Residue Management Effects on Soil Temperature
- Paul W. Unger
Soil temperatures are influenced by many factors, including surface residues. In turn, soil temperatures influence such factors as seed germination, plant growth, nutrient availability, insect populations, and pesticide degradation. Because of the increased use of conservation tillage involving surface residues, a better understanding of residue management effects on soil temperatures is needed. The objective of this study was to determine the effects of residue management practices on soil surface temperatures and on soil surface-air temperature relationships for the southern Great Plains. Soil surface and air (at 2-m height) temperatures were measured during the fallow period after winter wheat (Triticum aestivum L.) harvests in 1982 and 1983. Residue management treatments were disk, sweep, and no-tillage (with standing or shredded residues). Minimum surface temperatures differed only slightly among treatments at different seasons of the fallow period (summer, fall, winter, spring). Maximum temperatures were highest with no-tillage (standing residues) after dryland wheat in all periods, except in winter when they were highest with no-tillage with shredded residues. Relationships between soil surface and air temperatures were highly significant (R2 = 0.931, P ≥ 0.001). The relationships developed from the 1983 to 1984 data were used to predict surface temperature from weather station air temperatures for the 1982 to 1983 period. Differences between observed and predicted mean temperatures were significant only for no-tillage with standing residues in summer and fall and with shredded residues in spring. Normalized soil surface temperatures were affected more by season of the year than by residue management treatment.
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