Impact of Conservation Production Practices on Soil Moisture Availability in Alluvial Soils

Authors: Sassenrath, Gretchen; Fisher, Daniel; Williford, Julius

Submitted to: Southern Conservation Tillage for Sustainable Agriculture Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 7/5/2008
Publication Date: 8/5/2008
Citation: Sassenrath, G.F., Fisher, D.K., Williford, J.R. 2008. Impact of Conservation Production Practices on Soil Moisture Availability in Alluvial Soils. Southern Conservation Tillage for Sustainable Agriculture Proceedings. http://www.ag.auburn.edu/auxiliary/nsdl/scasc/Proceedings/2008/Sassenrath.pdf

Interpretive Summary: Conservation production practices, including reduced tillage and incorporation of cover crops, may benefit farmers by improving crop yield and enhancing profitability by reducing input costs, especially of fuel and fertilizer. Improvements have been shown in sandy soils with use of conservation management. However, heavier clay soils, such as those in the Mississippi Delta, are more difficult to physically manage due to high soil moisture levels, especially during the spring planting. These high moisture levels lower soil temperatures, limit access to the field, and can reduce plant stand establishment. In order to adapt conservation practices for the highly variable alluvial soils, we need to develop methods for timely residue management and good plant stand establishment. We found an only slight improvement in soil quality, as measured by the Soil Conditioning Index, after three years of conservation management. This improvement would result in only a small conservation payment to the farmer. Cotton yield was also only increased after the third year of the study. Retention of moisture in the soil during a wet spring made planting difficult and reduced the plant stand.

Technical Abstract: Conservation production practices have been shown to improve soil quality, and may increase crop yield and quality. Reductions in tillage and incorporation of cover crops have the potential to improve soil nutrients and water availability, reducing the need for supplemental irrigation. Traditional high-intensity tillage methods are frequently used in the Mississippi Delta. While the region enjoys high rainfall, increasing use of ground water for crop irrigation has begun to deplete the alluvial aquifer. We are interested in exploring the potential of conservation production practices to increase economic returns, in part by reducing fuel costs, and conserve ground water resources. Two critical issues are timely residue management and good germination of the cash crop. Conservation methods are compromised by early season rains that limit access to fields, increase soil water-logging, and decrease soil temperatures. This research was undertaken to examine differences in soil nutrients and water availability following different tillage practices and with incorporation of winter wheat cover crops into cotton production. We measured changes in cotton fiber quality and yield under different management practices. Improvements in soil quality, as determined by the Soil Conditioning Index, were minimal even after three years of conservation management. Increased yields of the cotton crop were observed only in the third year of the study. Adapting conservation practices for alluvial soils requires ingenuity in addressing early-season soil moisture levels that limit seed bed preparation, planting, and germination. Failure to establish a good plant stand reduces yield of the cash crop. Incentive payments made to farmers to encourage implementation of conservation production practices need to be examined for applicability to Delta soils and environment.