Assessment of crop productivity and soil organic C response to climate change in rainfed wheat-maize cropping systems under contrasting tillage using DSSAT

Climate change adaptation for agricultural systems requires resilience to both high intensity rainfall and extended drought periods. The increase of soil organic carbon (SOC) in the surface soil horizons associated to repeated no tillage practices, can contribute to improving soil structure and water absorption capacity. In the present study we assessed the effect of tillage management practices on SOC and crop yields in a rainfed durum wheat-maize rotation system (Agugliano, Italy) under temperate sub-Mediterranean conditions and a silty clay soil. The differential impact of no tillage (NT) management compared to conventional tillage (CT), both characterized by non-limiting nitrogen (N) fertilizer applications were evaluated under current and future climate scenarios by combining long-term field experiment outcomes with simulation approaches. DSSAT 4.5 was used to simulate crop yields and long term SOC dynamics following the calibration based on observed values in a long term experiment (1994–2008) run in central Italy (De Sanctis et al., 2012, Eur J Agron). Climate scenarios were generated using the regional model RAMS, bias calibrated with local observed conditions, considering a present (2000-2010) and near future (2020-2030) climatic contitions. NT management under non-limiting N conditions significantly contributed to increase SOC content in rainfed cereal systems through the greater soil cover offered by weeds in the 9-10 months intercropping period between wheat harvest (July) and maize seeding (end-April). Crop yield was significantly lower under NT than under CT and the simulated CO2 effect was greater than that expected from changed temperature and precipitation regimes in the near future.