1. Corn Nitrogen Management: Progress in Missouri Newell R. Kitchen, Kenneth A. Sudduth, and John Hummel USDA-ARS, Columbia, MO USDA-ARS, Columbia, MO Peter Scharf, Harlan Palm, and Kent Shannon Univ. of MO, Columbia, MO Univ. of MO, Columbia, MO Newell R. Kitchen, Kenneth A. Sudduth, and John Hummel USDA-ARS, Columbia, MO USDA-ARS, Columbia, MO Peter Scharf, Harlan Palm, and Kent Shannon Univ. of MO, Columbia, MO Univ. of MO, Columbia, MO

2. Over the Years Yield Mapping (1992-1996) Soil EC (1993-1998) Ambient Light Radiometers (1997-2002) Aerial Photos (1999-2001) Soil Sampling for Inorganic N (1999-2002) Characterizing Within-Field EONR (1999-2002) Sensing Technologies for Precision Farming, IFAFS grant (2002-2005) Yield Mapping (1992-1996) Soil EC (1993-1998) Ambient Light Radiometers (1997-2002) Aerial Photos (1999-2001) Soil Sampling for Inorganic N (1999-2002) Characterizing Within-Field EONR (1999-2002) Sensing Technologies for Precision Farming, IFAFS grant (2002-2005)

3. Adoption is being hindered because of lack of convenience. Peter Nowak, 7 th Int. Conf. on Precision Agriculture, July 26, 2004 Adoption is being hindered because of lack of convenience. Peter Nowak, 7 th Int. Conf. on Precision Agriculture, July 26, 2004

4. Nitrogen Cycle

5. OutlineOutline Sub-Field Economic Optimal N Rate Plant-Specific N Application in Corn Field Testing of VR N Applicator Using Active Light Sensors Sub-Field Economic Optimal N Rate Plant-Specific N Application in Corn Field Testing of VR N Applicator Using Active Light Sensors

6. Sub-field Economic Optimal N Rate 3 soil types: Mississippi delta, loess, claypan 3 years: 2000-2002 Producers’ fields Treatments were field-length strips of discrete N rates from 0 to 280 kg N ha-1 in 56-kg increments. Plots were six rows wide (4.5 m) and ranged in length from 400 to 1000 m. Corn grain was harvested from the center four rows of each plot using a combine equipped with a yield monitor and corn population sensors 3 soil types: Mississippi delta, loess, claypan 3 years: 2000-2002 Producers’ fields Treatments were field-length strips of discrete N rates from 0 to 280 kg N ha-1 in 56-kg increments. Plots were six rows wide (4.5 m) and ranged in length from 400 to 1000 m. Corn grain was harvested from the center four rows of each plot using a combine equipped with a yield monitor and corn population sensors

7. Oran00 Rep1 Block6 0 4 8 12 16 0100200300 N rate (kg ha -1 ) Yield (Mg ha -1 ) N opt Oran00 Rep3 Block26 0 4 8 12 16 0 100200 300 N rate (kg ha -1 ) Yield (Mg ha -1 ) N opt Deriving Spatially Variable Economic Optimum N Rate

8. Economic Optimum N Rate Claypan Soil Field 2001

9. whisker: range box: 25 th to 75 th percentile box line: median plus sign : mean asterisk: N rate based on mass balance and actual field-average yield

12. The Take Home EONR is highly variable within Missouri corn fields, and between fields EONR is highly-dependent on yearly climate conditions Yield is not a very poor predictor of EONR EONR is highly variable within Missouri corn fields, and between fields EONR is highly-dependent on yearly climate conditions Yield is not a very poor predictor of EONR

13. Plant-Specific N Application in Corn Field studies have shown increased corn yield with better plant uniformity, which generally was measured by plant-spacing standard deviation (Krall et al., 1977; Nielson, 1991; Doerge et al., 2002). The variability of plant spacing is primarily caused by one of the following: –skips due to either un-dropped seeds or non-emerged seedlings, –double, triple or more plants, where two or more seeds take the place of one, –misplaced plants, shifted from its designated location towards one of the within-row neighbors Field studies have shown increased corn yield with better plant uniformity, which generally was measured by plant-spacing standard deviation (Krall et al., 1977; Nielson, 1991; Doerge et al., 2002). The variability of plant spacing is primarily caused by one of the following: –skips due to either un-dropped seeds or non-emerged seedlings, –double, triple or more plants, where two or more seeds take the place of one, –misplaced plants, shifted from its designated location towards one of the within-row neighbors

14. High-Speed Population Data (1-mm resolution)

15. ObjectiveObjective To evaluate the agronomic response of corn plants to varying N fertilizer rate on a plant-by-plant basis in conjunction with plant spacing scenarios.

16. 1) Uniform XXXXXXXX 2) Single Skip XXXXXXXX 3) Double Skip XXXXXXXX 4) Double Plant XXXXXXXX Plant Spacing Scenarios

17. Nitrogen Treatments 1)No N 2)Adequate N, 269 kg N ha -1 shortly after emergence Treatments at or about V8 growth stage 3)Equal N, 179 kg N ha -1 4)VR1 “Robin Hood”, …179-224-134-134-224-179…. kg N ha -1 for UN, SS, and DS and …179-134-224-134- 179…kg N ha -1 for DP (treated as one plant) 5)VR2 “Sheriff of Nottingham”, …179-134-224-224-134- 179…kg N ha -1 for UN, SS, and DS and …179-224- 134-224-179… kg N ha -1 for DP

18. Two Sites in 2003/ Three Sites in 2004

19. UniformSingle Skip Double Skip Double a b c d Irrigated Site 2003

20. AdequateEqualVR 1VR 2No N a b ab b c Irrigated Site 2003

21. The Take Home

22. Field Testing of VR N Applicator Using Active Light Sensors

23. ProceduresProcedures Seven producer fields as research sites UAN + Agrotain for all N treatments Reference N strips were applied shortly after emergence VR and CR treatments were done at knee/waist-high corn, and also shoulder-high corn at two sites 6-row treatment strips, sensors over row 2 and 5 and averaged for calculations Algorithm used was developed based on radiometer measurements taken from small plot studies from 1998- 99 (unpublished) Sites include 16-m long response plots to be hand harvested Seven producer fields as research sites UAN + Agrotain for all N treatments Reference N strips were applied shortly after emergence VR and CR treatments were done at knee/waist-high corn, and also shoulder-high corn at two sites 6-row treatment strips, sensors over row 2 and 5 and averaged for calculations Algorithm used was developed based on radiometer measurements taken from small plot studies from 1998- 99 (unpublished) Sites include 16-m long response plots to be hand harvested

29. - Ceiling for Reference set to 0.25 Algorithm for Knee- to Waist-High Corn

30. Algorithm for Shoulder-High Corn - Ceiling for Reference set to 0.25

33. Reference Strips Ratio

39. Research supported in part by the USDA- NRI and IFAFS Grant Programs. Assistance also given by OSU, NTech, and Holland Instruments.