Soil microbial activity and earthworm abundance in orchards under conventional and organic growth management systems

摘要

The study was carried out in Gembloux, Belgium, to compare two adjacent experimental orchards, both planted in 2002, on a flat site with a common cultivation history. The first orchard was managed following organic guidelines and the second one was under conventional management. The orchards had different agricultural inputs (fertilizers, pesticides) and weed control systems. In year 2 (2003) of the study, the soil methane oxidation process was measured in order to compare the orchards' soil biological activities. In year 5 (2006), the overall soil microbial activity was assessed by measuring the basal respiration (BAS), the substrate induced respiration (SIR) and the in situ so/7 CO_2 efflux (CDE). Earthworm abundance as useful bio-indicators of agro-ecosystem sustainability was assessed together with chemical soil parameters. No significant difference in the methane oxidation rate was observed between the two orchard management systems in year 2. In year 5, however, important differences were detected for the microbial activity indicators in orchards subjected to different agricultural practices. The BAS, SIR and CDE values were significantly higher in the organic than in the conventional orchard on most sampling dates. Total earthworm abundancewas severely reduced by conventional practices. Soil mineral analysis did not show important differences between the two orchard management systems.