| Improving nitrogen use efficiency (NUE) with remote sensing devices is an emerging technology. With the utilization of optical sensors, researchers have demonstrated an ability to consistently improve NUE beyond that of previous N fertilization methods. This study characterized grain yield and biomass yield of corn (Zea mays L.) and evaluated the spatial variability of corn growth in terms of normalized difference vegetative index (NDVI). Four rows, 30 m in length were randomly selected for use in this study. A GreenSeeker(TM) Handheld sensor was used to collect NDVI readings at all possible growth stages during the life cycle of corn. NDVI increased with progression of vegetative growth stages until around V 10, where somewhat of a plateau was encountered, followed by a decline in NDVI after the VT growth stage. Coefficient of variation (CV) data from the NDVI readings of each row revealed two dominant peaks during the life cycle of corn, one between the V6 and V8 growth stages and the second during the late reproductive growth stages. The CV data illustrated that the greatest variation expressed by corn during the vegetative growth stages was between the V6 and V8 growth stages. NDVI was found to have the highest correlation with yield at the V7 to V9 growth stages. Coefficient of variation and plant spacing had the highest correlation from the V7 to V9 growth stages and CV had a high negative correlation with grain and biomass yields at all growth stages. As remote sensing technology progresses, results indicate that the V8 growth stage will be vitally important as a physiological stage to best recognize spatial variability for nutrient application in corn. |
