How much carbon input is required to preserve or increase projected soil organic carbon stocks in German croplands under climate change?

Aims Increasing soil organic carbon (SOC) stocks is discussed as negative emission technology with the potential to remove relevant amounts of carbon from the atmosphere. At the same time, climate change-driven losses of SOC to the atmosphere might impede such goals. Methods In this study, we used an ensemble of different SOC models and climate projections to project SOC stocks in German croplands up to 2099 under different climate change scenarios. We then estimated the required increase in organic carbon (OC) input to preserve or increase SOC stocks. Results Projected SOC stocks of German croplands are estimated to decline under current OC input levels and management, both with and without climate change. Depending on the climate scenario, we estimated that the OC input to the soil in 2099 needs to be between 51% (+ 1.3 Mg ha − 1 ) and 93% (+ 2.3 Mg ha − 1 ) higher than today to preserve current SOC stock levels. A SOC stock increase of 34.4% (4‰ a − 1 ) would even require an OC input increase of between 221% (+ 5.5 Mg ha − 1 ) and 283% (+ 7.1 Mg ha − 1 ). Conclusions Our study highlights that under climate change increasing SOC stocks is considerable challenging since projected SOC losses have to be compensated first before SOC built up is possible. This would require unrealistically high OC input increases with drastic changes in agricultural management.