Parametrization consequences of constraining soil organic matter models by total carbon and radiocarbon using long-term field data

Summary

This study examined how incorporating radiocarbon age information alongside total carbon measurements reduces parameter uncertainty in soil organic carbon decomposition models. Using 60+ years of data from the Zürich Organic Fertilization Experiment, researchers tested five model structures of increasing complexity, finding that the weighting assigned to SOC versus ¹⁴C data streams critically determines kinetic parameter estimates and model outcomes. The findings suggest that dual-constraint approaches using both carbon pools should be standard in future SOC modelling efforts to better account for the multiple timescales and pathways of carbon turnover in soils.

UK applicability

The methodological approach and findings are directly applicable to UK arable soils and long-term field experiments. The emphasis on constraining models with radiocarbon data would benefit UK soil monitoring and carbon accounting initiatives, though model parameters may require recalibration for different UK soil types and climatic conditions.

Key measures

Soil organic carbon (SOC) concentrations, soil organic ¹⁴C (SO¹⁴C) measurements, SOC decomposition kinetic parameters, model parameter uncertainty estimated through Bayesian calibration

Outcomes reported

The study quantified how radiocarbon (¹⁴C) measurements, in addition to total soil organic carbon (SOC) data, constrain kinetic parameters in SOC decomposition models across five competing model structures. It demonstrated that the relative weighting of SOC and ¹⁴C data streams significantly influences estimated model parameters and predictions.

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