Fluid Fertilization in Corn/Coybean Rotation in the United States.
Larry Murphy
Fluid Fertilizer Foundation
Introduction
The Fluid Fertilizer Foundation (FFF) sponsors research with fluid fertilizers at
state and federal research locations in the United States, Canada, Australia and
Mexico as part of the Foundation’s responsibilities in education and research.
Fertilization practices for corn/soybean rotations are an important part of the
research program simply based on the importance of that rotation in the Cornbelt
states. Some recent findings have important implications for overall production
levels in that rotation, especially for corn (maize).
This paper will outline some of those developments.
Fluid Starter Fertilizers for Corn: N-P Interactions
Many corn producers in either a corn-soybean rotation or continuous corn
systems in the central Cornbelt do not use starter fertilizers for several reasons.
One of the most often quoted reasons is that don’t want to take the time to fill
their fluid starter tanks when they are planting thus simplifying the logistics of the
operation. Another stated reason is that planters are not equipped for starters or
are so large that producers do not want to add more weight to the equipment
though the addition of openers for fluid placement. Others cite possible corrosion
to equipment and other reasons but all lead basically to the same result….lost
production potential in high yield capacity corn hybrids.
In the past, university research has frequently not shown a yield response to
starters. Unfortunately, much of that research was conducted 25-30 years ago
on essentially clean till corn. Movement to higher residue systems and the
higher yield capabilities of new hybrids has substantially modified the equation in
favor of starters.
Research sponsored by the FFF in recent years has shown that composition
of fluid starters has a major impact on yield of corn, particularly in high residue
systems. Further, fluid starter composition manipulation has produced additional
options for starter application that allow easy adaptation to large planters without
the addition of openers for starter placement.
Dr. Barney Gordon, Kansas State University, has demonstrated repeatedly
that responses to N-P-K-S-Zn fluid starters can be increased substantially by
increasing the amount of nitrogen (N) in the starter. That is effected by the
blending of urea-ammonium nitrate solution (UAN) with ammonium
polyphosphate (10-34-0) and a potassium (K) source such as potassium
thiosulfate. Nitrogen to P2O5 ratios of at least 1:1 and possibly higher have
produced much more frequent and higher yield responses even on high soil test
P soils.
Dr. Gordon’s work with irrigated no-till corn on near neutral pH, silt loam soils
in Kansas has shown that ammonium polyphosphate alone or even N-P-K-S-Zn
formulations whose N content is dictated by the compositon of the ammonium
polyphosphate (10-34-0) do not produce the same effects with a constant
amount of P (Table 1). Plant analyses indicate clearly that even with a high P
soil test, plant uptake of P is substantially increased with the higher N amounts in
the starter formulation.
Table 1. Starter composition and placement effects on irrigated no-till corn yield
(bu/A). 3 year average. Gordon, Kansas State Univ.
Starter
In-furrow
5-15-5
172
15-15-5
2x2
Dribble
Row Band
194
190
179
177
197
198
180
30-15-5
174
216
212
192
45-15-5
171
215
213
195
60-15-5
163
214
213
201
Average
171
207
205
189
One tonne corn/ha = 16 bu corn/acre
The higher amounts of ammonium N with the P are theorized to result in
improved P uptake due to (a) effects of ammonium on P movement into the roots
and (b) possibly slowed P fixation. pH of this soil, however, was approximately
6.8. Soil test P was high, approximately 40 ppm Bray P-1.
Another important aspect of this work is the flexibility in starter placement.
Note that the two center columns in Table 1 show values that are essentially
equal. The designation 2 x 2 is placement of the fluid band 5 cm to the side of
the row and 5 cm below the soil surface. This is considered the optimum starter
placement in corn production. However, note that the column labeled “dribble”
involves placement of the fluid band on the soil surface 5 cm to the side of the
seed row. The implication of this information is that corn planters can be
equipped for fluid starter application without the addition of openers to place the
starter below the soil surface. This seems to fly in the face of common belief that
P does not move appreciably in the soil. Yield results indicate otherwise.
Dr. John Kovar of the USDA-ARS Soil Tilth Laboratory in Ames, Iowa
researched the fate of P applied in this manner. His data, collected using a resin
impregnated membrane to adsorb the fertilizer P, showed that on a silt loam soil
by day 43 after application, P had moved about 10 cm into the soil directly below
the point of application. That information helps explain why Dr. Gordon was able
to effectively place starter P on the soil surface in bands with good effectiveness.
Dr. Terry Tindall has reported at this meeting on research by Dr. Gordon and
others using a high charge density co-polymer (Avail) in fluid starter which has
further enhanced the availability and uptake of P by corn, soybean and a number
of other crops. Action of the polymer chemistry delaying P fixation reactions by
Fe and Al in acid soils and Ca and Mg in high pH soils in the microenvironment of
the fluid band (or around a solid P particle) provides another tool to enhance fluid
starter band effectiveness. The polymer chemistry is not over shadowed by high
ammonium N concentrations in starters.
Fluid Starter Fertilizers for Corn: Sulfur in Starters
General thinking regarding the need for sulfur (S) on high organic matter soils
(4-8% organic matter) of the northern Cornbelt of the U.S. and southern Canada
has been, and still is, that mineralization of organic matter in these soils is
sufficient for crop needs. However, with the decline of S in the atmosphere from
various abatement programs, S deposition in rainfall has declined substantially in
the past 20 years. That S was adding to S availability from organic matter
mineralization. Further, with the increasing frequency of high residue cropping
systems and early planting into cold, wet and frequently compacted soils,
stresses on early plant growth have been magnified. Sulfur is one of the
nutrients whose availability and uptake is compromised by these un-measured
stresses. Potassium and zinc are also affected.
What ever the reasons, lower S deposition, less S released by organic matter
mineralization and less S in fertilizers, research supported by FFF is showing that
indeed corn in a corn soybean rotation does respond to inclusion of S in the
starter formulation.
A recent report by Dr. Gyles Randall of the University of Minnesota has
emphasized the importance of starters and S in starters for corn on pH 7.1, high
P, high organic matter (6.8%) clay loam soils. Grain yield was consistently
increased on this high P-testing soil over the no-starter control by the starter
treatments (Table 2). The starter NPKS treatments that contained 10 lb/A of K2O
and S consistently produced the greatest yields. When 20 lb/A of N and P were
applied, the inclusion of S gave an average yield increase of 18 bu/A compared
to where S was excluded. The presence of K in the starter did not appear to
effect yield. Placement position (2x0 or 2x2, 5 cm x 5 cm or 5 cm x 0)) did not
differ in their effect on yield similar to Dr. Gordon’s research, and there was no
interaction between starter rate and placement position.
Table 2. Grain yield, grain moisture, and plant population as influenced by rate, placement, and
source of fluid starter fertilizer. 2006. Randall, Univ. of Minnesota.
Starter Fertilizer Treatments
Trt
Rate
Placement
lb N+P2O5+K2O+S/A
Sources
1
0+0+0+0
None
None
4
20+20+6+4
2x0
APP + UAN + KTS
5
20+20+6+4
2x2
APP + UAN + KTS
6
20+20+0+4
2x0
APP + UAN + ATS
7
20+20+0+4
2x2
APP + UAN + ATS
8
20+20+6+0
2x0
UAN + 7-21-7
9
20+20+6+0
2x2
UAN + 7-21-7
10
20+20+10+10
2x0
APP + UAN + KTS + ATS
11
20+20+10+10
2x2
APP + UAN + KTS + ATS
Stats for RCB Design (All Treatments)
P > F:
LSD (0.05):
LSD (0.10):
CV (%):
Grain
Grain
Initial
Plant
Final
Plant
Yield
bu/A
H2O
%
Popl’n
p*103/A
Popl’n
p*103/A
209.2
233.0
221.0
215.5
229.0
206.3
208.5
231.1
223.5
20.2
18.9
20.0
19.7
19.4
19.8
20.9
19.3
19.2
34.1
34.5
34.3
33.0
34.2
33.8
34.5
34.2
34.5
33.1
33.1
33.1
32.5
33.1
32.6
33.1
33.1
33.0
0.006
14.9
12.4
4.7
0.025
1.2
1.0
4.4
0.016
1.1
0.9
2.2
0.223
NS
NS
1.2
One tonne corn/ha = 16 bu corn/acre
Fluid Starters for Corn and Soybean: Seed-Safe Applications of Fluids at
Seeding
Corn. A recently summarized 3-year study supported by FFF at the
University of Minnesota and supervised by Dr. George Rehm, compared three
fluid starter formulations for their effects on plant population and yield of corn,
soybean and sugar beets. The study found that for soils with a non-sandy
texture, the three fluid fertilizers (10-34-0 and low salt index 3-18-18 and 4-10-10)
can be applied in a band close to corn seed at reasonable rates (47 to 94
liters/ha) without having a serious effect on yield. The use of 10-34-0 at high
rates had a negative effect on germination. Although there were fewer plants,
the corn crop was able to compensate by producing larger ears on each plant.
The data collected over three years provide a strong base for the positive impact
for the use of seed placed fertilizer on yield if the soil texture is not sandy.
Management suggestions change for corn production on sandy soils.
Data collected for the three years show that there is a risk for reduction in
emergence if banded fertilizer is placed too close to the seed. Although there
was no objective to define an ideal distance between seed and fertilizer, there
was some reduction in emergence when this distance was 2 cm. A distance of at
least 2.5 cm between seed and fertilizer should reduce the risk of damage to
emergence when soils are sandy.
Soybean. In past trials conducted by Dr.Rehm, soybean emergence was
negatively affected by placement of fertilizer near the seed. Results of
emergence measurements taken in 2006 were consistent with results from
previous studies. Emergence was significantly affected by the grade used as
well as rate and placement. There was also a significant rate X placement
interaction. The effect of these factors on emergence is summarized in Table 5.
When averaged over placement and rate emergence was 91.0%, 95.2% and
97.3% of the control when 3-18-18, 10-34-0, and 4-10-10 respectively were
applied. Considering placement, greatest emergence was achieved when all
fertilizers at both rates were applied above the seed (97.8% of the control).
In 2006, the reduction in emergence (Table 3) was not as large as in past
years when reductions of approximately 35% were measured. This difference is
attributed to the fact that there was approximately 13 mm of rain within 2 hours of
planting in 2006.
Table 3.. The effect of rate and placement of three fluid grades on emergence
of soybeans in 2006. Rehm, Univ. of Minnesota.
Placement and Rate
with seed
top of seed
below seed
Grade
high
low
high
low
high
low
- - - - - - - - - % of control - - - - - - - - 10-34-0
89.2
99.4
99.0
101.7
89.5
92.6
4-10-10
97.2
96.3
99.7
96.0
95.5
98.9
3-18-18
81.1
95.8
93.8
96.9
85.8
92.9
control = 153,767 plants per acre; 380,000 plants/ha
The main effects of fertilizer grade, placement, and rate had no significant
effect on soybean yield in 2006 (Table 4). The interaction between fertilizer
grade and placement, however, was significant. Even though there were
differences in emergence, these differences were not reflected in yield. This is
not unusual for soybeans. Frequently, there is compensation for fewer plants
from more pods per plant.
Table 4. The effect of rate and placement of three fluid grades on yield of
soybeans. 2006. Rehm, Univ. of Minnesota.
Placement and Rate
with seed
top of seed
below seed
Grade
high
low
high
low
high
low
- - - - - - - - - bu./acre - - - - - - - - 10-34-0
68.4
65.3
69.2
69.2
68.3
69.0
4-10-10
70.6
69.6
66.4
66.9
66.7
66.0
3-18-18
65.0
67.1
71.1
74.3
67.0
control = 64.5 bu. per acre; 1 tonne/ha = 15 bu/A
67.8
The interaction between fertilizer grade and placement is explained by
examining yields when the fertilizer was placed above the seed. With the use of
10-34-0 and 3-18-18, this placement produced the highest yield. However,
placement with the seed produced the highest yield when the 4-10-10 was used.
Soybean is more sensitive than corn to fertilizer placed close to the seed.
All fluid materials, even though applied at lower rates, reduced emergence. This
was most noticeable when 10-34-0 was used. Soybeans, however,
compensated for the stand reduction and the yields were not affected.
Previous guidelines suggest that the sum of N and K2O should be
considered when rate of fertilizer placed close to the seed is in question. The
results from this study indicate, however, that N is the component most
responsible for reduced emergence.
Selected References:
Gordon, W.B. 2002. “Effects of Application Method and Composition of Starter
Fertilizer on Irrigated Ridge-Tilled Corn”, Kansas State University Report of
Progress 893, p. 73-76, Kansas State University, Manhattan, KS USA.
Randall, Gyles and Jeff Vetsch. 2007. “Optimum Placement of NPKS Starter
Fertilizers in High Testing Soils”, in 2007 Fluid Forum Proceedings, v. 24, p. 6774. Fluid Fertilizer Foundation, Manhattan, KS USA
Rehm, George and John Lamb. 2007. “Seed Safe Applications of Fluids at
Planting”, in 2007 Fluid Forum Proceedings, v. 24, p. 86-92. Fluid Fertilizer
Foundation, Manhattan, KS, USA.