Calibrating An Algorithm for On-the-Go Nitrogen Management for Second-Season Production of Corn in the Brazilian Cerrado.

There were several research and extension efforts with active crop canopy sensors (ACS) showing that farmers can save nitrogen and increase productivity of corn using on-the-go nitrogen (N) applications. Generally these sensors have been used in Brazil with algorithms imported from a completely different crop management system. However, there is a need to calibrate an algorithm that incorporates regional crop system conditions especially for the second-season production of corn after soybeans called safrinha that represents more than 90 % of the corn produced in the Mato Grosso state. Using this farming strategy the producer takes advantage of a long tropical growing season to produce two crops in a single growing season, thereby maximizing revenue per area. The objective of this study was to calibrate an algorithm developed for on-the-go N fertilizer applications for safrinha corn. The experiment was conducted in 21 site-years from 2010 to 2013 in the Brazilian Cerrado region. Several experimental plots of different N rates were sensed between V8 and V12 growth stage using ACS. Based on historical yield potential from reference farmers that use safrinha system combined with the nitrogen sufficiency index approach an algorithm for on-the-go nitrogen fertilizer application for safrinha corn was calibrated for optimum and late planting dates