Rates of 700, 1,400, 2,800, and 5,600 Pounds per Acre.

Increase in pounds per acre
Inorganic 
Organic 
fertilizer 
fertilizer 
plots
plots

.................. 115
At depth of 1 inch or less................................
.................. 68.7
At depth of 1 to 2 inches................................
At depth of 2 to 3 inches................................ .................. 17.5
.................. 26.2
At depth of 3 to 4 inches................................

Averages of the four depths..................

.................. 56.8

138.7
26.2
8.7
18.7

48

Other data, not given in the table, showed that fairly heavy appli­
cations of fertilizer Avere required in this experiment before the 
phosphoric acid commenced to accumulate below the surface inch. 
In the 700-pounds-per-acre plots there was no accumulation of phos­
phoric acid in the second inch or below. In the 1,400-pounds-per- 
acre plots phosphoric acid from the organic source failed to reach 
the second inch, but the inorganic penetrated to the fourth inch. 
With higher rates correspondingly more phosphoric acid from the 
inorganic source penetrated to the fourth inch. In the 2,800-pounds- 
per-acre plots phosphoric acid from the organic source also pene­
trated to the fourth inch, and correspondingly more penetrated with 
the higher rate of application.

Effect of Inorganic and Organic Fertilizers on Organic Content of the Soil
The claims of some fertilizer dealers that the use of organic fer­
tilizers increases the organic-matter content of the soil much more 
than does the use of inorganic fertilizers were considered in the 
experiment. It was thought that the abnormally heavy applications 
of fertilizers to be used on some plots in the experiment would tend 
to show wide differences in soil organic matter if the above conten­
tion were true.

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Vol. 13, No. 6

The organic matter in the soils in the plots was determined by 
loss on ignition. The organic matter was found to be high in the top 
inch and to become less at each inch of depth until the organic matter 
in the fourth inch became less than half the amount in the top inch. 
The organic contents of the soil to a depth of four inches was found 
by averaging the organic content of each different depth. By this 
method the organic content of the check plots was found to be 3 per 
cent, and a considerable increase of organic matter was found in all 
fertilized plots.

The amounts of humus found in the soil are considerable. As the 
plants grow, new roots are formed and finally die and thus increase 
the organic matter in the soil. Also on fine turf the clippings may 
materially increase the soil organic matter under certain conditions.
An acre of soil one foot deep weighs approximately 4,000,000 
pounds, and it was calculated that the 3 per cent of organic matter 
contained in the 1/3-foot in the check plots amounted to approxi­
mately 20 tons. The plots which were fertilized three times in two 
years with 700, 1,400, 2,800, and 5,600 pounds per acre showed an 
increase of 5.6, 6.1, 5.6, and 5.2 tons of organic matter to the acre, 
respectively, for the inorganic fertilizer plots. The organic fertilizer 
plots showed an increase of 4.5, 6.2, 4.9, and 6.8 tons to the acre, 
respectively.

It is interesting to note that the average increase per acre in the 
inorganic plots was 5.59 tons as against 5.58 tons in the organic plots. 
There were altogether 15.7 tons of fertilizer applied on the inorganic 
fertilizer plots, and the same amount on the organic fertilizer plots.
It has been frequently claimed that it is economical to pay a pre­
mium for organic fertilizers over the cost of inorganic fertilizers 
of the same analysis. The argument in favor of this additional 
expense being that the organic fertilizers would increase the soil 
organic matter, the implication was, if not so stated, that the inor­
ganic fertilizers do not increase the soil organic matter. In such a 
contention the power of the turf grasses, and other crops for that 
matter, to manufacture their own organic matter from carbon diox­
ide in the air, is ignored. When one considers the results of this 
experiment, in which a soil comparatively low in organic matter for 
soil which has been in sod so many years, and the fact that a great 
deal more fertilizer was applied than normally, it seems reasonable 
to expect that these particular claims regarding organic fertilizers 
would have been confirmed if they were founded on fact.

The increase of organic matter in the soil was surprisingly close 
in both cases. The inorganic fertilizer plots gained 20 pounds of 
organic matter to the acre over the organic, but this small differ­
ence is well within the range of experimental error. Organic fer­
tilizers have sufficient in their favor to be used for their fertilizing 
value alone, and apparently if they are of value as a fertilizer most 
of their organic matter is lost in decomposition while becoming avail­
able to the plants.

This experiment also indicates that it might be more economical 
and practical to build up the organic matter on fairways and other 
large turf areas by fertilizing rather than by direct application of 
organic materials of nonfertilizing value which are often used for 
this purpose. The 5.5 tons of organic matter to the acre built up in 
the soil by fertilizing is calculated on a dry-weight basis, and is 
actually humus incorporated in the soil. It represents something 

December, 1933

199

like two or three times this amount in more bulky organic materials, 
such as well-rotted manure, peat, leaf mold, and other materials com­
monly used to increase organic matter in soil. Also when such more 
bulky materials are used they must be incorporated in the soil by 
cultivation or other methods which can not be employed conveniently 
on turf areas.

Summary

A comparison was made, in the experiment described, of the 
effects of a 6-12-4 organic and a 6-12-4 inorganic fertilizer applied 
to a thin turf of Kentucky bluegrass on a fairway in the vicinity of 
Washington, D. C. The fertilizers were applied in October, 1931, 
October, 1932, and March, 1933.

By heavy applications of fertilizers, a thin turf of Kentucky blue­
grass was built up during the fall and spring growing seasons to a 
thick, dense turf free from clover and certain perennial weeds.

Some burning of the grass was observed where inorganic fer­
tilizer was used in a single application at the rate of 1,400 pounds to 
the acre, but in all such cases the Kentucky bluegrass soon recovered. 
The organic fertilizers did not burn even when applied at the heaviest 
rates.

Plots which received two fall and one spring application at the 
rate of 700 pounds to the acre have greatly improved, but theii’ turf 
is not yet as dense as plots which received heavier applications after 
only one or two previous applications.

The experiment has not shown how long turf brought to a condi­
tion of excellence with eithei’ inorganic or organic fertilizers can be 
maintained before exhibiting the need for additional fertilizer. It is 
however known that turf once brought to a thick, vigorous condition 
produces a great improvement in the condition of the soil, is less 
affected by conditions of weather, and may maintain itself in excel­
lent shape for a number of years without additional fertilizer.

The experiment bore out the fact which many previous experi­
ments have demonstrated, namely, that organic fertilizer is slower- 
acting than inorganic.

The inorganic fertilizer increased the soil acidity probably due to 
its content of sulphate of ammonia. The organic fertilizers did not 
affect the soil acidity.

There was a decided increase in the content of the available phos­
phoric acid in the surface inch of the fertilized plots. There was only 
a small increase in the phosphoric acid below the two-inch level.

It was shown that the phosphoric acid from the inorganic fer­
tilizer penetrated to the 2d, 3d, and 4th inches more readily than 
the phosphoric acid from the organic fertilizer.

It was found that the organic-matter content of the soil was 
greatly increased by the heavy applications of fertilizers. The inor­
ganic fertilizer proved equally as effective as the organic fertilizer 
in adding organic matter to the soil.

Burning over the rough in fall or winter is generally considered 
to be good practice. It doesn’t hurt the turf grasses and destroys in­
sects and weed seeds.

200

Vol. 13, No. 6

Annual Report of the Green Section for 1933
By Ganson Depew
Chairman, Executive Committee

The Green Section is glad to report that it has been able to effi­
ciently continue many of its activities during 1933, notwithstanding 
the work was crippled very materially by the reduction in its budget 
to $28,062, as compared with $44,759 for 1932. By exercising rigid 
economies, we were able to keep within the budget.

Since 1929, due to the business depression, available funds have 
been reduced over 40 percent. This has interfered greatly with the 
continuation of experiments started years ago, and which, to be of 
constant value, must be continued. Research work must also be 
continued in adequate study to solve the many and ever-increasing 
turf problems of the numerous golf clubs of the country. Many 
are yet to be satisfactorily solved, and a much larger technical staff 
could well be employed to obtain valuable information in the interest 
of turf maintenance and economy.

General Activities During the Year

The Staff has been enabled to perform its necessary travel to 
clubs and meetings through generous contributions by private clubs 
and other associations and organizations. There was a continued 
demand for all types of information on economy in course mainte­
nance, disease, and other unfavorable influences. During the year 
a larger proportion of the member clubs than usual requested the 
Green Section to examine and report on seed and soil samples and 
to give advice on numerous maintenance and construction problems. 
The advisory service has been carried on through correspondence 
and, as much as possible, by personal interviews on golf courses, 
Green Section gardens, in offices, and in laboratories.

The principal research of the Green Section has been conducted 
at Arlington, Washington, and at the Mid-West Turf Garden, Chi­
cago. A number of experiments were also conducted on golf courses 
in chosen localities on turf maintained under heavy playing condi­
tions. These tests were conducted through arrangements made with 
the golf club committees. Also, much valuable data has been 
accumulated through demonstration gardens established at various 
selected parts of the country. The extension or educational work 
has been carried on through various Green Section meetings and 
exhibits. Summer meetings were held, attended by large numbers 
of greenkeepers and chairmen of green committees. Educational 
work has been also carried on through the Bulletin and by selected 
articles in certain other publications. The Green Section staff has 
also helped in the educational work of the national and the various 
sectional greenkeepers’ organizations and of greenkeepers’ short 
courses held at various state colleges.

Experimental Work

Experimental work was continued at Arlington, supplemented 
with tests on local golf courses under playing conditions. Interesting 
observations were made on different species and strains of grass 
for putting green purposes and different mixtures for fairwaj’ pur­
poses. Earthworms were particularly troublesome, as they were 
elsewhere in the country, and remained so in spite of repeated trials 
of remedies hitherto effective. Considerable work was done in test­

December, 1933

201

ing some new remedies. Particularly good opportunity was afforded 
for advanced studies of brownpatch on a low-lying, shaded, more 
humid area planted to fine turf beside the Potomac River. This 
garden continued to prove its value, since, due to its location, disease 
studies may be continued there at times when diseases are inactive 
on the main garden with its open exposure. The systematic study 
of fertilizers, which has been under way for some years, was also 
continued. An experiment on the effect of different rates of inor­
ganic and organic complete mixed fertilizers on bluegrass fairway 
turf was continued on a nearby golf course, and information regard­
ing turf improvements, increased soil fertility, and organic matter 
in soil was obtained. Weed control studies were continued. Many 
positive results were obtained in controlling with chemicals a number 
of weeds, particularly crabgrass on fairways. With some further 
work on this subject, results should be obtained which should prove 
extremely valuable especially to the many golf clubs in the large 
area where crabgrass is the most troublesome turf problem.

The Mid-West Turf Garden contains different sets of tests, sup­
plementary to the Arlington work. Many of these tests were planned 
to procure a more complete understanding of the specific problems 
of the Middle West. Part of the original work planned has been 
discontinued, in order to curtail expense.

Demonstration Gardens

The series of demonstration turf gardens continued to provide 
much information for those interested in turf maintenance on courses 
in the vicinity of the gardens. There are now 18 gardens in various 
sections of the United States, and one in Canada, which is main­
tained through cooperation with the Royal Canadian Golf Associa­
tion. The Green Section has had splendid cooperation from those 
in charge of the courses where these demonstration gardens are 
located. Extensive reports have been received regularly this year 
and assembled for publication. Soil samples were sent in upon 
request. The taking of a number of samples from each plot, packing 
and shipping them, required considerable work on the part of the 
greenkeepers in charge of these gardens. The Green Section appre­
ciates their cooperation. An analysis of these soils from plots, most 
of which have received specific treatments for five years, should 
produce valuable information.

Well-attended gatherings of golf club officials and greenkeepers 
have been held at the gardens, and the behavior of the different 
grasses, fertilizers, and other treatments has been discussed on the 
grounds. At many of these meetings members of the Green Section 
staff have been present to explain the work. It has been found that 
discussions of turf problems are much more valuable where such 
demonstrations are at hand than are discussions of similar problems 
indoors, where direct examples of results cannot be exhibited.

Educational Program

The expenses of these summer meetings, including travel, were 
paid for by organizations in the districts interested. A series of 
meetings were held as follows:

May 31—Keller Golf Course, St. Paul, Minn.
June 9—Mid-West Turf Garden, Mill Road Farm Golf Course, 

Everett, Ill.

202

Vol. 13, No. 6

Aug. 7—Pine Valley Golf Club, Clementon, N. J.
Aug. 7—Philadelphia Country Club, West Conshohocken, Pa.
Aug. 9—Westwood Country Club, Clayton, Mo.
Aug. 21—Municipal Golf Course, Niagara Falls, N. Y.
Aug. 21—Santa Monica Municipal Golf Course, Santa Monica, Cal.
Sept. 11— Los Angeles Country Club, Los Angeles, Cal.
Sept. 14—Kenwood Country Club, Cincinnati, Ohio.
Sept. 18—Canterbury Golf Club, Cleveland, Ohio.
Sept. 20—Detroit Golf Club, Detroit, Mich.
Sept. 22—Wakonda Country Club, Des Moines, Iowa.
Sept. 25—Tulsa Country Club, Tulsa, Okla.
Sept. 25—Claremont Country Club, Oakland, Cal.
Oct. 10—Charles River Country Club, Newton Centre, Mass.

The Green Section also assisted in other educational programs. 
These included short courses given by the Pennsylvania State College 
of Agriculture, State College, Pa.; Michigan State College of Agri­
culture, East Lansing, Mich.; Iowa State College, Ames, Iowa; and 
the Annual Convention of the National Association of Greenkeepers 
of America. Members of the Green Section staff were present at 
various other local gatherings of chairmen of green committees and 
greenkeepers, in addition to the above meetings.

Correspondence and Service to Member Clubs

The staff was able to keep up with the usual large amount of 
seasonal correspondence with member clubs regarding the various 
problems encountered last season. Several periods of high humidity 
and heat occasioned serious turf problems on putting greens in sev­
eral parts of the country which required considerable attention by 
the staff, including correspondence, soil examinations, and inspection 
trips. Increased interest in information regarding soil improvement, 
fairway watering, and weed control was noticeable. The Green 
Section was able to supply helpful information in these instances.
The staff visited a large number of courses on request and gave 
advice on numerous turf problems. Due to the demands, at certain 
times, on the time of the staff, it was not always possible to visit 
courses immediately upon being requested. With few exceptions, 
however, it was eventually possible to visit the golf clubs which 
desired such service, and in some instances clubs were saved travel 
expense money by grouping the requests so that two or three clubs 
in one vicinity could be visited while the Green Section representative 
was in that neighborhood. During 1933, members of our staff visited 
courses located in 25 states, including California and Oregon, and 
in Canada, Mexico, Cuba, and Panama. The staff traveled over 
50,000 miles in service, extension, and research work, which was 
paid for by clubs requesting the visits.

Green Section Bulletin

The plan started in 1932 of publishing the Bulletin in six numbers 
instead of 12 was continued in 1933, grouping related material in a 
single number and making them in two cases much larger than the 
old monthly numbers. Some subjects cannot be effectively handled 
in Bulletins of smaller size, and under the old system of 12 numbers 
to the volume it was necessary to break up this material into two 
or three separate numbers.

December, 1933

203

QUESTIONS AND ANSWERS

All questions sent to the Green Section will be answered in a letter to 
the writer as promptly as possible. The more interesting of these questions, 
with concise answers, will appear in this column. If your experience leads 
you to disagree with any answer here given it is your privilege and duty to 
write to the Green Section. While most of the answers are of general 
application, it must be borne in mind that each recommendation is intended 
specifically for the locality designated at the end of the question.

Slime mold fungus on turf.—I am sending you a piece of sod on 
which is fungus growth which I have never seen before. Any infor­
mation on it will be appreciated. (Oregon)

Answer.—This is one of the slime mold fungi which frequently 
occur on grass. Ordinarily they do not do any damage beyond tem­
porarily disfiguring the turf. Usually they turn black when they 
become old enough to produce spores and then can be readily washed 
from the grass and no damage is apparent. In some cases there is a 
slight injury. There are different species of this type of fungus and 
some variation of species under different conditions.

Sulphur water for irrigation purposes.—In drilling for water on 
our course we struck sulphur water. Would this be suitable for use 
on putting greens? (Ohio)

Answer.—Sulphur water is frequently used on golf courses with­
out any apparent harmful effects. However, in most cases it is 
aerated by spraying it into the air, which removes the sulphur fumes. 
It depends upon the concentration of the sulphur as to whether it is 
safe to use on golf courses or not. We suggest that you have the 
water analysed. If you send us a report on the analysis we shall 
be glad to give you further advice on the subject.

Creeping bent nursery going to seed.—This season all the grass 
in our creeping bent nursery seems to be going to seed. Can this 
tendency be discouraged? If not, does it harm the stolons? (Ohio)
Answer.—We do not know of any way in which the tendency of 
creeping bent stolons to produce seed in a nursery can be discouraged 
except by cutting them with a mower. However, this does not always 
work, because so much of the seed is produced so close to the ground 
that it is difficult to reach the seed heads with a mower under nursery 
conditions without injuring the grass. We have found that stolons 
or plants which have produced seed are just as satisfactory for plant­
ing, but the growth of the stolons is somewhat checked during the 
time the seed is being produced. If nurseries are left for a long time 
in the same area, seed production is objectionable since the seed does 
not produce plants identical with the parent. Grass planted from 
stolons produced from seed formed in the nursery might be 
undesirable.

Anyone who hopes to achieve success, even 
the average, must know more, or at least as 
much, about some one thing as any other one, 
and not only know, but know how to do—and 
how to utilize his experience and knowiedge for 
the benefit of others.

—Theodore N. Vail.