Balancing Tillage, Irrigation, and Planting in Intercropped Cotton and Sorghum.

Water limitations on the Southern High Plains require management practices that maximize economic crop productivity. One practice is to share an irrigation system among multiple crops, allowing water to be applied at critical times in each crop.  Previous studies of crop rotations on the Texas High Plains have shown improved organic matter content, water holding capacity, and increased yields. However, limited research is available regarding the interaction between rotation and irrigation due to changing rainfall patterns and crop-water requirements.  The objectives of this study are to determine (i) economic productivity of various management practices including planting date, tillage, crop rotation, and irrigation, (ii) the impact of tillage on water-use efficiency, (iii) irrigation rate and timing on crop productivity, and (iv) the relationship between economic productivity and resource efficiency. We tested: two crops to be rotated which include cotton (Gossypium hirstum) and grain sorghum (Sorghum bicolor); irrigation consisted of four different irrigation zones with different timing: 75% ET, 50% which ends at mid-season, 50% which begins at mid-season, and dryland cotton and sorghum; planting dates consisted of early, mid and late plantings for the region; and tillage consisted of strip tillage and conventional tillage.  Discussion of results will include the relationship between crop rotation, tillage, planting date, and irrigation rate on resource efficiency and economic productivity.