Water Quality Assessment of a Conservation Reserve Program near an Oxbow Lake in the Mississippi Delta: Case Study of Beasley Watershed

摘要

A case study of Beasley Lake Watershed, located in the Mississippi Delta region of the U.S. was used to evaluate runoff from edge-of-field sites with row crop management practices and Conservation Reserve Program (CRP) sites with trees. Approximatelyone-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 managed for soybean, cotton, or corn production. Sub-drainage areas (1.2 to 6 ha) with similar topographyand soil types were either cropped (three sites under reduced tillage crop) 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 sampleswere analyzed for sediments and nutrients. This paper reports on runoff, soil loss, and nutrient loss for each site. Establishing trees within areas adjacent to the oxbow lake reduced the concentration of sediments and nutrients leaving the watershed ascompared to reduced-till crop management techniques. The impact of converting the cropped area into trees has reduced the sediment load entering the lake by an order of magnitude, resulting in improved water quality in Beasley Lake.