AN ADEQUATE SAMPLE OF CORN
PLOTS WITH REFERENCE TO
MOISTURE AND SHELLING
PERCENTAGES

Thesis for the Degree of M. S.
MICHIGAN STATE COLLEGE

Grafton F. Henry
1940

 

 

 

AN ADEQUATE SAMPLE OF CORN PLOTS WITH REFERENCE

TO MOISTURE AND SHELLING PERCENTAGES

by

Grafton F. Henry

A THESIS
Submitted to the Graduate School of Michigan
State College of Agriculture and Applied
Science in partial fulfilment of the
requirements for the degree of

MASTER OF SCIENCE

Department of Farm Crops

1940

THESE?)

A

ACKNOWLEDGMENT

The writer wishes to express his appreciation to Dr. E. E.
Down for the helpful suggestions and constructive criticism of this
thesis.

To Mr. H. M. Brown for his advice in arranging the tables
of the results.

To Mr. A. R. Marston for his personal interest and aid in

making this study possible.

140104

TABLE OF CONTENTS

INTRODUCTION
REVIEW OF LITERATURE
MATERIAL & METHODS
RESULTS
1. Size of Theoretical Moisture Sample
2. Size of Theoretical Shelling Sample
SUM-VARY

LITERATURE CITED

14
17
20

21

INTRODUCTION

One of the most important phases of agricultural statistics is sam-
pling from an unknown parent population. In many cases all of the infor-
mation concerning the parent population is obtained from a single small
sample or a small number of samples. The purpose of a representative sam—
ple is to secure on a small scale as accurate a picture as possible of a
larger whole.

The most important principle in sampling is to proceed in such a
manner that every case of the entire population covered in the investiga-
tion has as nearly as possible, a fair opportunity to be included in the
sample, even though not actually chosen for examination. Proper care must
be exercised to give each individual proper weight in its influence upon
the entire sample.

The purpose of this investigation was to determine the minimum num-

ber of ears necessary to sample adequately at harvest time a plot of corn
for moisfllre content of the grain and for shelling percentages.

Different methods of sampling corn plots for moisture and shelling
percentages are followed at the experiment stations in the corn belt.

These methods will be reviewed briefly.
REVIEW OF LITERATURE

The Illinois method of determining the moisture of corn plots as
reported by Bolin (3) is done by gathering all the corn from one replica—
tion 2 x 12 if the entry is replicated 10 times in a single experiment.
The shelling percentage is the total shelled weight from this particular

plot. A quart sample of the shelled grain is used to determine the mois-

ture by the use of a Tag-Heppenstall machine.

Miles (7) of Purdue University stated that in some of the hybrid
corn wrok, an entire plot 2 x 10 was harvested and shelled. A sample of
this was used to determine the moisture percentage, but in most tests the
time and expense of this method is too great and in most tests the ear
corn is husked and weighed from each individual plot. Five or ten repli-
cates are used of each entry. Ten ears are taken at random from the ear
corn hushed from each of three or four replicates for moisture and shell-
ing percentages.

Moisture samples are taken at Iowa State College (10) from three to
five replications, ten ears being chosen at random from each plot. A
screwdriver is used to remove two kernel rows from 30 - 50 ear sample.

The shelled corn is composited and determinations are made with the Tag-
Heppenstall moisture meter, or when moisture is too high with the Brown-
Duvall.machine.

Kansas State College (5) for determining moisture percentages make
up a 33 1/3 pound sample of equal amounts, from each of three replications,
sometimes a 50-pound sample is made up in this manner. The sample is
shelled the following day and a sample of corn is secured at time of shell-
ing. The moisture content of this sample is determined by a Tag-Heppen—
stall moisture meter. Under circumstances where it is not practical to
shell the sample, a sample of shelled grain is obtained by taking a strip
a couple of rows wide down about 25 ears from each of three replications.

Ohio State University (9) takes a sample by beginning with the first
hill of the first row. One hill is harvested from the first, third, fifth,
and seventh pair, alternating the rows until four complete hills have been
harvested. On lowayielding plots, a hill is harvested from the ninth pair.

The plots are 2 x 10 hills. A screwdriver is used to shell off two kernel

rows from each ear in the sample.

Minnesota (4) reported that moisture samples are taken from each
plot, using 12 to 15 ears and a screwdriver to take two rows of kernels
from each of the ears. A Tag-Heppenstall moisture meter is used for mak-
ing determinations.

Missouri (I) use a 2 x.lO hill plot replicated five times, and the
entire plot is harvested. About 20 ears are sampled by removing two rows
of kernels with a screwdriver to obtain a moisture sample. The moisture
is determined with a Tag-Heppenstall moisture meter. If the corn is fair—
ly dry, only one or two replications are used for moisture determinations.

Wisconsin (8) usually harvests the hybrid corn test plots late in
the fall when the corn is practically dead ripe. This is done to allow a
good infection of stalk rot. In view of this fact that the grain is Quite
ripe, a shelled sample is composited from three of the six replicates.

The moisture determinations are made by means of a Tag-Heppenstall mois-
ture meter. The shelled samples are made up of at least 12 ears from each
replicate.

The present method according to Marston (6) of determining the mois-
ture and shelling per cent of Michigan State College for overstate tests
where each entry is replicated 5 times in a 2 x 10 plot, two ears are taken
at random from each replicate. In experiments at East Lansing a 10 ear
sample is selected at random from each replication. The corn is shelled
and composited and moisture determinations are made with a Steinlite mois-

ture meter. The shelling per cent is determined from the moisture sample.

1+0

MATERIAL AND METHODS

The data were gathered October 17 and 18, 1939 from the followa
ing 10 corn varieties: Duncan Yellow Dent, Michigan Hybrid number 561,
Wisconsin Hybrid number 350, Michigan Hybrid number l2l8, Pickett Yellow
Dent, Indiana Hybrid number 416, Minnesota Hybrid number 402, Northwest—
ern Dent, Wisconsin Hybrid number 606 and Michigan Hybrid number 21-A.
These were located on a 4.3 acre tract of sandy loam soil north of the
Farm.Crops laboratory on the experimental farm. Each variety was repli-
cated ten times and the plots were 4 x.10 hills (3% x 3% feet), thinned
to 3 plants per hill. Only one row in each plot of 5 replicates was
analyzed, the balance of the parent plot being used for other investiga-
tions.

Due to a few missing hills and plants there were 1412 ears in the
entire population instead of 1500 ears as would be eXpected.

Each ear was labeled with its variety, plot, hill, and plant number
at harvest. Each ear was weighed and placed in a drier for two days to
reduce the moisture content and then reweighed and shelled. The moisture
content was immediately determined by the Steinlite moisture meter. The
shelling per cent of each ear was obtained after the kernels were removed
to obtain the moisture per cent.

The mean moisture and shelling percentage for the individual ears
and hills of each plot and for each variety were obtained for each of the
ten varieties. The standard error was calculated for each respective

mean 0

RESULTS*

The number of ears and hills per replication harvested, the mean
moisture percentage and the standard deviation for each replication, and
for all the replications of the entire variety are given in table I. Cor-
responding data are recorded in table II for the shelling percentages.

Nine of the 50 respective plots had thirty ears, two had thirty-two,
one had thrity—five, and the remaining thirty-six had from twenty-three
to twenty—nine ears. The mean value was based on the actual number pres-
ent in the replication.

The variation percentages were determined by the coefficient of var-
iability of the respective means of the plots. The greater the coefficient
of variability the greater the variation.

Tables I and II are recorded to make available the data used to cal-
culate the values in tables III and IV. However, the moisture contents
shown in table I show the corn varieties used in these investigations dif-
fered materially in date of maturity. Minnesota Hybrid number 350 and
Michigan Hybrid number 1218 are medium early. Michigan Hybrid number 2l—A
and Wisconsin Hybrid number 606 are medium late. Michigan Hybrid number
561 and Indiana Hybrid number 416 are late.

The range in moisture per cent varied considerably between varie-
ties. This is shown both by the standard deviation and by the coefficient
of variability.

* The original data showing the individual determinations for each ear

are filed with the Farm Crops department.

 

Table I. Size of parent population, mean moisture percentage, stand-
ard deviation, and coefficient of variability are given for
10 varieties of corn.
DUNCAN YELLOW DENT
Repli— No. Coef. No. Coef. _,A11 Repl.
cates Ears Mean S.D. Var. Hills S.D. Var. S.D.) ‘Coef. Var.
1 30 20.3 4.20 20.69 10 2.13 10.49
2 27 18.9 4.77 25.24 10 3.4 18.20
3 27 18.3 3.82 20.87 10 1.95 10.66
4 25 19.5 3.37 17.28 10 2.59 13.28
5 28 20.0 4.09 20.45 10 2.34 11.70
Ave. 27.4 19.4 4.05 20.91 10 2.49 12.87
All
Replica—
tions 137 19.4 4.09 21.08
MICHIGAN HYBRID 561
1 30 23.1 3.53 15.28 10 1.59 6.88
2 29 23.0 2.77 12.04 10 1.94 8.43
3 28 23.3 4.69 20.13 10 3.63 15.58
4 29 23.7 4.35 18.35 10 3.17 13.38
5 24 21.3 3.51 16.48 9 2.28 10.70
Ave. 28.0 22.9 3.77 16.46 9.8 2.52 10.99
All
Replica-
tions 140 22.9 3.86 16.86
WISCONSIN HYBRID 350
1 30 17.0 3.27‘ 19.24 10 2.09 12.29
2 27 17.1 2.28 13.33 10 1.47 8.60
3 29 17.4 3.42 19.70 10 2.15 12.36
4 30 17.5 2.16 12.34 10 1.16 6.63
5 27 19.7 4.96 25.18 10 3.65 18.53
Ave. 28.6 17.9 3.22 17.96 10 2.10 11.68
All
Replica—
tions 143 17.9 3.43 19.16

 

 

 

 

Table I (continued)

MICHIGAN HYBRID 1218

 

 

Repli- No. Coef. No. Coef. All Repl.
cates Ears Mean -312; Var. Hill§_ S.D. Var. S.D. Coef. Var.
1 28 17.3 2.74 15.84 10 2.01 11.62
2 28 16.0 2.57 16.06 10 2.19 13.69
3 29 17.8 2.97 16.69 10 2.42 13.60
4 31 18.0 4.07 22.61 10 2.28 12.67
5 29 17.1 3.30 19.30 10 1.58 9.24
Ave. 29.0 17.2 3.13 18.10 10 2.10 12.16
All
Replica-
tions 145 17.2 3.23 18.78
PICKETT YELLOW DENT
1 27 16.6 2.36 14.22 10 1.24 7.47
2 24 17.4 3.20 18.39 10 1.56 8.97
3 27 18.0 3.15 17.50 10 2.40 13.33
4 24 17.7 3.46 18.55 10 2.39 13.50
5 27 27.5 3.45 12.55 10 1.81 6.58
Ave. 25.8 17.4 3.12 16.44 10 1.88 9.97
A11
Replica—
tions 129 17.4 3.13 17.99
INDIANA HYBRID 416
1 28 23.0 2.75 11.96 10 1.89 8.22
2 27 22.3 3.20 14.35 10 2.30 10.31
3 29 22.5 3.43 15.24 10 2.24 9.96
4 29 23.3 3.96 17.00 10 2.41 10.34
5 29 22.1 4.66 21.09 10 2.25 10.18
Ave. 28.4 22.6 3.60 15.93 10 2.22 9.80
A11
Replica-
tions 142 22.6 3.64 16.11
MINNESOTA HYBRID 402
1 30 12.8 2.68 20.94 10 1.52 11.88
2 31 13.0 2.54 19.54 10 1.18 9.08
3 30 13.6 2.34 17.21 10 2.01 14.78
4 29 12.7 1.52 11.97 9 0.97 7.64
5 29 12.9 2.46 19.07 10 1.57 12.17
Ave. 29.8 13.0 2.31 17.75 9.8 1.45 11.11
All
Replica-
tions 149 13.0 2.34 18.00

Table I (continued)

NORTHWESTERN DENT

 

No.
Hills

10
10
10
10

9
9.8

(I)
U

I:

14rdldidld
moooo
mwmmo

H
\h
N

WISCONSIN HYBRID 606

Repli- No. Coef.

cates Ears Mean S.D. Var.
l 32 14-9 3.72 24.97
2 30 14.6 2.43 16.64
3 32 14.2 2.49 17.54
4 35 15.7 2.92 18.60
5 23 15.4 2.79 18.12

Ave. 30. 15.0 2.87 19.17

All

Replica-

tions 152 15.0
1 29 17.6 3.34 18.98
2 28 22.0 4.60 20.91
3 29 21.2 4.16 19.62
4 29 20.3 3.09 15.22
5 30 19.5 3.76 19.28

Ave. 29. 20.5 3.79 18.80

All

Replica-

tions 145 20.5
1 28 18.8 3.47 18.46
2 22 19.4 2.52 12.99
3 30 19.2 3.21 16.72
4 23 18.3 3.06 16.72
5 26 18.8 2.82 15.00

Ave. 25. 18.9 3.02 15.98

All

Replica-

tions 129 18.9

10
10
10
10
10

10

10
10
10
10
10

10

1.80
2.22
1.73

1.73
2.07

1.91

MICHIGAN HYBRID 21-A

2.14
1.71
2-35
2.11
1.50

1.96

Coef.

Var.

12.75
7.26
7.61

12.29

10.52

10.09

10.23
10.09
8.16
8.52
10.62

9.52

11.38
8.81
12.24
11.53
7.98

10.39

s.D;

2.93

3.88

3-03

All Repl.
Coef. Var.

19.53

18.93

16.03

Table II.

Size of parent population, mean shelling percentage, standard

deviation, and coefficient of variability are given for 10
varieties of corn.

DUNCAN YELLOW DENT

 

 

 

Repli- No. Coef. No. Coef.
cates Ears Mean S.D. Var. Hills S.D. Var.
1 30 84.0 2.92 3.48 10 1.98 2.36
2 27 82.8 3.40 4.11 10 1.89 2.28
3 27 84.2 2.66 3.16 10 1.57 1.86
4 25 82.8 2.75 3.32 10 1.49 1.80
5 28 83.2 3.76 4.52 10 2.13 2.56
Ave. 27.4 83.4 3.10 3.72 10 1.81 2.17
All
Replica-
tions 137 83.4
MICHIGAN HYBRID 561
1 30 77.8 3.77 4.85 10 1.16 1.49
2 29 76.6 3.58 4.67 10 1.69 2.21
3 28 77.3 4.12 5.33 10 3.31 4.28
4 29 76.9 4.86 6.32 10 1.09 1.42
5 24 78.3 3-60 4-60 9 2.97 3.79
Ave. 28.0 77.3 3.99 5.15 9.8 2.04 2.64
A11
Replica-
tions 140 77.3
WISCONSIN HYBRID 350
1 30 81.8 3.99 4.88 10 2.47 3.02
2 27 83.7 2.65 3.17 10 2.22 2.65
3 29 83.4 2.66 3.19 10 1.52 1.82
4 30 83.3 2.15 2.58 10 1.08 1.30
5 27 83.0 2.66 3.20 10 1.91 2.30
Ave. 28.6 83.0 2.82 3.40 10 1.84 2.22
A11
Repliea—
tions 143 83.0
MICHIGAN HYBRID 1218
1 28 84.2 2.53 3.00 10 1.25 1.48
2 28 83.7 3.54 4.23 10 1.63 1.95
3 29 84.6 2.48 2.93 10 1.07 1.26
4 31 84.0 4.96 5.90 10 2.73 3.25
5 29 84.1 2.70 3.21 10 1.20 1.43
.Ave. 29.0 84.1 3.24 3.85 10 1.58 1.87
A11
Replica-
84.1

tions

 

All Repl.
S.D. Coef. Var.
3.14 3.76
4.01 5.19
2.94 3.54
3.37 4.01

Table II (continued)

PICKETT YELLOW DENT

10.

 

 

 

 

Repli- No. Coef. No. Coef. A11 Repl.
cates Ears Mean S.D. Var. Hills S.D. Var. S.D. Coef. Var.
1 27 85.2 1.82 2.14 10 0.93 1.09
2 24 85.3 2.91 3.41 10 1.77 2.08
3 27 85.2 1.93 2.27 10 1.16 1.36
4 24 85.0 2.29 2.69 10 1.29 1.52
5 27 84.3 3.13 3.71 10 2.42 2.87
Ave. 25. 85.0 2.42 2.84 10 1.51 1.78
A11
Replica-
tions 129 85.0 2.45 2.88
INDIANA HYBRID 416
1 28 80.4 3.25 4.04 10 1.63 2.03
2 27 80.7 4.30 5.33 10 2.77 3.43
3 29 80.7 4.65 5.76 10 3.48 4.31
4 29 79.6 3.79 4.76 10 2.27 2.85
5 29 78.9 5.93 7.52 10 2.97 3.76
Ave. 28. 80.0 4.38 5.48 10 2.62 3.28
A11
Replica-
tions 142 80.0 4.48 5.60
MINNESOTA HYBRID 402
l 30 81.8 2.45 3.00 10 1.11 1.36
2 31 81.0 2.69 3.32 10 1.25 1.54
3 30 81.3 3.34 4.11 10 0.98 1.21
4 29 82. 1.96 2.38 9 1.16 1.41
5 29 80.9 3.02 3.73 10 1.99 2.46
Ave. 29. 81.4 2.69 3.31 9.8 1.30 1.60
A11
Replica-
tions 149 81.4 2.75 3.38

11.

Table II (continued)

NORTHWESTERN DENT

 

 

 

Repli- No. Coef. No. Coef. All Repl.
cates Ears Mean S.D. Var. Hills S.D. Var. S.D. Coef. Var.
1 32 80.2 5.85 7.29 10 3.84 4.79
2 30 79.4 8.11 10.21 10 4.57 5.76
3 32 80.2 6.13 7.64 10 4.09 5.10
4 35 82.0 3.12 3.80 10 1.82 2.22
5 23 81.6 5.01 6.14 9 2.56 3.14
Ave. 30.4 80.6 5.64 7.02 9.8 3.38 4.20
A11
Replica-
tions 152 80.6 5.85 7.26
WISCONSIN HYBRID 606
1 29 84.5 2.23 2.64 10 1.28 1.51
2 28 82.4 4.26 5.17 10 2.35 2.85
3 29 82.4 4.41 5.35 10 2.58 3.13
4 29 83.2 4.16 5.00 10 2.77 3.33
5 30 83.3 2.57 3.09 10 0.98 1.18
Ave. 29. 83.1 3.53 4.25 10 1.99 3.40
A11
Replica—
tions 145 83.1 3.67 4.42
MICHIGAN HYBRID 21—A
1 28 81.3 3.49 4.29 10 2.74 3.37
2 22 80.3 3.56 4.43 10 2.19 2.73
3 30 82.6 3.07 3.72 10 2.34 2.83
4 23 80.2 3.51 4.38 10 2.09 2.61
5 26 80.3 2.52 3.14 10 1.91 2.38
Ave. 25. 80.9 3.23 3.99 10 2.25 2.78
A11
Replica-
tions 129 80.9 3.32 4.10

12.

A formula developed by Carver (2) was used to determine the mini-
mum number of ears necessary to sample adequately a plot of corn for
moisture content of the grain and for shelling percentage.

The formula used and the meaning of each symbol is as follows:

 

 

SDz £\I r - n . SDv
1’6"“. .39
r = is the number of ears in the parent population.

n = theoretical number of ears or hills in each sample.

SDz = standard deviation of all possible sample averages.
SDv = standard deviation of parent population.

To solve for N it is necessary to accept some limits for the

.2;—

SD The limits set were 5% of the mean moisture percentage er 2% of

Z.
the mean shelling percentage as obtained from the respective parent pop—
ulations.

In table 111 are recorded the theoretical number of ears that are
necessary to sample adequately for moisture per cent. The N values
(theoretical number of ears) indicate that their mean moisture per cent
will fall within the limits set (5 per cent) for each parent population
in 68.2 per cent of the cases and will fall within two standard devia-
tions (10 per cent) in 19 out of 20 cases. These results indicate that
if moisture samples are taken from only one replication that the maximum
number of ears required for a sample would be 15 ears for Northwestern
dent. If as many as 5 replications were used then 11 ears on the average
are sufficient. Only the Duncan yellow dent variety required 11 ears.
With all other varieties the 10-ear sample normally used at the Michigan
Station was competent.

If sampling was taken by hills at random, 5 hills or 15 ears would

be needed for the Duncan yellow dent variety, but 4 hills or 12 ears would

13.

be ample for the remaining varieties.

For comparison with the Michigan method of sampling overstate
trials the total number of 15 ears is large enough in all cases except
for the Duncan yellow dent variety which requires 16 ears. The number
of ears taken at random from a replicate in the overstate trials should
be increased to 3 ears, making a total of 15 ears for the composite
sample.

The theoretical number of ears found to be adequate for a shell-
ing per cent sample are recorded in table IV.

The corn varieties used in this investigation are very suitable
for shelling percentage studies because their shelling percentages var-
ied from a low 77.3 per cent for Michigan Hybrid number 561 to a maximum
of 85.0 for Pickett yellow dent. These varieties varied considerably
.more in moisture per cent than in shelling per cent as shown by their
standard deviations. A study of these data shows that the number of
ears required for a moisture sample is more than adequate as a shelling

sample.

I

Table III. Theoretical number of ears and hills whose mean moisture
per cents fall within the limits of 5% of the mean mois-
ture percentage of the parent population.

DUNCAN YELLOW DENT
A11 Replications

 

 

Replicates NO. Ears No. Hills No.Ears
1 11.12 3.61
2 13-32 .So95
4 8'31 [+046
5 10.67 3.77
Average 10.84 4.22
A11 Replications 15.74
MICHIGAN HYBRID 561
l 7.31 1.74
2 4.95 2.22
3 10.46 5.20
4 9.40 4.40
5 7.69 3.22
Average 7.96 3.36
A11 Replications 10.52
WISCONSIN HYBRID 350
1 9.46 3.77
2 5.78 2.44
3 10.28 4.06
4 5.20 1.63
5 13.27 6.00
Average 8.80 3.58
A11 Replications 13.35
JICHIGAN HYBRID 1218
1 7.53 3.75
2 7.73 4.58
3 8.22 4.49
4 12.57 4.15
5 10.05 2.75
Average 9.22 3.94
A11 Replications 12.81

15.

Table III (continued)

PICKETT YELLOW DENT

All Replications

 

 

Replicates No. Ears No. Hillg No. Ears
1 6.39 1.97
2 8.88 2.68
3 8.59 4.42
4 9.54 4.38
5 10.07 3.21
Average 8.69 3-33
All Replications 11.75

INDIANA HYBRID 416

1 4.89 2.34

2 6.47 3.22

3 7.20 3.04

4 8.37 3.22

5 11.23 3.13
Average 7.63 2.99
All Replications 9.68

MINNESOTA HYBRID 402

1 11.30 3.85.

2 10.36 2.67

3 8.68 4.92

4 4.93 2.05

5 9.90 4.00
Average 9.03 3.50
A11 Replications 11.9

NORTHWESTERN DENT

1 14.19 4.23

2 8.24 1.87

3 9.04 2.00

4 10.11 4.05

5 8.58 3.13
Average 10.03 3.06

A11 Replications 13,95

16.

Table III (continued)

WISCONSIN HYBRID 606

All Replications

 

 

Replicates No. Earg No. Hillg Np. Ears
1 8.48 2.78
2 10.99 3.09
3 10.28 2.28
4 7.17 2.43
5 10.13 3.32
Average 9.41 2.78
A11 Replications 13.06

MICHIGAN HYBRID 21—A

l 9.37 3.63
2 5.34 2.57
3 8.31 3.98
4 7.70 3.69
5 6.86 2.23
Average 7.52 3.22

All Replications 9.53

17.

Table IV. Theoretical number of ears and hills whose mean shelling per
cents fall within the limits of 2% of the mean shelling per-

centage of the parent population.

Replicates

 

\J‘tJ-‘bJNf-J

Average

All Replications

\nb-UJNI-J

Average

All Replications

\nwaH

Average

All Replications

\JII-‘WNH

Average

All Replications

No. Ears

b.) bNNwN
H I‘mw-JOD
mCDO‘anQ

\O

bumbw

O D O
I-‘(fioo-QO
OJMUJUJm

W
\h
.L\

5.11
2-37
2.41
1.63
2.43

2.79

DUNCAN YELLOW DENT

No. Hills

1-34
1.27
0.88
0.83
1.54

1.17

MICHIGAN HYBRID 561

0.58
1.19

H wow
0
\J.)\JT\JO
\x)\).)\7

(D
O

WISCONSIN HYBRID 350

2.02
1.63
0.84
0.45
1.28

1.24

MICHIGAN HYBRID 1218

0.58
0.96
0.43
2.27
0.54

0.96

A11 Replications
No. Ears

 

3048

6.45

3.09

3.93

Table IV (continued)

Replicates

\nmeI-J

Average

All Replications

\nJ-‘le—J

Average

All Replications

manner—J

Average

All Replications

\nwaH

Average

All Replications

No. Ears

1.13
2.69
1.27
1.76
2.42

2.00

\O-L‘O‘U‘IM
\lmO‘-J-J
mocmxooo

MINNESOTA HYBRID 402

2.15
2.61
3.81
1.39
3.21

2.63

PICKETT YEILOW PEI-IT

0-49
0.62

0.39
0.71
1.44

0.73

NORTHWESTERN DENT

9.61

14.21
10.21

3.37
6.90

8.87

3.88
4.77
4.20
1.20
2.76

3.36

No. Hills

18.

A11 Replications
No. Ears

2.06

7.48

2.81

12.17

 

Table IV (continued)

Replicates

 

mwal-J

Average

All Replications

\JI-l-‘KJJIvInJ

Average

All Replications

No

. Ears

1070
5.55
5.91
5.29
2.28

4.15

WISCONSIN HYBRID 606

No

0.60
1.85
2.14
2.35
0.37

1.46

MICHIGAN HYBRID

2.40
1.69
1.82

1.59
1.36

1.77

. Hills

21-A

19.

A11 Replications
No. Ears

 

4.75

4.10

20.

SUMHARY

CarverIs formula was used to determine the minimum number of ears
necessary for an adequate sample at harvest time of a plot of corn for
the moisture content of the grain and for the shelling percentages.

It was found that the maximum number of ears required for a mois—
ture sample for one replicate was 15 ears for Northwestern Dent.

Using the values from five replications for a true moisture sample,
10 ears on the average were sufficient, horcver, one variety, Duncan
Yellow Dent, required a sample of 11 ears. The 10-ear sample from one

‘
replication normally used at the local experiment station, made an ade—
quate sample for the other nine varieties.

The composite moisture samples used in overstate trials should be
increased from two ears to three ears for each replication which would
require a random composite sample of 15 ears. The 15-ear sample was
found sufficient for all varieties except Duncan Yellow Dent which re-
quired 16 ears.

The number of ears found necessary for moisture samples were more

than adequate in all cases as samples for the determination of the shell-

ing per cent.

10.

21.

LITERATURE CITED

Anderson, Dean 0., Corn Sampling in Missouri. Letter, February
10, 1940.

Baten, W. D., "Elementary Mathematical Statistics" pp. 208.
John Wiley and Sons, Inc. New York. 1938.

Bolin, Oren E., Corn Sampling in Illinois. Letter, February
14, 1940.

Hayes, H. K., Corn Sampling in Minnesota. Letter, February
13, 1940.

Jugenheimer, R. R., Corn Sampling in Kansas. Letter, February
10, 1940.

Marston, A. R., Corn Sampling in Michigan. Oral statement.
May 1, 1940.

Miles, 3. R., Corn Sampling in Indiana. Letter, February 9,
1940.

Neal, N. P., Corn Sampling in.Wisconsin. Letter, February 13,
1940.

Pfaff, H. L., Corn Sampling in Ohio. Letter, February 12,
1940.

Sprague, G. F., Corn Sampling in Iowa. Letter, February 12,
1914-0 0

II w... i IIIJIII-ill.‘lllnilll nil-i .Il.
. I . I . . . . 1 III. 3.-

 

 

1|..- 2. 1.1.1.1111 11...; . . . . . .

 

1 (ZARA; L,

V ,,.
.,v "V”
t- 44

ROOM pusr: om»