Submitted to: Washington State University College of Agriculture and Home Economics
Publication Type: Experiment Station
Publication Acceptance Date: 2/15/2004
Publication Date: 4/1/2004
Citation: Kennedy, A. C. 2004. Soil quality of conservation tillage for wind erosion control. In: Washington State University Agricultural Research Reports. Pullman, WA. WSU Agricultural Research Station. p. 353-354. Interpretive Summary: (Background) Soil erosion from dryland farming in most regions of the United States exceeds the tolerable rate. Management practices that reduce disturbance may reduce this erosion. Understanding soil ecosystem changes with changing tillage practices will aid in developing strategies that minimize the impact of agriculture on the environment and foster the use of sustainable agricultural practices. (Description) Soil quality parameters were assessed at several long-term dryland cropping systems research sites in eastern Washington. The objective was to characterize soil quality changes over time as affected by no-till versus traditional tillage-based management systems. Soil organic carbon increased over time with long-term no-till. Changes in the microbial community and other soil quality parameters such as pH, electrical conductivity and microbial enzyme activity were variable in their response. Soil quality changes during the transition to no-till take longer and are more variable in the low precipitation zones. (Impact) Information from these long-term experiments will allow scientists and field people to better assess the health or quality of soils in the dryland cropping region of the Inland Pacific Northwest and aid farmers in developing management systems that reduce erosion, improve soil quality, and maintain productivity.
Technical Abstract: Soil quality parameters are being assessed at several sites to determine the health of a soil by defining management practices that are soil building rather than degrading. The objective of this research is to characterize biological, physical and chemical soil quality parameters and monitor their changes over time in minimum tillage and no-till seeding systems as affected by tillage, crop species and management systems. The goal is to identify soil quality parameters that can be used in the development of best management practices for conserving soil quality and enhancing crop production. We have found that soil quality changes during the transition to direct seed are less dramatic and more variable in the low precipitation zones (less than 12 inches annually) compared to the higher precipitation zones. In the early part of the transition period the amount of disturbance has greater immediate impact than surface residue management or crop rotation. Organic matter increases with long-term direct seed, although this increase may take many years to become apparent. We also continue to see that long-term direct seeding results in changes in microbial communities and an increase in fungi:bacteria ratios.