• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Introduction
 Population and spacing
 Fertilization
 Related publications
 Acknowledgement
 Data






Group Title: Research report - Agricultural Research and Education Center - 78-1
Title: Water and nutrient management for maximum corn yields in North Florida
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00073717/00001
 Material Information
Title: Water and nutrient management for maximum corn yields in North Florida
Series Title: AREC, Quincy Research report
Physical Description: 13 p. : ill. ; 28 cm.
Language: English
Creator: Rhoads, Fred ( Frederick Milton )
Agricultural Research and Education Center (Quincy, Fla.)
Publisher: Agricultural Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Quincy FL
Publication Date: 1978
 Subjects
Subject: Corn -- Yields -- Florida   ( lcsh )
Corn -- Irrigation -- Florida   ( lcsh )
Corn -- Nutrition -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 6).
Statement of Responsibility: by F.M. Rhoads.
Funding: Quincy AREC research report ;
 Record Information
Bibliographic ID: UF00073717
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 84656560

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Introduction
        Page 1
        Page 2
    Population and spacing
        Page 3
    Fertilization
        Page 3
        Page 4
        Page 5
    Related publications
        Page 6
    Acknowledgement
        Page 7
    Data
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
Full Text

AREC, Quincy Research Report-78-1


Water ',
and
Nutrient
Management For Maximum
Corn Yields in North Florida


By F M. Rhoads


Florida Agricultural Experiment Stations IFAS University of Florida


ri/,







AREC, Quincy Research Report-78-1


Water and Nutrient

Management For Maximum

Corn Yields in North Florida

By F M. Rhoads1



Institute of Food and Agricultural Sciences
Agricultural Research and Education Center
Quincy, Florida
W. H. Chapman, Agronomist and Center Director


SAssociate Professor of Soil Science, AREC Quincy, University of Florida, IFAS.












Water & Nutrient Management

for Maximum Corn Yields in North Florida


A common practice used to schedule irrigation for field crops

is to recharge the root zone when 50% of the available water is de-

pleted. However, the root zone is a constantly changing volume and

it is difficult to determine when 50% of the available water is de-

pleted. A more practical approach is to manage the water in the plow

layer. This approach has been successful in soil testing to recommend

fertilization practices based on nutrient content of the plow layer.

The plow layer is easily defined and many soils have physical or

chemical impedance to root penetration below the plow layer. Experi-

ments were started in 1970 at the Agricultural Research and Education

Center, Quincy, Florida to determine potential grain yield response

of corn to "plow layer soil-water management."

There are two basic questions to be answered before soil-water

can be successfully managed with an irrigation system to produce

maximum yields. First, how does one determine when and how frequent

to irrigate? Second, how much water should be applied per irrigation?

The answer to the first question depends upon the rainfall dis-

tribution, the crop species (only corn will be considered here) and

the water holding properties of the soil. The second question can

be answered if the water content of the soil at the refill and full

points per unit depth and the depth of soil to be managed are known.

Managing soil-water to plow depth is much simpler than managing the

entire root zone.





-t






Obviously, if the rainfall distribution is such that plants are

never under water stress irrigation will not be needed. From a

practical standpoint irrigation can be most efficiently scheduled by

keeping a record of the water content of the soil. A tensiometer is

a convenient and inexpensive instrument for measuring the water status

of the soil. However, the unique relation between soil-water content

and tensiometer reading must be known for each soil.

Figure 1 shows the relation between soil-water content and

tensiometer readings for a loamy fine sand plow-layer, a fairly common

situation in North Florida. The full point for this soil is at the 5

centibar tensiometer reading or 25% water content by volume which is .

3 in. per foot of depth. A vacuum gauge tensiometer is shown in

Figure 2. An 8-in. plowlayer would contain 2 in. of water at the full

point. If a tensiometer reading of 20 is selected as the refill point

which corresponds to 15% water by volume or 1.20 in. in the plowlayer,

the amount required to refill the plowlayer is 2 in., minus 1.20 in.

or 0.80 in. Frequency of irrigation will be determined by selection

of soil refill point and age of plants. By reading tensiometers

daily the crop manager can determine when to irrigate and how much to

irrigate from full and refill points for his particular soil conditions.

Each field should contain three tensiometers located at different

positions with respect to sprinklers.

Table 1 shows irrigation response of corn for three selected refill

points in a loamy fine sand soil. Highest yield was produced when the

refill point was at a tensiometer reading of 20. The peak water demand












for corn is about 0.25 in. per day; therefore, a 3-to-4-day irrigation

frequency (if rainfall is inadequate) is required during flowering and

filling which is about the maximum capacity of large center pivot

irrigation systems.

A good water management program is the key to maximum yields.

Other production practices such as weed control, pest control, planting

date, plant population, fertilization, and harvest date must be

optimized also, if high yields are obtained. All practices except

S' population and fertilization are independent of water management

(irrigation). Therefore, fertilization and plant population of

irrigated corn have been the subject of intensive research at the

Quincy AREC.

Population and Spacing

The water management and population studies were carried out

with the following fertilizer program: 2,000 lb/A of 5-10-15 preplant

and 600 lb/A of ammonium nitrate as sidedress. Table 2 shows yield of

irrigated corn at several plant populations. All following references

to irrigated corn implies a tensiometer reading of 20 at the refill

point and that the sensor cup was located at the 6 in. depth (Figure 2).

Yield response to row spacing is shown in Table 3. Obviously there

are interactions between population and spacing; however, results

indicate from a practical stand point that maximum yields can be

expected at a population of 29,000 plants/A with a row spacing of 30 in.

Fertilization

The data in Table 4 were obtained from corn plots with plants

spaced 12 in. apart in 18-in. rows for a total of 29,000 plants per acre.












for corn is about 0.25 in. per day; therefore, a 3-to-4-day irrigation

frequency (if rainfall is inadequate) is required during flowering and

filling which is about the maximum capacity of large center pivot

irrigation systems.

A good water management program is the key to maximum yields.

Other production practices such as weed control, pest control, planting

date, plant population, fertilization, and harvest date must be

optimized also, if high yields are obtained. All practices except

S' population and fertilization are independent of water management

(irrigation). Therefore, fertilization and plant population of

irrigated corn have been the subject of intensive research at the

Quincy AREC.

Population and Spacing

The water management and population studies were carried out

with the following fertilizer program: 2,000 lb/A of 5-10-15 preplant

and 600 lb/A of ammonium nitrate as sidedress. Table 2 shows yield of

irrigated corn at several plant populations. All following references

to irrigated corn implies a tensiometer reading of 20 at the refill

point and that the sensor cup was located at the 6 in. depth (Figure 2).

Yield response to row spacing is shown in Table 3. Obviously there

are interactions between population and spacing; however, results

indicate from a practical stand point that maximum yields can be

expected at a population of 29,000 plants/A with a row spacing of 30 in.

Fertilization

The data in Table 4 were obtained from corn plots with plants

spaced 12 in. apart in 18-in. rows for a total of 29,000 plants per acre.









4


Individual plot data indicate a yield potential in North Florida of

at least 250 bu/A. However, we are looking for a management system

that will produce 300 or more bu/A in this section of the state. A

regression analysis of yield versus nutrient uptake (Fig. 3) shows

that in order to produce high yields, corn plants must absorb nutrients

at a rapid rate. For example: at 100 bu/A yield, the nitrogen uptake

rate between 49 and 87 days after planting was 0.83 lb/A per day but

when yield increased to 200 bu/A the N uptake rate was 2.39 lb/A per

day. The rate of uptake was proportional to the amount applied in the

0 to 300 Ib/A range.

Another approach to fertilizing irrigated corn while varying the

population is to apply nutrients on a per plant basis. Yield response

to nitrogen is shown in Fig. 4 although phosphorus and potassium were

varied in proportion to the nitrogen. There were three plant populations

(12,000; 24,000; and 36,000 plants per acre). The highest yield for

each population occurred at 3 gms of nitrogen per plant. This was

equal to 80 Ibs/A for 12,000 plants, 160 lbs/A for 24,000 plants and

240 lbs/A for 36,000 plants/Acre. This indicates a need for more

information of population and fertilizer interaction. Perhaps

fertilizer recommendations for irrigated corn should be based on

population.

Another important aspect of nutrient management is reduction of

leaching losses. Conventional fertilization practices generally include

application of about one-third of the nitrogen and all of the phosphorus

and potassium before corn is planted and the remaining N would be applied












4 to 6 weeks after planting. However, corn plants take up less than

20% of their total nutrient requirement during the first 4 to 6 weeks

of growth. Frequent small applications of fertilizer would be expected

to reduce leaching losses due to excessive rainfall because application

rate and timing would more nearly approach the nutrient uptake rate

by the plant. Application of fertilizer (N-P-K) every 2 weeks for

12 weeks after planting increased corn yields by 46% in 1975 when yield

increase due to irrigation was 144%. Excessive rainfall occurred at

20, 50 and 80 days after planting followed by dry periods of 10 days

or more. Weekly applications of fertilizer in 1976 increased yields

still further. This was on a sandy soil.

Corn yields in excess of 200 bu/A can be produced in North Florida

if ALL production practices are managed properly. These include

irrigation, fertilization, pest control, population, planting date and

harvest date. Irrigation should be managed in a manner to prevent

plants from wilting but care should be taken so that too much water is

not applied at any one time in order to minimize leaching of plant

nutrients. Fertilization should include about 200 lb/A of nitrogen

and follow soil test recommendations for phosphorus and potassium and

seed should be planted during March for a final population of about

30,000 plants per acre. Harvesting should begin when grain moisture

drops below 30%. Pest control practices (weeds, insects, etc.) should

follow local extension service recommendations.










Related Publications


1 Stanley, R. L., Jr. and F. M. Rhoads. 1971. Response of corn
grown at low soil moisture tension to row and drill spacings.
Soil and Crop Sci. Soc. of Fla. Proc. 31: 42-45.

2 Rhoads, F. M. and R. L. Stanley, Jr. 1973. Response of three
corn hybrids to low levels of soil moisture tension in the
plow layer. Agron. J. 65: 315-318.

3 Rhoads, F. M. and R. L. Stanley, Jr. 1975. Response of
corn (Zea mays L.) grown on soils of three textural classes
to plow layer water management. Soil and Crop Sci. Soc.
of Fla. Proc. (1974) 34: 1-3.

4 Stanley, R. L., Jr. and F. M. Rhoads. 1975. Response of
corn (Zea mays L.) to population and spacing with plow-layer
soil water management. Soil and Crop Sci. Soc. of Fla.
Proc. (1974) 34: 127-130.

5 Rhoads, F. M. 1976. Leaf area and plant height as indicators
of plant response to fertilization of corn. Soil and Crop
Sci. Soc. of Fla. Proc. (1975) 35: 136-138.

6 Stanley, R. L., Jr. and F. M. Rhoads. 1977. Effect of time,
rate and increment of applied fertilizer on nutrient uptake
and yield of corn (Zea mays L.). Soil and Crop Sci. Soc. of
Fla. Proc. (1976) 36: 181-184.

7 Rhoads, F. M. and John C. Russell. 1977. Corn production
with irrigation in North Florida. University of Florida,
AREC, Quincy Res. Report 77-2.

8 Rhoads, F. M., R. S. Mansell, and L. C. Hammond. 1978. Influence
of water and fertilizer management on yield and water-input
efficiency of corn. Agron. J. 70: 305-308.


k -4



































Acknowledgement


The author appreciates the support of
Dr. Samuel Kincheloe of International Minerals
and Chemical Corporation in supplying materials
and services for the printing of this manuscript.


- W-
















Table 1. Grain yields of irrigated corn at three
selected soil-water refill points.

Tensiometer Number Total irri-
reading when of gation water Yield
irrigated irrigations applied (in.) bu/A

20 11 8.7 190
40 6 7.1 175
60 4 4.7 160
0 0 115















Table 2. Effect of plant population on grain yield
of irrigated corn. Average of 1973 and
1974 data.*

Plants Yield
per acre bu/A

19,000 132
23,000 147
28,000 156
29,000 171
35,000 183
44,000 177


* Courtesy of Dr. R. L. Stanley, Jr.
Associate Agronomist AREC, Quincy


c.-*


















Table 3. Yield response of irrigated corn to row and
drill spacing at a constant population.*

Row Drill
spacing spacing Population Yield
(in.) (in.) plants/acre bu/A

18 12 29,000 204
24 9 29,000 180
36 6 29,000 178


* Courtesy of Dr. R. L. Stanley, Jr.
Associate Agronomist AREC, Quincy.














Table 4. Effect of fertilization rate on yield of
irrigated corn.

Fertilization (lb/A) Grain Yield (15.5%)
N P205 K20 bu/A


75 50 75 76
150 100 150 149
300 200 300 240


n'4

















RATION


UJ II
-1
0

S30
3 FULL POINT
2 -
t t t t
8 20 10% 12% 13% 15%

FOR REFILL


10 t
REFILL POINTS


0-

0 20 40 60 80 100
TENSIOMETER READING (CB)
FIGURE 1: Relationship between soil-water content and tensiometer reading for a loamy
fine sand plow layer. Full point is water content 24 hours following rain or
irrigation. Refill points are selected according to crop needs and capacity of
irrigation system.






4























VACUUM GAUGE-,


A Tensiometer consists of an air-tight,
water-filled tube with a porous ceramic
tip at the bottom and a vacuum gauge
near the top. The porous ceramic tip
has small pores which allow water to
flow in and out but which because of
their very small size, prevent air from
entering the wetted tip. The unit is
installed with the porous ceramic tip
in firm contact with the soil.


SENSOR


SOIL LEVEL







SIZE OF UNIT
DEFINES DEPTH
TO ROOT ZONE

I


FIGURE 2:


I k


*


r
























49 DAYS
200
S87 DAYS


-J


100







0 50 100 150
N UPTAKE LB/A
FIGURE 3: Regression analysis of yield on nitrogen uptake 49 and 87 days
after planting corn under irrigation.



4-













250

.-.... ......... ..."36,000
200 .- --
.. 24,000


150 12,000
S/ PLANTS/ACRE


: 100
-**


1-240
50 1-160
1-80



0 1.0 2.0 3.0 4.0 5.0
N GMS/PLANT
FIGURE 4: Effect of fertilization and plant population on yield of irrigated corn. Fertilizer rate based
on amount of nutrients per plant. 1977 data.




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