Transcript Slide 1

Wheat Management Meeting
LACA
Dean Lee Experiment Station
October 10, 2007
Rick Mascagni
Feed Grain and Small Grain Agronomist
Northeast Research Station
St. Joseph, LA
Lime Recommendations for Wheat AR
Soil test Ca (lb/a)
Below
Soil pH
1000
Above
1000-3000
3001-4500
4500
Tons/a
Above 5.7
0
0
0
0
5.3-5.7
1
1.5
2
2.5
5.0-5.2
1.5
2
2.5
3
2
2.5
3
3
Below 5.0
Plant uptake for Wheat at Different
Yield Potentials
Nutrient Uptake
Yield
N
P2O5
bu/a
K2O
Mg
S
lb/a
40
75
27
81
12
10
70
130
47
142
21
18
100
188
68
203
30
25
Plant Food Removed in Harvested Crop
Crop
N
P2O5
K2O
lb/bu
Corn
0.75
0.44
0.29
Wheat
1.15
0.55
0.34
Nutrient uptake, lb/A
How much N, P, and K does
wheat take up?
38 bu/A spring wheat
140
120
K2O
100
N
80
60
40
P2O5
20
0
Growth stage
Johnston et al., 1999
P & K Fertilization
• Soil test should be taken and analyzed
for P & K content.
• If needed, P & K should be applied in
the fall and incorporated along with
lime, if required.
P Soil Tests – Alluvial clay
Category
Soil test P
P rec.
ppm
lb P2O5
Very low
<50
80
low
70
60
medium
140
40
high
160
0
P Soil Tests – Upland sil
Category
Soil test P
P rec.
ppm
lb P2O5
Very low
<10
80
low
30
60
medium
70
40
high
90
0
K Soil Tests – Alluvial clay
Category
Soil test P
K rec.
ppm
lb K2O
Very low
<160
80
low
240
60
medium
360
40
high
380
0
K Soil Tests – Upland sil
Category
Soil test P
K rec.
ppm
lb K2O
Very low
<70
80
low
110
60
medium
160
40
high
180
0
Wheat tillers
Fourth
leaf
L4
Fifth
leaf
L5
• Wheat produces
Second
two kinds of stems (culms):
Third
leaf
L3
tiller
T2
– Main stem
– Variable number of tillers Second
leaf
First
tiller
T1
• Tillering is not a random event
Coleoptile
• Follows a very strict pattern
tiller
T0
• Tillers initiated vary greatly
Seed
in vigor and potential
for grain production
L2
Goos and Johnson, 1996; Klepper et al., 1982
First
leaf
L1
Wheat Plant
Nodal roots
Seminal roots
Why is P needed
early in the
season?
Purple Wheat
• The common deficiency symptom of P is an
accumualtion of anthocyanins (plant pigment).
– As soon as soil temperatures warm enough to stimulate
root growth, free sugar concentration will drop,
anthocyanins are reduced and leaves return to a green
color.
• The addition of DAP (18-46-0) will not likely be of
benefit to purple wheat, provided adequate P was
applied at or near planting.
• Where no P was applied pre-plant and soil P levels
are low, the addition of DAP now will likely benefit
the wheat.
Fall Fertilization and Liming
• Fall fertilization and liming should be
carried out to supply any needs
indicated by soil testing
• P and K, where recommended, should
be incorporated into the seedbed
before planting time.
• If lime is required, apply before
seedbed preparation, if possible.
Nitrogen Fall Fertilization
• Fall fertilization of N is usually not
needed where no grazing is planned
and the wheat/oats follow soybeans.
• Where wheat/oats follow corn, sorghum
or rice, application of 15 to 20 lbs
N/acre may be beneficial
Fall N Fertilization - AR
• Consistently shown a benefit of
applying 30-40 lb N/a prior to or at
planting when wheat is following rice.
• For wheat following soybeans, corn ,
grain sorghum, cotton, or other crops
there has been no consistent benefit
from applying fall N.
• The lack of a yield response could be
related to high levels of carryover N,
especially after a soybean crop.
• Fall N is recommended for wheat
planted late.
Fall N Following Corn and Grain Sorghum
NEREC
SWREC
Fall N 1987 1988 1989 1987 1988 1989
bu/a
0
54.0 45.7 39.7 49.6 61.8 51.2
30
62.1 52.1 42.6 50.2 63.0 52.9
60
68.6 54.5 46.7 49.1 65.7 52.8
LSD
(0.05)
2.5
2.9
2.6
NS
NS
NS
Nitrogen Fertilization
• Timing of spring applications should consider plant growth
stage and crop condition rather than simply going by calendar
date.
• A field that begins stem elongation or jointing in early February
needs N earlier than a field that begins stem elongation in late
February.
• Similarly, a field that has a thin stand, making tiller production
and survival very important, will suffer more from early N
shortages than fields with thick stands where tiller conditions
are less important.
• Research has shown all N sources to be equal in their ability to
produce wheat/oats.
– N source should be selected on the basis of price,
availability and convenience.
• In recent years, many growers have expressed interest in
splitting N into two or more applications.
– This practice has not had a m\ajor effect on wheat yields
under the growing conditions experienced in Louisiana
research trials.
Spring N Fertilization Rates
• Alluvial soils
– Apply 70-90 lb/a in the spring before
jointing
– On poorly drained alluvial soils, split
applications with ½ applied before
jointing and the remainder by early
boot stage may be beneficial in some
years.
• Other soils
– Apply 60-80 lb/a in the spring before
jointing
Spring N Fertilization Rates - AR
• Sandy loams and silt loams which
do not waterlog
– 90 lb N/a
• Clays and silt loams which
waterlog readily
– 100 lb N/a
• Silty clays and clays (Ca>4500)
with yield potential >5 bu/a
– 140 lb N/a
Urea Fertilization
• Urea rapidly converts to ammonium (with concurrent
pH increases) in the presence of moisture and
urease enzyme.
– When banded or broadcast on the soil surface
free ammonia can form.
– When banded, ammonia can lead to root and
seeding damage.
– On the soil surface, free ammonia can form and is
lost to the atmosphere (volatilization).
• Conditions that lead to greater volatilization include
warm weather, moist and drying soils, high residue,
high soil pH, no rainfall after application, low soil
exchange capacity, and high application rate.
– Losses have been measured up to 30%
– Rainfall of 0.25-0.5 inches or tillage incorporation
within 2-3 days after application mimimizes
losses.
Influence of N rate and timing on grain yield of two
wheat varieties on Sharkey clay at the NERS, 1995.
N rate
PB 2684
lb/a (3&8 f.g.s.)
Terral 877
bu/a
60
54.0
46.6
90
63.9
52.1
60+30
56.1
51.9
120
62.6
51.9
90+30
66.3
56.0
150
66.3
52.1
120+30
68.0
53.8
LSD (V x N)
3.4
Influence of N rate and timing on grain yield of two
wheat varieties on Sharkey clay at the NERS, 1996.
N rate
PB 2684
lb/a (4,8, &10 gs)
Terral 877
bu/a
0
59.2
60.3
60
97.3
88.7
90
104.9
85.5
60-30-0
101.1
94.9
60-0-30
104.9
99.5
120
108.1
83.1
90-30-0
110.0
93.4
90-0-30
114.0
93.6
LSD
8.1
Influence of N rate and timing on grain yield of wheat
on Sharkey clay at the NEREC for three years.
N rate
1987
lb/a (3,5,9gs)
1988
1989
bu/a
0
22.3
19.5
14.4
50
54.8
49.7
40.6
100
73.6
60.9
58.6
50-50
74.7
59.8
65.9
50-25-25
73.5
63.4
70.3
150
76.1
63.4
62.7
75-75
75.3
60.5
72.0
75-50-25
77.4
59.6
69.5
LSD (0.05)
4.1
3.6
5.3
Influence of late N applications (1989-GS9;1990-GS10)
on Sharkey clay at the NEREC, 1989 and 1990.
1989
Late N
1990
Yield
Kernels
Yield
Kernels
0
49.9
17.3
49.6
22.5
30
57.5
20.2
57.3
25.6
30AN
59.1
20.1
58.0
26.2
60
59.0
20.5
61.5
27.0
LSD (0.05)
3.2
2.0
2.4
2.9
lb/a
How do N and P interact?
60
Winter wheat
50
yield, bu/A
40
17 bu:
35% increase
64.8
70
54.8
5 bu:
12% increase
46.7
47.9
42.3
41.7
30
20
17.0
10
14.6
40
0
110
N rate, lb/A
Grant et al., 1985; Grant et al., 1986
6 bu:
40% increase
20.4
20
55
0
0
P2O5 rate,lb/A
Influence of spring S fertilizer on
yield and yield components on
Commerce vfsl at St. Joseph in 2002
Sulfur
Yield
Spikes
lb SO4/a
0
bu/a
42.5
5
50.6
10
59.8
20
56.0
no./a
1,636,60
0
1,930,80
0
2,137,30
0
2,206,20
Kernel
wt.
g/100
3.82
Kernels
no./spike
19
3.75
20
3.62
22
3.53
20
70
0-15cm
15-30cm
30-45cm
60
Winnsboro
Soil S, mgkg
50
40
St. Joseph
30
20
10
0
2002
2003
2004
2002
2003
Year
Fig. 1. Soil S levels at three soil depths at St.
Joseph and Winnsboro, 2002-2004.
2004
Micronutrients
• In the south, Cu deficiencies have been
found on high organic matter soils in
North Carolina.
• More and more micronutrient
deficiencies will occur, particularly at
high soil pH values.