Optimum Irrigation Termination Timing in Furrow Irrigated Cotton

Properly terminating furrow irrigation in mid-southern United States (U.S.) crops could reduce irrigation costs, the likelihood of adverse harvest conditions, and agricultural withdrawal from the Mississippi River Valley Alluvial Aquifer (MRVAA). This research was conducted to determine an optimum termination window for furrow-irrigated cotton (Gossypium hirsutum L.) in the mid-southern U.S. The effects of irrigation termination timing on cotton lint yield, net returns, and irrigation water use efficiency (IWUE) were evaluated on a Leeper silty clay loam (fine, smectitic, nonacid, thermic Vertic Epiaquepts) and on a Dundee silty clay (fine-silty, mixed, active, Typic Endoaqualfs). Neither terminating nor continuing to irrigate cotton from cutout (NAWF = 5) up to three weeks past first cracked boll had an effect on lint yield or fiber quality (p ≥ 0.6107). Irrigation water use efficiency declined when water was applied past cutout (p < 0.0001). Results indicate that irrigation in cotton can be terminated at cutout without adversely effecting lint yield and fiber quality if soil water potential does not exceed -130 kPa prior to first cracked boll. Terminating irrigation in cotton at cutout could reduce late season irrigation cost and reduce water withdrawal from the MRVAA thus improving it sustainability.