Lint Yield and Crop Maturity Responses to Supplemental Irrigation In Tennessee

Cotton responses to supplemental irrigation need to be reassessed in Tennessee, where fewer than 3% of cotton acres are irrigated. We conducted a 4-year study on a Memphis silt loam at Jackson TN, to measure yield and maturity responses of contemporary cultivars to supplemental irrigation. Treatments were three rates of supplemental drip irrigation (nominally 1.5, 1.0, and 0.5 inch/week, adjusted for rainfall and prior irrigation), plus a nonirrigated check. Irrigation increased lint yields significantly in 3 of 4 years, by an average of 38% at the 1-inch rate. Yields were maximized with 13.8 to 14.6 inches of total water (irrigation + rainfall) between 40 and 120 days after planting. Irrigation delayed crop maturity by an average of 1.4 days for every additional inch water applied.