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Biogeosciences An interactive open-access journal of the European Geosciences Union
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Volume 14, issue 13 | Copyright
Biogeosciences, 14, 3253-3274, 2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Research article 10 Jul 2017

Research article | 10 Jul 2017

Modification of the RothC model to simulate soil C mineralization of exogenous organic matter

Claudio Mondini1, Maria Luz Cayuela2, Tania Sinicco1, Flavio Fornasier1, Antonia Galvez3, and Miguel Angel Sánchez-Monedero2 Claudio Mondini et al.
  • 1Consiglio per la Ricerca in Agricoltura e l'Analisi dell'Economia Agraria (CREA), Branch Office of Gorizia, Via Trieste 23, 34170 Gorizia, Italy
  • 2Centro de Edafología y Biología Aplicada del Segura (CEBAS-CSIC), Department of Soil and Water Conservation and Waste Management, Campus Universitario de Espinardo, Apartado de Correos 164, 30100 Espinardo, Murcia, Spain
  • 3Instituto Andaluz de Ciencias de la Tierra (CSIC-UGR), Avenida de las Palmeras 4, 18100 Armilla, Granada, Spain

Abstract. The development of soil organic C (SOC) models capable of producing accurate predictions for the long-term decomposition of exogenous organic matter (EOM) in soils is important for the effective management of organic amendments. However, reliable C modeling in amended soils requires specific optimization of current C models to take into account the high variability in EOM origin and properties. The aim of this work was to improve the prediction of C mineralization rates in amended soils by modifying the RothC model to encompass a better description of EOM quality.

The standard RothC model, involving C input to the soil only as decomposable (DPM) or resistant (RPM) organic material, was modified by introducing additional pools of decomposable (DEOM), resistant (REOM) and humified (HEOM) EOM. The partitioning factors and decomposition rates of the additional EOM pools were estimated by model fitting to the respiratory curves of amended soils. For this task, 30 EOMs from 8 contrasting groups (compost, anaerobic digestates, sewage sludge, agro-industrial waste, crop residues, bioenergy by-products, animal residues and meat and bone meals) were added to 10 soils and incubated under different conditions.

The modified RothC model was fitted to C mineralization curves in amended soils with great accuracy (mean correlation coefficient 0.995). In contrast to the standard model, the EOM-optimized RothC was able to better accommodate the large variability in EOM source and composition, as indicated by the decrease in the root mean square error of the simulations for different EOMs (from 29.9 to 3.7% and 20.0 to 2.5% for soils amended with bioethanol residue and household waste compost, respectively). The average decomposition rates for DEOM and REOM pools were 89 and 0.4yr−1, higher than the standard model coefficients for DPM (10yr−1) and RPM (0.3yr−1).

The results indicate that the explicit treatment of EOM heterogeneity enhances the model ability to describe amendment decomposition under laboratory conditions and provides useful information to improve C modeling on the effects of different EOM on C dynamics in agricultural soils.

Future research will involve the validation of the modified model with field data and its application in the long-term simulation of SOC patterns in amended soil at regional scales under climate change.

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Current soil C models do not adequately describe the quality of the amendments added to fields. In this study, we propose a modification of the soil C model "RothC" that was found to be effective in simulating the response of laboratory-incubated soils treated with contrasting amendments. We think that these findings could help to develop better soil C models and improve predictions of the effects of different amendments on soil organic matter dynamics on agricultural and managed land.
Current soil C models do not adequately describe the quality of the amendments added to fields....