On-Farm Implementation of Optical Sensing System to Increase Nitrogen Use Efficiency in Cotton Production in Louisiana.

The adoption of optical sensing and variable nitrogen (N) rate application systems has improved fertilizer N use efficiency in wheat and corn. The models for predicting cotton lint yield potential and probability of response to N fertilization were recently established; these are the two components of the fertilizer rate algorithm require to run the sensor-based variable N rate application system (VRT). Since 2012, six demonstration plots have been established in three producer’s fields in Tensas Parish, LA (Fields A, B and C) to demonstrate the feasibility and benefits of implementing VRT on cotton production in north Louisiana. Three different N management systems were compared in large strip plots (12-m wide run x 305-m long): producer’s current N management system (N1), a VRT based on GreenSeeker^TM optical sensing system (N2), and similar VRT optical sensing system as N2 but adjusted for soil productivity zones (N3). The N1 is the standard N fertilization practice of the participating producers wherein the application rates for Fields A, B, and C were 112, 140, and 151 kg N ha^-1 in 2012, and 112, 84 and 146 kg N ha^-1 in 2013, respectively applied one time at or immediately after planting. For both years, N2 and N3 plots at Field B received twice as much N fertilizer as N1 whereas Field A and C received slightly lower N fertilizer rates than N1. In 2012, the performance of N2 was positive in two fields. Similar levels of lint yield were achieved across treatments in Field A but N2 used 29 kg N ha^-1 lesser than N1 resulting in a net of $32.65 ha^-1 higher than N1. In Field C, N2 had lower lint yield (27 kg ha^-1) than N1 but used only 47 kg N ha^-1 outweighing the lost in lint yield which then resulted in a net return of $28.01 ha^-1 higher. Thus far, this study has demonstrated the potential of in-season N fertilization in cotton using sensor based predicted lint yield potential and estimate of cotton response to N fertilization in improving N use efficiency and net return to N in cotton production in Louisiana.