Understanding large‐extent controls of soil organic carbon storage in relation to soil depth and soil‐landscape systems

Abstract

In this work we aimed at developing a conceptual framework in which we improve our understanding of the controlling factors for soil organic carbon (SOC) over vast areas at different depths. We postulated that variability in SOC levels may be better explained by modeling SOC within soil-landscape systems (SLSs). The study was performed in mainland France, and explanatory SOC models were developed for the sampled topsoil (0-30 cm) and subsoil (>30 cm), using both directed and undirected data-mining techniques. With this study we demonstrated that there is a shift in controlling factors both in space and depth which were mainly related to (1) typical SLS characteristics and (2) human-induced changes to SLSs. The controlling factors in relation to depth alter from predominantly biotic to more abiotic with increasing depth. Especially, water availability, soil texture, and physical protection control deeper stored SOC. In SLSs with similar SOC levels, different combinations of physical protection, the input of organic matter, and climatic conditions largely determined the SOC level. The SLS approach provided the means to partition the data into data sets that were having homogenous conditions with respect to this combination of controlling factors. This information may provide important information on the carbon storage and sequestration potential of a soil.

Reviews and syntheses: The mechanisms underlying carbon storage in soil

“…C transferred laterally by erosion is lost at the pedon scale, but the integration of processes at the watershed scale (detachment, transport, sedimentation, burial in lowland areas) results in C budgets that often generate debate regarding C sinks and sources (Doetterl et al, 2016;Mulder et al, 2015).…”

Effects of temperature and grazing on soil organic carbon storage in grasslands along the Eurasian steppe eastern transect

“…At the local scale, topography usually has the greatest indirect influence on soil organic carbon storage by affecting the redistribution of temperature and water [ 10 , 16 ]. The vertical distribution of soil organic carbon storage is also controlled by a range of environmental factors: soil organic carbon storage in topsoil is mainly determined by climatic variables, whereas that in subsoil shows a significant association with soil texture [ 7 , 13 , 17 ]. The soil organic carbon content depends on the balance between the carbon input and output, and environmental factors affect soil organic carbon by impacting the input and/or output of carbon [ 6 , 18 ].…”

Services écosystémiques fournis par les espaces agricoles

“…Une attention particulière devrait être portée à la détermination de deux caractéristiques et propriétés clefs du sol : la teneur en matière organique et la densité apparente, actuellement déterminées sans distinction des types de systèmes de culture et de prairies. Par exemple, l'estimation de la teneur en matière organique sous prairies temporaires par Mulder et al (2015Mulder et al ( , 2016 55 ne tient pas compte de la durée de ces prairies. Dans la base de données sur les sols, la densité apparente est identique dans les sols de grandes cultures et de prairies.…”