Cropping System Management: Irrigation, Tillage and Crop Rotation in a Semi-Arid Climate.

Declining water availability in the Ogallala Aquifer coupled with increased water demand by row crops on the Texas High Plains has reached a point that cropping systems management decisions must be reevaluated. A study was undertaken in 2014 at Texas A&M AgriLife Research Center Helm Farm near Halfway, Texas, to begin systematically evaluating combinations of factors for determining optimum irrigation, tillage, nutrient application, crop rotation and economic return. The study area is a 53 ha pivot that has been subdivided into four crop rotations: continuous cotton, cotton –grain sorghum , cotton-wheat-fallow and cotton following a terminated wheat cover crop. Each wedge has been further subdivided by span into conventional tillage and reduced tillage and even further into three or four irrigation levels based on 60% return to plant evapotranspiration in an average year. Preliminary results have shown that reduced tillage appears to have a positive effect on both cotton and sorghum at irrigation rates of 1.0BI and 1.5BI. Conventional tillage had the same or higher cotton yields in all cotton rotations, and the incidence of Verticillium wilt can be reduced and managed through crop rotations. Results from this study will help provide management options to growers that will be more sustainable in a water deficient climate.