1. Current KSU N recommendations for corn & wheat
John Schmidt
Alan Schlegel
Kansas State University

2. Development of current N recommendations
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
This needs to be modified to be more brief.

3. Corn N recommendation 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
This needs to be modified to be more brief.

4. 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.

5. Corn yield response, Tribune, KS (92-00)
KSU’s rec, 218 lb acre-1
P2O5, lb acre-1
source: Alan Schlegel

6. Corn yield response, Topeka, KS (97-01)
KSU’s rec, 226 lb acre-1
P2O5, K2O, lb acre-1
source: Larry Maddux

7. Corn yield response, Scandia, KS (01, Ridge-till)
KSU’s rec, 314 lb acre-1
P2O5, K2O, S lb acre-1
source: Barney Gordon

8. Wheat N recommendation
(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
This needs to be modified to be more brief.

9. 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.

10. Wheat yield response, Manhattan, KS (98-00)
KSU’s rec, 82 and 88 lb acre-1
source: Dave Whitney

11. Wheat yield response, Hesston, KS (99, 01)
KSU’s rec, 144 lb acre-1
source: Mark Claassen

12. Wheat yield response, Hutchinson, KS (96-01)
KSU’s rec, 124 and 108 lb acre-1
source: Bill Heer

13. Wheat yield response, central KS (98-00), 11 site-years
KSU’s rec, 136 lb acre-1
source: Ray Lamond

14. Wheat yield response, Tribune, KS (94-97), 13 site-years
Inject
Broadcast
NO3-N, 55 lb acre-1
NO3-N, 21 lb acre-1
source: Alan Schlegel

15. Optimal N for wheat, Tribune, KS (94-97), 13 site-years
source: Alan Schlegel

16. Is an average N recommendation adequate?
Sometimes it’s ok
This needs to be modified to be more brief.