Tillage Impact On Carbon and Nutrient Dynamics within an Organic Transition, Sod-Based Vegetable Rotation.

Increased soil quality is one of the goals of sustainable organic farming. Greater soil organic C enhances soil physical, biological, and chemical properties which are important aspects of a sustainable system. Both, sod-based rotations and organic production lead to greater soil quality, but combined systems have not been well-documented.  Using conservation tillage within an organic system may provide increased benefits compared to frequent conventional tillage, which is often used for weed control in the southern U.S., but it decreases soil organic matter. This study integrates a sod-based rotation into organic vegetable production and compares intensive versus conservation tillage.  One objective was to determine the impact of treatments on soil C, N, and P dynamics. Treatments included 0, 1, 2, 3, and 4 years of a bahiagrass sod before using it in the crop rotation, under conventional versus strip-tillage. The rotation included two cash crops, green beans and broccoli, and two green manure cover crops, an oat/rye blend and soybeans. After being in rotation for one year, no differences were found in C mineralization rates between tillage treatments. However, after the system was in bahiagrass for 2 years, C mineralization doubled after one year of crop rotation, which indicates an increase in bioavailable nutrients.