In-Season N Management Tools in Commercial Cultivation System.

For the past sixty years, increasing food production has been a global priority of agriculture. During this time, supplemental application of nitrogen (N) as a fertilizer increased more than other nutrients because of its direct impact on greater crop yield over most agricultural land. The N is the most important nutrient for crop production and it is applied by growers in large amounts. Nitrogen is a difficult nutrient to manage in crop production because it can volatilize directly into the atmosphere, or it can be leached, immobilized, fixed, or transformed to nitrous oxides or nitrogen gas and made unavailable for plant uptake. The first step to optimize N use is to determine the variability of N in a field. Ground-based active-optical crop sensors can be used at any pre-flowering growth stage of crop without consideration of clouds and ambient light. The GBAO sensors were developed using certain light-spectrum wavelengths related to crop biomass or leaf chlorophyll. Different N rate study was conducted on corn, wheat, sunflower, and sugar beet between 2011-15. Randomized complete block design was used for corn, wheat, and sugar beet. Split plot design was used for sunflower N rate study. Two ground based active-optical sensors, the GreenSeeker^® and Holland Scientific Crop Circle Sensor^® ACS 470 were used to collect red NDVI or red-edge NDVI data in each plot at the V6 and V12 growth stages from corn, sunflower, and sugar beet however, in wheat data was collected at flag leave stage. A successful inseason N recommendation was being developed for yield prediction in corn, wheat, sunflower and sugar beet. In addition sensors were able to predict wheat protein, sunflower oil, and sugar beet total soluble solids. All algorithms were segregated with soil types (high clay vs medium textured) and cultivation system (conventional vs no-till system).