Cotton Response To Irrigation And Nitrogen Source In Differing Mid-South Soils

Cotton (Gossypium hirsutum L.) irrigation management is challenging in a humid region, where rainfall is unpredictable and soils range from coarse-textured to fine-textured. Loss of applied N in coarse-textured soils receiving high amounts of irrigation is a concern for producers. This study was conducted to improve cotton irrigation recommendations in differing soils in the Mid-South and to evaluate the effect of a controlled release N fertilizer on N uptake and yield of cotton grown in different soils and irrigation regimes. The effects of irrigation initiation/rate and N source on cotton yield and N uptake were investigated in Jackson, TN, in soils that differed in texture. In two wet growing seasons, cotton grown in deep silt loam soils did not respond to irrigation. Irrigation of cotton grown in coarse-textured soil could be delayed until bloom without yield loss, but then needed a supplemental rate of 38.1 mm wk(-1) to optimize yield. These results reveal a clear benefit to managing irrigation separately in differing soils, when possible. Cotton receiving ammonium nitrate (AN) generally yielded higher than cotton receiving controlled release N fertilizer. However, cotton yields were similar between N sources in coarse-textured soils. Our results support the notion that cotton grown in differing soils would benefit from multiple irrigation decisions, and indicate no apparent yield or N uptake benefit from the use of a controlled release N fertilizer in no-till cotton.