Ranking of wetting-drying, plant, and fauna factors involved in the structure dynamics of a young constructed Technosol

Dynamical in situ observation of biological and climatic structuring factors involved in pedogenesis has not previously been possible in a way that would consider the early stages of pedogenesis. If studies have explored the effect of pedogenetic factors on soil structure, none have succeeded in ranking them in view of the intensity of their effects. We propose a novel approach for describing the aggregation process for a constructed Technosol obtained from a process of pedological engineering. We focus on agents including plants, macrofauna, and water, and we use (i) a dynamic in situ observation and (ii) the quantification of the evolution of selected descriptors of pores and aggregates. They are quantified from high-resolution images obtained with the SoilinsightA (R) device. Associating those images with each other, movies of interactions between soil and organisms over a 14-month non-destructive soil evolution experiment are made. Agents influencing aggregation-plant roots, earthworms, and water-can be ranked according to their impact on soil structure. During the studied period of evolution, wetting-drying cycles are the first to operate. The intensity of their action on soil structure is dominant at the very first stages of pedogenesis. Despite this ranking of agents, over the long term, plants and earthworms have a more intense effect on soil structure than wetting-drying cycles. The method applied to observe and quantify soil structure dynamics is thus proposed as a helpful approach to modeling other processes involved in soil functioning and evolution in relation to their ability to fulfill ecosystem services.