Effect of different set-aside management systems on soil nematode community and soil fertility in North, Central and South Italy

•The set-aside management moderately increased organic carbon content in soil, but not the humification.•Only nematode colonizer species increased in abundance and richness.•Detritivores and plant parasitic nematodes are not efficiently regulated by predation.•Soil organic carbon and nematode structure were enhanced under mowing both in May and July.