Temporal Dynamics of Microbial Communities during Natural Wetting and Drying Cycles of Select Reduced Tillage Systems.

In the Upper Great Plains region, cold soils impede early germination for corn and soybean systems creating a natural short growing season. Before planting, farmers typically utilize intensive tillage to aerate/warm the soil for earlier planting and germination. Although tillage may extend the growing season, intensive tillage practices can be detrimental to soil health. Currently, new reduced tillage systems are being implemented to both extend growing season while minimizing the adverse effects of intensive tillage on soil health. This on-farm study aims to evaluate the temporal dynamics of various reduced tillage practices on soil biology (microbial community and activity) coupled with soil physical conditions [moisture (θ), temperature, (T), and penetration resistance] within the growing season of northern corn-soybean rotations with particular emphasis on natural soil wetting and drying cycles. Tillage systems in this study include vertical till (VT), strip till with shanks (ST-S), strip till with coulters (ST-C), and chisel plowed (CP). Tillage plots (12 x 550m per plot) were installed at three producer farms in North Dakota and Minnesota using randomized complete block designs with three replicates at each farm. Soils textures among the farms ranged from sandy loams to silty clays. Phospholipid Fatty Acid Analysis (PLFA) and enzyme assays were used to determine soil microbial community structures and activity on weekly obtained soil samples; whereas, soil T and θ was monitored at 30-minute intervals throughout the growing seasons at 5, 10, 25, and 40 cm depths. Results from the 2017 crop growing season will be presented.