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Impact of Conservation Practices at the Field-scale on Sediment Loss and Water Quality in Row Crop Agriculture in the Lower Mississippi River Basin
Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org
Citation: Soil Erosion Research Under a Changing Climate, January 8-13, 2023, Aguadilla, Puerto Rico, USA .(doi:10.13031/soil.23025)Authors: Michele L Reba, Niroj Aryal, Tina Gray Teague, Geoffrey Payne
Keywords: Erosion, Field-scale, Mid-South, Water quality
Abstract
Sediment has been identified as the most prevalent source of agricultural water quality impairment. With farm-scale knowledge of how production practices affect sediment loss, land managers and agricultural producers can make more informed decisions on implementing conservation practices that sustain productivity and protect resources. The Lower Mississippi River Basin is a major agricultural production region for rice, cotton, and soybeans; however, there is limited knowledge on how agronomic practices in these southern cropping systems affect water quality. To expand understanding of runoff water quality at the field scale, edge-of-field water quality monitoring studies were carried out in commercial rice, cotton, and soybean fields in northeast Arkansas over multiple years (Figure 1).
Year-round monitoring from 2014 through 2019 resulted in 40 site-years of measurements of sediment concentrations and loads with various soils and crop rotation regimes. Crop rotations included rice-soybeans, corn-soybeans, and cotton. Discharge from runoff and suspended sediment concentrations on a per-event basis were measured. During the crop production season, field notes and automated images were analyzed to determine if runoff was generated from either irrigation water or precipitation. The results indicate that the non-growing season loads and concentrations of sediment were statistically greater than those measured during the growing season, lending support to the need for off-season practices such as winter cover crops and shallow winter water storage. Lower concentrations and loads of sediment were observed in rice fields compared to cotton and soybean systems. These differences are likely due to soil type but are also related to the water management system of flooded rice fields compared to furrow irrigated row-crops. These findings provide baseline runoff water quality data and will help inform regional budgets of sediment loss. Such information can assist land managers and conservationists in directing resources more effectively. These data also will support modelers in their efforts to calibrate, verify, validate, and estimate uncertainty for simulations of sediment loss.
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