2026/06/11 by Elsa Coucheney, Stefano Manzoni, Emilien Casali +3 · 1 voice
Agricultural and Biological Sciences · Environmental Science · #Soil Carbon and Nitrogen Dynamics #Plant Water Relations and Carbon Dynamics #Plant responses to elevated CO2
paper · doi:10.1016/j.geoderma.2026.117886
openalex publication_date 2026/06/11 · openalex created_date 2026/06/12 · openalex updated_date 2026/06/19
Most soil carbon (C) models describe the effects of soil moisture on C mineralization rates using empirical response functions derived from laboratory incubations carried out on sieved soils. This pre-treatment alters the pore space structure controlling solute and oxygen diffusion and may also disturb the spatial distribution of microbial activity. Our objective was therefore to investigate the effects of disruption of the natural soil structure on the soil moisture response function for C mineralization. We measured CO 2 emissions at soil water pressure heads ranging from zero to −600 cm for both sieved and intact soil samples taken from tilled and untilled soil horizons at a field site in northern France. The derived soil moisture response curves were then combined with a simple analytical water balance model to predict CO 2 emissions in contrasting rainfall climates. We also explored the relationships between the parameters of the moisture response function and soil physical properties as well as metrics of soil structure quantified by X-ray scanning. Sieving significantly affected the shape of the moisture response function. In particular, the optimal degree of saturation for soil CO 2 emissions lay much closer to saturation (> 0.8) in the case of intact soil structures. The effects of repeated tillage were like those of sieving, although less pronounced. We identified relationships between some indicators of soil structure and the optimal degree of saturation, which suggests that it may be possible to derive pedotransfer functions linking soil properties to this critical model parameter. Finally, our modelling demonstrated that the use of moisture response functions derived from sieved soils in soil C models can lead to an underestimation of CO 2 emissions in wet climates.