Evaluación de indicadores biológicos en suelos de la región semiárida pampeana central

Abstract

In the semiarid Pampa, biological indicators have not yet been used to evaluate the effect of land-use on soil quality. Our objective was to characterize, evaluate and obtain base-line values for soil respiration, microbial biomass and metabolic quotient in agricultural and native vegetation soils of the central semiarid Pampa region. In two natural vegetation and two agricultural soils, we determined clay, silt, total porosity, total carbon and nitrogen contents, microbial respiration and biomass, fungi-bacteria ratio and metabolic quotient in the upper, middle and lower profile layers. Soil use significantly affected the activity and the size of soil biota, in the sense that the agricultural soils, with lower carbon and nitrogen contents, showed lower respiration and microbial biomass carbon and nitrogen contents compared to the natural vegetation. Microbial biomass and respiration were better indicators for soil degradation than the metabolic quotient. Soil use also had an effect on the fungi/bacteria ratio since agricultural soils had a lower proportion of fungi than soils under natural vegetation. These results enable us to establish baseline and threshold values for respiration and microbial biomass carbon contents.