A deficit irrigation trial in differing soils used to evaluate cotton irrigation scheduling for the mid-south

Abstract

Cotton (Gossypium hirsutum L.) irrigation management in the humid Mid-South is complicated by unpredictable rainfall and significant soil variability. Producers of irrigated cotton need guidance with making irrigation decisions to create conditions for optimal yield while efficiently managing irrigation water use. The objectives of this study were to demonstrate cotton yield response to varying irrigation across differing soils and to evaluate the ability of a water balance approach, and the use of soil moisture sensors to guide sound irrigation decisions. A three-year study was conducted in Jackson, TN where cotton was grown on soils ranging from primarily sandy-textured to deep silt loam soils and was drip-irrigated under several irrigation regimes. Three years of differing rainfall patterns demonstrated a need for different irrigation management between soils to optimize cotton yield each year. Sandy soils needed irrigation at a higher rate each year and an earlier initiation two of three years. A deficit between applied water and crop water use was especially important in silt loam soils, which required more judicious application of irrigation. Awater balance approach to irrigation scheduling was a good indicator of soil and crop water status in sandy and silt loam soils. Soil moisture sensors often reflect the status of the water balance, however, in some cases soil moisture sensors could have triggered unnecessary irrigation based on suggested irrigation thresholds. While each method of irrigation scheduling has shortcomings, using a water balance in conjunction with soil moisture sensors is recommended, such that each can verify the other.