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

Over the Years Yield Mapping ( ) Soil EC ( ) Ambient Light Radiometers ( ) Aerial Photos ( ) Soil Sampling for Inorganic N ( ) Characterizing Within-Field EONR ( ) Sensing Technologies for Precision Farming, IFAFS grant ( ) Yield Mapping ( ) Soil EC ( ) Ambient Light Radiometers ( ) Aerial Photos ( ) Soil Sampling for Inorganic N ( ) Characterizing Within-Field EONR ( ) Sensing Technologies for Precision Farming, IFAFS grant ( )

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

Nitrogen Cycle

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

Sub-field Economic Optimal N Rate 3 soil types: Mississippi delta, loess, claypan 3 years: 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: 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

Oran00 Rep1 Block N rate (kg ha -1 ) Yield (Mg ha -1 ) N opt Oran00 Rep3 Block N rate (kg ha -1 ) Yield (Mg ha -1 ) N opt Deriving Spatially Variable Economic Optimum N Rate

Economic Optimum N Rate Claypan Soil Field 2001

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

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

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

High-Speed Population Data (1-mm resolution)

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.

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

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”, … …. kg N ha -1 for UN, SS, and DS and … …kg N ha -1 for DP (treated as one plant) 5)VR2 “Sheriff of Nottingham”, … …kg N ha -1 for UN, SS, and DS and … … kg N ha -1 for DP

Two Sites in 2003/ Three Sites in 2004

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

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

The Take Home

Field Testing of VR N Applicator Using Active Light Sensors

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 (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 (unpublished) Sites include 16-m long response plots to be hand harvested

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

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

Reference Strips Ratio

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