Publication Date:
2017-01-31
Description:
The development of soil organic C (SOC) models capable to produce accurate predictions of the long term decomposition of exogenous organic matter (EOM) in soils is important for an effective management of organic amendments. However, reliable C modelling in amended soils requires specific optimization of current C models to take into account the high variability of 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 respiratory curves of amended soils. For this task, 30 EOMs from 8 contrasting groups (compost, anaerobic digestates, sewage sludges, agro-industrial wastes, crop residues, bioenergy by-products, animal residues, meat and bone meals), were added to 10 soils and incubated under different conditions. The modified Roth C model was fitted to C mineralization curves in amended soils with great accuracy (mean correlation coefficient: 0.995). Differently 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 squared error of the simulations for different EOMs (from 29.9 % to 3.7 % and from 20.0 % to 2.5 % for bioethanol residue and household waste compost amended soils, respectively). Average decomposition rates for DEOM and REOM pools were 89 y−1 and 0.4 y−1, higher than the standard model coefficients for DPM (10 y−1) and RPM (0.3 y−1). Results indicate that explicit treatment of EOM heterogeneity enhances the model ability to describe amendment decomposition under laboratory conditions and provides useful information to improve C modelling on the effects of different EOM on C dynamics in agricultural soils. Future researches involve the validation of the modified model with field data and its application to long term simulation of SOC patterns in amended soil at regional scale under climate change.
Print ISSN:
1810-6277
Electronic ISSN:
1810-6285
Topics:
Biology
,
Geosciences
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