RESIDUE MANAGEMENT FOR CONTINUOUS WINTER-WHEAT PRODUCTION WITH LIMITED IRRIGATION

Crop residue management was chosen as a key practice to help control erosion on nearly 75% of the highly erodible land covered by conservation plans. This study determined the effects of treatments that involved retaining all residues on the surface (NT+Res), removing some residues at harvest (NT-ResH) or at planting (NT-ResP), and conventional tillage (ConvT) on soil water storage and use, and yields of continuous winter wheat (Triticum aestivum L.) produced with limited irrigation. Water storage between crops was greater with NT+Res (95 mm) and NT-ResH (100 mm) than with ConvT (79 mm), but soil water depletion was not affected by treatments. Grain yield was greater with NT+Res (4.56 Mg ha(-1)), than with ConvT (4.26 Mg ha(-1)) and NT-ResH (4.18 Mg ha(-1)), but straw yield was not affected by treatments. Grain and straw yield differed among crops. Continuous wheat production with limited irrigation resulted in an estimated 2.2 Mg ha(-1) of residues on the surface at planting with the NT-ResH and NT-ResP treatments. The initial amount was 9.0 Mg ha(-1) with the NT+Res treatment, and much of this remained on the surface at planting of the next crop. In all cases, the residue amounts provided considerably more (a minimum of about 70%) than the 30% surface cover usually required to control erosion on highly erodible land. Hence, use of limited irrigation and no-tillage can help producers meet the surface residue requirements established for their conservation plans for highly erodible lands in the southern Great Plains.