Determination of Total Carbon Budget and Impact Assessment of Different Seasonal Drought on the Rangeland Soil Carbon.

Determination of Total Carbon Budget and Impact Assessment of Different Seasonal Drought on the Rangeland Soil Carbon. D.R. Joshi1, D. Clay1, A. Smart2 and S. Clay1 1Department of Plant Science, South Dakota State University, Brookings, SD, USA 2Department of Natural Resource Management, South Dakota State University, Brookings, SD, USA Soil is a reservoir containing three quarters of the Earth’s terrestrial carbon that helps to maintain and regulate the level of global carbon. Small changes in environmental factors, such as drought, might have high potential to return carbon dioxide (CO2)), a greenhouse gas, to the atmosphere. Our research objective was to determine the impact of grassland drought treatments on total carbon budget that will be determined using nonisotopic and isotopic approaches. The study sites were Highmore, Murdo and Chaimberlain and the treatments were: 1) spring one year drought (50% of rainfall), 2) spring two year drought, 3) summer one year drought, 4) summer two year drought, 5) ambient, and 6) control no drought. Rainout shelters were used to simulate the different seasonal drought and soil samples were collected are being taken at depths of 0-15, 15-30, and 30-45 centimeter at the beginning and at the end of each drought period, and 324 litter bags were installed to quantify decomposition rates. Initial research showed that the high productive site had more biomass production and soil organic C levels than the low productive site in the entire study site. This study will provide insight into the effects of drought on carbon cycling in grassland soils.