Modeling Soil Organic Carbon Levels in Select Eastern South Dakota Soils.

Soil Organic Matter (SOM) is composed of living biomass, dead plant and animal residues, and humus. Humus is a complex, organic molecule that is largely responsible for improving soil water holding capacity, nutrient mineralization, nutrient storage, and other critical soil functions. Soil Organic Carbon (SOC) accounts for 50 to 60 percent of SOM. SOC is recognized as a strong indicator of soil health. Land use changes and intense cultivation of arable soils in the United States over the past century have led to large decreases in SOM. The primary objective of this research was to develop a linear regression model to predict SOC levels in select Eastern South Dakota soils. Native unplowed prairie, no-till, and conventional tillage management systems were studied within South Dakota Major Land Resource Area 102B, 102C, and McCook County. Soils were matched at each location by identifying the same soil type on each management system. Six different soil series were studied across eight locations. Samples were collected at 0-10cm, 10-20cm, and 20-40cm. Variables studied include aggregate stability at the surface, texture, color, pH, electrical conductivity, SOC, total nitrogen, and soil classification. Differences in SOC levels associated with different tillage systems and selected soil properties were noted and will be presented.