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• Land management affect the weathering of minerals. • Decrease of net acidification through agricultural practice. • The change of soil chemical properties under agricultural practice is considered to be an expression of soil phenoforms. • Increase of organic carbon stock after conversion to cultivated land. • Formation of SRO aluminum promotes retention of organic carbon. We investigated changes in geochemical soil properties in response to deposition age and land use management over 30 – 50 years on tropical volcanic soils. Our purpose was to find out how weathering stage and land use interactively affect soil properties and organic carbon, and to check if phenoforms (management-related soil subtypes) exist within the genoforms (genetic soil types). Soil samples were taken at land uses that have been converted (pine forest and agricultural land) and a natural forest as the original land use. The results showed that pine forest soil displayed more intense weathering as indicated by higher values of three weathering indices. Intensive agricultural practices also improved soil chemical properties such as pH, exchangeable base cations, base saturation, and organic carbon stock leading to WRB-qualifier of " eutric" in cultivated soils, whereas the average of bulk density was relatively similar between forests and cultivated soils. Positive correlations were found between amorphous materials and Al o , specific surface area, and micropore volume. Correlations between the content of short-range order Al (hydr-) oxides (indicated by Al o) and organic carbon were found in pine forest and agricultural soils, particularly in subsoils. Our results clearly indicate the increase of base cations retention due to less acidification and an increase of organic carbon stock under agricultural land use, likely due to stabilization with non-crystalline materials. [ABSTRACT FROM AUTHOR]

Abstract: We explored the value of ergosterol, phospholipid fatty acid (PLFA) profiles and neutral lipid fatty acid (NLFA) 16:1ω5c as soil quality indicators for the intensive systems of vegetable production in the humid tropical climate of West Java, by comparing organic and conventional management. Additionally, we measured dehydrogenase and β-glucosidase activity. A secondary forest was included to obtain reference values under undisturbed conditions. Organic and conventional agriculture, and secondary forest each differed in the composition of the microbial community measured by PLFA profiles. Ergosterol appeared not to be universally applicable as a fungal biomarker and in this respect seemed to be inferior compared to PLFA fungal markers. NLFA 16:1ω5c may provide additional information as an indicator of arbuscular mycorrhizal fungi, but its high variability complicated the interpretation of data. The ratio of cy17:0 to 16:1ω7c was effectively applied as an indicator of physiological stress experienced by the bacterial community. Conventional vegetable production resulted in higher cy17:0/16:1ω7c ratios. Finally, a soil quality index, developed by stepwise canonical discriminant analysis and based on the absolute amount of PLFA 16:0, the relative amount of PLFAs 10Me16:0 and 10Me18:0, and dehydrogenase activity, was successfully validated. [Copyright &y& Elsevier]

Abstract: We compared the effect of organic and conventional farming practices on soil microbial dynamics in West Java, Indonesia. A secondary forest was included to obtain natural reference values. On the organic farms, soil fertility is maintained mainly with composted organic matter in contrast to conventional farmers who combine fresh manure and chemical fertilizers, and typically apply large amounts of pesticides. Parameters measured were dehydrogenase, β-glucosidase, acid phosphomonoesterase and β-glucosaminidase activity, microbial biomass C (MBC) and microbial community composition by phospholipid fatty acid analysis. A strong negative impact of intensive chemical fertilizer and pesticide use on soil enzyme activities was demonstrated. Dehydrogenase and β-glucosidase activities were correlated with soil organic matter content and pH. β-glucosidase activity under organic management approached that under forest, while MBC and dehydrogenase activity remained higher under forest. The composition of the soil microbial community strongly differed between forest and cultivated soil, a clear difference in composition was also observed between conventional and organic farming. Dehydrogenase activity and C16:1ω5c, marker fatty acid for arbuscular mycorrhizal fungi, appeared to be particularly suited as indicators of the impact of management on soil quality and on the soil microbial community. [Copyright &y& Elsevier]