Transcript No Slide Title

LATE SEASON N APPLICATIONS FOR IRRIGATED HARD RED WHEAT PROTEIN
ENHANCEMENT. S.E. Petrie*, Oregon State Univ, B.D. Brown, Univ. of Idaho.
Nitrogen fertilizer is frequently applied late in the growing season to
enhance hard red wheat (Triticum aestivum L.) protein to avoid low
protein discounts. Both furrow and sprinkler irrigation are used for
hard wheat production but N management options are limited when
using furrow irrigation. Several furrow or sprinkler irrigated studies
(1985-1996) were conducted in southwestern Idaho to evaluate late
season N manage-ment practices for increasing wheat protein.
Treatments evaluated included N rates (0-67 kg/ha), sources (urea,
uran), timing (tillering, jointing, heading, flowering), and application
methods (foliar, soil). Late season N generally increased protein but
the protein increase was not affected by N sources or application
methods when soil applied N was adequately incorporated with
subsequent moisture. The protein response to late N was limited if
protein in untreated wheat was already high. Urea was less
phytotoxic than uran as a foliar N source. N applied at tillering or
jointing was less effective at increasing protein than heading or
flowering growth stage applications. Late season N did not
consistently increase hard red wheat protein to market-acceptable
levels if the previously applied N was inadequate for maximizing
yield.
A series of field trials were conducted between 1985 and 1996
at the Southwest Idaho Research and Extension Center near
Parma, ID examining the effects of N rate, source, method of
application and stage of wheat development on hard red
winter and spring wheat grain yield and protein. The tillage,
planting, variety, crop management, fertilizer (except N), weed
control and irrigation practices varied between years but was
typical for recommended Best Management Practices for the
area. Winter wheat was furrow irrigated and spring wheat was
sprinkler irrigated. The trials were seeded using a double disk
drill with 7 inch row spacing and the plots were harvested
using a small plot combine. The treatments in all trials were
arranged in a randomized block design with four or five
replications. Grain samples were cleaned, weighed and test
weights determined. Leaf injury, when measured, was
estimated by visual observation. Grain protein was
determined using NIR at the University of Idaho Aberdeen
Wheat Quality Lab.
Table 1. Irrigated hard red winter wheat
yield and protein response to late season N
as affected by fall and spring applied N.
Table values are three year means.
N Application Rate and Time
Fall Spring Heading Total
--------------- kg/ha --------------0
0
0
0
Yield
kg/ha
4775
Protein
-- % -8.0
a
r
m
a
,
1
9
9
4
9
5
1
6P
30
Urea
25
1
5
UAN Sol'n
168
0
0
0
0
168
168
0
56
0
56
168
224
168
224
8743
9146
8945
9281
9
9
4
1
21
10
0
17
12.0
11.1
12.4
34
50
67
Figure 1. Furrow irrigated winter wheat leaf injury from boot
stage applied foliar urea and UAN at different N rates.
Preplant N was 224 kg ha-1. Parma, 1985. Leaf injury varied
among years and was worse in 1985 than the other two
years. Leaf injury was significantly related to yield
reduction in individual years but not when all years were
combined (data not shown).
N Sources--Late season urea and UAN N sources did not
generally differ in their effectiveness in increasing protein in
three years of testing. UAN caused more leaf burn than urea
solutions. Appreciable leaf burn was associated with
significant yield reductions in some years.
Solution pH--Solutions with higher pH generally caused more
leaf burn than solutions closer to pH 7.
Soil vs Foliar Late N--Soil and foliar applied late N did not
differ in two years of testing in their effectiveness for
enhancing protein provided there was no leaf burn from foliar
applied UAN and topdressed N was sufficiently incorporated
with subsequent sprinkler irrigation.
•Late season N applications did not
consistently increase grain protein
to market acceptable levels if the
previously applied N was not
sufficient to maximize yield.
•There were no yield or protein
differences between foliar and dry N
if the topdressed N was
incorporated by irrigation following
application.
•Foliar applications of urea caused
less leaf injury than UAN solution
•Slightly acidic spray solutions
caused less leaf injury
I
1
9
9
5
L
S
D
.
0
5
1
3
35
30
25
20
1
21
9
9
4
I
S
o
l
u
t
i
o
n
3
2
L
S
D
.
0
5
1
1
0 1
02
03
04
05
06
07
0
N
R
a
t
e
a
t
H
e
a
d
i
n
g
(
l
b
/
A
)
Figure 3. Hard red spring wheat
protein as affected by urea and UAN
solutions and equivalent dry N
sources and N rates. Dry N sources
were incorporated with sprinkler
irrigation. Foliar N sources were
applied the day after the sprinkler
wetting. Parma, 1994-95.
1
5
P
a
r
m
a
1
4
Urea pH 6
Urea pH 8
UAN pH 6
UAN pH 8
F
o
l
i
a
r
D
r
y
9
5
0
9
9
8
5
1
31
Protein (%)
Timing---Hard red winter wheat yielded higher and had higher
protein when N was spring topdressed rather than preplant
incorporated. Late season applied N generally increased
winter wheat protein and the protein increase with late N
depended on the timing of N previously applied. Late season
N also increased spring wheat protein from low protein values
and the protein increase was generally linear with N rate. The
protein increase from late N was limited if protein otherwise
exceeded 14%. The protein increase with N tended to be
greater the closer the application was made to flowering.
1
5
1
4
N Rate (kg/ha)
Leaf Injury (%)
The higher market prices and the premiums associated with high
protein hard red wheat (winter and spring) have sparked
considerable grower interest in these market classes of wheat.
Unfortunately, we do not have the management tools to consistently
produce hard red wheat with acceptable protein levels. The use of
high pre-plant N application rates increases the likelihood of
acceptable protein levels but also increases the potential for
unacceptable N losses due to leaching and may increase lodging.
Mid-season and late season N applications in sprinkler irrigation
systems have been used to increase grain protein levels but N
applications in surface irrigation systems (flood, furrow, etc.) are
problematic. Non-uniform water application due to differences in
infiltration rates, tailwater runoff and system inefficiencies all
contribute to non-uniform N applications and subsequent differences
in N availability and grain yield and protein responses. The
objectives of this work were to (1) determine the most effective N
application rate for mid-season applications, (2) compare foliar and
soil applications, (3) compare foliar urea and solution 32, (4) and the
time of application (tillering, jointing, heading, flowering).
F
o
l
i
a
r
D
r
y
1
6 P
a
r
m
a
,
1
9
9
4
9
5
•N applications made later in the
growing season tend to increase
grain protein.
Results
I
U
r
e
a
L
S
D
.
0
5
1
1
5
Summary
Introduction
L
S
D
.
0
5
1
3
15
10.0
I
1
9
9
5
1
4
20
0
168
Wheat Protein (%) Wheat Protein (%)
Materials and Methods
Leaf Injury (%)
Abstract
U
r
e
a
U
r
a
n
Y
d
=
1
3
6
2
1
15
1
1
10
1
9
8
7
Y
d
=
1
1
2
0
1
1
9
8
6
9
5
Y
d
=
1
2
9
V
a
r
i
e
t
y
:
U
t
e
8
0
0
22
45
N Rate (kg/ha)
Figure 2. Hard red spring wheat flag leaf injury from boot
stage applied urea or UAN as affected by N rate and solution
pH. Parma, 1994.
0 1
5 3
0 4
5 6
0
F
o
l
i
a
r
N
R
a
t
e
(
l
b
/
A
)
Figure 4. Hard red winter wheat protein
as affected by N rate and foliar N source
and year. Parma, 1985-87.