Environmental Implications of Conservation Management in Mid-Southern, Irrigated Corn.

Mid-Southern, USA row-crop production practices are depleting the region’s groundwater supply at an alarming rate. Additionally, row-crop agriculture is cited as a major contributor of nutrient and sediment to receiving surface waterbodies. Adapting management practices to employ cover crops or no-tillage may increase irrigation efficiencies and reduce nutrient and sediment contamination of downstream waters. The effects of cover crops and tillage system on infiltration and nutrient runoff under furrow irrigation were investigated at Stoneville, MS on a Commerce very fine sandy loam (fine-silty, mixed, superactive, nonacid, thermic Fluvaquentic Endoaquepts) from 2017 to 2019. From 2017 to 2018, no-tillage increased time to runoff inception under furrow irrigation by 133%, which resulted in a 24.8% decrease in runoff volume, while in 2019, an increase in time to runoff inception under no-tillage did not translate to reduced runoff. Cover crops did not reduce runoff relative to standard regional tillage and winter fallow. After two years, cover crops do not have a significant effect on solids and nutrient transport. Conversely, no-tillage can increase nutrient concentrations in runoff water, but may or may not increase nutrient loading. Sediment and nutrient results from 2019 will be presented as well.