Effect of Soil Nitrogen Rates on Residual Soil N, Plant Growth Parameters, Yield, and Quality: An Economic Analysis

Nitrogen and irrigation water are critical agricultural inputs for cotton production. A multi-year field study was conducted to examine the effect of soil nitrogen (residual nitrogen plus applied nitrogen) on cotton agronomic growth parameters, yield, and fiber quality attributes under a drip irrigation production system. Fixed-rate nitrogen application experimental plots consisted of five augmented nitrogen fertility levels (0, 50, 100, 150, and 200 lb/acre) with five replications. Each year, soil in each experimental plot was sampled for residual nitrogen analysis prior to planting or before treatment deployment. Rates of applied N exceeding 100 lb/acre resulted in higher residual nitrogen detection during the following season. Increased N levels corresponded to increased leaf chlorophyll content, but leaf chlorophyll content was generally consistent across nitrogen levels exceeding 100 lb/acre. Leaf N generally followed the trend that was observed for leaf chlorophyll content. Rates of N application exceeding 100 lb/acre resulted in higher lint yield, but micronaire values were significantly reduced. In this study, we examine the effect of augmented soil N and residual N in cotton production in the Texas High Plains. Specifically, we estimate the marginal product value of water and nitrogen inputs in Texas High Plains cotton production.