THE EFFECT QF % PESTECIDES ON
TUEFGRAfl GROW ANQ NEWER
TRANSFG‘RMATEONS EN SQBL

 

Thesis {or “10 Degree of M. S.
MICHEGAN STATE UMVERSLITY

James W. Timme‘rman

R968

 

 

 
  
 
 

THESIS ‘ L [BR/1R Y
Michigan State
fa...‘ University

ABSTRACT
THE EFFECT OF SELECTED PESTICIDES ON
TURPGRASS GROWTH AND NITROGEN TRANSFORMATIONS
IN SOIL

By James W. Timmerman

A study was made of the effects of selected pesticides on turfgrass
growth, interactions with turf fertilizers, and nitrogen transformations
in soil. In general, the two organophosphate insecticides B25141 and
Diazinon and the fungicide Tersan-OM increased top growth, per cent
nitrogen in the leaf tissue and nitrogen uptake during certain periods
of growth in both the greenhouse and field experiments. Turf color
was also improved by these pesticides in the field. Acti-dione thiram
depressed growth in the greenhouse. All other pesticides had no effect.
These effects were more noticeable in the first month after application,
and were magnified when 10 times the recommended rate of the pesticides
were used.

Soil mineral nitrogen (ammonium + nitrate) in pots receiving
Milorganite as the nitrogen source was significantly higher than the
no pesticide treatment when treated with B25141 and Cadminate at the
recommended rate, and B25141, Diazinon, Dieldrin, and acti-dione
thiram at 10 times the recommended rate in the greenhouse. This was

not observed in the field.

In a laboratory incubation study, Tersan-OM applied at rates of
possible accumulations over a period of time increased ammonification
and nitrification in soil receiving Milorganite as the nitrogen source.
Diazinon, 325141 , Dieldrin, and Calo Clor at these rates resulted in
inhibition of ammonification. All pesticides caused significant changes
from the control soil in patterns of ammonification and nitrate accumula-

tion from Milorganite .

THE EFFECT OF SELECTED PESTICIDES ON
TURFGRASS GROWTH AND NITROGEN TRANSFORMATIONS

IN SOIL

By

. “'0“
\

.‘ “ .
James W. 1mmerman

A THESIS

Submitted to
Michigan State University
in partial fulfillment of the requirements
for the degree of

MASTER OF SCIENCE

Department of Soil Science

1968

‘1'

@4997) D
rj~as«68

To Barbara

ii

ACKNOWLE DGMENT

The author wishes to express his sincere appreciation to
Dr. P. E. Rieke who has given generously of his patient guidance,
helpful advice, and understanding encouragement in the preparation
of this thesis. Grateful acknowledgment is also extended to
Dr. A. R. Wolcott, IX. I. B. Beard, and Dr. B. D. Knezek for
serving on the author's graduate committee and for their valued
counsel and support.

The author is deeply grateful to his wife, Barbara, for her
constant encouragement and tireless efforts in making this

publication a reality .

iii

TABLE OF CONTENTS

INTRODUCTIONO...O.OOOOOOOOOOOOOOOOOOOOOOO
LITERATURE REVIEW
Effect of Pesticides on Plant Growth-Beneficial . . . . . .

Effect of Pesticides on Plant Growth-Detrimental . . . . .
Effect of Pesticides on Microbial Numbers . . . . . . . . .

Effect of Pesticides on Ammonification and Nitrification

METHODSAND MATERIALS . . . . . . . .

Greenhouse Experiment 1 . . . . . .
Greenhouse Experiment 2 . . . . . .

Field Experiment . . . . . . . . . .

Laboratory Incubation Experiment .

RESULTS AND DISCUSSION . . . . . . .

Greenhouse Experiment 1 . . . . .
Greenhouse Experiment 2 . . . . .

FieldExperiment .............

Discussion of Greenhouse and Field Results

laboratory Incubation Experiment

Discussion of Results of Laboratory Experiment
SUMMARYAND CONCLUSIONS . . . . . . . . . . . . . .
BIBHmRAPHYO......OOOOOOOOOOOOOOOOOOO

APPENDIXO...OOOOOOOOOOOOOOOOOOOOOOOO

iv

25

25
31
35
54
59
69

73

77

83

LIST OF TABLES

Tables Page

1. Pesticide chemicals used in greenhouse, field, and
laboratorYStUdieS OOOOOOOOOOOIOOOOOOOOOOIO 17

2. Materials compared as nitrogen source . . . . . . . . . . . . . l8

3. Soil treatments imposed on air-dried Hodunk sandy loam
priortoincubation 23

4. Effect of pesticides on top growth of Pennlawn creeping
red fescue and soil mineral nitrogen in Hodunk sandy
loaminthegreenhouse..................... 26

5. Effect of pesticides and nitrogen carriers and rate on top
growth of Pennlawn creeping red fescue, grown in
Hodunk sandy loam in the greenhouse . . . . . . . . . . . . 33

6. Effect of pesticides and nitrogen carriers on top growth
of Cohansey bentgrass under field conditions . . . . . . . 36

7. Effect of pesticides and nitrogen carriers on per cent
nitrogen in leaf tissue of Cohansey bentgrass
underfieldconditions .. 40

8. Effect of pesticides and nitrogen carriers on nitrogen
uptake of Cohansey bentgrass under field conditions . . 43

9. Effect of pesticides and nitrogen carriers on relative
turf color rating and density counts of Cohansey
bentgrass under field conditions . . . . . . . . . . . . . . . 46

10. Effect of pesticides and nitrogen carriers on mineral
nitrogen content of field soil on October 5 . . . . . . . . . 49

11 . Effect of pesticides on relative numbers of microbial
groups in field treated soil, September-October 1967 . . 52

12. Effects of pesticides and time of incubation on the
change in soil ammonium levels between each
sampling date in Hodunk sandy loam with Milorganite
appliedasthenitrogensource ................ 60

LIST OF TABLES (Continued)

Table Page
13. Effect of pesticides and time of incubation on change

in nitrate nitrogen levels between each sampling

date in Hodunk sandy loam with Milorganite applied

asthenitrogensource....................... 64
14. Effect of pesticides and time of incubation on the change

in total soil nitrogen levels (ammonium + nitrate)

between each sampling date in Hodunk sandy loam

with Milorganite as the nih‘ogen source . . . . . . . . . . . . 67
15. Analyses of variance for data of greenhouse experiment 1 . . 84

16. Analyses of variance for data of greenhouse experiment 2 . . 85

17. Analyses of variance for clipping weights data of the
fieldexperimento0....OOOOOOOOOOOOOOOOOOOOO 86

18. Analyses of variance for per cent nitrogen in leaf tissue
dataofthefieldexperiment . 87

19. Analyses of variance for turf color rating and density count
dataofthefieldexperiment .. 88

20. Analyses of variance for soil mineral nitrogen data of the
fieldexperiment........................... 89

vi

LIST OF FIGURES

Figure Page

1 . Effect of pesticides on ammonification of Milorganite
inHodunksandyloam................... 62

vii

INTRODUCTION

The sport of golf today is enjoying it's greatest popularity. This
is partly due to the impact of television, increasing population, and
increasing leisure time of the people. Years ago, a golf course could
expect around 5,000 to 7,000 rounds of play per year. Today, many
courses have 20,000 to 50,000 rounds per year. This figure can be
expected to rise as the population increases and lighted courses
become prevalent.

As a result of this increase in play, conditions under which the
turf is grown have been affected. One fact stands out clearly; growing
conditions have so been altered that greater stress has been put on the
actively growing turf. For example, increased irrigation and traffic
lead to greater compaction of soil, causing a reduction in the oxygen
supply available for plant growth. Furthermore, this added stress has
been responsible for an increasing susceptibility of the grass plants to
be injured from disease and soil insects and for weeds to invade turf
areas. Compounding this situation is the problem that today's player
demands the finest playing conditions that turf managers can produce.
All this has led the turf manager of today to use increasing amounts of
pesticides to control plant parasites and weeds.

Outside the area of golf courses, there has been an increased
emphasis on quality home lawns with high maintenance requirements .

Requirements have also risen for industrial grounds, parks, cemeteries,

and school grounds. The trend here is toward applying more pesticides,
either separately or contained in fertilizers, at increased levels.

Much research has been done in the area of how effective these
pesticides are in controlling plant parasites and weeds. However,
little research has been done on the possible effects these pesticides
have on plant growth, other than controlling the target species.

Considerable research has been conducted with pesticides as
they affect mineralization and nitrification of soil nitrogen. In the
realm of turfgrass management, a number of different nitrogen fertili-
zers are used. Certain of these fertilizers require breakdown by the
microbial population in the soil for release of available nitrogen. It
is in this area that information is lacking on the possible effects
pesticides may have on microbial activity and transformations of
fertilizer and soil nitrogen.

It is the purpose of this investigation, first to study the effect
of selected turf pesticides on turfgrass growth; second, to study
possible interactions between these pesticides and turfgrass fertilizers;
and third, to study what effect these pesticides have on nitrogen

transformations in soil.

LITERATURE REVIEW

Turf fungicides and insecticides in current use have not been
extensively studied as to their effects on turfgrass growth, other than
controlling target species. Research on the fungicides in this respect
is especially lacking. The following review of literature will focus on
what is known of the effects pesticides have on plant growth and

microbial activity .

Effects of Pesticides on Plant Growth — Beneficial

Ever since pesticides were first applied to plants and soil to control
plant parasites and weeds, agricultural scientists have been interested
in the effects these chemicals exert on plants, soils and non-target
organisms, as well as on the target organisms.

If parasites or weeds are retarding plant growth and a pesticide
application to the soil or plant reduces the concentration of the parasite,
the normal effect is improvement in plant growth. Sometimes, however,
a pesticide will improve plant yield in the apparent absence of the
parasite or when a known parasite is not killed. This type of response
has been called Increased Growth Response (35) and its cause ascribed
to the killing of unrecognized parasites or to various side effects.

Early workers believed this IGR was due to the increased availability
of plant nutrients from the decomposition of the killed microbial cells,

from the decomposition of soil humus, or from the pesticidal chemicals.

4

Fred (18) was of the opinion that, while moderate to large concentra-
tions of a chemical might be toxic, small amounts could stimulate plant
growth. Other investigators (48, 63) believe that improved biological
control by Trichoderma and other organisms are the factors responsible
for IGR.

Several interesting biological control effects could be mentioned.
Vaartaja (63) has shown that certain strongly antagonistic fungi and
bacteria are relatively tolerant to some of the fungicides and fumigants.
This fact was made use of by Bliss (4) who reported that treatment of
infested soil with CS2 did not kill Armillaria mellea (oak root fungus),
but Trichoderma viride, which became dominant after treatment, para-
sitized and killed the fungus. Garret (21) stated that the C32 may not
kill the root parasite, but may weaken it, and _T_. Egg, stimulated by
the treatment, finishes the job.

Muj e et al (39) noted that certain chemicals added to the soil would
stimulate growth of specific fungus species. Acrylic acid, sorbic acid,
and furoic acid greatly stimulated growth of I. girlie. In a greenhouse
study (3 5) to determine if Phytophthora cinnamoni-infested soil treated
with these chemicals would improve growth of avocado seedlings, they
found the treatments stimulated growth of I. 113%, improved growth of

the avocado seedlings, but did not kill the P. cinnamoni.

 

In the area of physiological growth responses to pesticides, a

number of effects have been investigated.

Ries et a1 (51) showed that peach and apple trees, growing in a
soil sprayed with a mixture of simazine and amitrole-T had a higher
leaf nitrogen content and longer terminal growth than trees grown in
a weed-free environment. They suggested that the mixed herbicide,
which is applied to the soil and not the plant, affected nitrogen up—
take or nitrogen metabolism.

Freney (19) reported that simazine increased the yield of corn
tops by 36%, and nitrogen uptake by 37%, but did not increase mineral-
ization of soil nitrogen. These results suggest that simazine increased
plant growth by a direct effect on plant metabolism and not through any
interaction with the soil.

In other experiments by Ries and co-workers (49,50, 62), simazine
was shown to increase growth and nitrogen content of corn, and this
effect was not due to a lack of weed competition nor to the additional
available nitrogen in simazine. These responses to simazine occur in
plants grown with nitrate, but not in plants grown with ammonium as the
nitrogen source, and are greatest when nitrate and temperature are at
sub-optimal levels. They also reported nitrate reductase activity in
corn growing on sub-optimal levels of nitrate increased in a linear
fashion with simazine concentration. From these observations, they
presented the hypothesis that simazine enhanced nitrate utilization by

increasing nitrate reductase activity.

Cooke (10) showed an increase in the soluble and total nitrogen
content of legumes treated with monuron, although no increase in
plant growth was found.

Roots of bluegrass treated with DCPA, amine methylarsonate,
calcium propylarsonate and DMPA were shown by Singh and Campbell
(54) to be significantly longer than on control plants.

Thompson (61) observed that bermudagrass turf sprayed with
Daconil 2787 fungicide exhibited a darker green color than either the
check or plots receiving kromad or velsicol 2/1 fungicide, although
the plots receiving the latter two were not more diseased.

Eno and Everett (14) results showed that heptachlor, TDE, and
DDT increased germination of Stringless Black Valentine beans.

Published results from greenhouse and laboratory work with
atrazine suggest that its use for pre-emergent weed control may also
result in an increase in the efficiency of water use for corn production.
Smith and Buchholtz (55, 56) reported a reduction in transpiration of
several species, including 40% by corn and 65% by soybean plants
six hours after addition of 20 ppm of atrazine to their nutrient solution.
'I‘ranspiration was reduced in plants grown on atrazine-treated soil as

well. Foliar applications were also effective.

Effects of Pesticides on Plant Growth — Detrimental
Occasionally, following the application of a pesticide which kills

a known plant parasite or weed, plant growth is not improved and may

even be further retarded. Various factors may cause these unexpected
results. i

Almost any pesticide, if present in the soil in high enough
concentrations will injure sensitive plants. Therefore, if insufficient
time is allowed for a residual fumigant, fungicide, insecticide or
herbicide to decompose, volatilize or leach out of the plant root area,
the chemical itself may retard growth of sensitive crops. If the dosage
is high, the temperature low, the soil excessively wet or high in
colloids, longer intervals between pesticidal treatments will be
necessary.

Repeated applications of the persistent chlorinated hydrocarbon
insecticides may increase concentration to levels which are toxic to
sensitive plants. Martin (34) noted that concentrations of residual
DDT, toxaphene, chlordane, and other chlorinated hydrocarbons were
high enough to injure some plants. Cucumbers, cantaloupes, water-
melons, some varieties of beans, and potatoes were sensitive to one
or more of the insecticides. Morrison et al (38) found that 137.5 pounds
of DDT per acre caused severe stunting to bush and pole beans.
Tomato transplants were slightly stunted and had small leaves.

Eno and Everett (14) showed that BHC reduced germination of Black
Valentine beans 14.3% compared to the check. Root and top weights
were reduced by chlordane, lindane, aldrin, dieldrin, TDE, and BHC.

Martin and Pratt (37) point out that inorganic end products, such

as bromides and chlorides, released during the decomposition of

8
pesticides may increase to sufficiently high levels to injure plants .
Several crops are sensitive to bromine containing organic compounds
or to the bromide ion. Included are beans, cabbage, celery, onions,
peas, and potatoes. Often, citrus trees replanted in soil previously
treated with high dosages of ethyiene dibromide to control citrus
nematodes, grow much slower initially than trees planted in soil
treated with other fumigants (36) .

Sherman and Fujimoto (53) showed that increases in extractable
or soluble Mn, Cu, of Zn following soil fumigation may be sufficient
to cause plant injury.

Another little-understood temporary toxicity observed by Martin
(34) may occasionally occur when soils are treated with a chemical
which kills a large number of soil organisms. The toxicity may last
from a few weeks to a year. Affected plants fail to absorb phosphorous
even though the treatments may have increased the soluble or extractable
soil phosphorous. The plants cease growing, but continue to adsorb
Na, K, and B, which may reach toxic levels. With time and in a
spotty manner, the toxic condition dissipates and the plants resume
normal growth.

In the area of turfgrasses, certain effects on growth have been
observed. Gaskin (23) reported that Kentucky bluegrass plants treated
with crabgrass herbicides showed reduction of rhizome number and
length and number of tillers. Zytron, dacthal, and trifluralin produced

the greatest reduction at 1 1/2 times the Standard rate of application.

9
Bandane and chlordane reduced rhizome development only at 1 1/2
times the standard rate. Crab-e-rad reduced the number of tillers
and length of rhizomes.

Engel and Callahan (13) showed that bensulide, terbutol, chlordane,
DMPA, and DCPA reduced top growth and that bensulide and terbutol
seriously inhibited root development.

Singh and Campbell (54) noted that bluegrass turf treated with

trifluralin and polychlorodicyclopentodiene resulted in considerably
reduced turf density.

Iagschitz and Skogley (2 7) presented data that showed dacthal
caused a reduction in turfgrass cover where nitrogen was not used.
Red fescue was reduced more than bentgrass or bluegrass. Where
nitrogen was applied no apparent reduction of turfgrass was caused

by the addition of dacthal.
Effects of Pesticides on Microbial Numbers

Pesticides added to the soil can cause varied effects. First,
there is the possibility of a direct, toxic action on a microorganism
by affecting some aspect of its essential metabolic activity. Second,
the pesticide may have a selective toxicity for certain groups of
microorganisms, and third, pesticides may promote, either directly
or indirectly, the growth of one or more types of soil organisms.

One of the earliest and most striking cases of increase in bacterial

numbers in the field, due to the utilization of an herbicide as a substrate

10
for growth, is that of calcium cyanamide. Allison (1) showed that
over a period of one or two weeks after application the total bacterial
number can increase over thirty times and this is correlated with a
general increase in soil respiration.

In a very extensive review of the phenoxy herbicides , Audus (3)
points out that in some cases adverse and beneficial effects were
noted, but on the whole the great majority of observations show
that with normal practical rates of application there are no adverse
effects of the phenoxy herbicides on the total number of microorgan—
isms in the soil.

The effects of the halogenated aliphatic acids on the total soil
populations are as diverse as those of the phenoxy herbicides.
Kratochvil (30) reports a transitory reduction induced by herbicidal
TCA, while Hale (25) notes that Dalapon has a slight stimulating
effect on the general soil population.

The carbamates show the same diversity of effect. Reduction
in the total numbers, as measured by soil respiration, has been
reported with propham by Kratochvil (30) but could not be detected
by Newman (42). EPTC temporarily depresses soil respiration (9);
while, on the other hand, chloropham apparently increases it (60).

Audus (3) states that the nitrophenol herbicides are quite toxic
to all soil microorganisms, although marked inhibitory effects are

not always observed at normal rates of application.

11

Chandra et al (9) showed that simazine temporarily increased the
carbon dioxide evolution 12 to 14% in two soil types.

Observations by Dubey (11) show that prometryne at 100 ppm had
practically no effect on microbial population. Ametryne at 100 ppm
reduced the actinomycete population in heavy soils, while diuron and
picloram at 100 ppm reduced the actinomycetes in all types of soils.

In early studies on insecticides by Smith and Wenzel (57), DDT
was shown to have no detrimental effects on soil microbes when applied
up to 400 pounds per acre.

Wilson and Choudri (69), in laboratory studies, showed that BHC
and DDT in amounts considerably exceeding practical field applications,
had no significant effect on development of bacteria and molds nor on
physiological activities important to soil fertility.

Bollen et al (5) found BHC isomers added to clay adobe soil at
1000 ppm varied in their effects on the number of bacteria and molds
which developed during incubation. They also made field application
of gamma BHC at 20 pounds per acre on several loams and found no
effects. These same investigators (6) also report that parathion,
dieldrin, toxaphene and EPN applied at 10 pounds per acre on several
loams had no immediate harmful effects on soil microorganisms.

Fletcher and Bollen (16) determined that aldrin at 200 to 1000 ppm
in several types of soil had a stimulating influence upon the total

number of soil organisms.

12
Richardson (48) showed that the fungicides thiram, nabam and
ferbam increased the numbers of bacteria in the soil. Thiram and ferbam
reduced the number of fungi; whereas, nabam killed nearly all fungi in

the soil. The actinomycetes were unaffected by all the chemicals.

Effects of Pesticides on Ammonification and Nitrification

Ammonification is a very essential part of the nitrogen cycle. It
represents the first stage in the decomposition of complex nitrogenous
compounds of plant and animal origin and is carried out by the decay
organisms in the soil. Whenever these microorganisms decompose
organic matter, they set free more nitrogen than they are able to assimilate
into their own protoplasm when excess nitrogen is present. Under aerobic
conditions, the excess nitrogen appears in the soil as ammonium.

Several investigators (17, 28) have been able to demonstrate no
adverse effects from 2,4-D on ammonification.

Jones (29) observed that DDT applied to the soil at less than 0.1%
did not injure any ammonifiers. Pochon (45) concluded that simizine
and other triazine herbicides are similarly without action on ammonifying
bacteria.

Allison (1) points out that cyanamide can itself be ammonified and
thus contributes to total ammonium in the soil.

Nitrification is the next stage in the nitrogen cycle, and is one
of the most important phenomena occurring in soils. More attention

has been giVen to nitrification because it is easier to observe in both

13
the field and laboratory than is ammonification. It includes two steps.
First, ammonium is transformed to nitrite, which is an unstable compound;
and second, nitrite is oxidized to nitrate. Nitrosomonas and Nitrobacter
are the dominant microorganisms among the nitrifying population, which
includes heterotrophic bacteria, actinomycetes and fungi.

The effects of arsenic compounds on the activity of these organisms
in soils enriched by perfusion of ammonium chloride solutions have been
followed by Quastel and Scholefield (46). They found that M/ 400
sodium arsenate had no effects on the activity, but that the same
concentration of sodium arsenite halved the rate of ammonium oxidation
and completely inhibited nitrite oxidation. This constituted a direct
effect on the enzymatic processes themselves, since the soil columns
used contained saturating populations of nitrifying organisms.

The phenoxy herbicides at normal field rates of application have
either no effect or only a transitory one in the soil, although Flieg (17)
showed that the activity of nitrifying organisms in culture can be con-
siderably checked by such concentrations of 2, 4-D. The addition of
soil removes this inhibition, a phenomenon which may be related to the
adsorption of 2,4-D by the soil colloids or to its degradation by other
soil organisms .

From the majority of reports , it would appear that the chlorinated
aliphatic acid herbicides are quite toxic to the nitrifying bacteria (44).
The effect is temporary, however, and recovery can be complete in

three weeks to a month (71).

14

A number of investigators (25, 47 , 60) have determined that the
carbamates and acetamide herbicides and their homologues all inhibit
nitrification in soils. However, with normal rates of application
recovery takes place after a month. This again suggests that the
nitrifiers acquire some kind of tolerance to them.

Reports for monuron are conflicting. Quastel and Scholefield (47)
claim it is a powerful inhibitor of nitrification; whereas , Hale (25)
could not confirm these findings.

Dubey (11) found that prometyrne did not affect nitrification.
Ametyrne at 100 ppm inhibited the Nitrobacter bacteria. This effect
lasted longer in heavy soils. Diuron showed no effect on nitrification
in fertile loam soil, but in light and heavy-textured soils it caused
increased inhibition of nitrification with increases in its level.
Picloram inhibited nitrification in all soils.

Farmer et a1 (15) carried out studies on nitrification with a
perfusion unit in the presence of varying concentrations of simazine.
Inhibition of nitrification was noted at concentrations of 6 ppm and
above. A similar effect was noted with pure culture studies of
Nitrobacter, but not with Nitrfiomonas.

Several investigators (15,69) have shown no harmful effects to
the nitrifiers from DDT.

Gray (24) observed that BHC and its isomers were toxic to the

nitrifiers at a concentration of 0. 01%.

15

Aldrin, dieldrin, and chlordane as reported by Brown (8), were
shown to cause a significant retardation of nitrification in soil at the
rate of 0.05% and 0. 5%. Heptachlor and lindane decreased nitrifica-
tion at 0. 5% only, while DDT had little effect on nitrification.

Nishihara (43) found that diazinon, dithane, BHC, vapam and
maneb are inhibitors of nitrification. He also points out that the
effectiveness of these chemicals is increased under soil conditions
which suppress the activity of the nitrifiers. Their effectiveness
varied with the kind of soil.

Garretson (22) was able to show that aldrin, lindane and TDE at
final medium concentration of l ug/ml were toxic to Nitrobacter _a_gi_li§,
i with lindane being least toxic of the three. Malathion and parathion,
two organic phosphate compounds, differed widely in their toxicity for
Nitrobacter. Malathion was the least toxic, causing only delayed
nitrification at 1000 ug/ml. Parathion, as toxic as aldrin, gave complete
inhibition at 10 ug/ml or greater. Baygon, a methyl carbamate delayed
nitrification by Nitrobacter at concentrations of 10 ug/ml. Lindane,
malathion and baygon were also tested against Nitrosomonas europaea.
All three compounds were at least 100 times more toxic for the

Nitrosomonas culture than for the Nitrobacter.

 

METHODS AND MATERIALS

Greenhouse Experiment 1

In this study, the growth response of grass and nitrogen trans-
formations in the soil were surveyed as affected by nine pesticides
at two rates. Pennlawn creeping red fescue (Festuca rubra) was
seeded in each of eighty 6-inch diameter pots. Each pot was lined
with a polyethelene liner and 3,800 grams of an air-dried Hodunk
sandy loam added. Soil test analysis showed this soil to be high in
phosphorous and medium-high in potassium for turfgrasses, and to
have a pH of 6.6. The cation exchange capacity was 5.65 me/100 g soil.

Milorganite, described in Table 2, was applied at the rate of
2/ 3 pound nitrogen per 1000 square feet at seeding time and on the
fifteenth of each month until the experiment was completed. No
additional phosphorous or potassium was added. The plants were
grown in the greenhouse on tables with supplemental light to provide
a photo period of 12 hours or longer until daylength reached this
duration. Position of the pots on the tables was changed periodically
to reduce border effects. Watering was done every third day or as
needed to bring the soil up to field capacity.

Analysis and rate of application of the pesticides used are given
in Table 1 . Each pesticide was applied at the recommended rate and
10 times the recommended rate of application. Treatments were started

March 14, 1967. The insecticides 825141, Diazinon, dieldrin, and

16

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l8

chlordane were applied once a month and the fungicides Calo Clor,
Cadminate, Tersan-OM, Dyrene and acti-dione thiram were applied
every 14 days. All treatments were replicated four times.

The plants were clipped to a 1 1/2-inch height every 10 days.
The clippings were collected and oven-dried at 35°C. Dry clipping
weights were recorded on a monthly basis for three months. On
June 14, 1967, soil samples were taken from each pot and the soil
analyzed for total mineral nitrogen (ammonium + nitrate) by a micro-

Kj eldahl procedure (7) .

Greenhouse Experiment 2
In this experiment, the effects of four pesticides superimposed
on nitrogen treatments of 0, 1/6, and 2/3 pounds of nitrogen per

1000 square feet per month for three nitrogen carriers were studied.

The nitrogen analysis of these carriers is given in Table 2. Pennlawn

creeping red fescue (Festuca rubra) was seeded in 140 six-inch pots.

 

The preparation of the pots and the soil, the date and rate of seeding

and other cultural practices used were the same as in experiment 1.

Table 2. Materials compared as sources of nitrogen.

 

 

 

Material Formula % N Source
Ammonium nitrate NH 4N03 33.5 Spencer Chem. Co.
Milorganite Activated sewage 7.0 Milwaukee Sewage

sludge Commission
Urea-formaldhyde Mixture of 38.5 E. I. duPont

methylene ureas Uramite

19

Analysis of the pesticides used and rates of application are
given in Table 1 . The insecticides 325141 and Diazinon were applied
once a month and the fungicides Calo Clor and Cadminate were applied
every 14 days. Treatments were started March 14, 1967, with four
replications .

The plants were clipped to a 1 1/2 inch height every 10 days;
clippings were oven-dried and weights recorded on a monthly basis

for 5 months.
Field Experiment

The experiment was located on a five-year-old stand of Cohansey
bentgrass (Agrostis sp.) turf at the Soils Research Farm of Michigan
State University. The soil was a specially prepared soil mixture
consisting of 2 parts coarse concrete sand, 1 part Hodunk sandy loam
soil, and 1 part peat by volume. Individual plot size was 3 by 6 ft.
and each plot was separated by a 6-inch strip of aluminum grass guard
placed vertically between plots .

In the year of the test, 1967, the plots were fertilized once each
in April and May, with a 10-10-10 grade fertilizer at the rate of 1 pound
nitrogen per 1000 sq. ft. No additional fertilizer was applied until
treatments were started.

Four pesticides, Diazinon, B25141 , acti—dione thiram and
Tersan-OM were used at rates outlined in Table 1 . A no pesticide

treatment was included in the study. Treatments were begun July 2,

20
1967 , and applied every 10 days thereafter until completion of the
experiment. The pesticides were applied with an Ortho Spray-ette
hand sprayer, having a fan-type nozzle, and the pressure used was
40 psi. When spraying, a 3 by 6 by 3 ft. plywood box (no bottom)
was placed over the plot. On August 15, the entire area was sprayed
with Cadminate fungicide to control a slight infestation of Dollar
Spot disease.

Superimposed on these treatments were applications of 0 and 1
pound of nitrogen per 1000 square feet applied July 1 , August 1 , and
September 1 . Nitrogen carriers were ammonium nitrate and Milorganite
described in Table 2. In addition, a treatment of Tersan-OM applied
every 10 days at 10 times the recommended rate of Table l with no
nitrogen was studied.

The area was irrigated when necessary, {so as to keep the soil
moisture as close as possible to field capacity and also following
each nitrogen application.

The plots were mowed every 5 days to a l/2—inch height with
a Jacobsen greens mower. Clippings were collected from a 7.6 sq. ft.
area of each plot at each mowing, oven-dried at 35° C and weights
recorded on a monthly basis for three months .

Color quality ratings were taken for each plot at the end of each
month. A 1-10 scale, with 1 being darkest green color and 10 being.

lightest green color was used for rating.

21

Density counts were obtained from two 3-inch plugs randomly
selected from each plot. Counts were taken on October 5, 1967 .

Soil samples were taken from each plot on October 2, 1967 , and
analyzed for ammonium nitrogen and nitrate nitrogen by a micro—
Kjeldahl procedure (7).

The plots receiving Tersan—OM, Diazinon, and acti-dione thiram
and the control with ammonium nitrate as the nitrogen source were
tested for effects on microbial populations. Sampling dates were:
for Diazinon, September 11; for Tersan-OM, September 27; and for
acti-dione thiram, October 12, 1967. An estimate of the population
of fungi, actinomycetes, and bacteria in treated and untreated soil was
obtained by use of soil dilution plate counts. The actinomycetes
population was estimated after 5 days growth on chitin agar (31) , the
fungal population after 5 days on OAES agar (66) , and the aerobic
bacteria after 5 days on soil extract agar (32) . In addition, three other
media were used for estimation of aerobic bacteria. These were variations
of media developed by Valera and Alexander (64) and Woldendorf (70).
Their composition is listed below:

M1132:

#121 - Glucose - nitrate .agar plus growth factors

#103 — Glucose - nitrate agar without growth factors

#120 - Glutamate — nitrate agar without growth factors
Aneorobic bacteria were estimated on media 103, 121 , and 120 incubated

in 98% N2 and 95% CO2 atmospheres for 7 days. Bacteria suppressed by

22
the N 2 and COZ, but still viable, were estimated by counting the

additional colonies which had appeared 3 days after removal from

anaerobic conditions. All incubations were conducted at 25° C.
Laboratory Incubation Experiment

The objective of this experiment was to study the effects of some
of the insecticides and fungicides used in the greenhouse and field
studies on microbial activity and nitrogen transformations in soil.
Milorganite fertilizer was used as the nitrogen source.

Prior to incubation, 200 gram lots of an air-dried Hodunk sandy
loam were mixed with the insecticides B25141 , Diazinon, and Dieldrin
and the fungicides Calo Clor, acti-dione thiram, and Tersan-OM. At
this time, Milorganite at 350 ppm (2 pounds nitrogen per 1000 sq. ft.)
was also mixed with the soil. In addition to these treatments, a
control receiving Milorganite but no pesticide and a check receiving
no nitrogen and no pesticide were studied. Two blanks with no soil
and no pesticide were included. Table 3 gives the rates of pesticides

used per 200 grams of soil and a 5-fold rate.

23

Table 3. Soil treatments imposed on air-dried Hodunk sandy loam
prior to incubation.

 

 

 

ppm Added per 5-Fold rate--ppm per
Pesticides 200 grams of soil 200 grams of soil
B25141 320* 1600
Diazinon 320 1600
Dieldrin 60 300
Acti—dione thiram 560 2800
Calo Clor 450 2250
Tersan-OM 560 2800

 

* Active ingredients added.
Incubation Procedure

In this experiment, a static method of incubation was used as
described by Stotsky (59). Ten gram samples of the soil from the treated
and untreated lots were placed in 60 ml plastic cups containing 30 grams
of a 30-60 mesh white silica sand. The sand and the soil were
thoroughly mixed. Six ml of distilled water was then added to each
cup. Groups of 16 samples for each pesticide treatment were placed
in one-gallon respirometer jars to permit continuous collection of CO2
and periodic sacrifice of subsamples for determination of ammonium
and nitrate nitrogen levels in the soil.

Incubation was carried out in a growth chamber, with a constant

temperature of 300 C beginning January 27, 1968. Two subsamples of

24
soil were removed from each respirometer jar for determination of
ammonium-N and-nitrate-N by a micro-Kj eldahl procedure (7) every
fourth day beginning with January 27 , 1968 until the experiment was

completed.
Collection of Carbon Dioxide

A small vial containing 5 ml of 1N NaOH solution was placed in
the bottom of each jar to collect the evolved carbon dioxide. The
carbon dioxide was determined every day for the first two days and
then every other day until the experiment was completed. The unused
NaOH was titrated against 0. SN HCl in the presence of phenolpthalien
and excess barium chloride. Carbon dioxide was calculated by
difference (59) and is reported as mg. carbon per 100 grams soil
(oven—dried basis) per day.

All data from the above experiments were analyzed statistically
by analysis of variance (58). In some cases, means were compared

by the Duncan's Multiple Range Test (12).

RESULTS AND DISCUSSION

Greenhouse Experiment 1

The treatments employed in this study were applied at two rates;
the recommended rate and 10 times the recommended rate of application.
For the insecticides the recommended rate is that required to control sod
webworms and chinch bugs in turf, and for the fungicides the recommended
rate was the manufacturer's recommendation for disease control.

In some instances, larger than normal rates are recommended for
the control of a plant parasite. For example, some fungicides are used
at 2 times the recommended rate to control a severe infestation of
disease. They may be applied every 7-10 days in critical periods.
Some insecticides are used at 3 times the recommended rate for chinch
bugs in order to control nematodes. For these reasons, 10 times the
recommended rate of application was used in this experiment. This rate
may reflect the effects of large applications or accumulations of a
pesticide over a period of time.

All data will be compared using the Least Significant Difference or
Duncan's Multiple Range Test at the 5% level.

The results in Table 4 show that effects on top growth did occur with
pesticide treatments. Analyses of variance for data is given in Table 15
of the Appendix. Insecticides will be compared first. For the sake of
brevity, the notation "x" and "10x" will denote the recommended and

10 times the recommended rates of applications, respectively. During

25

26

 

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27

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28
the first two weeks of the experiment (March 27—April 14), top growth
was not significantly affected by any of the insecticide treatments at
the recommended rate of application. At the 10x rate, 825141 was the
only insecticide to significantly increase top growth compared to the
control. In the last two months and for the entire 2 1/ 2 months of the
experiment, B25141 at the x rate and diazinon at both rates, significantly
increased growth over the control. B25141 at the 10x rate was signif-
icant over the control in the month of April 14-May 14, but in the last
month, it became toxic and plant growth was greatly reduced. Visual
observation showed that, while growth was still stimulated in the last
month, the blade tips became yellow and the plants eventually died.
Dieldrin and chlordane, at both rates of application, did not differ
significantly from the control.

When comparing means for insecticides against each other (Duncan's
Multiple Range Test), it is seen that at the x rate B25141 significantly
increased top growth over Dieldrin and chlordane during the entire
growing period. At the 10x rate, clipping weights from Diazinon-treated
pots were significantly greater than for Dieldrin or chlordane. B2 5141
probably would have been significant over Dieldrin and chlordane had
the plants not died. These results indicate that the organophosphate
insecticides, Diazinon and 825141 , significantly influenced top growth
while the chlorinated hydrocarbons had no effect.

Among the fungicide treatments, the recommended rate of application

of Calo Clor and Tersan-OM significantly increased top growth for the

29
month of April 14-May 14, but not for the entire 2 1/2 months of the
experiment. In addition, acti-dione thiram significantly decreased
top growth over the 2 1/2 month period compared to the no pesticide
treatment.

At the .10x rate, it is seen that Tersan-OM greatly influenced
growth for each harvest period. Calo Clor gave a significant increase
over the control, but not to the extent that Tersan-OM did. Dyrene
and iacti-dione thiram significantly reduced growth, while Cadminate
had no effect.

When comparing means for fungicides against each other, it is
seen that Calo Clor and Tersan-OM significantly increased growth
over Dyrene and acti—dione thiram at the x rate for the 2 1/ 2 months
of growth. This was also evident at the 10x rate, especially with the
Tersan-OM treatment as it became significant over Calo Clor. Further-
more, Dyrene was significant over acti-dione thiram.

The effect of these pesticides on the mineral nitrogen (NH4, N02,
and N03) in the soil was determinedat the conclusion of the experiment.
Milorganite was used as the nitrogen source. Results in Table 4 reveal
that for the insecticide B2 5141 at both rates of application, and
Diazinon and Dieldrin at the 10x rate, significantly increased mineral
nitrogen over the unireated control. B25141 was, at the 10x rate, the
most effective treatmentunearly tripling the mineral nitrogen level.

Soils treated with Diazinon, B2 5141 , and Dieldrin at the 10x rate

significantly increased mineral nitrogen over chlordane-treated soils,

30
according to Duncan's Multiple Range Test. At the x rate, only the
B25141-treated soil contained significantly more mineral nitrogen
compared to chlordane.

For the fungicides, only Cadminate at the x rate and acti—dione
thiram at the 10x rate were effective in increasing mineral nitrogen
over the control. Acti-dione thiram at the 10x rate gave increased
nitrogen over all other fungicide treatments. This may have been due
to decreased top growth of grass under the high rate of acti-dione

thiram. allowing a buildup of mineral nitrogen.

31

Greenhouse Experiment 2

In our modern era of turf management, there are a variety of
nitrogen sources being used at varying rates. Also, in some instances,
such as turf maintenance programs on golf courses, many insecticides
and fungicides are used in connection with these nitrogen fertilizers.

It was, therefore, the purpose of this experiment to study the effect
of applying certain pesticides on growth of Pennlawn red fescue when
treated with three different forms of nitrogen carriers. These sources
were ammonium nitrate, a readily available form of nitrogen; activated
sewage sludge, a natural organic form of nitrogen; and ureaform, a
slow release synthetic organic carrier.

The results given in Table 5 show the effect of fertilizers and
pesticides on top growth over a 5-month period in the greenhouse.
Analyses of variance for data is given in Table 16 of the Appendix.
Where no fertilizer was applied, the insecticide 825141 was the only
pesticide treatment to significantly increase growth over the no pesticide
control. Compare means for pesticides horizontally using the LSD
(5% level) of 0. 59 for a given nitrogen treatment.

When ammonium nitrate was the nitrogen source used, no pesticide
treatment significantly increased growth over the untreated control for
either nitrogen rate. However, it can be seen that while clipping
weights for the 825141 treatment were not: significantly greater than the

control, it was significant over the effects of the Cadminate treatment

32
at the low rate of nitrogen; and that 825141, Diazinon, and Calo Clor
were significant over Cadminate at the high rate of nitrogen.

Where Milorganite and ureaform were the nitrogen sources used,
825141 again significantly increased growth over the untreated control,
and over the Cadminate treatment for both rates of nitrogen and both
carriers; but, Cadminate was not significantly different from the
control in either instance. In addition, the Diazinon treatment was
significant over the control under Milorganite applied at the lower rate
and ureaform applied at the higher rate. Diazinon and Calo Clor
significantly increased growth over Cadminate at both rates of ureaform,
but not for Milorganite.

The overall average effect of pesticides, regardless of nitrogen
source, is given in the last row of Table 5. It shows that 825141 ,
Diazinon, and Calo Clor stimulated growth significantly, while
Cadminate had a depressing effect.

When comparing the effectiveness of the nitrogen carriers under
the different pesticide treatments, certain differences are noted
(Pesticide means compared by Duncan's Multiple Range test within
vertical columns). For the no pesticide and Diazinon treatments, and
for the average effect of nitrogen fertilizers regardless of pesticide,
the order of effectiveness is the same; i.e. ammonium nitrate at the
high rate is significant over all other fertilizer treatments: Milorganite
and ureaform at the high rate and ammonium nitrate at the low rate,

Milorganite and ureaform at the low rate; and the no nitrogen treatment.

33

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34

For the remaining pesticide treatments , 825141 , Cadminate,
and Calo Clor, ammonium nitrate at the high rate is again significantly
greater than all other fertilizer treatments . Differences occur with the
other carriers and rates. Where 825141 is used under the Milorganite
and ureaform at the high rate, top growth is stimulated to the point
where it is significant over ammonium nitrate at the low rate. Further,
the Milorganite and ureaform treatments at the low rate of nitrogen
compare favorably with ammonium nitrate at the low rate.

For the Cadminate treatment, the only difference seen is that the
top growth from ureaform at the high rate is depressed to a point where
it is significantly lower than top growth from ammonium nitrate at the
low rate .

Where Calo Clor is used, the only difference compared to the
no pesticide treatment noted is that top growth under the Milorganite
applied at the high rate isstimulated to the point where it is significant

over ammonium nitrate at the low rate.

35

Field Experiment

The field experiment was conducted in the summer of 1967 .
Treatments employed were based on results from the two preceding
greenhouse experiments. The nitrogen carriers used were ammonium
nitrate and activated sewage sludge. A no nitrogen level was also used
as a comparison against the nitrogen carriers.

The insecticides used were 825141 and Diazinon, and the fungicides
were Tersan-OM and acti-dione thiram. In addition, Tersan-OM' was
applied at 10 times the recommended rate of application, under the no
nitogen level. All pesticide treatments were applied 9 times over a
3-month period. For the insecticides (825141 and Diazinon) and
Tersan-OM at the 10x rate of application, this rate exceeds the normal
usage for turf, although the insecticides are applied at 5 times the
recommended rate for nematode contol. Normally, these insecticides
are used only on turf once or twice during a growing season. The more
frequent applications were used to determine what effects on plant
growth and soil nitrogen tansforrnations may result from more numerous
applications or from a build-up in the soil over a period of time under
field conditions.

Analysis of variance for all field data is given in Tables 17, 18,

19, and 20 of the Appendix.

Clipping Weights

The results in Table 6 show that in the month of July the insecticides

36

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37

 

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38
825141 and Diazinon significantly increased clipping weights over the
check when ammonium nitrate and Milorganite were used as the nitrogen
sources. This trend continued in August and September for Diazinon.
825141-treated plots gave greater yields in August, but in September
they were about equal with the check, indicating that toxicity may have
occurred. For the total seasonal clipping weights, these two insecticides
again were significant over the check for the ammonium nitrate treated
plots. The significance was not evident under Milorganite, but the
values tended to be higher. This trend of higher clipping weights over
the check for 825141 and Diazinon was also evident in all three months
under the no nitogen treatment and resulted in a significant increase
for the total clipping weights for the 825141 teatnent.

Among the fungicide treatments, Tersan-OM significantly increased
top growth over the check in August and for the three-month period of
growth under the ammonium nitate teatnent. Values were also higher
in July and September. This trend for higher clipping weights from the
application of Tersan-OM was also observed for the Milorganite and
no nitrogen teatnent, but was significant only for the total clipping
weight under the no nitrogen treatment. Acti-dione thiram showed a
slight tendency to increase top growth for all nitogen treatments over
the season, but no significant differences were noted.

A very definite increase in growth was observed from Tersan—OM

applied at 10 times the recommended rate under the no nitrogen teatnent.

39
Growth for each month compared favorably with plots receiving
Milorganite.
The last section of Table 6 shows the average effect of pesticides,
regardless of nitogen teatments. 825141 , Diazinon and Tersan-OM
stimulated growth significantly over the check, particularly in July

and for the total clipping weight.

Per Cent Nit'ogen in Leaf Tissue

The data presented in Table 7 show that when ammonium nitrate
was the nitogen source, applications of the insecticides 825141 and
Diazinon resulted in a significantly greater percentage of nitogen in
the leaf tissue than the check in July. 825141 continued to be signif-
icant in August but not in September.

When Milorganite was the nitogen source used, 825141 , Diazinon,
and Tersan-OM increased the per cent of nitrogen in the leaf tissue
over the check in July. In August and September, however, this trend
was not significant.

When no nitogen was applied, no significant increase in per cent
nitrogen in the leaf tissue was observed for the months of July and
September, but in August 825141 and Diazinon caused a significant
increase. The acti-dione thiram treatment resulted in a significant
decrease in per cent nitrogen in the leaf tissue in August. This tendency
was also observable in August and September under the two nitogen

carriers, although not significant.

 

40

 

on He.m no me.m mm ao.e gauge
on eq.m e mm.m ew dm.¢ Sorceeuea
o om.m e0 m¢.m mom s~.s saunas muone-nuo<
n «o.m e mo.m we wo.¢ Hennmm
en ~¢.m e qo.m ewe m¢.¢ cocnnmnn
"Neufiaowuonnz
e n~.¢ n ~n.¢ we no.9 xeeno
m em.e no m~.¢ en on.q Zeucwmney
m mo.¢ n no.9 en mm.¢ Emunnu ecoawnauew
m mn.¢ m m¢.¢ w ou.m anmmn
m mm.q no mN.q tnw oo.m ooaauwan
"neuwuuwo.aswcoaa<
uenaeuaem umsme< know uaeaumeuu :owouunc

 

osmmnu ween an cemouuac ucee Hem

wan ownenumem

 

 

.mcowuwwcoe wnenm Hows: mmeuwucen mewcwnoo mo esmmnu
noon on :ewouunc name you no onenuume cowouuna woe mewHeHumem mo ueommm .n enan

41

.n manna an nopfiw mm .euwu wewceaaoeeu meaau seam
.nuaoa you .um .vo ooon Hen newouunc .nn n no eumu one am wennnnw euacmeOHHzN
.nucoa Hem .um .ve OOOH Hem nemouuwn .nn n no mean enu um wewnmmo eumuunc Eswaoaa¢n

.Nn um uceuemmnw mnuaoenmncwnm uoa one Houuen meow kn wenamaaoeew mesno>
.maaanoe canun3 eecenu>nsve no woman“ onmnunaa m.cwe::nuuw wan .m.e.w.e.n.m r

 

nu on.m on as.m n kn.q rouse
m an.m n 9m.m a ~m.q zo-ammuoa
n om.m u H9.m n o~.q amuanu «cone-nuo<
a mm.m a kk.m a oo.¢ anmum
m kn.m m ao.m a Hm.s aosnnann

"newnenuoem you ewmne><

we aH.m e nm.m_ meg m¢.¢ mxon zetamauma
em Hm.~ a ma.~ am ow.m sumac
em sk.~ m mm.N aw sw.m zouammuoa

e wo.~ e mm.~ n m~.m sauna” muone-nuo<
we wa.~ e -.m am No.9 HanNm
emu Na.~ e on.m new no.9 aoanumnn

“demonuwc oz

42
Again, as with the clipping weights, Tersan-OM at the 10x rate
under no nitogen compared quite favorably with Milorganite-teated
plots.
The averages for the pesticides, regardless of nitrogen carrier or
level, show that the two insecticides 825141 and Diazinon were

significant over the check in July and August, but not in September.

Nitrogen Uptake

In Table 8, clipping weights and nitrogen composition data were
used to determine total nitrogen uptake. The results show that on
plots receiving ammonium nitrate, Diazinon caused a significant
increase in nitrogen uptake over the check in July but not August or
September, although values tended to be higher in these two months.
825141 was significant over the check in July and August, but not in
September. Tersan-OM gave a significant increase in nitrogen uptake
in August, but not in July or September; however, again values tended
to be higher in these two months than for the check. All three materials
were significant over the check for total seasonal nitogen uptake.

Diazinon, 825141 , and Tersan—OM tended to increase nitogen
uptake for the plots receiving Milorganite and no nitogen. However,
the only significant difference noted over the check was for Diazinon
and 825141 in July under Milorganite and for 825141 over the 3-month

period of growth for both nitogen teatnents.

 

43

 

w mwm e nmn e oum ow oom neenu
we moo e own e mom ow NHN SolaoouoH
w moo e mun e now w onw Sounnu econwunue<
e Nmo e mon e omm e CAN nonmmm
we woo e won e mom e omN :oanuowm
“mouwcowHOan
n amm no Nnm n com on Now neono
o noOn o mmm o How n mum SOuaoouoH
n mom n oom no mum on mom Eouflnu econwuaue<
o omen n mam o moo o own nonmwm
o menn o nom no oom to now cocnuonm
“nououunc Eoncoae<
nouoe nonseumom uo=w=< hnsw uaeauoeuu-aomouuwa

 

.um .vo 000n Hem exoums cowouuno maouw

woo owneneoem

 

 

.oconunwcoe wnenm.uewca.

moouwuaon homconoo mo oxoums :omouunc no onenuuoe comouuaa woo oownenuoea mo ueomwm .w ennoH

44

.n onnoa on oo>nw oo .ouou wowooaaoeou ooaau ooH

m

.nuooE poo .um .vo oooH you oowouuao .nn n no euou onu uo wonnooo euwoowumnHZN

.nuooE Moo .um .wo OOOH Moo oowouuao .nn H mo ouou one no wonnooo ououuwo_aoflooaa<

hn wonoooaoeeo moono>

n

.Nm uo uoonowwww anuooenmnowfio uoo ouo nouuon eaoo

.ooaonoe onnuHB.oeoono>Hove mo oowoou ononunoa o.ooeoonuum woo .o.w.e.n.o r

 

U0

m0

m0

m0

coo a
one a
owe a
fink on
non no
moo o
mam e
men e
son a
mum e
“mm a

#5n
nmn
Nun
own

won

non
oo
as
ch
mm

on

no

mNN
mom
me
don

wow

mmu
mm

onn
can
own

Hun

H0

mom
Hmm
HHN
ohm

mum

mnw
own
«on
omn
Hun

oon

neono

Eoiooouoa

aounnu ooonwunueo
nonmu m

oooanofin

“mownewuooo Mom omouo><

moon Sciooouea
noose

Zorooouoh

Bounnu ooOnwuaueo
nonnmm

ooonoown

“oowouuno oz

45
Acti-dione thiram had no effect under any nitrogen treatment.
Tersan-OM at the 10x rate under no nitogen again performed as well
as plots receiving Milorganite.
The averages for all pesticides showed Diazinon, 825141 , and
Tersan-OM caused increases in nitogen uptake throughout the

experime nt .

Turf Color Rating and Density Counts

For plots receiving ammonium nitrate, the data in Table 9 show
no significant difference in color rating was observed for any pesticide
teatnent in July, but Diazinon and Tersan-OM plots rated significantly
better than the check in August and September.

Tersan—OM-treated plots also rated significantly better than the
check in August when Milorganite was the nitogen source. No other
pesticide affected turf color ratings.

Where no nitogen was applied, plots receiving Tersan-OM showed
significantly better color than the check in all three months. In addition,
825141-teated plots were significantly better in September. A marked
effect on color was observed for Tersan-OM applied at 10 times the
recommended rate. In July and August, these plots rated with those
receiving ammonium nitrate. In September, they were as good as plots
receiving Milorganite.

The average for the pesticides regardless of nitogen source shows

that again Tersan—OM rated significantly better than the check for all

ll] llll IIIInili I

Aomoao:

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46

 

o mmon e w.m ow m.m n w.~ xeono
o oo0n ow m.m eno m.~ n m.~ So-ooouoe
o ooon o n.m wen m.~ n m.~ Bounnu moonwunueo
o Amen owe ~.m owe m.m n m.~ nonmmn
o «men owe ~.m we o.m n m.~ ooonooan
"Nounoowuonnz
o mmOn wen m.~ en w.~ en n.~ xeono
u soon a m.o a k.o no k.o 20-nomuoo
o mw0n eno m.~ eno m.N n m.~ Bounne oooawufiueo
o wenn no w.n no o.N n n.~ nonmmm
o Amen o m.n o w.n *no o.~ ooownonn
“neuouuno aoaooaao
.Ew .vo woo ouoonm uonEeuoom uoowoo know uooaeoouu oowouuno

 

ouoooe munooom..

 

wonuou nonoe muou owouo><

woo owwenuoom

 

 

.ooonunwooe wnonm Howoo ooouwuoon heooonoo mo ouoooe
zunooow woo wonuou nonoe «you o>nuonou oo ouoauuoe oowouuno woo oownenuoeo mo ueomwm .m onnoe

47

.uonoe ooouw uoounwnn H OH .uonoe oooum uooxuow u n monoeo Cain oo ooon wowuou nonooo

.n onnoH on oo>ww mo .ouou wowooaaoeou one moanu ooam

.nuooa poo .um .vo OOOH woo oowouuwo .nn n we ouou onu uo wownooo ounoowMOanN

.nuooa uoo .um .uo oooH uoo oowouuao .nn H mo ouou onu uo wownooo ououuwo_aowooaa<n

.Nm 88 uaoumoooe mouaooooonmom sea was nouumo use.
kn wonoooaoeeo ooono> .ooaonoe onnuna oeoono>novo mo mowoou ononunoa o.ooeoonuum woo .o.w.e.n.o «

 

n m.e o H.s a o.m noose
o o.m o w.~ o ~.N Sciooouoa
n H.e on ~.m n m.m swoon“ «cooououoo
o m.m n m.m n k.m osnmuo
o o.m n q.m n m.m accommoo

"mowaenuooo you owouo>¢

omen m m.m no o.~ no o.o moon zouaomuoe
mom m 5.0 o m.n a m.n sauce
8 mam o n.m a «.9 o o.¢ souaomuaa
moon mo m.o o m.m o o.m among» maooououoo
mas o m.m o ~.m a o.m HennNm
noon mo ~.o o m.m o m.m aoaouoon

"oowouuno oz

48
three months, and that Diazinon and 825141 rated significantly
better in August and September.
No significant effect on density counts taken October 1 was
observed from any pesticide; however, plots receiving nitogen tended

to have higher counts than those receiving no nitogen.

Mineral Soil Nitrogen

Mineral nitogen (ammonium + nitate) was determined on soil
samples taken October 5. The results in Table 10 show that no
significant differences in the level of ammonium nitrogen in the soil
resulted from the use of these pesticides under either nitogen carrier
or where no nitogen was applied.

For the plots receiving ammonium nitate, the insecticide 825141
significantly increased the level of nitate nitogen over the check.
All other pesticides tended to give higher values than the check,
although no significance was noted.

Where Milorganite was applied and for the plots receiving no
nitogen, no significant difference in the level of nitrate nitogen in
the soil was observed from any pesticide treatnent.

For the total mineral nitogen (ammonium + nitate) in the soil,
again no significant differences were noted from the use of these
pesticides for either nitogen carrier or where no nitogen was used.
The averages for the pesticides, regardless of the nitogen source or
level, show no significant effect on ammonium and nitate levels or

total mineral nitrogen in the soil.

 

 

49

 

weno o.on we N.m o m.m xeono
oweno n.0n wen o.o no o.o Sciooouoa
owe m.m we o.o no o.o Eoanu ooonwunue<
eno c.nn wen o.o o o.o nonmmn
eno N.nn weno n.o no n.m ooonuonn
"Nouaoowuonwz
eno o.nn wen o.o o o.o neono
eno m.nn weno m.o o o.o zoioooHoH
no w.~n no ¢.n no o.o aounnu ooonwinueo
o m.mn o o.o no m.q Honmmm
eno o.nn eno o.o rno o.o oooanonn
"nououuno_aonooaao
oowouuno oowouuno oowouuno uooauoonu oowouuno
ououuno +
aoHooaao Boo ououunz_aoo .aonooaa¢_aoo woo owwenuoom

 

 

.n Honoueo oo nHoo wnoam.mo
uoouooe oowouuwo nouoona oo ouowuuoe oowouuno woo ownefiuoom mo ueommm .OH onnoH

50

.n onnoH on oo>am oo .ouou wowooaaoeou ooaau oon

.nuooa uoo .uw .vo coca woo oowouuao .nn n no ouou one no wonnooo ounoowHOHHzN

.nuooa Moo .um .vo oooH poo oomouuao .nn H mo ouou onu uo wonnooo ououuno.aonooaaon

.Nm uo uoouommww knuooenmwowno uoo ouo uouuon oaoo kn onoooaoeeo
moono> .ooaonoe onnuw3 oeoonopnovo mo oomoou ononunoa o.ooeoonuno woo .w.e.n.o *

 

o m.On o N.m o n.m xeono
o n.m o N.m o o.o solooouoa
o m.m o o.o o m.¢ Bounnu ooonuaueo
o n.nn o m.o o o.o nonnum
o o.on o o.o o o.o ooonooen

”mowwefiuooo Mom owouo>o

weno a.0n weno N.o no n.o moon sciooouoa
30 no a are e... 4.9 rouse
o i: e o.o n in 20.53.;
8 w; o o.o no 5.... ago: «83-304
8 N5 8 as so To 333
33 ea 8 in e. is 8333

"oowouuwo oz

51

Microbial Counts

The soil samples for microbial studies were taken over a 3—week
period starting in the last week of September. The variation in counts
for the control plots is probably due to differences in sampling dates.
Time and facilities did not allow counts to be taken for all pesticide or
nitogen teatments. The plots receiving Diazinon, acti-dione thiram
and Tersan-OM using ammonium nitrate as the nitogen source were
the only plots tested.

Data in Table 11 show that Diazinon significantly reduced the
number of bacteria grown on media 116 (soil extact agar). This effect
was not noticeable on the other media. Tersan-OM had no effect on
bacteria counts for any of the media. Acti-dione thiram significantly
increased bacteria able to grow in a C02 atmosphere when media 103
was used. This effect was not observed with media 120. While no
other significant differences Were noted for acti-dione thiram, there
was a tendency for bacteria counts to be higher than the control for all
media and incubation conditions where it was applied.

No significant difference occurred in fungal or actinomycetes

numbers from the application of any pesticide.

 

 

52

 

.m.z m.mm~ m.m- n.9mu m.-~ o.owm m.ow~ = = you msoa =
.m.z 3.4m n.~m k.a~ ~.s~ o.om o.mm = own Noe
a o.aNH n «.mk o.ouo k.wm k.moH o.ooo = = “on mane =
a a.mo n m.m o.~o o.oH a.sm s.ao = moH Noe
.m.z “.mmq m.m¢m a.sws o.oom o.omm k.wmm = = no. mafia =
.m.z H.Nm ~.ms a.ms m.~¢ N.km a.Hs = own Nz
.m.z o.owm «.mmm o.~om o.~km m.em~ H.ms~ = = Nona mans N:
.m.z m.no o.oH w.mH «.mo «.mo m.~H = mod 2
.m.z o.~soH o.~ma w.Nma o.ksoH o.~oa a.m~m = oNo “no
.m.z m.ako o.moo s.ask o.oko o.omo ~.Hkn = man goo
.m.z m.mmk m.mmo o.ook o.omk a.omm w.~mm manoeumm HNH Moo
.m.z o.~ o.o o.o o.o m.~ s.~ nouns moo “no
mwuwo
.m.z o.koo o.oso «.mso o.ooo s.aqo a.mso -saoaoeoo kHH “no
o.oqu m.kmm w.e~m ~.awm a ~.oan on a.mHk «Homeoam eon .uno
Eoanu Houuooo so Houuooo oooHuoHa Houuoou moouw aonoz ouonoooEuo
oeooeH ooOHw noooHoH HoHnoHeHz H oOHuonoeoH
-onome unueo

 

30H x HHoo how w Moo ouonaoo oooE eHHuoEoow

 

 

.nomH HonoueoiuonEoumom
.HHom woeoouu wHon oH monoum HoHnoueHE mo muonaoo o>HuoHou oo mowHeHuooo mo ueommm .HH oHnoH

53

.wouoooe ouoa “Ho oH

woooHo>ow neHns ooHooHoe zoo kHoo .ouonoooauo «00 no Nz oH okow m Houmo uHo oH okow m wooooxo oouonN
.nouoone HoHuouoz woo owonuoz mo owoo ooounouH woo .moH .HNH

1.33.. 28V ammo more .a: enema 25 Home 5qu .k: 53% .38 name 3388 :8 6: 533:

.Ho>oH Rm uo uooeHMHowHo uoo
ouo HouuoH oaoo kn onoooaoeeo o3ou oHnuHsnooHo> .oeooHo>Hovo wo mowoom oHoHuHoz o.ooeooniun woo o r

54
Discussion of Greenhouse and Field Results

The results of the greenhouse and field experiments indicate
that pesticides may exhibit stimulatory, inhibitory, or no influence
on plant growth. Under higher than recommended rates, it was seen
that effects tended to be magnified.

If a pesticide is successful in killing a plant parasite, plant
growth should be improved. However, in both the greenhouse and
field experiments no apparent effects from disease or insects were
noted on control plants receiving nitrogen in any form. A, slight
infestation of dollar spot did occur on the no nitogen plots of the
field experiment. This was cleared up with an application of
Cadminate, which was applied to all plots. No changes in patterns
of growth were observed after this application. This does not, however,
rule out the possibility that unrecognized parasites could have been
contolled.

If no apparent disease or insects were contolled, these results
suggest that the stimulus to growth may be physiological or micro-
biological in nature. A number of explanations may exist for these
influences and will be discussed here and in the laboratory incubation
study that follows .

The results of the field experiment substantiate, to a certain
degree, the results of the two greenhouse experiments. It is seen

that, in most cases, the two organophosphate insecticides, 825141

55

and Diazinon increased growth over the no pesticide treatment in both
the greenhouse and field experiments, but differences occurred with
nitrogen carriers. In the greenhouse, when Milorganite was used, the
two insecticides increased growth. This was not evident when ammonium
nitrate was used. In the field, they increased growth under both nitogen
carriers. The difference in turf species or environmental or soil con—
ditions between the greenhouse and field experiments may be responsible.

The increased growth response due to applying Tersan-OM was also
evident in both the greenhouse and field, especially at the higher rate
of application. For acti-dione thiram, the apparent decrease in growth
in the greenhouse was not observed in the field. Again, specie tolerance
or environmental factors may play some role in this result. 6

The field results point out that the percentage nitrogen in the leaf
tissue and nitogen uptake were stimulated by Diazinon, 825141 and
Tersan-OM. This effect was more noticeable in July for the two insect-
icides Diazinon and 825141 , and more noticeable in August for Tersan-OM.

Increases in growth and nitogen uptake caused by pesticides have
been observed by other investigators. Freney (19) and Ries et a1 (51)
showed increases in growth and nitrogen uptake in fruit trees and corn
teated with simazine. The work of Ries and co—workers (50, 62)
demonstrated that small amounts of simazine stimulate nitate reductase
activity in corn and they have presented the hypothesis that simazine

enhances nitate utilization by increasing nitate reductase activity.

 

 

 

.
‘ .
. v.

 

56
Roberts et al (52) observed that the action of DDT and nonherbicidal
concentrations of 2,4-D on plant growth closely resemble that of
some plant hormones.

These observations indicate that pesticides can have an effect on
the physiology of the turf plants which enhances growth and nitogen
uptake.

Musser and Duich (40) have raised a question as to whether serious
consideration should be given to an increase in growth and nitrogen
uptake unless color quality of the turf is improved. To many turf
managers, the quality of color or how green the grass is has become
a leading criterion for rating turfgrasses. In this respect, it was seen
that Diazinon and Tersan-OM were effective in producing significantly
better color in the field during certain periods of growth for all nitogen
teatnents.

The increases in the total mineral nitogen in the soil found for
Diazinon, 825141 , and acti—dione thiram in the greenhouse were not
detectable under field conditions. Possibly, the soil and management
conditions could explain these differences. In the greenhouse, the
turf was grown in plastic-lined pots so no leaching took place. Also,
the soil used was considerably less sandy than out in the field. The
field soil was a specially prepared soil mixture that was approximately
50% coarse sand. This required more frequent applications of water
than for the greenhouse soil. Any appreciable increases in nitate

nitrogen would have been subjected to leaching. If the soil had been

57
had been sampled to a deeper depth or sampled more frequently during
the experiment, these increases in soil nitogen may have been detectable.

The increase in total mineral nitogen in the soil observed for
acti-dione thiram in greenhouse experiment 1 , may have been due to
the decreased growth of the turf resulting in less nitrogen uptake.

This was not the case with 825141 and Diazinon, as total mineral
nitogen and growth were increased, suggesting that these two insecti-
cides enhance mineralization and nitification.

Another possible explanation for increases in mineral nitrogen is
that these pesticides may cause destuction of certain predators whose
cell material becomes an added food supply to the surviving microbial
population and upon decomposition increases the amount of nitrogen
in the soil.

Clipping weights, nitrogen composition, and uptake were all increased
by nitrogen application. The greater availability of nitogen in
ammonium nitate compared to Milorganite and ureaform was particularly
apparent.

This increase in growth from ammonium nitate over Milorganite and
ureaform has been observed by other investigators (26,40). This is due
to a greater amount of nitogen available to the plant in the first few
weeks after application. Lunt (33) points out that, usually, about one-
third to one-half of the nitogen in Milorganite is mineralized by soil
organisms in four weeks time when conditions are favorable. The

remaining fraction is very slowly available. He further notes that about

58
25% of the nitrogen in ureaform is cold water soluble, with the remaining
cold water insoluble fraction able to mineralize at a rate of about 7 to
11 per cent per month depending on soil conditions influencing micro-
bial activity. A possible explanation for the increase in growth over
the control when pesticides are applied to turf receiving Milorganite
or ureaform, is that the pesticide could influence microbial activity
to a point where more rapid mineralization of the fertilizers occurs,
thus releasing more nitrogen for plant growth. Waksman (65) has
suggested partial sterilization effects could be responsible for a
phenomenon of this type. He points out that partial sterilization of
a soil, brings about a chemical change in the organic matter of the soil,
making it more available as a source of energy for microorganisms,

resulting in higher nitogen levels in soils.

59
Laboratory Incubation Experiment

The laboratory experiment was designed to investigate effects
of some of the pesticides used in the greenhouse and field experiments
on microbial activites in Hodunk sandy loam. Of specific concern,
was the microbial activity as it affected nitogen tansformations in
the soil using Milorganite as the nitrogen source. This carrier requires
microbial breakdown for release of its nitrogen, and is used extensively

in the turfgrass field.

Nitogen Transformations

The data for nitogen transformations are given in Table 12, 13,
and 14. The tables are designed so that quantitative changes in
ammonium, nitate, and ammonium plus nitate, respectively are shown
for each 4-day incubation period.

During the 28 days of incubation marked changes in patterns of
ammonium accumulation were caused by the added pesticides. The
results in Table 12 show that Tersan—OM at both rates of application
greatly stimulated ammonification ova' the 28 days of incubation. This
is illustrated in Fig. l .

Calo Clor and 825141 at both rates and Dieldrin at the high rate
stongly inhibited ammonification. In addition, Dieldrin at the low
rate caused significantly less ammonification than the contol, but not

to the extent of the high rate.

 

60

 

 

 

~.~m w.mm H.no «.mu H.H~ ¢.kH m.kH o.o no. own
so.H n.~u o.o: om.H o.o: oo.o om.~ so.o xm :
so.oH o.o m.H *m.~ o.NHu o.m «o.o so.H x HoHo oHoo
so.qu o.om m.Hm *o.mo sm.om o.mo o.~m so.¢m on :
so.nmm m.wq «m.mm *o.om m.¢n so.mw *m.mm so.mm x Ectooouoa
n.¢NH o.om o.nH *o.om o.o o.om m.nm o.o on :
n.HwH m.mH *O.mo *m.o~ km.ok to.o km.H m.NH x aoanu oooniHue<
sn.m n.o o.H so.Hu o.o: on.m so.Hu rm.¢ on :
so.moH m.mm sm.m¢ on.HH n.nu sm.o *o.oH *m.m x oHuwHoHn
*m.Hm n.o o.mmu m.mm om.mH so.mu on.~ *o.m on :
m.owH o.nm o.omn om.H so.kH sm.oo o.oo «o.mH x oooHooHo
n.nH o.o- o.o on.~ *o.H so.o *m.H om.¢ xn :
on.mH o.o m.ou ow.o- *o.o so.Hu so.oH *m.m x HquNm
o.~oH m.wH o.Nu m.mn o.o: m.m~ n.No m.HH mHouuooo
m.Ho- n.H- o.o- n.~ o.o- n.~- n.m o.H- NAz oav noose
owoone on om om oH NH w o ouo.H uooEuooHH
Houoa okow .ooHuonoeoH mo oSHH owHenuoom

H

 

oowoouHo EsHooEEo Son 1 oHo>oH aoHooEEo HHoo oH owoono

 

 

.oeuooo oomouuHo onu oo onHooo ouHoowuoan nuH3.aooH~::ao xoowom oH ouow onHoaoo neoo

ooo3uon oHo>oH EsHooEEo HHOo oH owoone onu oo ooHuonoeoH mo oEHu woo mowHeHuooo mo ueommm .NH oHnoH

61

.ouHoowHoHHz.oo wowwo oowouuHo.aoo omm uon .wowwo owHeHuooo 02m
.wowwo HooHHHunom ouHoowuoHHz_oo woo owHeHuooo ozN

.Houoone oHoHHouoz woo

owonuoz one no m oHnoH oH oo>Hm oo HHoo oaouw CON non ouou wHomam u on .HHoo oaoum com non ouou u xH

.Hm>oH on on» no Houuaou aouo paramoooo knuaoooooamom *

62

 

 

 

 

_ —-- -- - Acti—dione thiram
-- --- —-- Dieldrin
/
400 _ .. . _ . .— - Tersan-OM / ~
No pesticide / ’
350 _ .l
I
l
300 . '
l
/
5 / °
8 o
3:; 250 _ l
.8 .
S .’
o
g 200 .. .l
E
o.
o.
150 F
100 ....
/
50 _ '
/
I ’
of . .. —— —- —- -
o " 1 l l 1 L I l
4 8 12 16 20 24 28

Days

Fig. 1 Effect of pesticides on ammonification of
Milorganite in Hodunk sandy loam.

63

While Diazinon at the low rate and acti-dione thiram at both rates
did not significantly affect ammonification, patterns of accumulation of
ammonium were significantly altered from the control. For example,
the control soil showed a disappearance of 9. 5 ppm ammonium between
the twelfth and sixteenth day, and an increase of 75. 5 ppm between the
sixteenth and twentieth days. Whereas, Diazinon-treated soils showed
an increase of 17 ppm ammonium between the twelfth and sixteenth
day and only an increase of l . 5 ppm between the sixteenth and
twentieth day.

Similar fluctuations in rate of release appear for the other pesticides
that allowed ammonification.

Table 13 shows the effect of pesticides on soil nitrate levels. Here
it is observed that the accumulation of nitrate in the control soil was
inhibited by Milorganite itself. This would suggest that some other
factor associated with Milorganite inhibited activity of nitrifying
organisms or stimulated activity of microbial groups using nitrate
assimilatively or in dentification. It has been reported by Fuller (20)
that high ammonium salt concentration under high soil pH inhibits nitrate
production. However, the pH of the control soil was 6.3. This would

indicate that something other than high pH inhibited the Nitrobacter

 

activity. On the basis of these data, it was impossible to identify what
effects 825141 , Diazinon, Dieldrin, and Calo Clor at both rates and acti-
dione thiram at the low rate may have had on any specific microbial processes

leading to the appearance or disappearance of nitate.

 

64

 

 

 

w.~o «.mo o.o o.ao o.oo a.m N.” ~.m no. no;
m.o m.H m.o- o.o- m.o o.o n.o o.o- on =
o.o o.o o.o- m.o- m.oH- so.~n m.o- m.H x none come
om.om «m.wm- on.om o.oo- o.o- o.o oo.mm o.o xm =
oo.km om.as o.o m.o- m.m- o.m o.o on.oo- x so-ammumo
..n.os o.o om.sm o.o m.oH- to.no on.oH- oo.mo on =
m.o- m.~- m.m o.o- o.o- n.m o.n- o.m x saunas oaooo-ouo¢
o.~- o.o o.o o.o o.~- o.o o.o- o.o- on =
o.o n.m m.o- m.o- m.H- o.o m.o m.o- x anueoooa
n.o- m.o o.o o.o- o.o o.m- o.o n.o on =
o.m- o.o m.o- o.o m.m- o.o m.o m.H- x socoumon
n.o- o.o o.m- o.o m.o o.o o.o o.~- xm =
m.m- o.m- o.o o.o o.~ o.o- o.m m.m- x HsHmNm
m.o m.o o.o m.o- o.o o.o o.o- o.o moouuaoe
o.m~ m.~ o.~ o.o m.o- m.a o.o o.o «Hz oav noose
momaone om 3N ow 3 NH o 3 Son uooeeooea
Houoa okow .oOHuonoeoH mo oEHH owHeHuoom

 

oowouuHo ououuHo Boo a mHo>oH ououuHo HHoo oH omoono

H

 

 

.oenooo oowouuHo one mo onHooo ouHoomuoHHz nuHB BooH kwooo xoowom oH ouow onHoEoo neoo

oooBuon oHo>oH ooonUHo ououuHo oH owoone oo oOHuonoeoH mo oaHu woo oowHeHuooo mo ueommm

.mo annoy

65

.ouHoownoHH=_oo wowwo oowouuHo.aoo onm uon .wowwo owHeHuooo 02m
.wowwo nouHHHunom ouHoowuoHHz_oo woo owHeHuooo ozN

.uouoone HoHuouoz woo
owonuoz onu mo m oHnoH oH oo>Hm mo HHoo oaouw oom Moo ouou wHomum u on .HHoo oaoum oow Moo ouou a xH

.Ho>oH fin one no Houuooe Eonw uoouomme kHuooeHMHomHm k

66

The data of Table 13 do, however, reveal that Tersan-OM at both
rates and acti-dione thiram at the high rate significantly increased
nitrate accumulations. These pesticides were evidently able to over—
come the apparent inhibition.

The effect of these pesticides on total nitogen changes (ammonium
+ nitrate) as shown in Table 14, follows closely the patterns for
ammonium. This is related to the apparent inhibition of nitrate
production. However, due to the increases in nitrates caused by
acti-dione thiram at the high rate, a significant increase in total

nitogen over the control was observed.

Carbon Dioxide Evolution

Data for the carbon dioxide evolution were not consistent. With
certain pesticides, evidence of microbial activity was shown by
increases in ammonium in the (soil. This apparent microbial activity
did not consistently result in increases in carbon dioxide evolution.
These results indicate that the carbon dioxide evolved was in some way
being held in the soil. Therefore, no basis for comparison of pesticides

is valid .

 

67

 

 

 

k.mm n.0m m.m9 k.m~ 0.0N 0.0H ~.0~ n.~H no. can
o.o o.o- o.o- 90.0 0.0- «0.9 o0.m 90.H- on =
0.HH 90.m *0.0 *0.H m.-- 0.H~ 90.0 n.~ x “one come
*O.Nkm sm.ou so.wo so.9m so.om so.m9 *o.ok *o.~oH on :
so.-o so.w¢ sm.kw *m.m~ o.o: em.wm *n.om sm.om x SOuooouoH
*0.0H~ 0.~m m.o9 0.9m om.0o- on.9n 0.n~ n.0H on =
0.00s 0.kH 9m.~m 9m.m~ *0.m0 m.0 rm.m- m.mH x among“ oa0n0-nuoo
90.o 0.~ 0.~ tn.0- 0.0- 90.9 90.~- n.m on =
40.90H 0.km 90.09 40.0H 0.0- m.k 40.0H 0.m x coueooon
90.05 o.o 0.0m- m.~0 n.0m 90.0- 40.9 n.m x0 =
0.0ko 0.nm o.om- om.H m.mH 9m.90 n.m9 m.HH x coaoumna
90.0H 0.m- 0.m on.~ m.H 90.H «m.~ n.~ xm =
40.0H 0.m m.~- rm.0- 0.0 90.“- 90.mH 0.0 x H9Hmmm
0.~0H 0.0o 0.N- 0.mk n.0- m.m~ m.H9 0.~H moouuaoe
0.~H o.o 0.0- 0.0 0.0- 0.“ m.HH 0.0 NAz ocv x0050
mousse 0m 9m 0m 0H NH 0 9 mean uamauomua
HouoH okow .ooHuonoeoH mo oBHH HowHeHuoom

 

oowouuHo Houou Eon u oHo>oH AououuHo +_EoHooaaov oowouuHo Houoofia Houou oH owoono

 

 

.oeuooo oowouuHo one no
ouHoowuoHHz nuHB EoOH kwooo nonwom oH ouow onHoEoo neoo oooBuon AououuHo.+ aoHooaaov

oHo>oH oowouuHo HHoo Houou oH owoone one oo ooHuonoeoH mo oaHu woo oowHeHuooo mo ueommm .oH oHnoH

68

 

.ouHoowuoHHz oo wowwo oowouuHo Boo omm uon .wowwo owHeHuooo 02m

.wowwo nooHHHuHom ouHoowuoHHz.oo woo owHeHuooo ozN

.uouoone HoHuouoz woo

owonuoz one no m oHnoH oH oopHm mo HHom oaouw com poo ouou wHOMIm u Mm .HHoo oaouw CON poo ouou u NH

.Ho>oH Rm uo Houuooe Boom uooquMHw kHuooeHMHome *

69
Discussion of Results of Incubation Experiment

Pesticides added to soil in the laboratory produced some stimu-
lating and depressive effects on ammonification and nitification.
Two rates of application were used for each pesticide, as shown in
Table 3 of the Methods and Materials chapter. The high rates are
higher than recommended for field use. This was done to allow for
effects of potential residues resulting from long periods of extended
use and to force possible microbial effects. The rates are based on
a one-inch depth of soil as the effective zone of pesticidal action.

The low rate, however, may represent amounts that reach the
soil in the course of one growing season. For example, Tersan-OM
applied at 4 oz. per 1000 sq. ft. is equivalent to 35 ppm, based on
a one-inch depth of soil with a density of l . 55. It is not uncommon
for fungicides to be applied every 7-10 days by turf managers as a
disease preventative during a growing season giving a likely maximum
of 16 applications per year. Therefore, 16 times the recommended rate
(35 ppm) of Tersan—OM was used to study effects of possible accumu-
lation in the soil over the course of one growing season. Actual
amounts used will depend on turf and environmental conditions. This
basis for application rates was used for the other fungicides as well.
For the insecticides, 6 times the recommended rate was used.

The point can be raised as to what depth of soil pesticides can

exert an influence on microbial activity. If the solubility of pesticides

70

is low and they are adsorbed onto clay minerals, they may be concen-
trated in the top 1/4 to 1/ 2 inch of soil. This would result in even
greater concentrations of pesticides in the soil than were used in
this experiment, assuming no decomposition of the pesticide takes
place. Further research on pesticide residues is certainly needed to
determine what actually is the effective zone of soil pesticide influence.

Certain effects of pesticides observed in this incubation study
.may explain some of the responses in the greenhouse and field experi-
ments. It was seen that Tersan—OM, at both rates of application
greatly stimulated ammonification. Lunt (33) has reported that from
1/3 to 1/2 of the nitrogen in Milorganite is mineralized in four weeks
time when conditions are favorable. This is consistent with data
in Table 12, where 162 ppm (nearly half of the 350 ppm nitogen added
to the control soil) was mineralized during the four weeks of incubation.

When Tersan—OM was applied, however, 380 ppm (over 100%) of
nitrogen was released from Milorganite. The amount of nitrogen
recovered above the 350ppm added may have resulted from the break-
down of organic matter already in the soil, stimulated nitogen fixation,
or variation in the per cent nitogen in Milorganite. Regardless of the
greater nitrogen recovery, the data do suggest that Tersan-OM may
stimulate microorganisms that are able to decompose Milorganite
rapidly. Increases in growth observed in greenhouse experiment 1
when Tersan-OM was applied at 10 times the recommended rate may

have been due to the increased availability of nitogen from Milorganite.

 

71

Another (possible explanation for increases in ammonium levels
from soil treated with Tersan-OM, is that partial sterilization may
occur (65) . Tolerant organisms may decompose killed microbial cell
material, resulting in increased nitrogen availability. Increases in
growth observed in the greenhouse and field experiments from 825141 ,
Diazinon, and Calo Clor could not be correlated with responses in the
incubation study. Rates used may have been toxic to ammonifying
organisms. Furthermore, these responses may be physiological in
nature and not related to microbial activity.

One point brought out in this experiment that is of particular
interest is the apparent cyclic pattern of ammonification and nitifica-
tion of Milorganite (see Fig. 1). This suggests that high populations
of specific microbes may be present in the soil at certain periods. As
was seen in Tables 12 and 13 , when ammonification and nitification
occured a number of the pesticides caused significant variation in
the pattern of ammonium accumulation and nitification. This would
indicate that microbial activity is also being affected. Naumann (41)
has shown peak ofmicrobial populations at 5-7, 11-12, and 21—22
days from a 1% application of Parathion to soils.

What effects on plant growth the cyclic patterns of ammonification
and nitrification of Milorganite have cannot be determined by this
experiment. Further investigations are certainly needed to establish
if this effect will influence soil fertility and plant growth to any

significant degree .

72

Disappearance of ammonium and nitrate is evident from Table 12
and Table 13, and in many cases is not accounted for by nitrification.
Milorganite is high in carbonaceous material. It is possible that during
its decomposition the high population of specific microbes suggested
by the observed cyclic patterns may result in assimilation of some
mineral nitrogen. As shown in Table 11 , acti-dione thiram increased
the populations of carbon dioxide tolerant and nitate utilizing bacteria.
This could account for some of the disappearance of nitrate, if these
microorganisms were stimuh ted.

Denitrification losses can occur in well-aerated soils (67). It is
possible that disappearance of nitogen in this experiment was due to
this process. Fixation by certain clay minerals, as reported by
Allison et a1 (2) can result in apparent losses of nitogen by rendering

significant amounts of ammonium unavailable for nitification.

SUMMARY AND CONCLUSION

The purpose of this investigation was to study the effect of selected
pesticides on turfgrass growth, interaction with turf fertilizers, and
nitrogen tansformations in soil. The following conclusions were drawn

from greenhouse, field, and laboratory incubation experiments.

Greenhouse Experiment 1:

1. The organophosphate insecticides 825141 and Diazinon increased
top growth of Pennlawn red fescue significantly over the contol at both
the recommended and 10 times the recommended rate of application.
Tersan-OM and Calo Clor fungicides greatly stimulated growth at 10
times the recommended rate. Acti-dione thiram at both rates and Dyrene
at the high rate depressed growth.

2. 825141 at both rates, Diazinon, Dieldrin, and acti-dione thiram
at 10 times the recommended rate, and Cadminate at the recommended
rate resulted in higher levels of soil mineral nitogen than the contol at

the conclusion of the experiment.

Greenhouse Experiment 2:

l . Pots treated with the insecticide 825141 gave significantly greater
top growth of Pennlawn red fescue over a 5-month period when Milorganite
or ureaform were used as the nitogen source. This was also. tue when

no nitogen was applied. Diazinon-teated pots gave greater top growth

73

74
when ureaform was used at the higher rate. Pots receiving ammonium

nitrate were not significantly affected by any pesticides.

Field Experiment:

1 . Top growth of Cohansey bentgrass, receiving ammonium nitate
and Milorganite as the nitogen source, was significantly increased
over the no pesticide t'eatment when treated with 825141 and Diazinon.
This stimulus to growth was especially noticeable in July.

2 . Continued usage of Tersan—OM increased top growth significantly
over the no pesticide treatment when ammonium nitate and no nitogen
were used.

3. Diazinon and 825141- treated plots, receiving ammonium nitrate
or Milorganite as the nitogen source, had a significantly higher per
cent nitogen in the leaf tissue in July and in August when no nitogen
was applied.

4. Nitrogen uptake was significantly increased over the no pesticide
treatment in plants receiving ammonium nitate or Milorganite, when
825141 , Diazinon, and Tersan-OM was applied, especially in July.
When no nitrogen was used, the 825141 teatnent resulted in a significant
increase in nitogen uptake over the 3—month period of growth.

5. Tersan-OM-treated plots receiving ammonium nitrate as the
nitrogen source and no nitogen had significantly better color than the

no pesticide treatnent in all three months of growth. Diazinon—treated

75
plots receiving ammonium nitrate rated better than the no pesticide
treatment in August and September.

6. Applications of 825141 insecticide resulted in a significantly
higher soil nitrate level than the no pesticide treatment at the end of the
experiment, when ammonium nitrate was the nitrogen carrier used.

7. When ammonium nitrate was used, Diazinon treatments resulted
in lower numbers of bacteria in the soil than the no pesticide treatment
in September. Acti-dione thiram treatments resulted in increased CO2
tolerant and nitrate utilizing bacteria in September.

8. For all evaluations, plots treated with Tersan—OM at 10 times
the recommended rate receiving no nitrogen rated with plots receiving

Milorganite .

Laboratory Incubation Experiment

1. Ammonification and accumulations of nitate were significantly
increased over the no pesticide treatment in soil receiving Milorganite
as the nitrogen source when Tersan-OM was applied at rates that may
accumulate in soils over a period of time.

2. At these rates, 825141 , Diazinon, Dieldrin and Calo Clor
resulted in inhibition of ammonification.

3. All pesticides caused significant changes in patterns of ammonif-

ication and nitrification of nitrogen released from Milorganite.

76
The results of this investigation indicate that pesticides may
affect the physiology of turfgrasses, the ecological system, or the
nitogen relations in the soil With the increased use of pesticides on
turf, turf managers should be aware of these possible effects. This
study indicates a need for further research in this area and suggests

that caution should be used when applying pesticides to turf.

10.

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APPENDIX

83

84.

Table 15. Analyses of variance for data of greenhouse exPeriment 1.

 

 

 

Approximate

Source d.f. Mean sq. F significance

Clipping weights March 27 - April 14
A (pesticide) 8 0.062 4.671 0.0005
8 (rate) 1 0.220 16.623 0.0005
A x B 8 0.024 1.799 0.098
Error 54 0.132

Clipping weights April 14 - May 14
A 8 0.454 32.290 0.0005
8 1 0.056 3.994 0.051
A x B 8 0.130 0.276 0.0005
Error 54 0.014

Clipping weights May 14 - June 14
A 8 0.242 18.548 0.0005
8 1 0.003 0.197 0.659
A x B 8 0.206 15.770 0.0005
Error 54 0.013

Total clipping weights
A 8 1.693 29.162 0.0005
8 1 0.429 7.395 0.009
Error 54 0.058
ppm Soil mineral nitrogen

A 8 78.288 8.033 0.0005
8 1 264.883 29.9942 0.0005
A x B 8 37.592 3.831 0.001
Error 54 9.813

 

85

Table 16. Analyses of variance for data of greenhouse experiment 2.

 

 

 

Approximate
Source d.f. Mean sq. F significance
Total clipping weight
A (pesticide) 4 5.036 28.104 0.0005
B (nitrogen carrier) 6 45.231 252.402 0.0005
A x B 24 0.312 1.741 0.029

Error 105 0.179

 

86

Table 17. Analyses of variance for clipping weight data of the field

 

 

 

experiment.
Approximate

Source d.f. Mean sq. F significance

Clipping weights - July
A (pesticide) 4 2582400.199 12.053 0.0005
B (nitrogen carrier) 2 32653196.183 152.404 0.0005
A.x B 8 481240.806 2.246 0.054
C (replication) 2 . 827325.640 3.861 0.330
Error 4 28 214253.733

Clipping weights - August
A 4 990740.233 ‘ 4.328 0.008
B 2 102720518.141 448.772 0.0005
A x B 8 76828.425 0.336 .0.945
C 2 989811.287 4.234 0.023
Error 28 228892.520

Clipping weights - September
A 4 511952.188 2.764 0.047
B 2 92155654.082 497.456 0.0005
A x B 8 106943.988 0.577 0.788
C 2 9472.514 0.053 0.949
Error 28 185253.805

Clipping weights - Total
A 4 5894592.391 6.490 0.001
B 2 640218930.516 704.873 0.0005
A x B 8 474302.262 0.522 0.830
C 2 21704.601 0.024 0.976
Error 28 908275.834

 

 

87

 

 

Table 18. Analyses of variance for per cent nitrogen in leaf tissue
data of the field experiment.

Approximate

Source d.f. Mean sq. F significance

 

Per cent nitrogen in leaf tissue - July

A (pesticide) 4 0.279 10.815 0.0005
B (nitrogen carrier) 2 3.701 143.513 0.0005
A x B 8 0.016 0.612 0.760
C (replication) 2 0.013 0.501 0.611
Error 28 0.026

Per cent nitrogen in leaf tissue - August
A v 4 0.186 12.544 0.0005
B 2 5.747 387.466 0.0005
A x B 8 0.019 1.304 0.282
C 2 0.042 2.855 0.074
Error 28 0.014

Per cent nitrogen in leaf tissue - September
A 4 0.076 3.673 0.016
B 2 7.561 367.239 0.0005
A x B 8 0.030 1.470 0.213
C 2 0.010 0.485 0.621
Error 28 0.021

 

88

 

 

 

Table 19. Analyses of variance for turf color rating and density
count data of the field experiment.
Approximate

Source d.f. Mean sq. F significance

Turf color rating - July
A (pesticide) 4 1.361 4.744 0.005
B (nitrogen carrier) 2 30.717 107.062 0.005
A x B 8 0.369 1.288 0.290
C (replication) 2 2.317 8.075 0.002
Error 28 0.287

Turf color rating - August
A 2 1.986 9.931 0.0005
B 2 39.267 196.333 0.0005
A.x B 8 0.315 1.576 0.177
C 2 0.950 4.750 0.017
Error 28 0.200 r

Turf color rating - September
A 4 1.425 6.401 0.001
B 2 64.550 289.957 0.0005
A x B 8 0.154 0.693 0.695
C 2 1.217 5.465 0.010
Error 28 0.223

Density counts

A 4 2318.611 0.373 0.862
B 2 27482.067 4.416 0.022
A x B 8 161.594 0.026 1.000
C 2 130.400 0.021 0.979
Error 28 6223.995

 

89

Table 20. Analyses of variance for soil mineral nitrogen data of the
field experiment.

 

 

Approximate

Source d.f. Mean sq. F _. significance

' ppm Ammonium nitrogen
A (pesticide) 4 0.826 1.072 0.389
B (nitrogen carrier) 2 5.931 7.695 0.002
A x B 8 0.394 0.511 0.838
C (replication) 2 5.435 7.051 0.003
Error 28 0.771

ppm Nitrate nitrogen
A 4 1.981 1.406 0.285
B 2 21.095 14.997 0.0005
C 2 1.558 1.106 0.345
Error 28 1.408

ppm Total nitrogen
A 4 3.047 1.242 0.316
B 2 46.430 18.929 0.0005
A x B 8 1.744 0.711 0.680
C 2 10.238 4.147 0.026
Error 28 2.453