Effect of the diversification and intensification of crop rotation on soil mesofauna in no-till systems of the Pampa region of Argentina

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

Congreso; 7th World Congress on Conservation Agriculture; 2017

In the Pampa region of Argentina, a group of farmers have implemented a fi eld essay of diversifi cationand intensifi cation of crop rotations (DICR) under no till. It consists in increasing the amount ofdiff erent crops per unit of time on the same area. Soil mesofauna, with a body diameter of 0.1 to2 mm, is composed by mites (Acari) and springtails (Collembola), both sensible to changes in soilmanagement. The present study aimed to analyze the eff ect of the DICR on the abundance of soilmesofauna. Eighteen sites were selected from three private farms near Pergamino city (Buenos Airesprovince) where a DICR essay was established 3 years before sampling, in a fi eld with the same landuse history and soil type. The treatments had diff erent indexes of crop rotation calculated as: daysof the year with plants/365 days, from 0,43 for typical crop rotation (wheat/soybean-corn-soybean)to 1 in pasture: typical rotation, high intensifi cation with legume, high intensifi cation with 100%grasses, and pasture. Two reference systems, a soybean monoculture and a natural environmentwere also studied. Five soil samples, 10 cm deep and 5 cm in diameter, were collected at each site,divided into litter and 0-5 cm. They were processed in the Berlese system to extract the organisms.The mites were identifi ed in Oribatida, Mesostigmata, Prostigmata and Astigmata. Oribatid mitesin the litter layer responded positively to the DICR in the three farms. In the mineral soil (0-5cm),they showed a positive response to DICR in two of the farms. Oribatids are functionaly important insoil because they are actively involved in the decomposition of crop organic residues and thereforefosters nutrient cycling. Mesostigmata showed a positive response to DICR only in litter, in two of thefarms. Prostigmata and Collembola did not increase their abundance with DICR. We conclude thatthe DICR produces changes in soil biology after a rotation cycle of 3 years, increasing the abundanceof some biological groups essential for the decomposition and cycling of soil nutrients