Surface runoff in Beasley Lake watershed: Effect of land management practices in a Lower Mississippi River Basin watershed

Abstract

Several United States Department of Agriculture (USDA) conservation programs are promoting conversion of cropland to nonagricultural use, e.g., buffer establishment for wildlife habitat and Conservation Reserve Program (CRP). These areas set aside for nonagricultural use may serve as barriers to mitigate runoff within a watershed where agricultural activities are conducted. CRP and wildlife buffer areas were established in Beasley Lake watershed (BLW), Sunflower County, Mississippi, United States, in 2003 and 2006, respectively. The objectives of this study were to assess catchment runoff and runoff water quality through both measured data and model simulations from three scenarios of land management in BLW from 2011 to 2017: row crop with no edge-of-field buffer (Crop), row crop fields adjacent to wildlife buffers (CropBuff), and CRP. Measured data were collected at the field-scale from nine subcatchments. Median runoff from Crop sites was greater than that from CRP catchments (123 m³ ha⁻¹ versus 39 m³ ha⁻¹ across seasons and years). Median loads of suspended solid loads in runoff averaged 108 kg ha⁻¹ for Crop compared to 42 kg ha⁻¹ in CropBuff areas (across seasons and years). Similar trends were observed for median total Kjeldahl nitrogen (TKN) and total phosphorus (TP) loads in runoff: TKN 0.26, 0.18, and 0.07 kg ha⁻¹; and TP 0.06, 0.06, and 0.02 kg ha⁻¹ for Crop, CropBuff, and CRP, respectively. For both CRP and CropBuff, the proportion of soluble/fine particle (<0.45 μm) TKN and TP lost in runoff was greater than that of particulate-bound TKN and TP from Crop. Overall, efficacy in mitigating runoff losses were generally in the order of CRP, CropBuff, and Crop. In addition to field measurements, watershed simulations were conducted with and without the practices using Annualized Agricultural Non-Point Source (AnnAGNPS) pollution model. AnnAGNPS simulations independently confirm the measured results and account for differences in soil types among the different land use practices that could influence measured results. These results demonstrated that wildlife buffers and CRP conservation practices helped to improve and maintain environmental quality of soil and water resources in BLW.