Comparative Evaluation of Turfgrass and Row Crop Management on Soil Carbon Dynamics and Nutrient Availability.

Natural and agricultural landscapes have undergone significant land use changes due to global urbanization. In last two decades, urban lands grew over 34% in the United States and is projected to increase by 79% by 2025. Residential lawns are dominant in urban systems, which require intensive management and provide a suite of environmental benefits. Changes in soil properties among natural, row crop, and permanent turfgrass have not been comprehensively reported despite the potentially significant soil-mediated environmental impacts caused by such changes. Our objective was to evaluate the effects of C3 and C4 turfgrasses on soil properties, in comparison with managed row crop systems and an undisturbed secondary forest system. Soil samples were collected from the existing research plots at the East Tennessee Research and Education Center in Knoxville, TN during March 2017, from 0-5, 5-15, and 15-30 cm depths from five cropping systems: (i) bermudagrass, (ii) Kentucky bluegrass, (iii) tall fescue, (iv) corn-soybean rotation, and (v) continuous soybean. All turfgrass species were established 5-6 years ago, and are managed uniformly similar to low input residential lawns (mowed at 2.5 to 3-inch height weekly, added 196 kg N ha^-1). Agricultural lands have been under production for 20 to 25 years. Soil properties measured included bulk density, gravimetric moisture content, soil pH, dissolved organic carbon, total organic carbon, total nitrogen, soil inorganic nitrogen, extractable phosphorus and extractable potassium. Results showed that turfgrass systems had higher dissolved organic carbon, total organic carbon and inorganic nitrogen than the corn and soybean systems and this trend was similar for all depths. Bulk density was the highest in bermuda grass plots for the top two depths. This study implies that turfgrass management results in higher soil carbon and nutrient status as compared to the row crop systems.