Examining Short Term Drainage Impacts to Soil Health in Hydric and Non-Hydric Soils of Waseca County, Minnesota

Subsurface drainage is implemented throughout the Midwest United States to remove excess moisture from soil to enhance crop growth. Hydric soils are ubiquitous throughout Minnesota and are commonly drained due to their historically saturated conditions. Changing a soil's hydrology can impact its formation and properties. The alteration of physical, biological, and chemical soil properties can occur to both hydric and non-hydric soils, impacting overall soil health. The purpose of this study is to examine the short-term effects of tile drainage on the soil health of hydric and non-hydric soils in southern Minnesota. Research methods include: 1) collect soil-sediment cores to a depth of 1 m from hydric and non-hydric soils in recently tile drained and undrained agricultural fields; 2) quantify physical (i.e., gravimetric water content, bulk density, aggregate stability, particle size), biological (i.e., organic matter content), and chemical (i.e., magnetic susceptibility, pH, soluble salts, cation exchange capacity, nutrient concentrations) properties of cores in 10-cm intervals, and 3) perform statistical analyses to examine relationships among drainage, hydric status, and depth and their impact on soil health. Changes to physical and biological soil properties primarily followed expected patterns as drained soils had significantly lower moisture content and organic matter content (upper 30 cm only) and higher bulk density than undrained soils. Aggregate stability was not impacted by drainage but was significantly higher in hydric soils than non-hydric soils. Magnetic susceptibility was significantly higher in drained soils and non-hydric soils. Cation exchange capacity and calcium and copper concentrations were all significantly lower in drained soils, while copper and magnesium concentrations were higher in hydric soils. Additional chemical properties (i.e., pH, zinc, potassium, iron, and manganese) were significantly different due to drainage-hydric status interactions and when considering variations with depth. Subsurface drainage is extensively used across Minnesota due to the ubiquity of hydric soils, thus understanding the impacts to soil health is imperative for agricultural success and future soil conservation.