Tillage system does not affect soil macrofauna in southeastern Buenos Aires province,Argentina

Soil degradation increased incessantly in the Pampas region of Argentina, due to the intensification of agricultural activities, when carried out with conventional tillage (CT) systems. No-tillage system was adopted as conservation practices by the farmers. The objectives of this study were: a) to determine the macrofauna taxa and their relative abundance under CT and NT in two different seasons; and b) to evaluate soil tillage and seasonal effects on the density of the main macrofauna taxa. The study was conducted from 2002 to 2004 in 46 production farms, in Balcarce, Argentina. Ten soil monoliths (25.2 cm side; 30 cm depth) ramdomly directed field at July-August; and at October- November to determine the number of individuals of macrofauna and Enchytraeidae. Soil macrofauna density did not differ between tillage systems. Oligochaeta Megadrilli density was generally not affected by the tillage system (P > 0.05) except in 2004 when it was greater under CT in July-August (P = 0.0002). Chilopoda density was greater in soils under NT, with significant differences in 2002 in October-November (P = 0.0070). In July-August of 2003 it was higher in CT (P = 0.0109). Diplopoda were more abundant only under NT in July-August 2004 (P = 0.0010). In July-August a significantly (P < 0.05) higher density of Enchytraeidae was found in CT than NT fields. No differences were observed in the taxonomic composition and the relative abundance of the macrofauna when comparing CT and NT. It can be then concluded that in the study region tillage systems affected slightly soil macrofauna and significantly Enchytraeidae.