Spatially Variable Soil Salinity, Chemistry, and Physical Properties Affect Soil Health.

Soil chemical properties as related to salinity and soil health were investigated on a 65-ha agricultural field in southeastern North Dakota. The field historically has areas of low productivity as a result of salinity.  The salinity is a result of evaporative deposition of salts from the shallow groundwater and is influenced by micro-topography. Yield maps indicate that the areas of low yield correspond very closely to areas of high apparent electrical conductivity (EC_a) as mapped by Veris and EM38. Soil cores taken on a 58-m grid indicated higher calcium, sodium, magnesium, and sodium adsorption ratio (SAR) in the upper 30 cm in areas of high salinity.  The spatial extent of high concentrations of these ions increased with depth.  Soil physical properties were measured on a 174-m grid.  These data will be used to model unsaturated and saturated water flow.  Research is ongoing to investigate the effects of subsurface drainage on soil salinity in the area.