Role of soil microarthropods in leaf decomposition and N release under various land-use practices in the humid tropics

The role of microarthropods in leaf decomposition and N release was studied in various land-use practices: secondary forest, bush regrowth, Pueraria phaseoloides relay cropping, Leucaena leucocephala alley cropping, and cropping without cover crop or tree hedgerows (control treatment), using litterbags with mesh-size of 0.5 mm and 0.08 mm for 98 days. Litterbags with 0.5 mm mesh-size allowed access by microarthropods, whereas those with 0.08 mm mesh-size excluded microarthropods. Microarthropod-mediated leaf decomposition and N release varied with the land-use practices, particularly the last named. Inclusion of microarthropods in most cases increased leaf decomposition and N release rates, with the highest value 38% for decomposition in control treatment and 29% for N release in relay cropping. A decrease in leaf decomposition rate (10%) and N release (32%) was observed in the secondary forest. Microarthropod-mediated leaf decomposition and N release, which mainly occurred in later stages of decomposition, increased as microbial decomposition decreased. The results suggest that microarthropods have a "buffering effect" in regulating leaf decomposition and N release, which is mediated by land-use history.