Proceedings of the 2023 Mississippi Water Resources Conference

Year: 2023 Authors: Roberts C., Gholson D., Locke M., Spencer D., Steinriede R.W.

Improved cropping systems are needed to reduce irrigation water use of cotton where irrigation water is drawn from the declining Mississippi River Valley Alluvial Aquifer. A study conducted in Stoneville, MS, from 2021 to 2023 is assessing viable cropping systems for the mid-south to conserve irrigation water. Study treatments were established in the fall of 2020 and include reduced tillage, subsoil, winter fallow (RT); strip till, winter fallow; strip till, cover crop; strip till, subsoil, cover crop; no till, winter fallow; no till, cover crop; and no till, minimal surface disturbance subsoil, cover crop. Each treatment was individually irrigated based on tension-based soil moisture status. In the first year of full study implementation (2021), high amounts of timely rainfall made irrigation unneeded. Lint yield during that year was decreased in no-till treatments by up to 16% (1382 kg ha-1) compared to conventional reduced tillage (1647 kg ha-1). In 2022 precipitation was closer to normal. Cover crops improved soil moisture by as much as 47 kPa compared to the conventional, RT treatment. Compared to all winter fallow treatments, the treatments with a cover crop retained more soil moisture with soil moisture tension being 57% lower. This resulted in more irrigation water used in treatments with winter fallow. There were few differences in lint yield between the treatments, and yields were not improved by increased irrigation. Cover crops can be used to conserve water in cotton without reducing yield in years with normal precipitation.