Abstract

LARROULET, María Sofía et al. Organic carbon and microbial activity in a pampean caldenal soil with different management. Cienc. suelo [online]. 2020, vol.38, n.1, pp.95-105. ISSN 1850-2067.

Roller chopping induces changes in organic fractions, which alter biological activity and subsequent burning causes losses of organic carbon and decreased microbial activity. The objective was to quantify changes produced in organic fractions and microbial activity in a Caldenal Pampean soil, after roller-chopping with or without controlled burning application. Treatments studies were: shrub control, gramineous-herbaceous control, shrub roller chopping, gramineous-herbaceous roller chopping, shrub roller copping and burnt and gramineous-herbaceous roller chopping and burnt. Six sampling plots were selected for each treatment and in each one, a composed sample of superficial 2.5 cm was taken. Then total, particulate, and mineral organic carbon contents; total nitrogen; average activity and biomass of bacterial population of the soil were determined. Roller-chopping increased the fine fraction and total carbon, and nitrogen compared to the control. After controlled burning, the total carbon and the fine fraction decreased until there were no differences with the control. The C:N ratio decreased to lower values than the control, after burning. Roller-chopping increased edaphic respiration with respect to the control queand after burning it decreased to values similar to the control. Dehydrogenase activity and substrate-induced respiration decrease after burning to significantly lower values than the control. Roller-chopping produced plant biomass accumulation and was generated a favorable microenvironment for microbial activity and residues transformation. The combustion of organic matter caused losses of total carbon, where the fine fraction was the only one affected and microbial activity decreased, especially in the soil under coarse fuel. Selective roller-chopping improved soil properties studied and the burning in the performed conditions did not produce negative changes. The application of these managements in Caldenal soils could be recommended but it is partial since an integral study of this ecosystem is necessary.

Keywords : particle-size fractions; microbiological properties; roller-chopping; prescribed fire.

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