IMPACTS OF CHANGING PRECIPITATION PATTERNS ON WATER QUALITY

Authors: Hatfield, Jerry; Prueger, John

Submitted to: Journal of Soil and Water Conservation Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2003
Publication Date: 1/15/2004
Citation: Hatfield, J.L., Prueger, J.H. 2004. Impacts of changing precipitation patterns on water quality. Journal of Soil and Water Conservation Society. 59(1):51-58.

Interpretive Summary: Change in the amount and timing of precipitation is one consequence of the changing climate in the upper Midwest. There is evidence that the increasing frequency and intensity of rainstorms could overwhelm the capacity of our current soil management practices to withstand these changes. We conducted a literature review of the effect of changing precipitation patterns on soil management and water quality from agricultural practices and found little information in the literature to help guide the development of new practices. Through a series of simulation studies we were able to show that both surface runoff and leaching through the soil profile will increase with the anticipated amounts of rainfall. To offset these increases will require more crop residue and less tillage be practiced on the land. Producers need to be aware that increasing rainfall amounts can have serious impacts on their soil and current management practices may not provide adequate protection against erosion. Development of improved soil management practices will be required to withstand the changes predicted in precipitation intensity and frequency, and will benefit crop producers and the environment.

Technical Abstract: Changing climate across the United States has been observed in the increasing intensity and amount of precipitation. One of the predicted areas for this impact is in the upper Midwest or the Corn Belt, and one concern is that current soil management practices in this region may not adequately protect the soil under these changes resulting in water quality impacts. To address this concern this study was conducted to survey the current literature on the water quality impacts from current soil management practices and evaluate potential impacts on runoff and drainage from soil management practices under a number of precipitation scenarios. Soil management practices, e.g., crop residue, no-till, incorporation of manure, provide protection under today's climate. However, increasing precipitation amounts or frequencies rapidly decrease the effectiveness of these practices with the deleterious effect being even greater on soils with low water holding capacity and limited depth. The water quality impacts may be even more dramatic with the likelihood of increased surface runoff events. Soil management practices need to be developed and evaluated under precipitation patterns that may represent future scenarios so that producers can begin to adopt these practices into their management programs.