Evaluation of the IPCC Tool for predicting soil organic carbon changes in Pampean soils of Argentina

G. BERHONGARAY Y R. ÁLVAREZ; R. ALVAREZ

AGRICULTURE, ECOSYSTEMS AND ENVIRONMENT

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2013 vol. 181 p. 241 - 245

0167-8809

The Intergovernmental Panel on Climate Change (IPCC) has developed a methodology for predicting soil organic carbon (SOC) stocks and changes known as the IPCC Tool. We tested the potential use of this tool in soils of the Pampean Region of Argentina by comparing its predictions with results from a soil survey performed on 82 farms widely distributed over the region.  Uncultivated fields as well as agricultural soils, both under the crop or the pasture phase of a mixed rotation, were sampled. Using the default parameters, the IPCC Tool could not predict SOC stocks of uncultivated fields with an acceptable performance (R2= 0.249 RMSE= 27.7 t ha-1 = 48.5% of the mean SOC stock). On average, the methodology estimated SOC decreases by cultivation of 21%, but measured SOC changes were 10-14%. We therefore propose that default parameters values should be calibrated using local data. Using measured SOC stocks from uncultivated fields as reference values and locally calibrated parameters, led to an improvement in the estimation of land use change effect on SOC, but the fitting to observed results was still poor (R2= 0.403, RMSE= 14.9 t ha-1 = 31 % of the mean SOC stock). Possible causes of this failure of the methodology to capture land use change effects on SOC are discussed, as well as the performance attained by other methodologies for estimating SOC in the Pampas.