A comparison of the performance of nine soil organic matter models using datasets from seven long-term experiments

Nine soil organic models were evaluated using twelve datasets from seven long-term experiments. Datasets represented three different land-uses (grassland, arable cropping and woodland) and a range of climatic conditions within the temperate region. Different treatments (inorganic fertilizer, organic manures and different rotations) at the same site allowed the effects of differing * Corresponding author. Tel,: +44 1582-763133 ext. 2110; Fax: +44 1582-760 981; E-maih [email protected] 0016-7061/97/$17.00 © 1997 Elsevier Science B.V. All rights reserved. PII SO01 6 7 0 6 1 ( 9 7 ) 0 0 0 8 7 6 154 P. Smith et al. / Geoderma 81 (1997) 153-225 land management to be explored. Model simulations were evaluated against the measured data and the performance of the models was compared both qualitatively and quantitatively. Not all models were able to simulate all datasets; only four attempted all. No one model performed better than all others across all datasets. The performance of each model in simulating each dataset is discussed. A comparison of the overall performance of models across all datasets reveals that the model errors of one group of models (RothC, CANDY, DNDC, CENTURY, DAISY and NCSOIL) did not differ significantly from each other. Another group (SOMM, ITE and Verberne) did not differ significantly from each other but showed significantly larger model errors than did models in the first group. Possible reasons for differences in model performance are discussed in detail. © 1997 Elsevier Science B.V. Kevwords: soil organic matter; model; soil organic matter model; model evaluation; model comparison; long-term experiment; datasets; soil organic carbon