THE EFFECT OF FERTILIZER, ROW SPACING AND IRRIGATION ON ...

THE EFFECT OF FERTILIZER, ROW

SPACING AND IRRIGATION ON

GRAIN SORGHUM YIELDS

by

J. JOE WRIGHT, B.S.

A THESIS

IN

CROP SCIENCE

Submitted to the Graduate Faculty of Texas Tech University in

Partial Fulfillment of the Requirements for the

Degree of

MASTER OF SCIENCE

Approved

Accented

May, 1974

TEXAS TEC?? ll?PA«?Y

13

l\lo> ^0

t

ACKNOWLEDGEMENTS

I am deeply indebted to both Dr. Bob Stevens and Dr. Daniel R. Krieg for

their encouragement, patience and guidance in the preparation of this thesis.

Special thanks are also extended to Dr. Sujit Roy for his work on my committee

and to Dr. Thomas C. Longnecker for allowing me to continue my education

while an employee of the High Plains Research Foundation.

I would like to acknowledge the H i ^ Plains Research Foundation at Halfway,

Texas for the provision of land, labor and facilities. I am also appreciative of

the financial assistance given to this research project by Phillips Petroleum

Company.

11

CONTENTS

Page

ACKNOWLEDGEMENTS ii

LIST OF FIGURES iv

LIST OF TABLES v

I. INTRODUCTION 1

II. LITERATURE REVIEW 4

Fertilization 4

Irrigation 6

Row Spacing 7

III. MATERIALS AND METHODS 9

1971 Study 10

1972 Study 12

1973 Study 16

IV. RESULTS AND DISCUSSION 21

1971 Study 21

1972 Study 24

1973 Study 27

Combined Study 29

V. SUMMARY AND CONCLUSIONS 33

LITERATURE CITED 35

111

LIST OF FIGURES

Figure Page

1. Rainfall dates, rainfall amounts, and irrigation dates for 13 1971



4. Yield response of grain sorghum to preplant nitrogen in 28 1973

5. Average yearly grain sorghum yields from 1971 through 31 1973

iv

LIST OF TABLES

Table Page

1. Dates of cultural procedures, seeding rates, varieties 11 used and total rainfall for the 1971, 1972, and 1973 grain sorghum cultural studies

2. Chemical and physical characteristics of the soil from 14 the 1972 and 1973 test locations

3. Methods of soil analysis used and references 15

4. Nitrate nitrogen residues found at the 1973 test location 20

5. Composite statistical analysis of data for 1971, 1972 and 22 1973

6. The effect of irrigation and row spacing on average grain 23 sorghum yields in 1971

7. Effect of fertilizer on average grain sorghum yields for 24 1971, 1972, and 1973


9. The effect of sulfur and row spacing on average grain 26 sorghum yields in 1972


11. The effect of irrigation and row spacing on average grain 32 sorghum yields from 1971 through 1973

CHAPTER I

INTRODUCTION

Grain sorghum is grown in the temperate and tropical parts of the world

under a wide range of environmental conditions. Although world statistics are

difficult to obtain, it has been estimated that more than 80 million acres are

seeded each year.

In the United States grain sorghum is grown throughout the Great Plains

states from South Dakota to Texas and in the hot, irrigated valleys of California

and Arizona. Major sorghum producing regions in other parts of the world are

located in Sub-Saharan Africa, southern and eastern Asia, and in the temperate

regions of South America.

Grain sorghum's wide adaptability is probably due to the plant's ability to

withstand heat and drought better than many other crops. Grain sorghum can

adapt to regions with as litde as 15 inches of annual rainfall, but produces best

in humid regions or under irrigation. The sorghum plant becomes practically

dormant during periods of drought and then resumes growth as moisture becomes

available. Much of the plant's drought tolerance can be attributed to a waxy cu

ticle on the leaves which helps prevent dessication and to the plant's fiberous

root system which aids in efficient soil moisture uptake.

During 1971, Texas supplied 310 million bushels of the 743 million bushels

of grain sorghum produced in the United States. It was the largest acreage and

cash-producing crop in the state at that time. The main grain sorghum producing

area in Texas is the High Plains region where 2.0 million acres of land are uti

lized in the production of grain sorghum. Annual production on this total acre

age exceeds 220 million bushels and provides a gross income to farmers of ap

proximately 210 million dollars.

Most of the grain sorghum produced in the High Plains and as much as 80

percent of the grain sorghum produced in the United States is consumed by the

cattle feedlot industry. The vast importance of both grain production and cattle

feeding points out the need for continuing research to improve both grain sorghum

yields and nutritional quality.

During the past decade, plant breeders have vastly improved the yielding

potential of commercial grain sorghum hybrids. However, unless proper cul

tural practices are followed, grain yields will fall far short of their genetic po-

,/ tentials. Many cultural studies have been conducted on grain sorghum at loca-

/

tions throughout the Midwest. However, in recent years few of these studies

have been located on the Texas High Plains.

This study was conducted for three consecutive years, 1971-73 at the fa

cilities of the High Plains Research Foundation. At its conception, it was de

signed to investigate both yield and nutritional effects of key cultural controls.

This thesis deals only with the yield portion of the experiment. Thus the pur

pose of this study was to provide current information on the effect of irrigation,

row spacing, and fertilization on grain sorghum yields. Hopefully, this data

can be used by both producers and researchers to increase their knowledge of

this valuable crop.

CHAPTER II

LITERATURE REVIEW

Some of the most important cultural controls affecting grain sorghum

yields include rates of fertilization (especially nitrogen), irrigation levels, and

row spacings.

FERTILIZATION

Nitrogen has been shown to be one of the most important fertilizer nutri

ents utilized in the production of grain sorghum. Vanderlip (1972) reported that

inproducing a 7, 000 pound per acre grain crop, as much as 175 pounds per acre

of nitrogen is removed from the soil. Over 65 percent of this total is accumu

lated in the head with the remainder primarily in the leaf and stalk portions of

the plant.

Nelson (1952) reported yields of 7000 pounds per acre in a spacing-nitro

gen trial conducted near Moses Lake, Washington. He found that the addition

of nitrogen increased 3delds by as much as 2200 pounds per acre. Studies near

Tucumcari, New Mexico by Painter and Leamer (1953) showed that with increas

ing nitrogen rates, yields increased in a Micherlich-like curve. This type of ni

trogen response was also noted by Robertson and Walker (1966) and by Robertson,

Onkenand Walker (1969). In both of these experiments the greatest yield increas

es were realized from increments of nitrogen up to 60 pounds per acre. Higher

rates resulted in further yield increases but the increase per increment of ni

trogen became progressively smaller. Grimes and Musick (1960) found small

but significant responses to 80 and 100 pound per acre applications of nitrogen

4

in Garden City, Kansas plots. Porter, Jensen, and Sletten (1960) found by com

paring 80 and 160 pound per acre rates of nitrogen at Bushland, Texas that the

higher rate produced yields of over 1000 pounds per acre more than the lower

rate.

In a later study conducted at Garden City, Kansas, Musick, Grimes, and

Herron (1962) found that nitrogen response curves were directly related to i r

rigation treatments. Nitrogen rates of 0, 40, 80, and 120 pounds per acre were

observed in combination with irrigation treatments of one, two, three, and four

applications of water. With one irrigation at preplant the first 40 pounds per

acre of nitrogen significantly increased yield but additional amounts of nitrogen

had no appreciable effect. Yields did, however, increase steadily in the wetter

treatments with increasing nitrogen rates up to the maximum nitrogen level.

These investigators also noted that applied nitrogen not only increases yields

but also increases water use efficiency. A similar test by Valliant and Longnecker

(1967) at Halfway, Texas also concluded that nitrogen response was increased

only as irrigation water was increased. In more recent research at Bushland,

Texas, Onken and Sunderman (1972) reported that increasing nitrogen rates of

0, 50, 100, 150, and 200 pounds per acre generally produced significant yield

increases where water was not limiting.

Sulfur has not been shown to be an important fertilizer nutrient in grain

sorghum production. It may, however, affect grain sorghum protein. Yield

response to sulfur at rates of 0 and 40 pounds per acre was not found by Owen

and Furr (1967)in their Pantex, Texas test. Similar results were also reported

by Robertson, Onken, and Walker (1969) in their Bushland, Texas studies.

The developing problem of nitrate residues was noted by Onken, Sunderman,

and Jones (1970). They found a highly significant linear relationship between

residual NOo-N and grain yields. Onkenand Robertson (1968) reported that some

nitrate is leached from the root zone but that the remaining unused nitrate ac

cumulates in the soil year after year. Robertson, Onken, and Walker (1969)

also found that nitrates do accumulate but recommended that nitrogen still must

be applied every year to maintain yields.

IRRIGATION

Past research has proven that irrigation increased yields. Recent invest

igations have been concerned with the correct amounts and timings of grain sor

ghum irrigation. Painter and Leamer (1953) reported that more frequent i r r i

gations increased yields. Grimes and Musick (1960) found that in numerous

years of grain sorghum cultural tests, the highest yields consistently came from

plots grown under the highest soil moisture levels.

A study by Swansonand Thaxton (1957) stated that the variability of rain

fall and extended periods of drought are the greatest problems encountered in

producing grain sorghum on the Texas High Plains. They reported that the water

requirement for grain sorghum is not a fixed value. In hot dry years, transpi

ration by the plant is higher than in relatively humid seasons. Low relative

humidities, high temperatures and wind movement also increase evaporation

from the soil surface, further increasing consumptive use. Restricted moist

ure was shown to reduce transpiration, while frequent irrigation increased evap

oration. They also noted that grain sorghum usually needs between 16 and 24

inches of moisture for production of maximum yields. In an average year, rain

fall will account for only about half this amount. Their findings indicated that

preplant, panicle initiation, and half-bloom were the most important irrigation

periods.

Musick, et al (1962) found that grain sorghum yields were greatly increas

ed by irrigation. Their studies showed that sorghum yields were curvilinearly

related to soil moisture availability as controlled by number of irrigations.

They also concluded that irrigation between the boot and soft dough stages of

plant development was crucial to good yields. Onken (1970) added that he had

found the period of maximum water use for grain sorghum to be during the boot

stage of development and that this water need could be as high as 0.30 to 0.40

inches per day depending on the climate.

ROW SPACING

Row spacing has been shown to be of prime importance in attempting to

make the most efficient use of soil moisture and nutrients. Grimes and Musick

(1960) found that regression equations indicated that increased row width de

creased yields. Porter, Jensen, and Sletten (1960) reported increased yields

due to narrower row spacings. They attributed this increase to more efficient

use of water, nutrients, and solar energy as a result of more uniform plant

8

spacing. In addition to increased yields, narrower rows were found to reduce

weed control problems by shading a greater soil area. Choy and Kanemasu

(1974) attributed increased yields in narrow rows to decreased evapotraspira-

tion. In a study conducted on a very sandy soil near Big Spring, Texas, Welch,

Burnett and Eck(1966) noted increased yields with 20-inch spaced rows as com

pared to 40-inch spaced rows.

In a test conducted at Bushland, Texas on dryland grain sorghum. Bond,

Army, and Lehman (1964) reported that 40-inch spaced rows produce more than

20-inch spaced rows when moisture reserves were less than five inches per acre

foot. Their findings also indicated that while 20-inch spaced rows provide more

residue for erosion protection, they lodged more severely than 40-inch spaced

rows.

A more recent experiment at Bushland by Allen, Musick, Wood, and Duseck

(1970) concluded that two rows spaced 10 to 12 inches apart on 40-inch spaced

beds are superior to single rows planted 30 to 40 inches apart and are equal to

row spacings of 10 and 20 inches. They also pointed out that the benefits of

narrow row spacings are maximized only under optimum irrigation.

Seeding rates must be considered when comparing row spacings. Grimes

and Musick (1960) reported that plant population may vary widely without ser i

ously affecting grain yields. Bond, et al (1964) found that high populations r e

duced yields where water was limiting. Porter, et al (1960) noted that high seed

ing rates increased water competition and increases the incidence of the spread

ing of seedling diseases.

CHAPTER ni

MATERIALS AND METHODS

In the spring of 1971, a three year study on the effect of various cultural

practices on grain sorghum yields was initiated at the High Plains Research

Foundation. This agricultural research facility is located near the community

of Halfway, approximately thirteen miles west of Plainview, Texas. The soil

at this testing site is a uniform Pullman clay loam. During the past five years

precipitation at the Foundation averaged 22.6 inches per year.

The basic experimental design for the test was as follows:

(1) Irrigation blocks were established by dividing the test area in half.

(2) Row spacings were arranged with every other four beds planted in

single and double rows.

(3) Fertilizer treatments were arranged in randomized complete blocks

with each plot composed of four single rows and four double rows

randomized within each replication of the irrigation blocks.

The statistical description for the experimental design would be called a split,

split, randomized complete block.

In the first year of this study each irrigation level was divided into four

subdivisions. Two of these subdivisions received a high herbicide rate and the

remaining two received a low herbicide rate. Fertilizer treatments, row spac

ings, and herbicide rates were replicated twice within each irrigation level. The

herbicide variable was deleted from the study after 1971 and fertilizer and row

spacing variables were then replicated four times within each irrigation level.

9

10

Individual plots were four beds wide and thirty-three feet in length.

During all three years of this study seedbed preparation included deep

breaking, two tandem diskings, and bedding. The previous crop grown was

always soybeans. Preplant nitrogen was applied at rates of 50, 100, and 150

pounds of nitrogen per acre as anhydrous ammonia and ammonium sulfate. Sul

fur was applied preplant at rates of 0 and 50 pounds as ammonium sulfate per

acre . It should be noted that on plots that received both preplant nitrogen and

sulfur, the total pounds of ammonia applied was adjusted in order that the total

nitrogen levels were the same as in plots receiving only preplant nitrogen. Side-

dress nitrogen was applied between the seven leaf and boot stages of plant growth

at rates of 0, 50, and 100 pounds of nitrogen per acre as anhydrous ammonia.

Planting, fertilization, irrigation, and harvest dates as well as seeding rates

and rainfall data for all years are listed in Table 1. Time of irrigations was

determined by visual observation of plant stress and stage of plant development.

Each irrigation is equal to approximately five inches of water. Normal farm

ing procedure sand equipment were generally used in the production of each grain

sorghum crop.

1971 STUDY

In 1971 the grain sorghum hybrid used was Dekalb F-65. This test was

planted on May 15 at seeding rates of 7.6 (single row) and 10.2 (double row)

pounds per acre. Sidedress nitrogen in the form of anhydrous ammonia was

applied at the seven leaf stage of plant development. The low irrigation portion

11

-a a cd

. cs t ^ c 1 ^

r>. OS ^ (U

•3 u o MH

1=1 al

inf

cd M

1—1

B o 4->

•a cd

T3 (U CO 3 CO (U

• i H 4-1 (U

. . H U cd >

«% CO (U 4-* c4 M

S' . .H

'S CO

• CO d) U

edu

CJ O u

1—1 cd

u B 3 u

<*H

o CO o 4.J

td

• U)

• iH

1 4_> m 13 H 3 -3 o a 3

•6 u o CO

.s cd u bo

CO

r- o O -H

(L>

cd

H

CO r o r-\

0)

o Q

(U u c • i H

CO

1 pc:;

^ o 0^

eg

O N

ON

0)

•§ o Q

Pc:;

'SI CO

II

•in pi^ CO

O

CM

d

vO

C M

O

4.J H cd o

pc5 Jti

^ •»-l

^

CM

cs

3

ON ID I w

Q

ON i n

I

W

cd

0)

Q

in

cd

(U 4-1

Cd Q bd CO

C/3 'C? OH

in NO I

.o

I Q

o CO

•T-t

(0 d o

^ cs r cs cs cs

cd cd a

CO CS

O CO i n i-i <-i c s

cd cd ti

S S a

2 CO

^'B 3'S a .i cd

0)

•8

bd

o

xj bd

I H4

r ^ ON

f-H 3

i n 00

0) CO

3 -3 bo 1=1 ^ 3

a 3

i n

bo 3

<:

X! bd

I

0 0 ON ^ , ^ cs ^

00 I—I

cd I — I

3

<q ^ii ' CU O, CO

1=: o •d bo cd H P

CO

cs

vO

0)

> o Z

oo

<u

S 0) o 0)

Q

o cs

in 1—1

u

o 4-) o O

CO 0) >

u ^ cd

- ^ • ^

cd bo

pc; .3

CO 0) 4-1

Cd

Q 4-) CO

& cd X

12

of the test received a total of only two irrigations while the high portion was

irrigated four times.

The herbicide (Propazine SOW) was applied preplant at rates of 1. 5 and 3.0

pounds of active material per acre. During the growing season it became ne

cessary to apply DiSyston (15% granules)at a rate of six pounds per acre on July

7 and ethyl parathion at a rate of one pint per acre on July 27 for greenbug con

trol.

Sixteen and one-half feet of each of the two center rows of each plot were

hand harvested on October 15. After harvest, the heads were threshed with an

Almaco plot thresher to determine plot weight. All plot weights were adjusted

to 14.0 percent moisture.

Rainfall and irrigation data for 1971 are shown in Figure 1. It should be

noted that the spring of this year was unusually dry while the fall was unusually

wet. Precipitation for the year totalled 28. 5 inches with 20.1 inches of this to

tal falling between the plantingand harvest dates of the test. Average daily tem

peratures were nearly ten degrees below normal throughout the growing season.

1972 STUDY

Prior to planting, top soil samples were taken from random locations

within the test area. Data and methods of analysis of these soil samples are

shown in Tables 2 and 3.

In 1972 the study was planted on June 2 using the variety Dekalb E-59.

The test was planted with the same equipment and using the same seeding rates

13

U CO

« <;

I •a •r-t

u

^ o 4-1 u O

u .s Fl

epte

CO

4-1 CO 3 bn -J

<;

> .

-3 1—>

(U

3 1—>

>» CQ *5

1—1

CJN 1—1

>-i

o '4H to 0) 4->

Cd

a o 4->

•<H Vl u

• .H

TS C cd

., m

4 J

3 O B cd

1—1 1—4

^ •r-( Cd >-(

• V

CO a> 4-)

•s ^

infa

cd oc; 1 1

r H

bb •«-t

fe

1 I i 1 NO i n Tji CO CS

17VdMIVH dO SaHONI

CO a o •d cd u o

CO 0) 4->

CO

cd

0)

x:

o i-i

M-l

o CO

4->

a

o CO

a

1 cd

-^ o

B

u

t—I

cd H

g

bO

a> CO

" CO CO

O cd U

O CN|

in O cs

I ICO

O

K a

cS Q

}-<

CO 0)

H

tH cd

o o cs

o in cs

o CO cs

o in cs

CO

cs CO ' ^

ON i n vO

CO CO ON

o in

o 00

o cs

CO in cs

14

CJN OO

in

NO VO

U J

cs l> CJN

CO t^ C3N

15

CO 0)

u

0)

cd

CO

3 CO

CO

>» f—I a cd

o CO CO

•s

CO

t—I

u a (D tH .?> <*H

(U

CO • tH CO

a> •g M

4.J

o (D I—1

w tH

^

-Fis

cd

Bee

;w

ate

:zl o

>E3' cs • •

1—1

y—\

.954

o vO

• o

ook

N<

CJ cd

r 1—1

1 t ^

a,

< ^

w

'S cd

• •

^

• 1—»

s,

R.

H ^ >>

(196

8)

^

Paul

vO CS O I - I

• a

^•^ i n VO Ov r-i '

-•

< •

• k

M O

vO CS o ^H

• Ou

^—V i n vO CJN r-i ' •

~ •

<

U ^

M O cd

VO CS o l - <

• 04

^^^ i n VO ON ^H ' — •

« h

• < :

^ M 0 cd

I—1 OQ

VO CS 0 t—1

• a

^ , 0 ^

i n vO ON ^H ' •

^ •

< •

•% M 0 cd

vO Cv| 0 r—1

% cx

i n VO 0 1—1

•

•

•« M 0 cd

> n u 3

•H O

U

0) •o o tH

o 0)

1—1

4-> Cd tH

tH 0) 4-> 0)

o IH

^

X

o • iH 4->

u a *->

w

o -s • ^ 4 ->

X <i> g S •^ o

O CD

O Cd u

0)

6 Q

X 2 w ^ o o O o

X ex

o cd

o •d CJ cd tH 4-1 X

w o < O

o

o CO

X < Z o 2 6 O O

DC a

p ^ CO

1^ ^ CO CO

ro Q Z

a> tH 3 4.J

X <D H

i n 0 cs

PH

0 cs

t>

0 cd U

o •I-I 4->

o 2 X

w

O

1 ^ o •a

o CO

X <:

^ B o o

o •a

>< 2

o o

O o

g c o

^ § O cd

. I—I

rH fo

bo g

16

as were used in 1971. The experimental design was similar to the one used in

1971 with the exception being that the herbicide variable was not included in the

1972 study. Rainfall delayed the sidedress application of anhydrous ammonia

until the early boot stage of plant development. The low irrigation portion of

the test was irrigated twice compared to only three irrigations for the high ir

rigation portion.

Propazine 80Wwas sprayed broadcastand incorporated on June 2 atarate

of 1. 5 pounds per acre for seasonal weed control. DiSyston (15% granules) at

a rate of six pounds per acre was applied aerially on July 21 for insect control.

After over a month of delays due to rain and snow, the entire length of the

interior two beds in all plots was combine-harvested on December 8. The com

bine used was a model A-11 Gleaner-Baldwin mounted with a Roll-A-Cone pick

up attachment. Plot weights and moisture sample readings were taken at har

vest and then all plot weights were adjusted to 14.0 percent moisture.

Rainfall and irrigation data for 1972 are shown in Figure 2. One will note

that July and August were extremely wet months during which little irrigation

water was needed. A rainy September and October delayed harvest, and a No

vember 1st ice storm caused the test to lodge. Lodging scores were taken and

indicated that yield reductions were as much as 15 percent.

1973 STUDY

Prior to planting the 1973 study, top soil samples were taken from random

locations within the test area (see Table 2). Twelve soil profile samples were

17

Z o p <; o HH

CO

w

I %

u CD

O 4-> CJ

O

tH

CD 4->

0) CO

CO

3

i-H

3

I I N O in Tt« CO cs

nVdMIVH dO SaHONI

CSI ON

tH

CQ (U 4-1 Cd -d a o

• iH 4->

.& IH tH

•i-f

•s cd

CO

O B cd

1—4

a • i H

Cd u *

CO

o 4->

.cd

cd

I I

cs

bb • iH

fo

18

also taken at the testing site. Each major sample contained six subsamples

taken from six inches to five feet in depth. Table 4 shows the nitrate carry-over

from soil profiles that had 0, 50, and 250 pounds per acre applied to them in

1971.

The e^qjerimental design was exactly the same one that was used in the

previous year. It should be noted that each plot in die high irrigation portion

of this study was located on the exact same site as it was in the 1971 study. Low

irrigation plots were planted on land that had been in soybeans the previous two

years.

The study was planted onMay 24 using the variety Dekalb E-59. The seed

ing rates were increased to approximately 11.0 and 17.0 pounds per acre for

the single row and double row variables respectively. Seeding rates were in

creased in an attempt to get more significant row spacing by irrigation inter

actions. The high irrigation portion of the test was irrigated four times while

the low irrigation portion of the test received only one irrigation. Anhydrous

ammonia was sidedressed on June 27 at the seven leaf stage of plant development.

Propazine and DiSyston applications were applied at the same rates as they

were in 1972. The center two beds in all plots were combine harvested on No

vember 6. Harvest, sampling, and calculating procedures were the same as

they were in the previous year.

Irrigation and rainfall for 1973 are shown in Figure 3.

19

2^

2°

^

3 •a

E

I 1 I I

C

E

u (U n O 4-1

u O

mbe

r

d)

a, CO

4-) CO 3 hn 5r <3

>> 1—«

3 1—»

(U

1—>

> v

Oc5 <

w 3: H fo O CO X

Z o :^

973

1—1

iH

tes

fo

on d

a

•fH 4-)

iga

tH tH

• iH

? Cd

• k

CO 4-»

o B cd

I—1 1—1

dat

es,

rain

fa

cd

3.—

Rai

nf

Fig

.

VO in rji CO cs

17VdNIVH dO SaHDNI

Table 4. Nitrate nitrogen residues found at the 1973 test location.

20

Lbs . of N Applied in

1971

0

0

0

0

0

0

Average

50

50

50

Average

250

250

250

Average

6

30.8

13.2

30.8

26.4

26.4

30.8

26.4

30.8

26.4

22.0

26.4

48.4

39.6

48.4

45.5

Depth 12

26.4

8.8

30.8

17.6

26.4

30.8

23.5

39.6

13.2

22.0

24.9

48.4

39.6

48.4

45 .5

of Soil Sample in 24 NO3

17.6

52.8

26.4

35.2

35.2

35.2

33.7

35.2

44.0

44.0

41.1

52.8

52.8

52.8

52.8

36 -N Lbs/A(

17.6

35.2

61.6

17.6

44.0

26.4

33.7

35.2

26.4

26.4

29.3

26.4

61.6

26.4

38.1

Inches 48

c.

26.4

26.4

26.4

17.6

35.2

17.6

20.5

26.4

35.2

35.2

32.3

79.2

96.8

26.4

67.5

60

79.2

26.4

52.8

17.6

35.2

26.4

39.6

35.2

35.2

35.2

35.2

61.6

61.6

26.4

49.8

Total Lbs. N03-Nin Five Feet

of SoU

198.0

162.8

228.8

132.0

202.4

167.2

177.4

202.4

180.4

184.8

189.2

316.8

352.0

228.8

299.2

CHAPTER IV

RESULTS AND DISCUSSION

A composite statistical analysis of data from 1971, 1972, and 1973 is

shown in Table 5. Preliminary analysis of the 1971 data showed no herbicide

response, therefore, this variable was not considered in the data reported here.

1971 STUDY

In 1971, both row spacing and irrigation response were highly significant

while the interaction between row spacing by irrigation was shown to be slightly

significant.

Double row plots averaged 6120 pounds per acre as compared to an aver

age yield of 5610 pounds per acre in single row plots. The yield of high irriga

tion plots averaged 6487 pounds per acre while the low irrigation plots averaged

5242 pounds per acre.

The combined effects of irrigation and row spacing are shown in Table 6.

Under low irrigation, double row plots averaged just under 400 pounds per acre,

more than the single row plots. Under high irrigation the double row plots

yielded almost 700 pounds per acre, more than the single row plots. The aver

age yield of the high irrigation plots was 21.2 and 26.1 percent more than the

average yield of the low irrigation plots with single and double row spacings,

respectively.

No other variable or interaction produced a significant response during

1971. This was somewhat surprizing in that a response to applied nitrogen had

been anticipated. However, as can be seen from Table 7 this was not the case

21

22

Table 5. Composite statistical analysis of data for 1971, 1972 and 1973.

Term ]

Name

Replications Irrigations E r r o r A Preplant Irrigation x Preplant Sidedress Irrigation x Sidedress Preplant x Sidedress Irrigation x Preplant

X Sidedress Sulfur Irrigation x Sulfur Preplant x Sulfur Sidedress x Sulfur E r r o r B Row Spacing Irrigation x Row

Spacing Preplant x Row

Spacing Sidedress x Row

Spacing Sulfur X Row Spacing Irrigation x Preplant

X Row Spacing Irrigation x Sidedress

X Row Spacing Preplant x Sidedress

X Row Spacing E r r o r

Degrees of Freedom

3 1 3 2 2 2 2 4 4

1 1 2 2

102 1 1

2

2

1 2

2

4

108 ** Significant at 1% level. * Significant at 5% level.

1971

2435106 111645379**

1722994 635654

15815 761852

1562304 220973 726142

66096 14182

173590 1302355

648838 18708334**

2039021*

435382

318316

515027 50632

331267

300320

369822

Mean Squares 1972

1460651 118211969*

3964499 7239765 1349408 1054618

533763 297148

1476183*

85250 15268

114130 86679

482129 48756989*

7077262**

16141

416575

2486264** 266718

1127112*

760809

341775

1973

59110978 861152666**

10053870 10928732*

1034453 6683291 3743147 2087311

153069

11365322* 1359325 3116944

256469 2844664

14988725** 3399962**

15904

132400

52920 322420

116890

72294

334564

23

soil samples were not taken in 1971. Without this data the primary explanation

that previous nitrogen build-up in the soil prevented significant yield response

can be speculated but cannot be proven.

Table 6. The effect of irrigation and row spacing on average grain sorghum yieldsl in 1971.

Irrigation Row Spacing Percent

Level Single Double Increase

Low 5071 5412 6.7

High 6148 6826 11.0

% Increase 21.2 26.1

^Pounds per acre.

The highly significant yield increases noted in the row spacing and i r r i

gation variables as well as the slightly significant irrigation by row spacing in

teraction agree with the findings of Allen, et al (1970).

1972 STUDY

In 1972, the effect of preplant nitrogen, irrigation by row spacing, and

sulfur by row spacing responses was highly significant. Significant responses

were noted for irrigation, row spacing, irrigation by preplant nitrogen by side

dress nitrogen, and irrigation by sidedress nitrogen by row spacing. (Table 5).

Yields of double row plots averaged 7047 pounds per acre while yields of

single row plots averaged 6224 pounds per acre. The yield of high irrigation

24

Table 7. Effect of fertUizer on average grain sorghum yields for 1971, 1972, and 1973.

Fertilizer Treatment Preplant

Nitrogen Sulfur

0

50

50

0

100

50

0

150

50

Sidedress Nitrogen

0 50 100

0 50 100

0 50 100

0 50 100

0 50 100

0 50 100

1971

5841 5653 6257

6045 5838 5875

5997 5926 6002

5825 5825 5846

5472 5991 6069

5915 5468 5709

Year 1972

6926 6914 6737

6874 6949 6802

6885 6761 6310

6861 6757 6670

6288 6395 6349

6301 6441 6220

1973

5932 6253 5966

6867 6844 6161

6434 6500 5982

6738 6853 7232

6163 6352 5362

6248 6246 5332

Average

6233 6274 6320

6596 6544 6280

6439 6396 6098

6475 6478 6583

5974 6246 5927

6154 6052 5754

All figures in pounds per acre.

25

plots averaged 7276 pounds per acre as compared to an average yield of 5995

pounds per acre for the low irrigation plots.

Increases in preplant nitrogen applications of 50, 100, and 150 pounds per

acre resulted in yields of 6867, 6707, and 6332 pounds per acre respectively.

Thus, increasing preplant nitrogen levels above 50 pounds per acre resulted in

significant decreases in yield. Even thoughfertUizer bands were placed 6 inches

from the grain sorghum seeds, this response indicates ammonium toxicity at

the higher nitrogen levels.

The irrigation by row spacing response is shown in Table 8. These find

ings show that high irrigation, double row plots produced higher yields than

single row, high irrigation; double row, low irrigation; or single row, low ir

rigation treatments respectively. Note also that the double row plots produced

a 29.4 percent increase in yield over the single row plots even under the low ir

rigation level. The greater percentage increase of double row yields over single

Table 8. The effect of irrigation and row spacing on average grain sorghum yields^ in 1972.



Low 5427 7022 29.4

High 6563 7531 14.7

^ Increase 20.9 7 2 ^Pounds per acre.

26

row yields can probably be attributed to the relative lack of moisture stress en

countered by the grain sorghum plants in 1972 due to uniformly spaced rainfalls.

Since the ammonium sulfate was applied broadcast, thus eliminating the

possibility of seedling damage due to band placement, no e^lanation can be re

liably given for the highly significant row spacing by sulfur response. (Table 9)

Table 9. The effect of sulfur and row spacing on average grain sorghum yields^ in 1972.

Row Sulfur Rate Percent

Spacing 0 lbs/Ac. 50 lbs/Ac. Increase

Single 6300 6148 -2.5

Double 6937 7157 3.2

% Increase 10.1 16.4 •'•Pounds per acre.

The most obvious results were again that narrower row spacings and high

er irrigation levels resulted in significant increases in yield. In looking at the

irrigation response the high level received only one more irrigation than the

lower level (see Figure 2). This indicates the importance of timing as well as

amount of water applied in analyzing irrigation test results.

Even though there were other significant fertilizer interaction responses

in 1972, CTable 5) there were no other significant trends. Nitrate nitrogen in

the top six inches of soil (Table 2) averaged nearly 50 pounds per acre before

27

the addition of fertilizer, thus limiting any response to applied nitrogen. Low

levels of phosphorous in the soil (Table 2) probably resulted in nutrient imbal

ances at the higher nitrogen levels and thus also contributed to the lack of yield

response to applied nitrogen.

1973 STUDY

Results of the 1973 study showed highly significant responses to the row

spacing and irrigation variables, and to the row spacing by irrigation interaction

(Table 5). Two fertilizer variables, sulfur and preplant nitrogen, produced

significant yield responses.

Double row plots averaged 6531 pounds per acre as compared to an aver

age yield of 6075 pounds per acre in single row plots. The high irrigation plots

yielded an average of 8033 pounds per acre while low irrigation plots averaged

4574 pounds per acre in yield.

The row spacing by irrigation interaction is shown in Table 10. Under high

irrigation the double rowplots yielded almost 9.0 percent more than the single

row plots. Even under low irrigation the double row plots still averaged over

5.0 percent more than the single row plots. The average yield of the high ir

rigation plots was 72. 7 percent and 78.3 percent more than the average yield of

the low irrigation plots in single and double row spacings respectively.

Response to preplant nitrogen is shown in Figure 4. Any increase in yields

as a result of applied nitrogen is surprizing considering the high levels of ni

trate nitrogen levels found in the soil profile (see Table 4).

a 6 o o o

2 c '-' 5 9

4 -

28

t 50 100 TI 0

RATE OF PREPLANT N IN LBS./A

Fig. 4. —Yield response of grain sorghum to preplant nitrogen in 1973.

29

Table 10. The effect of irrigation and row spacing on average grain sorghum yieldsl in 1973.



Low 4455 4694 5.4

High 7696 8370 8.8

% Increase 72.7 78.3

Pounds per acre.

The addition of sulfur increased yields on the average from 6105 to 6502

pounds per acre . Since a sulfur response was not noted in the two previous

conditions of 1973. However, the most reliable explanation of why there would

be such a reaction might be that at the higher seeding rates used in 1973 sulfur

did become a limiting plant nutrient.

Measurement of yield response in 1973 was made difficult by an early

August hail storm damaged two replications in each irrigation level, and by the

accidental rupture of an anhydrous ammonia tank which severely damaged a num

ber of plots in the same replications. However, statistical analysis of the two

undamaged replications when compared to the analysis of all four replications

did not show any major changes in the statistical results.

Combined Study

In comparing all three studies, the year of the study becomes a variable

along with row spacing, irrigation levels, and fertilizer.

30

Analysis of the combined data indicated highly significant responses to the

year, row spacing, and irrigation variables, along with the row spacing by ir

rigation interaction. Response to fertilizer variables was not as significant as

was e jec ted .

Average yields for the three years are shown in Figure 5. The main dif

ference in the three years was the variation in rainfall. The years 1971 and

1972 were relatively wet, in comparison to 1973 which was relatively dry (see

Table 1). The fact that the yields were highest in 1972 can be attributed to the

more even distribution of rainfall in that year, thus producing higher average

yields in the low irrigation treatment than during the 1971 and 1973 seasons.

Over-all, the yield of double row plots averaged 6566 pounds per acre as

compared to the yield of single row plots which averaged 5970 pounds per acre.

Similarly, the yield of the high irrigation plots averaged 7265 pounds per acre

as compared to the yield of the low irrigation plots which averaged 5270 pounds

per acre.

Row spacing by irrigation interaction results are shown in Table 11. Of

special interest is the fact that the double row spacing increased the yields by

about 600 pounds per acre over the single row spacing in both the high irrigation

plots and the low irrigation plots. This finding is not consistent with the find

ings of other researchers, including Clegg, Sullivan, Maranville and Eastin

(1973) who had concluded that narrow row spacings were not advantageous at

low irrigation levels.

8

31

CO

a 6 o o o I - I

9 V I—I 1

1971 1972 YEAR

1973

Fig. 5. --Average yearly grain sorghum yields from 1971 through 1973.

32

As in the studies of the individual years, the responses to the fertilizer

variables for all three years did not show noticeable trends. Again note Table

7 which shows the effect of fertilizer on grain sorghum yields for all three years

for all three years of this study. The lack of results was primarily attributed

to the high levels of residual nitrate nitrogen found in the soil (Table 4) and pos

sibly by low soil phosphorous levels (Table 2).

Table 11. The effect of irrigation and row spacing on average grain sorghum yields^ from 1971 through 1973.



Low 4984 5556 11.5

High 6955 7575 8.9

% Increase 39;_5 3 6 J Pounds per acre. _ _ _ _ _ _ ^

The greatest yields of the high irrigation plots were recorded in 1973;

this is probably due to the higher seeding rates in that year's study. This would

agree with the findings of Castieberry, Eastin, and Clegg (1973) who reported

increased grain sorghum yields at unusually high plant populations.

CHAPTER V

SUMMARY AND CONCLUSIONS

During three seasons, 1971 through 1973, the effects of various cultural

practices on grain sorghum yields were investigated. This study was conducted

at the High Plains Research Foundation with the main cultural variables being

two irrigation levels, two row spacings, and eighteen fertilizer combinations.

From this study five major findings were noted:

(1) Over a period of years irrigating grain sorghum three to four times

as compared to one or two times increased yields by an average of

over 2, 000 pounds per acre.

(2) Double rows spaced twelve inches apart on 40-inch spaced beds in

creased yields by an average of 600 pounds per acre more than is

produced by single row spacings. In this experiment, yield response

was not affected by the irrigation level.

(3) Increasing total levels of nitrogen did not consistentiy result in in

creased yields in any year of this study. Over-all, increasing ni

trogen above the base 50 pounds per acre reduced yields. The re

sponse to different rates of preplant and sidedress nitrogen simply

was too diverse to draw any positive conclusions. It appeared that

in all three years of this study a preplant nitrogen application of 50

pounds per acre would have produced the greatest economic returns.

(4) Soil tests in 1972 and 1973 show that at the testing site very high ni

trate residuals have been built up under reasonably normal farming

33

34

conditions. This should point iqj the extreme importance of soil

testing to prevent over-fertilization.

(5) The fact that this study followed soybeans all three years indicates

that the importance of soybeans in a crop rotation system deserves

further investigation.

LITERATURE CITED

Allen, R. R., j . T . Musick, F. O. Wood, andD. A. Duseck. 1970. Grain sorghum yield response to row spacing in relation to seeding date, days to maturity and irrigation level in the Texas Panhandle. Tex. Agri. Exp. Sta. PR-2697.

Black, C. A. 1965. Methods of Soil Analysis, part 2. Chemical and Microbiological Properties, p. 1026. Society of Agronomy, Inc. Madison, Wisconsin.

Bond, J. J., T. J. Army, and O. R. Lehman, 1964. Row spacing, plant populations and moisture supply as factors in dryland grain sorghum production. Agron. J. 56:3-6.

Castieberry, R. M., J. D. Eastin, and M. D. Clegg. 1973. Relationship of duration of the grain filling period to population density. Research in the Physiology of Yield and Management of Sorghum in Relation to Genetic Improvement. Annual Report No. 7. University of Nebraska. Lincoln, Nebraska, p. 6-24.

Choy, E. W. C , and E. T. Kanemasu. 1974. Energy balance comparisons of wide and narrow row spacings in sorghum. Agron. J. 66:98-100.

Clegg, M. D. , C. Y. Sullivan, J. W. Maranville, and J. D. Eastin. 1973. Dryland response of four grain sorghum hybrids grown in three row spacings and at three plant populations. Research in the Physiology of Yield and Management of Sorghum in Relation to Genetic Improvement. Annual Report No. 7. University of Nebraska. Lincoln, Nebraska, p. 24-33.

Grimes, D. W. and J. T. Musick. 1960. Effect of plant spacing, fertility, and irrigation management on grain sorghum production. Agron. J. 52:647-650.

Meyers, R. J. K., and E. A. Paul. 1968. Nitrate ion electrode method of soil nitrate nitrogen determination. Can. Jour, of Soil Sci. 48:369-391.

Musick, J. T., D. W. Grimes, and G. M. Herron. 1962. Irrigation water management and nitrogen fertilization of grain sorghums. Agron. J. 54: 295-298.

Nelson, C. E. 1952. Effects of spacing and nitrogen applications on yield of grain sorghums under irrigation. Agron. J. 44:303-305.

35

36

Onken, A. B. 1970. Cultural practices for grain sorghum production. Tex. Agri. Esq). Sta. PR-2938.

Onken, A. B. andW. Robertson. 1968. Time and rate of nitrogen application on grain sorghum. Tex. Agri. Exp. Sta. PR-2534.

Onken, A. B. and H. D. Sunderman. 1972. Applied and residual nitrate-nitrogen effects on irrigated grain sorghum yield. Soil Sc. Soc. of Amer. Proc. 36:94-97.

Onken, A. B., H. D. Sunderman, and R. Jones. 1970. Effects of nitrogen on irrigated grain sorghum yield-Olton clay loam soil. Tex. Agri. Exp. Sta. PR-2774.

Owen, D. F. and R. D. Furr. 1967. Effect of sulfur and trace minerals on forage sorghum yield and mineral composition. Agron. J. 59:611-612.

Painter, C. G. and R. W. Leamer. 1953. The effects of moisture, spacing fertility, and their interrelationships on grain sorghum production. Agron. J. 45:261-264.

Porter, D. B., M. E. Jensen, and W. H. Sletten. 1960. The effect of row spacing, fertilizer, and planting rate on the yield and water use of irrigated grain sorghum. Agron. J. 52:431-434.

Robertson, W., A. B. Onken, and H. J. Walker. 1969. Fertilizing grain sorghum on the Texas High Plains. Tex. Agri. Exp. Sta. MP-940.

Robertson, W. and H. J. Walker. 1966. Effect of nitrogen source and rate on irrigated grain sorghum. Tex. Agri. Exp. Sta. MP-806.

Swanson, N. P. and E. L. Thaxton, Jr. 1957. Requirements for grain sorghum irrigation on the High Plains. Tex. Agri. Exp. Sta. B-846.

U. S. Salinity Laboratory Staff. 1954. Plant response and crop selection for salineand alkali soils. Ch. 2 in U.S.D.A. Agri. Handbook No. 60. L. A. Richards (ed.)p. 67.

Valliant, J. C. and T. C. Longnecker. 1967. Grain sorghum irrigation-fertilizer study. Annual Research Report of the High Plains Research Foundation. Plainview, Texas, p. 27-30.

Vanderlip. R. L. 1972. How a sorghum plant develops. Kan. Agri. Exp. Sta. Contribution No. 1203.

37

Welch, N. H., E. Burnett, and H. V. Eck. 1966. Effect of row spacing, plant population, and nitrogen fertilization on dryland grain sorghum production. Agron. J. 58:160-163.

THE EFFECT OF FERTILIZER, ROW SPACING AND IRRIGATION ON ...

Documents

Transcript of THE EFFECT OF FERTILIZER, ROW SPACING AND IRRIGATION ON ...