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

ORTIZ C; DOMINGUEZ A; RODRÍGUEZ MP; GALANTINI J; WALL LG; BEDANO JC

Rosario

Congreso; 7th World Congress on Conservation Agriculture; 2017

CAAPAS-AAPRESID

In the Pampa region of Argentina, a group of farmers have implemented a field essay of diversification and intensification of crop rotations (DIRC) under no till. It consists in increasing the amount of different crops per unit of time on the same area. Soil mesofauna, with a body diameter of 0.1 to 2 mm, is composed by mites (Acari) and springtails (Collembola), both sensible to changes in soil management. The present study aimed to analyze the effect of the DICR on the abundance of soil mesofauna. Eighteen sites were selected from three private farms near Pergamino city (Buenos Aires province) where a DICR essay was established 3 years before sampling, in a field with the same land use history and soil type. 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: typical rotation, high intensification with legume, high intensification with 100% grasses, and pasture. Two reference systems, a soybean monoculture and a natural environment were 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 identified in Oribatida, Mesostigmata, Prostigmata and Astigmata. Oribatid mites in the litter layer responded positively to the DIRC in the three farms. In the mineral soil (0-5cm), they showed a positive response to DIRC in two of the farms. Oribatids are functionaly important in soil because they are actively involved in the decomposition of crop organic residues and therefore fosters nutrient cycling. Mesostigmata showed a positive response to DIRC only in litter, in two of the farms. Prostigmata and Collembola did not increase their abundance with DIRC. We conclude that the DICR produces changes in soil biology after a rotation cycle of 3 years, increasing the abundance of some biological groups essential for the decomposition and cycling of soil nutrients.