Complementary effects of sorption and biochemical processing of dissolved organic matter for emerging structure formation controlled by soil texture

Background Percolating dissolved organic matter (DOM) from the topsoil is considered main source of subsoil carbon (OC) in temperate soils, but knowledge about its influence on OC storage and structure-forming processes limited. Aims We conducted a 30-day incubation experiment with artificial soils to study effects percolating DOM soil texture turnover initial structure formation. Methods Artificial contrasting texture, identical mineral composition, were used mimic conditions, where surfaces free OM come into contact DOM. After incubation, we assessed solution exchange, covers minerals, microbial community turnover, aggregate formation stability. Results A higher sand content caused lower porosity, accompanied by moisture content. In contrast, retention (21% input), activity, size unaffected texture. The covered 10% within an otherwise OC-free matrix. large, water-stable aggregates occurred all was pronounced clay-rich (58% mass contribution), which also supported mechanical stability aggregates. Conclusions mineralization are decoupled pore sizes exchange driven composition input. biochemical processing can induce large Here, presence fine particles enhances aggregates, irrespective their surface charge or sorptive properties.