Simulated responses of soil organic carbon stock to tillage management scenarios in the Northwest Great Plains

Zhengxi Tan¹ , Shuguang Liu¹^,2 , Zhengpeng Li¹ and Thomas R Loveland³

¹SAIC, contractor to US Geological Survey (USGS) Center for Earth Resources Observation and Science, Sioux Falls, SD 57198, USA

²Geographic Information Science Center of Excellence, South Dakota State University, Brookings, SD 57007, USA

³US Geological Survey (USGS) Center for Earth Resources Observation and Science, Sioux Falls, SD 57198, USA

author email corresponding author email

Carbon Balance and Management 2007, 2:7doi:10.1186/1750-0680-2-7


Published:	24 July 2007

Abstract

Background

Tillage practices greatly affect carbon (C) stocks in agricultural soils. Quantification of the impacts of tillage on C stocks at a regional scale has been challenging because of the spatial heterogeneity of soil, climate, and management conditions. We evaluated the effects of tillage management on the dynamics of soil organic carbon (SOC) in croplands of the Northwest Great Plains ecoregion of the United States using the General Ensemble biogeochemical Modeling System (GEMS). Tillage management scenarios included actual tillage management (ATM), conventional tillage (CT), and no-till (NT).

Results

Model simulations show that the average amount of C (kg C ha^-1yr^-1) released from croplands between 1972 and 2000 was 246 with ATM, 261 with CT, and 210 with NT. The reduction in the rate of C emissions with conversion of CT to NT at the ecoregion scale is much smaller than those reported at plot scale and simulated for other regions. Results indicate that the response of SOC to tillage practices depends significantly on baseline SOC levels: the conversion of CT to NT had less influence on SOC stocks in soils having lower baseline SOC levels but would lead to higher potentials to mitigate C release from soils having higher baseline SOC levels.

Conclusion

For assessing the potential of agricultural soils to mitigate C emissions with conservation tillage practices, it is critical to consider both the crop rotations being used at a local scale and the composition of all cropping systems at a regional scale.