Biochar reduces early-stage mineralization rates of plant residues more in coarse-textured soils than in fine-textured soils – an artificial-soil approach

Abstract. Quantifying the impact of biochar on carbon persistence across soil textures is complex, owing to the variability in soil conditions. Using artificial soils with precise textural and mineral compositions, we can disentangle the effects of biochar from the effects of soil particle size. We can show that biochar application significantly reduces the early-stage carbon mineralization rates of plant residues in various soil textures (from 5 % to 41 % clay) but more significantly in sandy soils. Clay and silt particles alone also reduce C mineralization, but the magnitude of the changes is negligible compared to the impact of biochar. This finding suggests that biochar can compensate for the lack of clay in promoting C persistence in soil systems. This short report contributes substantially to understanding soil texture and biochar application interactions.