A Retrospective Review of Cotton Irrigation on a Production Farm in the Mid-South

Abstract

The water table of the primary irrigation source for agriculture in the Lower Mississippi River Basin is declining at an alarming rate. Irrigation practices that sustain cotton lint yields and reduce irrigation water use include adoption of termination guidelines based on plant growth stage and weather conditions. Production records from a large northeastern Arkansas cotton farm were examined to gauge how well a plant maturity-based irrigation termination guideline (final irrigation at 350 Growing Degree Days (60°F base) following crop cutout) was followed. Irrigation logs and yield records from the producer plus plant monitoring data from the farm’s crop advisor were used to evaluate irrigation practices in 70 field entities over eight production seasons. Results indicate that irrigation termination timing for furrow-irrigated fields generally occurred prior to the termination guideline. Adherence to the termination guideline allowed the producer to reduce late season pumping. These results are encouraging given that yields from the studied fields were above county averages for all years studied, which spanned wet to dry conditions. Nearly twice the amount of water was applied in furrow-irrigated compared to pivot-irrigated fields, yet lower average yields were produced in furrow-irrigated fields in six of the eight years. Furrow-irrigated fields had higher yield variability compared to fields with pivot irrigation. These results suggest that conversion of furrow irrigation to pivot irrigation likely would result in increased productivity and reduced water use, and that use of plant-based irrigation termination guideline could reduce the need for costly, late season pumping without a yield penalty.