Modelling Soil Organic Carbon Stocks in Agriculture: Conservation Tillage Practices and Grassed Waterways under various Climate Scenarios in Lower Austria

Soil organic carbon (SOC) sequestration plays a critical role in mitigating climate change and enhancing soil health; however, the effects of land management and climate change remain poorly quantified in agricultural landscapes. This study simulates SOC sequestration under different land uses and climate scenarios in a 28,311 ha Lower Austrian watershed. The impacts of land management change and climate scenarios on SOC stocks in the topsoil (0–15 cm) were modelled using the Rothamsted Carbon (RothC) model up to 2050. Four climate scenarios were considered: ‘Historical’, ‘SSP1-1.9’, ‘SSP2-4.5’, and ‘SSP5-8.5’. The results indicate that the implementation of two low-barrier but effective soil conservation practices - (i) grassed waterways and (ii) conservation tillage practices (mulch tillage and no-tillage) - could store more than 15,000 t C across the watershed by 2050. Grassed waterways and no-tillage could sequester up to 0.07 t C ha-1 yr-1, while mulch tillage could sequester up to 0.04 t C ha-1 yr-1 under the ‘Historical’ climate scenario. Among the future climate scenarios, only SSP5-8.5 notably reduced SOC sequestration, lowering rates to 0.06 t C ha-1 yr-1 for grassed waterways and no-tillage, and to 0.03 t C ha-1 yr-1 for mulch tillage. Overall, the study provides a scalable framework for assessing SOC sequestration under future land-management and climate scenarios, with direct relevance for carbon farming and certification schemes under current EU regulations such as the Carbon Removals and Carbon Farming Regulation (CRCF).