Soil invertebrate fauna affect N2O emissions from soil

Nitrous oxide (N2O) emissions from soils contribute significantly to global warming. Mitigation of N2O emissions is severely hampered by a lack of understanding of its main controls. Fluxes can only partly be predicted from soil abiotic factors and microbial analyses – a possible role for soil fauna has until now largely been overlooked. We studied the effect of six groups of soil invertebrate fauna and tested the hypothesis that all of them increase N2O emissions, although to different extents. We conducted three microcosm experiments with sandy soil and hay residue. Faunal groups included in our experiments were as follows: fungal‐feeding nematodes, mites, springtails, potworms, earthworms and isopods. In experiment I, involving all six faunal groups, N2O emissions declined with earthworms and potworms from 78.4 (control) to 37.0 (earthworms) or 53.5 (potworms) mg N2O‐N m−2. In experiment II, with a higher soil‐to‐hay ratio and mites, springtails and potworms as faunal treatments, N2O emissions increased with potworms from 51.9 (control) to 123.5 mg N2O‐N m−2. Experiment III studied the effect of potworm density; we found that higher densities of potworms accelerated the peak of the N2O emissions by 5 days (P