Effects of soil mesofauna and farming management on decomposition of clover litter: a microcosm experiment

The effects of soil mesofauna and different farming systems on decomposition of clover (Trifolium repens) litter were investigated in a laboratory experiment. Microcosms were incubated for 16 weeks with fine and coarse litterbags in soils from three types of management systems: fallow, integrated farming and organic farming, the latter two cropped with wheat. The effects were studied by analysing litter mass loss, C and N content, DOC, nitrate and pH in soil leachate, and CO2 production, as well as mesofauna. Mesofauna significantly accelerated mass loss and C and N release from clover litter in all three soils. With mesofauna access, at the end of the experiment average clover mass loss was almost twice as high and clover C and N content were 60% lower than without mesofauna. Farming systems influenced the decomposition through affecting both element turnover and mesofauna. Although in the first weeks less N was leached from organic farming than from integrated farming soil, cumulative N leaching did not differ between these soils. However, more than 20% less N was leached from the fallow soil than from the field soils. CO2 production was highest in fallow soil. Here, mesofauna had no effect on this variable. In soil with integrated farming, mesofauna reduced cumulative CO2 production by 10% whereas in soil from organic farming it increased CO2 production by 20%. Our data suggest that differences in C and N turnover in different management systems are strongly mediated by soil mesofauna.