Effects of Optical Sensing and Variable Rate Technology on Nitrogen Fertilizer Use, Lint Yields, and Profitability in Cotton Production

Nitrogen (N) fertilizer is expensive and can be harmful to the environment. Precision agriculture (PA) has the capability to reduce the amount of excess N from crop production released into the environment, increase net returns to the grower, and reduce the risk of profit loss due to spatial and temporal variability. The objectives of this study were to evaluate the profitability, risk management potential, and N use efficiency of using real-time optical sensing with variable-rate technologies (VRT) to manage spatial variability in cotton production. Data collected from 29 field trials in Tennessee, Louisiana, Mississippi, and Missouri from 2011 to 2014 included lint yields harvested and N rates calculated from three N rate management strategies. The first N treatment was the existing farmer practice (FP), the second was a VRT treatment using optical sensing technology Greenseeker™, and the third was a VRT treatment using Greenseeker™ and yield monitor information. The two PA strategies were compared to the existing farmer practice. In addition, soil properties and weather were examined to determine their effects on lint yields, net returns, N rates, and N use efficiency.

Three methods used in this study each include an analysis of lint yields, N rates, net returns, and N use efficiency. The first model was an analysis of variance (ANOVA) to identify treatment mean differences. The second model was an ANOVA that measured soil and weather effects on mean differences between technology and FP. The third model was a logistic analysis to test for risk of a loss using VRT. Results indicated differences in technology net returns versus the FP and no differences between VRT and FP in yields, N rates, or N use efficiency. Warmer temperatures were negatively associated and a greater percentage of organic matter had positive associations with VRT net returns and N use efficiency relative to FP. Profit risk management benefits were identified using Greenseeker™ versus the FP. Results can be used by Extension offices and cotton farmers in Tennessee, Mississippi, Louisiana, and Missouri to determine if adopting optical sensing and VRT would be beneficial to their operations.