Ecological Sustainability of an Organic Four-Year Vegetable Rotation System: Carabids and Other Soil Arthropods as Bioindicators

A four-year investigation comparing organic and conventional horticultural vegetable rotation systems was carried out in Central Italy using soil arthropods as bioindicators. The indexes of biodiversity showed, in general, higher values on organic in comparison with conventional management, but the differences were strongly affected by the crops. An index specifically designed to select the Carabid species, which benefit from organic versus conventional, was calculated in order to understand faunistic data on this group. Our data demonstrated that the spray intensity adversely affects the Carabid species richness, as proved by the lowest diversity values recorded in the conventional plots. The experiment, planned by following a system approach research, was suitable to understand the ecological sustainability in organic farming in comparison with conventional. The better conservation of arthropod fauna in the organic seems to be coherent also with the enhancement of organic matter in this system. For this reason, a holistic effect of the organic system can provide a reasonable interpretation of the better conservation of the living component and, in particular, of Carabid beetle biodiversity, during the four-year period.