Modelling the effects of long-term tillage practices on soil organic carbon stocks in Pyhra

In contrast to conventional tillage, conservation practices can increase carbon storage in the topsoil. However, it remains unclear how soil organic carbon (SOC) changes under future climate, which would be essential striving towards sustainability. Process-based models are useful for exploring future environmental changes and understanding how systems may respond to multiple future drivers. Here, we applied the model N14CP, an integrated terrestrial C-N-P cycle model, to a nearly three-decadal long-term field experimental site in Lower Austria to simulate and determine the impacts of conventional tillage (CT), mulch tillage (MT), and no-till (NT) practices in combination with climate scenarios on SOC stocks in the topsoil (0-15 cm). Presumably, the experimental site was used as a grassland for centuries before being converted into conventionally tilled arable land in 1970; the MT and NT tillage plots were laid out in 1994. Since then, the study site was comprehensively sampled in 2002, 2013, and 2023. The research quantifies the long-term SOC stock changes from 1994 to 2100, considering the three tillage practices and RCP4.5 and RCP8.5 climate scenarios in the near (2021-2050) and far (2071-2100) future. The N14CP model performed well with the measured and simulated data validation. Based on our estimations, the NT is the only tillage practice that could increase SOC stocks between 1994 to 2100. However, considering +1.4 °C and +2.3 °C (RCP4.5) as well as +1.3 °C and +4.0 °C (RCP8.5) potential changes in the short-term and late-term future led to a decrease in the carbon stocks in the NT topsoil. SOC stock significantly decreased under CT and MT. Since the NT was the tillage practice that could retain the topsoil carbon, it can be considered an appropriate approach to deal with climate change in comparable agro-ecosystems.