1. O K L A H O M A S T A T E U N I V E R S I T Y Nitrogen Management for Wheat and Corn, What you Shouldn’t Do

2. O K L A H O M A S T A T E U N I V E R S I T Y Reference Strips (Schepers, Francis, UNL) Interfering factors present without them Interfering factors present without them –Weed coverage in the center of the row –Low end could be due to something other than N –Valid paired comparisons –Scale between the bottom and the top must be defined if it is going to be used for ensuing recommendations –N rate associated with high NDVI –N rate associated with low NDVI –Low NDVI could be due to water logging, low P, K, etc. Interfering factors present without them Interfering factors present without them –Weed coverage in the center of the row –Low end could be due to something other than N –Valid paired comparisons –Scale between the bottom and the top must be defined if it is going to be used for ensuing recommendations –N rate associated with high NDVI –N rate associated with low NDVI –Low NDVI could be due to water logging, low P, K, etc.

3. O K L A H O M A S T A T E U N I V E R S I T Y Near Marshall, OK - IKONIS NDVI N Rich No P

4. O K L A H O M A S T A T E U N I V E R S I T Y 1992 1993

5. O K L A H O M A S T A T E U N I V E R S I T Y 1993 1994 1995

6. O K L A H O M A S T A T E U N I V E R S I T Y 1996 1997 1996 1998 Variable Gain

7. O K L A H O M A S T A T E U N I V E R S I T Y 2001

8. O K L A H O M A S T A T E U N I V E R S I T Y Pics of old sensors Pics of old sensors 2002 2003

9. O K L A H O M A S T A T E U N I V E R S I T Y Variable Rate Technology Treat Temporal and Spatial Variability Wheat, 0.4m 2 Corn, by plant 2007

10. O K L A H O M A S T A T E U N I V E R S I T Y Argentina Zimbabwe Uzbekistan Canada FLAT RATE

11. O K L A H O M A S T A T E U N I V E R S I T Y Some of our equipment is much less complicated

12. O K L A H O M A S T A T E U N I V E R S I T Y Agronomic journey 1993, linear scale, uncalibrated red and NIR 1993-1995, variants of linear sufficiency 1995-1998, based of predicted yield potential YP0 1999, based on YP0 and RI (Wade Thomason) 2000, optimum resolution, 0.4m2 wheat 2002, RI NDVI, RI Harvest (Robert Mullen) 1999-2004, refinement of yield prediction 2005, YP0, RI, and CV, RAMP 2007, YP0, RI, CV, NUE 1993, linear scale, uncalibrated red and NIR 1993-1995, variants of linear sufficiency 1995-1998, based of predicted yield potential YP0 1999, based on YP0 and RI (Wade Thomason) 2000, optimum resolution, 0.4m2 wheat 2002, RI NDVI, RI Harvest (Robert Mullen) 1999-2004, refinement of yield prediction 2005, YP0, RI, and CV, RAMP 2007, YP0, RI, CV, NUE

13. O K L A H O M A S T A T E U N I V E R S I T Y Appropriate Strategy? NDVI Application Rate “Starve the Rich” NDVI Application Rate RI =1.5 RI = 2.0 Multiple Factors + N Limiting Yield NDVI Application Rate Compromise Strategy Application Rate NDVI “Feed the Rich”

14. O K L A H O M A S T A T E U N I V E R S I T Y Variability in yield and nitrogen demand

15. O K L A H O M A S T A T E U N I V E R S I T Y Predicting Yield Potential in Corn NDVI, V8 to V10 INSEY  Days from planting to sensing CORN

16. O K L A H O M A S T A T E U N I V E R S I T Y YP MAX INSEY (NDVI/days from planting to sensing) Grain yield YP 0 YP N RI=2.0 RICV-NFOA CV Nf = ((YP 0 *RI)*(100-CV/100-CV lim )) – YP 0 / expected NUE ??

17. O K L A H O M A S T A T E U N I V E R S I T Y 200 0 15 30 45 60 75 100 115 N Rate, lb/ac 200 0 0 15 30 200 RAMP Calibration Strip

18. O K L A H O M A S T A T E U N I V E R S I T Y Ramp Calibration Strip 0 N 195 N Limited differences by V8 in corn? Wheat N Ramp Limited differences by V8 in corn? Wheat N Ramp

19. O K L A H O M A S T A T E U N I V E R S I T Y 10 on-farm trials, Triticum aestivum L. avg. RI 1.3 PreplantEarlyLateTotal NYieldReturn Treatment N rate, lb/ac Topdress N rate, lb/acbu/ac$/ac VRT4115237939.8104 VS33521359137.393 VS2499248235.491 Farmer Check5221209234.686

20. O K L A H O M A S T A T E U N I V E R S I T Y 2007, Dryland, Zea mays L. Preplant N, lb/ac Sidedress N, lb/ac Total N Rate, lb/ac Yield, bu/ac$/ac N-Rich2000 88216 SBNRC045 73234 SBNRC40286885266 Flat Rate800 76230 SBNRC, sensor based nitrogen rate calculator

21. O K L A H O M A S T A T E U N I V E R S I T Y NUE and Yield Increases, Zea mays L.

22. O K L A H O M A S T A T E U N I V E R S I T Y NUE = 0.60 NUE = 0.40 Can NUE be determined for mid- season N applications? Ramps? 120

23. O K L A H O M A S T A T E U N I V E R S I T Y Decision No need for reference strips – –Process of elimination, confounding factors, Liebig’s law of the minimum Apply all N preplant, risk of mid-season applications is just too high – –$0.46/ lb N, low NUE’s, environment, 1B excess N Use yield goals, less risky – –Yield prediction models corn, wheat, sorghum, canola, weather data (MESONET) Apply same N rate year after year, less complicated – –Demand for N changes from year to year, as do NUE’s No need for reference strips – –Process of elimination, confounding factors, Liebig’s law of the minimum Apply all N preplant, risk of mid-season applications is just too high – –$0.46/ lb N, low NUE’s, environment, 1B excess N Use yield goals, less risky – –Yield prediction models corn, wheat, sorghum, canola, weather data (MESONET) Apply same N rate year after year, less complicated – –Demand for N changes from year to year, as do NUE’s

24. O K L A H O M A S T A T E U N I V E R S I T Y Extension Clint Mack, David Zavodny (586 Ramps 2006) CountyFert. Dealer Bob WoodsDanny Peeper Stan Fimple 2005-2007 (>2500) Brad Tipton Farmer acceptance? Chad Otto Rodney King Roger Gribble Clint Mack, David Zavodny (586 Ramps 2006) CountyFert. Dealer Bob WoodsDanny Peeper Stan Fimple 2005-2007 (>2500) Brad Tipton Farmer acceptance? Chad Otto Rodney King Roger Gribble

25. O K L A H O M A S T A T E U N I V E R S I T Y Thank you Farmer training, Ciudad Obregon, Mexico, January 2007 www.nue.okstate.edu