Soil Health Initiatives Impact on Water Conservation.

Controlling off-site transport of non-point source pollutants from agricultural fields is critical to maintaining and improving surface water quality.  On-farm management practices that promote soil health, such as reducing tillage and introducing cover crops, have shown potential to control non-point source pollution.  Benefits from these practices may be multiplied on soils prone to surface crusting, where runoff and agrochemical volumes are increased exponentially.  Our study seeks to determine the effect of varying tillage and cover crop practices on irrigation runoff volume and off-site transport of sediment and agrochemicals in the Mississippi Delta under continuous soybean (Glycine max (L.)) production.  Treatments include conventional tillage without cover crop (CT/NC), reduced tillage without cover crop (RT/NC), reduced tillage with sub-soiling and no cover crop (RT/SS), reduced tillage with cereal rye (Secale cereale L.) cover crop (RT/RC), reduced tillage with tillage radish (Raphanus sativus L.) cover crop (RT/TR), zone tillage without cover crop (ZT/NC), and zone tillage with tillage radish cover crop (ZT/TR).  Reduced tillage/sub-soil, RT/TR, and ZT/TR treatments were added in the second year of the trial.  Experimental units (8.13-m wide by 153-m long) were separated by 3-m wide levees, planted with soybean at 345,935 seeds ha^-1, and instrumented to mass balance off-site transport of water, sediment, and agrochemicals.  Year one results indicate ZT/NC and RT/RC reduced cumulative sediment losses by at least 66% relative to CT/NC and RT/NC.  Relative to CT, only ZT/NC reduced total Kjeldahl N transport, while Total P decreased in the order of RT/NC (0.07 kg ha^-1) > RT/RC (0.04 kg ha^-1) = CT/NC (0.03 kg ha^-1) = ZT/NC (0.02 kg ha^-1).  Second year results and multi-year trends will be discussed at length.