TY - JOUR
T1 - Nitrogen recommendations for corn
T2 - An on-the-go sensor compared with current recommendation methods
AU - Schmidt, John P.
AU - Dellinger, Adam E.
AU - Beegle, Doug B.
PY - 2009/7
Y1 - 2009/7
N2 - Precision agriculture technologies provide the capability to spatially vary N fertilizer applied to corn (Zea mays L.), potentially improving N use efficiency. The focus of this study was to evaluate the potential of improving N recommendations based on crop canopy reflectance. Corn was grown at four field sites in each of 2 yr in Centre County, Pennsylvania. Preplant treatments included: zero fertilizer, 56 kg N ha-1, and manure. Split-plot treatments included the following N sidedress rates as NH4NO 3: 0, 22, 45, 90, 135, 180, and 280 kg N ha-1, and one at-planting N rate of 280 kg N ha-1. Light energy reflectance (590 and 880 nm), chlorophyll meter (SPAD) measurements, and the presidedress NO 3 test (PSNT) results were obtained at sidedress. The late-season stalk NO3 (LSSN) test was determined. The economic optimum nitrogen rate (EONR) was determined based on grain yield response to sidedress N rates. Relative green normalized difference vegetation index (GNDVI) and relative SPAD were based on relative measurements from the zero sidedress treatment to the 280 kg N ha-1 at-planting treatment. The EONR from 24 preplant treatment-site combinations was related to relative GNDVI (R2 = 0.76), the PSNT (R2 = 0.78), relative SPAD (R2 = 0.72), and the LSSN test (R2 = 0.64), suggesting that relative GNDVI was as good an indicator of EONR as these other, more conventional tests. Because relative GNDVI can be obtained simultaneously with a sidedress N fertilizer application, the potential to accommodate within-field spatial and season-to-season temporal variability in N availability should improve N management decisions for corn production.
AB - Precision agriculture technologies provide the capability to spatially vary N fertilizer applied to corn (Zea mays L.), potentially improving N use efficiency. The focus of this study was to evaluate the potential of improving N recommendations based on crop canopy reflectance. Corn was grown at four field sites in each of 2 yr in Centre County, Pennsylvania. Preplant treatments included: zero fertilizer, 56 kg N ha-1, and manure. Split-plot treatments included the following N sidedress rates as NH4NO 3: 0, 22, 45, 90, 135, 180, and 280 kg N ha-1, and one at-planting N rate of 280 kg N ha-1. Light energy reflectance (590 and 880 nm), chlorophyll meter (SPAD) measurements, and the presidedress NO 3 test (PSNT) results were obtained at sidedress. The late-season stalk NO3 (LSSN) test was determined. The economic optimum nitrogen rate (EONR) was determined based on grain yield response to sidedress N rates. Relative green normalized difference vegetation index (GNDVI) and relative SPAD were based on relative measurements from the zero sidedress treatment to the 280 kg N ha-1 at-planting treatment. The EONR from 24 preplant treatment-site combinations was related to relative GNDVI (R2 = 0.76), the PSNT (R2 = 0.78), relative SPAD (R2 = 0.72), and the LSSN test (R2 = 0.64), suggesting that relative GNDVI was as good an indicator of EONR as these other, more conventional tests. Because relative GNDVI can be obtained simultaneously with a sidedress N fertilizer application, the potential to accommodate within-field spatial and season-to-season temporal variability in N availability should improve N management decisions for corn production.
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U2 - 10.2134/agronj2008.0231x
DO - 10.2134/agronj2008.0231x
M3 - Article
AN - SCOPUS:68149176630
SN - 0002-1962
VL - 101
SP - 916
EP - 924
JO - Agronomy Journal
JF - Agronomy Journal
IS - 4
ER -