Lehrstuhl für Bodenkunde
The Research Unit Biogeochemistry of Paddy Soil Evolution will focus on the identification of main processes responsible for paddy soil evolution. To understand paddy soil evolution, we have to relate the dynamics of hydrologically and microbially mediated redox processes to the dynamics of soil minerals and soil organic matter. This is strongly related to the question of the microbial accessibility of organic carbon (OC) and nitrogen (N), but also of iron (Fe). These elements form stable organo-mineral associations. The research approach for this question includes the quantitative study of effects of redox conditions on production and stabilization of organic matter, mineral transformations and the related consequences for the geochemistry of the soil solution in paddy soils. A major focus will be on the availability of iron species in paddy soils for microbially mediated redox processes. These investigations are closely linked to investigations on the stabilization of dissolved organic matter by sorption on iron (hydr)oxides and clay minerals and (co-)precipitation withFe in dependence on redox conditions. Paddy soils are characterized by preservation of organic matter predominantly derived from the rice plant itself, from manure or straw combustion residues, and from associated microbial consortia under at least periodically anaerobic conditions due to submergence.