Estimation of soil organic carbon in Colombia, a territory management tool

Abstract

Soil performs base functions that provide valuable ecosystem services, such as carbon sequestration. In land planning management framework, it is important to have reliable and representative national information to manage the quality and health of the soil in the country. This study aimed to establish the content and distribution of soil organic carbon (COS) up to 30 cm in Colombia, with a spatial resolution of 1 km, using digital mapping techniques. The main motivation was to document the contribution of Colombia to the global COS of the FAO. Information from 4329 soil profiles of 32 departments collected between 1970 and 2012 was used. These data were related to information of 140 covariates that describe soilforming factor (climate, topography, land cover and use, soil type, parent material). Predictive spatial modeling was performed with Regression Kriging and evaluated by cross-validation and expert knowledge. Fitted model residuals were interpolated to obtain the prediction uncertainty map. The results were compared with pre-existing similar products with higher spatial resolution (SoilGrids 250m), obtaining that the fitted model represents the variability of COS with greater accuracy (r2=0.49 and RMSE=0.71). Climate is the factor that explained the behavior of the variable to a greater extent. The product was validated by national experts and it is sought that this input be considered as a support for decision-making in the management of the lands and thus strengthen the country's commitments in land degradation and climate change.