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Big Sioux aquifer, nitrates, crops, eastern South Dakota


This report contains background data for a study on possible impacts of the 1996 Farm Bill ("Federal Agricultural Improvement and Reform Act of 1996") on crop system diversity. The study, being conducted by the Economics Department at South Dakota State University (SDSU), is focused on the 7-county area of eastern South Dakota shown in the map on the following page. This area constitutes a major portion of the Big Sioux River drainage area in South Dakota. The aquifer underlying the Big Sioux River in these counties provides drinking water for a significant portion of the State's population. Therefore, agricultural practices that potentially affect the river and underlying aquifer are of great interest to both farmers and the general public. Of special interest are practices that might affect nitrate leaching. Nitrate leaching can be impacted by the types of crops grown, how they are grown in rotation, and the types of tillage and fertilization practices used. This report contains information only on the crops grown in these seven counties, and how patterns have changed over the last half of the twentieth century. The narrative is limited to historical descriptions in this report. Analyses of the historical patterns and potential future changes as a result of new provisions in the 1996 Farm Bill will come in later reports. Information obtained in recently completed focus group meetings with farmers in two of the seven counties Codington and Moody--will contribute to those analyses. Changes in acreage of six major crops in the 7-county study area are shown in the figure on the following page. Five-year averages were used, to make trends more clear. Clearly, corn was the major crop in this region throughout much of the 45-year period running from 1950 to 1995. oats went from a major crop, with more acreage even than corn in the early 1950s, to a minor crop by the 1990s. Flax acreage also declined to negligible levels by the end of the period. The most dramatic increase was in soybean acreage, especially from the late 1970s onward. Wheat acreage increased some in the 1970s, and remained at higher levels than in the first half of the time period examined. Changes in hay acreage in this same 7-county area are shown in the figure on page 5. Hay acreage declined by over 40 percent between 1959 and 1992. We turn now to the crop system changes that have taken place over the last half of this century in the seven individual counties--Codington, Hamlin, Deuel, Brookings, Lake, Moody, and Minnehaha.


Economics Pamphlet 97-1