Corn and Soybean Responses to Soil Salinity Gradients in Richland County, North Dakota.

The purpose of this research was to determine the effects of soil salinity on corn and soybean growth and development. Bioindicators of growth and development for each crop were measured across natural variation in salinity on six quarters (65 ha) in Richland County, North Dakota (three corn and three soybean). Apparent electrical conductivity (ECa) for each field was collected using a geo-referenced EM-38 instrument, with data being used as a proxy for soil salinity. Five transects within each field were then established across identified salinity gradients. Plant height, leaf area index (LAI), nitrogen content, root biomass and length, and crop yield were measured at four pre-determined locations along each transect. Post-harvest, the EM-38 measurements were calibrated using a 1:1 soil to water electrical conductivity analysis on four composite soil samples collected at the four pre-determined locations along each transect where crop parameters were measured. Samples were collected from six depths: 0-15 cm, 15-30 cm, 30-60 cm, 60-90 cm, 90-120 cm, and 120-150 cm. Crop parameters were analysed using an ANOVA to determine if significant differences in these variables exist at varying salinity ranges. Crop yield response to salinity was analysed using a non-linear regression model. This curve is intended to establish thresholds for crop growth and development as a function of soil salinity specific to North Dakota soils.