Development and test of a new software library for simulating carbon and nitrogen dynamics in agricultural soils

We present a software model library (UNIMI.CRONO) to simulate carbon and nitrogen dynamics in agricultural soils. The modelling approaches included reproduce the soil organic matter decomposition, the biological mediated reactions in aerobic and anaerobic conditions, the transport of molecules in the gaseous and liquid phases, the soil-plant interactions at root level, and the effects of agricultural management practices. Three case studies are presented: we developed a modelling solution targeting the simulation of the paddy rice cropping system to demonstrate the capability of UNIMI.CRONO to be used in integrated simulation environments. The software architecture allowed to couple UNIMI.CRONO with other models to simulate meteorology, crop growth, and soil water and temperature dynamics. A screening sensitivity analysis method is then applied to assess the variability of CO2, CH4 and N2O emissions as a function of parameters changes. Results highlighted the large relevance of parameters driving soil organic matter decomposition in modulating greenhouse gases emissions, with variable responses according to boundary management and agro-environmental conditions. Finally we test the accuracy of the modelling solution in reproducing reference data collected in a dedicated field campaign. The results indicate a correct reproduction of rice biomass accumulation (R2 = 0.99), CH4 (R2 = 0.89) and CO2 emission fluxes (R2 = 0.79), thus proving models adherence to the real system. UNIMI.CRONO proved a viable modelling tool to be employed for operational purpose, which will be further tested in follow-up studies.