current ksu n recommendations for corn & wheat john schmidt alan schlegel kansas state...
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Current KSU N recommendations for corn & wheat John Schmidt Alan Schlegel Kansas State University. Development of current N recommendations. Based on historical recommendations / concepts Modified to include soil N “mineralization potential” - PowerPoint PPT PresentationTRANSCRIPT
Current KSU N recommendations for corn & wheat
John SchmidtAlan SchlegelKansas State University
• Based on historical recommendations / concepts• Modified to include soil N “mineralization potential”• “Loosely” updated with more recent field research results• Emphasis on Extension education tool
Development of current N recommendations
N rec =
(Yield Goal x 1.6) – (SOM x 20) – Profile N – Manure N – Irr. Water N + Previous crop adj.
• Yield goal, bu acre-1
• Soil organic matter, %
• Profile soil N test, lb acre-1, 0-2 ft, (0.3 x sampling depth, inches x NO3-N, ppm)
• Manure N applied, lb acre-1 • Irrigation water N applied, lb acre-1
• Previous crop adjustment, lb acre-1
Corn N recommendation
-50
0
50
100
150
200
250
300
350
400
60 90 120 150 180 210 240
Yield Goal (bu acre-1)
N r
ec
(lb
ac
re-1
)
1234
Corn N recommendation, STN = 30 lb N acre-1
Soil OM, %
N rec =
(Yield Goal x 1.6) – (SOM x 20) – Profile N – Manure N – Irr. Water N + Previous crop adj.
0
20
40
60
80
100
120
140
160
180
200
0 50 100 150 200 250
Nitrogen Treatment (lb N acre-1)
Yie
ld (
bu
ac
re-1
)
0
40
80
source: Alan Schlegel
Corn yield response, Tribune, KS (92-00)
P2O5, lb acre-1
KSU’s rec, 218 lb acre-1
0
50
100
150
200
250
0 50 100 150 200 250
Nitrogen Treatment (lb N acre-1)
Yie
ld (
bu
ac
re-1
)
30, 150
0, 0
0, 150
30, 0
60, 0
60, 150
Corn yield response, Topeka, KS (97-01)
P2O5, K2O, lb acre-
1
source: Larry Maddux
KSU’s rec, 226 lb acre-1
100
120
140
160
180
200
220
240
260
150 200 250 300 350
Nitrogen Treatment (lb N acre-1)
Yie
ld (
bu
ac
re-1
)
30, 0, 0 - 28,000
100, 80, 40
100, 80, 40
30, 0, 0 - 42,000
100, 80, 40
100, 80, 40
Corn yield response, Scandia, KS (01, Ridge-till)
P2O5, K2O, S lb acre-1
source: Barney Gordon
KSU’s rec, 314 lb acre-1
N rec =
(Yield Goal x 2.4) – (SOM x 10) – Profile N – Manure N + Previous crop adj. + Tillage adj. + Grazing adj.
• Yield goal, bu acre-1
• Soil organic matter, %
• Profile soil N test, lb acre-1, 0-2 ft, (0.3 x sampling depth, inches x NO3-N, ppm)
• Manure N applied, lb acre-1 • Previous crop adjustment, lb acre-1
• Tillage adjustment, 20 lb acre-1 for no-till• Grazing adjustment, 40 lb acre-1 per 100 lb beef weight gain
Wheat N recommendation
0
20
40
60
80
100
120
140
160
180
200
30 40 50 60 70 80 90
Yield Goal (bu acre-1)
N r
ec
(lb
ac
re-1
)
1234
Wheat N recommendation, STN = 30 lb N acre-1
Soil OM, %
N rec =
(Yield Goal x 2.4) – (SOM x 10) – Profile N – Manure N + Previous crop adj. + Tillage adj. + Grazing adj.
0
10
20
30
40
50
60
0 40 80 120
Nitrogen Treatment (lb N acre-1)
Yie
ld (
bu
ac
re-1
)
after sorghum
after soybean
source: Dave Whitney
Wheat yield response, Manhattan, KS (98-00)
KSU’s rec, 82 and 88 lb acre-1
0
10
20
30
40
50
60
70
0 40 80 120
Nitrogen Treatment (lb N acre-1)
Yie
ld (
bu
ac
re-1
)
after sorghum
source: Mark Claassen
Wheat yield response, Hesston, KS (99, 01)
KSU’s rec, 144 lb acre-1
0
10
20
30
40
50
60
70
0 25 50 75 100 125
Nitrogen Treatment (lb N acre-1)
Yie
ld (
bu
ac
re-1
)
CT
NT
source: Bill Heer
Wheat yield response, Hutchinson, KS (96-01)
KSU’s rec, 124 and 108 lb acre-1
0
10
20
30
40
50
60
70
0 30 60 90
Nitrogen Treatment (lb N acre-1)
Yie
ld (
bu
ac
re-1
)
after wheat
source: Ray Lamond
Wheat yield response, central KS (98-00), 11 site-years
KSU’s rec, 136 lb acre-1
source: Alan Schlegel
Wheat yield response, Tribune, KS (94-97), 13 site-years
Wheat Yield Response to Nitrogen
25
30
35
40
45
50
55
0 10 20 30 40 50 60 70 80 90 100
APPLIED N (lb acre-1)
YIE
LD
(b
u a
cre
-1)
Inject
Broadcast
NO3-N, 55 lb acre-1
NO3-N, 21 lb acre-1
source: Alan Schlegel
Optimal N for wheat, Tribune, KS (94-97), 13 site-years
Economic Optimal N Fertilizer Rate
0
20
40
60
80
100
120
140
160
180
10 15 20 25 30 35 40 45 50 55 60 65 70
Residual Soil NO3-N (lb acre-1)
Op
tim
al N
(lb
acr
e-1
)
Inject
Brdcst
KSU's rec
• Sometimes it’s ok
Is an average N recommendation adequate?