Submitted to: Journal International Environmental Application and Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/21/2010
Publication Date: 11/2/2010
Citation: Cullum, R.F., Locke, M.A., Knight, S.S. 2010. Effects of conservation reserve program on runoff and lake water quality in an oxbow lake watershed. Journal International Environmental Application and Science. 5:318-328. Interpretive Summary: Sediment and its associated pollutants entering a water body can be destructive to the ecological health of the system. Water quality from best management practices at Beasley Lake watershed was evaluated to determine if the recommended farming practices were reducing pollutants entering Beasley Lake. Water quality at drain outlets from fields either in conservation tillage soybeans or in fields planted to trees was compared. Establishing trees within CRP adjacent to the oxbow lake reduced the concentration of sediments and nutrients leaving the watershed as compared to reduced-till crop management techniques. The reduced-till crop management practice resulted in average annual soil loss of 2.1 t/a soil loss, lower than the NRCS tolerance limit of 3 t/a. The impact of converting one third of the cropped area of Beasley watershed into trees reduced the sediment load leaving the watershed ten times lower than that from the cropped area, resulting in improved water quality in Beasley Lake.
Technical Abstract: Sediment and its associated pollutants entering a water body can be destructive to the ecological health of the system. Best Management Practices (BMPs) can be used to reduce these pollutants, but understanding the most effective practices is difficult. A case study of Beasley Lake Watershed, typical of topography and cropping systems in the Mississippi Delta region of the United States, was used to research activities that included continued monitoring of lake water quality, evaluating runoff from edge-of-field sites with various row crop management practices, and quantifying effects of areas in the watershed that have shifted to forest (Conservation Reserve Program or CRP). Approximately one-third of the Beasley Lake watershed (ca. 280 ha) was converted from cropped land to CRP beginning in 2003, and the remainder of the cropland is still managed for soybean, cotton, or corn production. Sub-drainage areas (1.2 to 6 ha) with similar topography and soil types were either cropped (three sites under reduced tillage crop production) or placed in CRP (three CRP sites) and were instrumented in 2005 to collect water samples from field drainage slotted-inlet pipes during all surface runoff events. Runoff samples were analyzed for sediments and nutrients. This paper reports on runoff, soil loss, and nutrient loss for each site. Reducing soil loss and nutrient loads in runoff from edge of field through the use of best management practices results in lower sediments and agrichemicals entering Beasley Lake. Establishing trees within CRP adjacent to the oxbow lake reduced the concentration of sediments and nutrients leaving the watershed as compared to reduced-till crop management techniques. The impact of converting one third of the cropped area into trees has reduced the sediment load leaving the watershed by an order of magnitude, resulting in improved water quality in Beasley Lake.