Conservation Tillage and Rye (Secale cereale) Cover Crop Impacts on Runoff and Transport of Sediment and Nutrients in Irrigated Soybeans of the Mid-South.

            Efficient irrigation of the Mid-South's most productive silt loam soils is hampered by surface sealing, characterized by the development of a thin, dense crust on the soil surface.  These soils typically seal shortly after initiation of irrigation events, resulting in irrigation application efficiencies of approximately 36%.  Many chemical and cultural practices have been proposed to increase infiltration rates and, consequently irrigation application efficiency.  Our study seeks to determine the effects of varying tillage practices, and tillage combined with a rye (Secale cereale L.) cover crop on irrigation application efficiency, runoff, and sediment, nutrient and agrochemical transport in the Mississippi River Delta, under continuous soybean production.  Treatments include conventional spring tillage without cover crop as a control, fall tillage without cover crop, fall tillage with rye cover crop, and minimum tillage-irrigation tillage without cover crop.  Plots are 153-m long by 8-m wide and separated by levees.  Asgrow 4632 soybeans were planted twin row on 1.02-m beds with a seeding rate of 345,940 seeds ha^-1.  All irrigation events are metered onto plots, and each plot is equipped with flowmeters and autosamplers on the downslope end to measure runoff and collect water quality samples.  Results including irrigation application efficiency, sediment transport, nutrient transport, yield and economic return will be discussed at length.