Soil Disturbance-Residue Management Effect on Winter Wheat Growth and Yield

The need to reduce soil erosion, maximize soil water conservation, and optimize grain production in dryland cropping systems in the Central Great Plains has culminated in development of nonfilled fallow systems. These systems have greatly reduced the degree of soil disturbance, and the amount and degree of residue incorporation. The objectives of this study were to evaluate the influence of soil disturbance and residue management on soil temperature, soil water, and winter wheat (Triticum aestivum L.) growth. Two field studies were established in 1981 and 1982 on an Alliance silt loam (Fine-silty, mixed, mesic Aridic Argiustoll) with treatments consisting of various degrees of soil disturbance (moldboard plow, tandem disk, and no tillage), residue incorporation (on the soil surface or incorporated), and amount of residue applied (0.0, 0.5, and 1.0 of that produced by the previous crop). Decreased soil disturbance (tillage) and increased residue application decreased maximum, and increased minimum, soil temperatures. In all tillage treatments, soil water content showed a significant positive linear relationship to residue application rate. Grain yield was similar for all treatment factors, except tillage within the 1983-1984 season when tilled (3.48 Mg ha⁻¹) treatments produced more grain than the nontilled (3.20 Mg ha⁻¹) treatment. Early development and growth of winter wheat was slowed by the presence of residues (surface or incorporated) or the absence of tillage. However, by completion of heading, phenology and yield were similar for all treatments. Cooler soil temperatures slowed development and growth during those stages when the meristem temperature was influenced most by soil temperature. However, after jointing, when air temperature and photoperiod were controlling development and growth, differences among treatments disappeared. Interaction of wheat development with soil temperature, air temperature, and daylength may contribute to the crop's inability to consistently capitalize, in terms of grain yield, on the greater amount of water stored in nontilled and mulched systems. Contribution from USDAARS in cooperation with the Agric. Res. Div., Univ. of Nebraska-Lincoln, Lincoln NE.Published as Paper no. 8610 Journal Series, Agric. Res. Div.