“Effects of cropping sequences and rotational grazing on diversity, biomass, density and body mass of earthworms”

Abstract

Earthworms are classified as ecosystem engineers, given their ability to modify resources and habitats for other organisms. However, they are also strongly influenced by the land uses changes. Our study investigated the impact of different agricultural systems (rotational grazing versus continuous grazing ; cropping systems in pasture phase versus crop phase) on earthworm communities (diversity, biomass, density and body mass) in Uruguay, a context that is still poorly documented. We found a total of nine earthworm species. Rotational and continuous grazing systems exhibited similar mean richness (2.67–2.33, respectively), while in the crop phase, the mean richness was 2 points higher than that of the pasture phase (5.67 and 3.67, respectively). The results of the principal component analysis confirmed an overlap between the two grazing systems, rotational and continuous, indicating similarities in earthworm species composition in these systems. On the other hand, the pasture phase showed partial overlap with the grazing systems but the crop phase did not overlap with any of other three land uses. No significant difference was found in biomass in rotational grazing versus continuous grazing and in pasture phase versus crop phase. Earthworm density was significantly higher in rotational grazing compared to continuous grazing and in the crop phase compared to pasture phase. Body mass differences were observed in different land uses or developmental stages, observing in average smaller earthworms in rotational grazing compared to continuous grazing. Co-inertia analysis revealed associations between soil variables and earthworm biomass and body mass. Soil variables, including clay and calcium, strongly correlated with earthworm biomass. This study highlights the complexity of earthworm responses to land use, challenging logical interpretations. Further research is needed to elucidate the nuanced interactions between earthworm communities and environmental variables, providing valuable insights for sustainable land management practices, since both soil and plant health is known to be enhanced by the presence of earthworms.