Managing Irrigated Winter Wheat Residues for Water Storage and Subsequent Dryland Grain Sorghum Production

Abstract

Abstract Better cropping and residue management systems are needed to improve precipitation‐use efficiency, minimize ground water depletion by irrigation, reduce pumping costs, and conserve energy. An irrigated winter wheat ( Triticum aestivum L.)‐dryland grain sorghum [ Sorghum bicolor L. (Moench)] cropping system was evaluated from 1972 to 1978 for water storage between wheat harvest and sorghum planting time and for subsequent grain sorghum growth and yields. No‐tillage, sweep, and disk methods were used during the 11‐month period between crops for wheat residue management and weed control. Precipitation stored as soil water during the 11 months of fallow averaged 35, 23, and 15%; available soil water contents to the 1.8‐m depth at sorghum planting averaged 21.7, 17.0, and 15.2 cm; sorghum grain yields averaged 3,140, 2,500, and 1,930 kg/ha; and water‐use efficiencies (WUE) for sorghum grain averaged 89, 77, and 66 kg/ha‐cm for the respective treatments. Sorghum forage yields were slightly higher than grain yields and, therefore, WUE for forage production were higher than for grain. The WUE for forage, however, decreased in the same order as for grain. Based on March 1978 production costs and grain prices, net returns (excluding land, taxes, and interest costs) for sorghum production were four and two times greater with no‐tillage and sweep tillage, respectively, than with disk tillage, the most widely used tillage method after irrigated wheat in the Southern Great Plains.