The diversification and intensification of crop rotations in no-till systems improve soil macrofauna in the Pampa region of Argentina

RODRÍGUEZ, MP, MOREIRA, M., DOMÍNGUEZ, A ORTÍZ, C, WALL, L; BEDANO J.C.

Rosario

Congreso; 7th World Congress on Conservation Agriculture; 2017

A group of farmers have begun to explore new alternatives for diversifi cation and intensifi cation ofcrop rotation (DICR) under no-till, aiming to increase crop yields and productivity per unit area, atthe same time that reducing negative environmental impact. The impact of DICR on soil biology hasbeen little explored. The aim of this contribution was to analyze the eff ect of DICR on soil macrofaunacommunity, in the Pampa region of Argentina. A total of 24 sites were sampled in 4 farms locatednear Pergamino city (Buenos Aires province) where a DICR essay was established 3 years beforesampling. In each farm, 5 treatments with diff erent rotations were established in a fi eld with the sameland use history and soil type: soybean monoculture (MC), typical rotation (Ty), high intensifi cationwith legume (HL), high intensifi cation with 100% grass (HG), pasture and a natural grassland as areference. The treatments had diff erent indexes of crop rotation calculated as: days of the year withplants/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 washand-sorted, taxonomically identifi ed and counted. Earthworms presented higher abundance in theHL rotation than in the Ty and HG rotations. Beetles had a similar response, whereas ants were moreabundant in HG and HL than in Ty and MC. Enchytraeids -indicators of disturbed soils-showed aninverse response to the increase in the DICR. Regarding the taxonomic composition, a response ofthe whole fauna together with the management changes was observed, showing that the rotationsHL and HG were the more diff erent from the rest. We conclude that after only 3 years from thebeginning of the DICR essay, important changes occurred in soil macrofauna. These fi ndings refl ecttheir sensitivity and importance as indicators