Sorption and desorption of organic matter in soils as affected by phosphate

The contribution of different adsorption processes to soil organic matter (SOM) stabilization and the consequences intensification land use on SOM are not yet fully understood. Therefore, this study aimed explore dissolved carbon (DOC) in soils as well desorption (OC) caused by phosphate addition. We conducted sorption experiments with DOC, (Na2HPO4), chloride (KCl) topsoil subsoil samples from a Ferralsol, an Andosol, Podzol. Furthermore, we quantified size DOC size-exclusion chromatography. found that addition strong increase concentration all soils. was elevated up factor 4.5 compared control (water only) within five minutes after kept increasing further time, particularly Ferralsol. After 10 days, concentrations P treatment were between 5.5 18.0 times higher than treatment. In contrast, did lead increased only). Phosphate led mostly medium molecular (10–100 100–1000 kDa) Ferralsol Andosol large (>1000 potassium shifted distribution solution towards small compounds (<10 kDa), likely because KCl affected aggregation compounds, contrast Na2HPO4 also decreased subsequent 2.9 2.1, respectively. Our results have far-reaching implications they show can desorption, thus destabilization SOM, Ferralsols, prevent provides mechanistic explanation why decrease sequestration stabilization. This mechanism should be considered analysis land-use tillage effects future. our indicates is stabilized through