Digging deep into soils and weather to unravel how ploughing alters the capacity of agricultural lands to store carbon

Agricultural soils constitute almost half of the world’s arable land and have sent about 100 Pg of carbon to the atmosphere since the 1850s.

The implementation of ‘carbon farming’ practices in agriculture can contribute to restoring part of the carbon (C) lost, while also improving soil health and fertility. Tillage has been in the spotlight due to its key role in regulating soil organic carbon (SOC) mineralization. In general, reduced tillage has been found to increase SOC content in the top 15 cm of soil.

However, this effect has been decreased or even reversed when deeper layers, or soils from generally humid ecosystems, are considered.

The lack of understanding of this phenomenon raises serious doubts about our ability to predict the consequences of ploughing for SOC in soils from different climates.

The aim of this project is to determine how ploughing affects the C fluxes induced by precipitation, and to unravel its implication for SOC stocks over depth.

To do so, I propose an innovative approach combining empirical and modelling approaches to quantify the impact of cycles of drying-rewetting on soil biogeochemistry within the soil profile and resolve the resulting patterns of C emission/sequestration.

Finally, I will identify the mechanisms responsible for these dynamics and provide evidence of the best climate-dependent ploughing practices to increase SOC stocks.