Chemical and Physical Characteristics of Saline Soils in Grand Forks county North Dakota

Saline soils reduce the productivity of over 80,000 hectares, or 23% of the land area, in Grand Forks County, an agricultural county in eastern North Dakota. A geochemical analysis was completed on soils from two salt-affected areas to determine if the salinity is depression-focused in saline spring areas and dominated by ground-water discharge, or landscape-wide and controlled by saline flushing and evapotranspiration. The areas chosen for study were an ephemerally wet, cultivated farm field and Kellys Slough, a perennial wetland. Two soil borings were completed at each site with samples taken in 15-cm increments to a depth of approximately 1 m. Samples were analyzed using laboratory procedures advocated by the National Soil Survey Center including reaction to dilute HCl, pH, particle-size analysis, carbonate and gypsum content, electrical conductivity, and soluble cations and anions. The results of the geochemical analyses indicate that soils from the farm site and Kellys Slough are quite different. pH values were mildly to moderately alkaline with the most alkaline soils at the farm. The slough soils appeared to have a higher clay content than the farm soils. Concentrations of carbonate generally increased with depth at the slough and were concentrated in the upper horizons at the farm. The slough soils were more saline than the farm soils. Sodium and chloride were the dominant ions in the slough soils, and calcium and sulfate dominated the farm soils suggesting that different salinization processes are taking place at the two sites; the salinity at the slough appears to be depression-focused and dominated by ground-water discharge while the salinity at the farm site appears to be controlled by precipitation and evapotranspiration