Wheat Residue Management Effects on Soil Water Storage and Corn Production

Corn (Zea mays L.) grown in the semiarid southern Great Plains usually is irrigated fully because yields decline if water stress occurs at any time during the growing season, but the groundwater supply for irrigation is being depleted. To decrease the dependence of corn production on the declining groundwater supply, practices must be developed to improve the storage and use of precipitation. This study was conducted to determine the effects of residue management practices after wheat (Triticum aestivum L.) on precipitation (and preplant irrigation) storage during fallow; corn growth, yield, and seed quality; and water use and use efficiency by corn. The soil was Pullman clay loam (fine, mixed, thermic Torrertic Paleustolls). Because of high initial water contents at the start of fallow in 1982, relatively little water was stored from precipitation during the 1982 to 1983 fallow. For the 1983 to 1984 fallow, water storage was higher with disk and sweep tillage than with no-tillage because the disk and sweep plots received a preplant irrigation to wet the tillage-loosened soil. Water use by corn was not affected significantly by tillage in 1983, but was significantly lower with no-tillage than with disk or sweep tillage in 1984. Corn grain yields were lowest with a no-tillage standing residue treatment in 1983 due to N deficiency. In 1984, yields were not affected significantly by tillage, but avg 0.29 Mg/ha higher on fertilized than on nonfertilized low-residue plots and 2.0 Mg/ha higher on fertilized than on nonfertilized high-residue plots. Kernel weight (mg/kernel) and kernel test weight were affected significantly by tillage in 1983, but not in 1984. The study showed that crop residues can be managed to use a greater proportion of precipitation for producing corn, thus reducing the dependence on irrigation. However, soil fertility must be adequate for obtaining high yields, especially on high-residue plots.