Foliar N in Winter wheat, Droplet size

Report
Ethan Wyatt
Plant and Soil Sciences
Oklahoma State University
 The United States ranks fourth in
global wheat production.
 In the United States more than
21 million hectares of wheat is
produced each year.
 Hard red winter wheat (HRWW) is
grown extensively in the Great
Plains region which accounts for
40% of the total wheat grown in
the U.S.
iwheat.org, 2013



In recent years hard red winter wheat protein levels
have been a concern with milling and baking
companies.
Grain protein concentration (GPC) levels determine
the degree of milling and baking quality of
processed wheat products and price
As of November 30, 2010, marketable grades of
HRWW must contain a protein level of at least 11%
or a 10 cent dockage to the contract price with a
protein level of 10.5% (KCBT, 2010)
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
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Grain protein levels are variable across locations due to
environmental and genetic factors (Kramer, 1978)
Rao et al., (1993) GPC is controlled by many different aspects
including environment, cultivar, nitrogen fertilizer rate and timing
Research on late-season top-dress N as either dry or liquid material
has shown an increase in GPC (Woodward and Bly, 2003)
Woolfolk et al., (2002) GPC was increased with late season foliar N
before and following flowering
According to Mercer (2007) decreasing droplet size increased uptake
of the active ingredient and increased the spread area of the droplet
which increased uptake of the active ingredient

To evaluate the effects of adjuvant, droplet size,
and foliar N rate on wheat grain protein and yield


Efaw, Stillwater, OK, Perkins, OK, and Lake Carl Blackwell
Randomized complete block design (RCBD), 3 reps
Treatment
Foliar N (kg N ha-1)
Droplet size
Nozzle
PSI MPH
1
2
0
11.2
—
Fine, with adjuvant
—
FC- TR110-015
—
25
—
5
3
11.2
Medium, with adjuvant
GRD120-01
60
5
4
11.2
Coarse, with adjuvant
GRD120-015
25
5
5
11.2
Fine
FC- TR110-015
25
5
6
7
8
9
10
11.2
11.2
22.4
22.4
22.4
Medium
Coarse
Fine
Medium
Coarse
GRD 120-01
GRD 120-015
FC-TR110-02
GRD120-02
GRD120-02
60
25
60
60
40
5
5
5
5
4


Foliar N applications were applied
immediately following anthesis.
Alleys included in the design so
foliar N application could be
applied without damaging plots
with the ATV applicator
Experimental design and treatment layout for the Lake
Carl Blackwell experiment
Gary James at HYPRO Global Spray
Solutions provided spray tips and
technical support
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Three to five days following application 15
flag leaves were chosen at random
throughout each plot
At harvest, grain yield and subsamples of
the grain were collected from each plot.
Grain and flag leaf samples were processed
and analyzed for total N using a LECO
Truspec CN dry combustion analyzer
Grain protein % and N uptake were
calculated by:
    % = % × 5.7
  (  ℎ−1 ) =
%
100
×   ℎ−1
Massey Ferguson 8XP combine used to harvest
plots. Combine has subsampling and yield
recording capabilities
Trt. 5
Trt. 2
Differences visible showing awn burn from the
foliar N*adjuvant treatments in 2012
Foliar N burn was more frequent in all treatments in 2013.
Left, visual burn signs of foliar N application compared to
the right which was the check.
Grain yield by treatment at LCB, OK, 2012.
Relationship of grain yield and foliar N rate at Perkins, OK, 2013.
2500
Yield kg ha-1
2000
a
ab
abc
cdef
1500
f
bcde
bcd
def
def
def
1000
500
Yield
0
Treatment
Yield kg ha-1
Treatment comparisons for grain yield as influenced by droplet size and foliar
N rate, LCB, OK, 2013
a
4400
ab
bc
4300
d
4200
4100
e
e
e
4000
3900
Yield
3800
3700
0
11.2
11.2
11.2
22.4
22.4
22.4
Check
C
M
F
C
M
F
Foliar N Rate (kg N ha -1) and Droplet Size
Relationship of yield and nitrogen uptake with droplet size (coarse,
medium, fine) LCB, OK, 2012.
Treatment means for grain protein with mean separation
at Lake Carl Blackwell, 2013.
Foliar N kg ha-1 Droplet Size
Adjuvant
Protein %
0
None
No
12.65 g
11.2
Fine
Yes
14.70 a
11.2
Medium
Yes
14.40 ab
11.2
Coarse
Yes
14.30 abc
11.2
Fine
No
14.00 abcdef
11.2
Medium
No
13.44 bcdefg
11.2
Coarse
No
13.61 abcdefg
22.4
Fine
No
14.25 abcd
22.4
Medium
No
14.14 abcde
22.4
Coarse
No
13.20 cdefg
a
LSD.05
denotes significant differences in means, LSD.05
Check vs foliar N, 1 vs 2-10, single degree of freedom contrast LCB,
OK, 2013.
1.11
Relationship between grain protein and foliar N rate, Efaw, OK, 2012.
Non-adjuvant vs adjuvant, 2,3,4 vs 5,6,7, single degree of freedom
contrast, LCB, OK, 2013.
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Yield differences observed were relatively small across locations
and years
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For most locations and years GPC was increased linearly with
higher rates of foliar N applied
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When compared to the check, late season foliar N application can
improve grain protein by up to 2.0%
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Use of the fine droplet size with a foliar N rate of 11.2 kg N ha-1
with an addition of an adjuvant resulted in the highest GPC

This work suggests that more emphasis should be placed on
protein prediction and improving mechanisms to improve late
season foliar N uptake

Late season foliar N to improve protein levels
should be applied to:
◦ Growing wheat under high yielding production systems
 Irrigation production systems
 High rainfall areas/years
◦ Growing wheat with less than optimum nitrogen requirement
applied

Late season foliar N application should be applied
when:
◦
◦
◦
◦
Crop is healthy
Temperature is below 65 degrees F
Low humidity
Low wind days

Funding, Soil Fertility Research and Education
Advisory Board

Spray nozzles and droplet size technical support
was provided by Gary James at HYPRO
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Foliar N applicator built by Dr. Randy Taylor, BAE
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Committee Members: Dr. Raun, Dr. Arnall, Dr.
Taylor

PASS graduate students

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