Preplant and early-season cotton irrigation timing with deficit amounts using subsurface drip (SDI) systems in the Texas High Plains

Abstract

Two major irrigation challenges of cotton producers in the Texas High Plains (THP) include the depletion of the Ogallala Aquifer and the highly evaporative, semi-arid environment during late spring and early summer. A recent cotton experiment using center pivot irrigation at deficit irrigation capacities showed the reduction in seasonal irrigation by 20% with minor yield loss by reducing irrigations during the vegetative period instead of attempting to store soil water during this period of high evaporative losses. Due to its method of delivery, subsurface drip irrigation (SDI) should reduce evaporation losses during the preplant and early-season periods and improve water storage efficiency and crop yield even at low irrigation capacity. Two experiments having different SDI installation designs and irrigation capacities were conducted in adjacent fields on clay loam soils over 4- and 5-year periods. Treatments included levels of preplant (PP) and vegetative (Veg) period irrigations. In both experiments, under seasonal growing conditions ranging from favorable to unfavorable, yields and crop values were only modestly increased by additional PP irrigations above that required for germination. Among treatments with common PP amounts, larger irrigation amounts during the vegetative period did not significantly (p < 0.05) increase yield or crop value in any individual year or any group of years. In three growing season groupings, with unfavorable to favorable weather conditions, as seasonal irrigation increased, gross irrigation value decreased. Results suggest that in most years, on heavy soils within the THP, SDI productivity can be improved by limiting PP and early-season irrigations under deficit irrigation conditions.