Submitted to: Journal of Theoretical and Applied Climatology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/28/1995
Publication Date: N/A
Interpretive Summary: Adoption of conservation tillage or no-till farming practices requires that the crop residue be left on the soil surface to protect the soil from water and wind erosion. There is a concern by many producers that crop residues will decrease the soil temperature and cause delayed planting and emergence of the crop in addition to other detrimental effects on the biological system. This study was conducted to evaluate the changes in the soil and air environment caused by the addition of crop residue. Studies were conducted on standing wheat residue in the High Plains of Texas compared to a bare soil field. Cotton was planted into both fields. Cotton within the standing residue grew faster and used less soil water than the cotton in the bare soil field. The standing residue created an environment that was less stressful to the cotton plant. This practice has potential of being a valuable management option in dryland agriculture. In the humid, temperate area of Iowa, corn residue left on the surface after harvest caused the soil temperatures to cool more slowly in the fall compared to both chisel-plow and moldboard plow. In the spring, the mean daily soil temperatures in the upper 20 cm of the soil were not affected by the presence of residue; however, the range of temperatures between the maximum and minimum were affected with the residue having the smallest diurnal range. Crop residues on the surface reduced the amount of water lost from the soil prior to planting and in springs with dry conditions, increased the amount of water available to the crop. Crop residues can be managed to change the soil and air environment around the crop in a positive way and promote conditions that are favorable to crop growth.
Technical Abstract: Residues from crops left on the soil surface have an impact on the microclimate within the soil and the atmosphere; however, the impact on the biological system is largely unknown. The effect of standing and flat residue in semi-arid and humid environments on the microclimate and plant response was evaluated at two locations. A study was conducted during 1987 and 1988 in a semi-arid climate at Lubbock, Texas, using wheat stubble to shelter cotton. In this study, soil water, microclimatic variables, and plant growth were measured within standing stubble and bare soil during the early vegetative growth period. Air temperatures were warmer at night within the standing residue and the air more humid throughout the day. This led to a reduction in the soil water evaporation rate and an increase in the water use efficiency of the cotton plant within the stubble. Studies on corn residue with continuous corn and corn-soybean rotations with no-till, chisel-plow, and moldboard plow tillage practices in central Iowa showed that the average soil temperatures in the upper soil profile were not affected by the presence of residue. The largest effect of the residue on soil temperature was in the fall after harvest when no-till fields cooled more slowly than tilled fields. In the spring, surface residue decreased the soil water evaporation rate and increased the soil water storage within the soil profile. The additional stored soil water due to the surface residue was used by the plant to maintain transpiration rates at optimal levels during the early vegetative growth period. Increasing our understanding of the physical environment and biological system interactions will lead to improved resource management.