Analyzing the Effectiveness of Cover Crops in Reducing Pollutant Loads in the Mississippi Alluvial Valley.

Surface water quality is a concern in the Mississippi Alluvial Valley (MAV). In this area of extensive row-crop production, sediment and nutrients, primarily from agricultural landscapes, are a primary pollutant of surface water resources. Within Mississippi, voluntary conservation efforts in the MAV are the central strategy utilized to assist agricultural producers with reducing soil and nutrient losses from fields and improving surface water quality. This study assessed the effects of one effort, cover crops, on total suspended solids (TSS), total nitrogen (TN), and total inorganic phosphorus (TIP) loads in runoff from corn-soybean rotation production systems. The goal of this study was to assess the effectiveness of cover crop implementation on working farms. Edge-of-field monitoring (EOFM) stations at 12 paired fields (6 sites) were used to measure TN, TIP, and TSS loads at the field scale for two years. Each site was separated and graded to drain surface flow to outflows where EOFM stations were positioned to sample runoff and record discharge data. At each paired study site, one field was managed in accordance with prior practices (routine tillage and fallow, non-growing season fields), and the other field was managed as a cover crop minimum tillage system. After two years (February 2018 – August 2019), preliminary data analyses indicate that winter cover cropping significantly reduced total suspended sediment (TSS: chi-squared = 6.3256, p = 0.0119), total nitrogen (TN: chi-squared = 4.0701, p = 0.04365), and total inorganic phosphorus (TIP: chi-squared = 5.2581, p = 0.02185) loads in runoff. This study supports the hypothesis that winter cover cropping is a useful tool to reduce nutrient and sediment loading to downstream waterbodies from agriculture in the study region, and despite beneficial findings relative to water quality, more research is warranted to optimize cover cropping systems to minimize yield losses and maximize economic feasibility.