Active Crop Canopy Sensors Effect on Nitrogen Use Efficiency and Yield.

Recent research in Nebraska has shown that while improvements have been made in nitrogen use efficiency (NUE) in recent decades, those increases may be starting to plateau. The objective of this study was to explore the use of active crop canopy sensors to increase NUE while also improving awareness of crop canopy sensors for the use of nitrogen (N) applications among growers. This investigation was conducted on producers’ fields in central Nebraska, with 17 sites in 2015 and 19 sites in 2016. Treatments were arranged as field length strips in a randomized complete block design with 6 replications.  The treatments consisted of the growers’ preferred N management strategy and variable-rate application using OptRx^® active crop canopy sensors available from Ag Leader^®, which were used to detect crop N stress at approximately the V9 growth stage, with supplemental N applied using a high clearance applicator.  Mean strip N rate and grain yield collected by yield monitoring combine were used to compare treatment performance. The sensor-based approach resulted in a decrease of 45 kg N ha^-1 compared to the grower strategy with a 0.31 Mg ha^-1 decrease in yield.  This resulted in higher partial factor productivity of nitrogen (PFP_N) of 86 kg grain kg N^-1 vs 66 kg grain kg N^-1 for the grower approach. On average, the sensor-based approach was successful in reducing N rates while protecting yield. Adoption of sensor-based application has the potential to improve NUE.