Multi-site validation of a soil organic matter model for arable fields based on generally available input data

Abstract

The paper describes a simplified carbon balance model, derived from the CANDY model, which works in annual time steps requiring only clay content, soil type of the German classification system “Reichsbodenschätzung”, average air temperature and rainfall as site characteristics, a value for organic carbon content as the initial value as well as crop yield and organic matter amendments as management data. The Candy Carbon Balance (CCB) model has been validated using a dataset from 40 long-term experiments situated in Central Europe including 391 treatments with a total number of 4794 C org observations. Statistical measures to prove model validity were mean error (ME = − 0.001) and root mean square error (RMSE = 0.119). In addition a number of tests were performed to make sure that the model has no systematic error for different types of site conditions and management activities. After this successful validation the CCB model is considered applicable for advisory service for arable fields on a wide range of site conditions. Due to the poor representation of clay soils in this study some more model tests on these soils would be recommendable.