Effects of Crop-pasture Rotations in No-tillage, with Grazing, on Oligochaeta Communities

Abstract

Terrestrial oligochaetes are important components in agroecosystems. They have effects on the dynamics of organic matter, nutrient cycling, soil structure and in the diversity and activity of subordinated trofics levels. Climate, soil, topography, vegetation, and management practices affect communities´composition. The objective of this study was to evaluate the effect of different soil use intensities on earthworms´ communities. Oligochaeta were evaluated during 2007 in a long-term experiment, located in INIA Treinta y Tres – Palo a Pique Experimental Unit. The treatments considered were: continuous agriculture, short rotation, long rotations of crops and pastures, and permanent pasture. Three species predominated: Aporrectodea caliginosa (Lumbricidae), Eukerria stagnalis and Eukerria sp. (Ocnerodrilidae). Soil use had significant effects on the Oligochaeta communities’ composition. The highest and lowest Ocnerodrilidae densities were found in continuous agriculture and permanent pasture, respectively. A. caliginosa was less and more abundant in permanent pasture and continuous agriculture respectively. The highest and lowest densities of inmatures and cocoons corresponded to permanent pasture and continuous cropping. Short and long rotations had intermediate values for all variables considered. Oligochaeta communities’ composition, as well as adults/inmatures ratio, and cocoons counts, reflected the impact of different soil use intensities for no-till and grazed soils on organic carbon content and soil bulk density.