Corn Residue Age and Placement Effects on Evaporation and Soil Thermal Regime

Abstract

AbstractDifferentiation between tillage‐ and residue‐induced effects on soil moisture and thermal regimes is necessary to improve residue management practices. The objective of this research was to quantify the influence of corn (Zea mays L.) residue age and placement on evaporation from and heat flow in two soils. Soil temperature, thermal conductivity, heat flux, and moisture content were monitored in duplicate monoliths (0.45 [length] by 0.35 [width] by 0.5 [height] m) of Nicollet loam (fine‐loamy, mixed, mesic Aquic Hapludoll) and Monona silt loam (fine‐loamy, mixed, mesic Typic Hapludoll) in a controlled environment chamber. Mass changes of one monolith of each soil were measured with load cells to estimate evaporation. Surface cover types consisted of a bare soil surface (B), fresh residue (F), weathered residue (W), and weathered residue with a 0.15‐m‐wide bare strip (S). Bare‐soil evaporation averaged 9.97 ± 0.66 mm for both soils during a 96‐h period and was reduced to an average of 5.76 ± 0.70 mm with residue cover. Nicollet soil with weathered residue had an average evaporation rate of 1.33 to 1.4 mm d−1. By comparison, evaporation rates measured in a field having Nicollet and associated soils with weathered corn residue averaged 1.37 and 1.11 mm d−1. Residue cover had no significant effect on thermal conductivity measured at 0.15 m that averaged 1.22 and 1.35 W m−1 K−1 for the Nicollet and Monona soils, respectively. Phase shift in soil temperature and average daily conductive soil heat flux were similar for field and chamber measurements but the amplitude of the soil temperature wave and conductive soil heat flux were much greater in the field.