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

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”

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

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  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

  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

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

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

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

  8. Wheat N recommendation • 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

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

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

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

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

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

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