CONICET | Buscador de Institutos y Recursos Humanos

A group of farmers have begun to explore new alternatives for diversification and intensification of crop rotation (DICR) under no-till, aiming to increase crop yields and productivity per unit area, at the same time that reducing negative environmental impact. The impact of DICR on soil biology has been little explored. The aim of this contribution was to analyze the effect of DICR on soil macrofauna community, in the Pampa region of Argentina. A total of 24 sites were sampled in 4 farms located near Pergamino city (Buenos Aires province) where a DIRC essay was established 3 years before sampling. In each farm, 5 treatments with different rotations were established in a field with the same land use history and soil type: soybean monoculture (MC), typical rotation (Ty), high intensification with legume (HL), high intensification with 100% grass (HG), pasture and a natural grassland as a reference. The treatments had different indexes of crop rotation calculated as: days of the year with plants/365 days, from 0,43 for typical crop rotation (wheat/soybean-corn-soybean) to 1 in pasture. To obtain the macrofauna, 5 soil samples (25x25x20cm) were collected at each site, macrofauna was hand-sorted, taxonomically identified and counted. Earthworms presented higher abundance in the HL rotation than in the Ty and HG rotations. Beetles had a similar response, whereas ants were more abundant in HG and HL than in Ty and MC. Enchytraeids -indicators of disturbed soils- showed an inverse response to the increase in the DIRC. Regarding the taxonomic composition, a response of the whole fauna together with the management changes was observed, showing that the rotations HL and HG were the more different from the rest. We conclude that after only 3 years from the beginning of the DIRC essay, important changes occurred in soil macrofauna. These findings reflect their sensitivity and importance as indicators.

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