The multi-year effect of different agroecological practices on soil nematodes and soil respiration

International audience

English. Background and aims : Agroecology practices can induce profound positive changes in soil physical and chemical properties, and inevitably influence soil biological properties and soil functioning. However, we still lack understanding of how soil biodiversity responds to agroecology practices and to what extent such practices, alone or combined, can be beneficial for soil functioning and ecosystem services. Understanding soil biological activities under different agroecology practices is important for predicting carbon cycling in agroecosystems.Methods : By taking advantage of a long-term agricultural experimental research station in northern France, we monitored soil microbes, nematodes and soil respiration over three to five years in response to agroecology practices that varied in the rate of nitrogen (N) fertilization (low vs high), the tillage type (deep vs reduced), and the crop residue management (retain vs removal).Results : Shifting from conventional to agroecology practices had a strong effect on microbial biomass, nematode community and soil respiration. Specifically, reduced N and reduced tillage significantly increased microbial biomass carbon, bacterivore and fungivore density. Perennial biomass crop significantly decreased total nematode density and herbivore density, but increased microbial biomass carbon. Perennial biomass crop also significantly increased the structure and maturity index, but decreased the plant parasite index. Structural equation modelling showed that microbial biomass carbon had a positive correlation with soil respiration in reduced nitrogen, reduced tillage, and residue removal treatments. Bacterivores had a positive correlation with omnivores/predators and soil respiration, while herbivores had a negative correlation with soil respiration in all the treatments.ConclusionsThe different agroecological practices tested in this 5-year trial revealed the resilience of nematode communities and associated functions like CO2 respiration according to practices.