Abstract

ANRIQUEZ, Analía et al. Roller-chopping of shrub-thickets and soil quality in the western Chaco, Argentina. Cienc. suelo [online]. 2005, vol.23, n.2, pp.145-157. ISSN 1850-2067.

In the western Chaco region the suitability for cow-calf operations of areas dominated by shrub thickets of Acacia, Celtis and Prosopis ('fachinales') is reduced because of their low carrying capacity and poor accessibility. Our objective was to assess the effect of practices commonly used to increase the standing forage of 'fachinales' on some indicators of soil quality (bulk density, total soil organic carbon, respiration, particulate organic carbon, microbial biomass carbon and dehydrogenase activity) at three range sites of the Chaco region: upland, midland and bottom. The treatments applied were roller chopping, roller chopping plus seeding of Panicum maximum cv trichoglume cv Green panic, roller chopping followed by prescribed fire and controls. Bulk density, total soil organic carbon, particulate organic carbon and microbial biomass carbon were not altered by the treatments. A higher dehydrogenase activity was observed in the bottom site, irrespective of treatments, probably due to a greater soil water content. Soil respiration increased in the upland site in all treatments, probably because of the modification of soil microbial activity, attributable to the stimulation produced by the root exudates of green panic, native grasses and forbs that appeared after the treatments. In general, soil quality indicators were not significantly affected by the treatments used, a fact attributed to their 'low' intensity of application. However, there was a significant effect of range site.

Keywords : Soil degradation; Organic matter; Semiarid region; Range management; Ecological sustainability.

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