Earthworm community in conventional, organic and direct seeding with living mulch cropping systems

Summary

The loss of biodiversity by intensification of agricultural practices is a major environmental issue that calls for the design of new cropping systems. For instance, negative effects of tillage on earthworm populations have been reported. However, few field studies have compared full cropping systems. Here, we assessed diversity, density and biomass of earthworm populations for 3 years. We use a combined method involving a diluted solution of allyl isothiocyanate to expel earthworms followed by hand sorting. In a long-term trial, we compared 3 systems: (1) a conventional system, (2) a direct seeding living mulch-based cropping system, named a living mulch cropping system, and (3) an organic system. These three cropping systems differed in terms of soil tillage, pesticide and nitrogen use, and crop biomass production. The results showed that measured variables, except diversity, varied depending on the year of sampling. Further, anecic and epigeic density was 3.2–7.2 times higher in the living mulch cropping system than in the conventional and organic systems. There were 3.4–12.5 times more anecic and epigeic earthworm biomass in the living mulch cropping system. The conventional and organic systems showed, respectively, 2.8 and 2.2 times more earthworm density, and 1.9 and 1.8 times more endogeic earthworm biomass than in the living mulch cropping system. Shannon-Wiener and equitability indices were superior in the living mulch cropping system compared with the conventional and organic systems. Cropping systems thus modified specific and functional diversity as well as earthworm community biomass. On the other hand, the organic and conventional systems did not differ in their earthworm density, biomass or diversity.