Tropical Andosol organic carbon quality and degradability in relation to soil geochemistry as affected by land use

Abstract. Land use is recognized to impact soil geochemistry on the centennial millennial timescale, with implications for distribution and stability of organic carbon (SOC). Young volcanic soils in tropical areas are subject much faster pedogenesis, noticeable already or even decadal timescale. As land a factor formation, it thus conceivable that relatively recent conversion such would bear significant resulting formed soils., e.g., terms content pedogenic oxides. Very scarce observational evidence exists, so indirect SOC cycling largely unknown. We here investigated fractions, substrate-specific mineralization (SOC added plant residue), net priming as function forest agricultural Indonesian soils. The oxalate-extracted Al (Alo) correlated well (OC) associated sand-sized aggregates, particularly subsoil. proportion ultrasonication-resistant (400 J mL−1) aggregates was also higher compared pine use, likewise contrast existed Alo. These combined observations suggest enhanced formation (hydr)oxides promoted aggregation physical occlusion OC. This was, importantly, consistent lesser degradability sites, though we found no difference 13C-labeled ryegrass native between uses. expected amorphous under mainly have mineral association but indications this. Improved small-scale Andosols caused by agriculture high input via fertilizer may partially counter otherwise expectable decline stocks following cultivation. Such effects balance appeared relevant correct interpretation prediction long-term C (agro)ecosystems intense development, like here-studied Andosols.