Resumo

DUVAL, MATÍAS EZEQUIEL; GALANTINI, JUAN ALBERTO; MARTINEZ, JUAN MANUEL  e  IGLESIAS, JULIO OSVALDO. Comparación de índices de calidad de suelos agrícolas y naturales basados en el carbono orgánico. Cienc. suelo [online]. 2016, vol.34, n.2, pp.197-209. ISSN 1850-2067.

Literature exhibit a great number of soil quality indices, many of them based on organic carbon and its fractions, for a wide variety of natural and cultivated soils. In four sites located in the argentine Pampa region, the effect of the sequence and intensity of crop rotations on different organic carbon fractions in no-tilled soils, and the sensitivity of some quality indices to management practices were evaluated. At each site, three treatments were identified: two different agricultural scenarios in terms of crop rotation, fertilizers and use of agrochemicals (diversified intensive and regional representative managements, MID and MRR, respectively) and an undisturbed environment, natural (ASD) adjacent to agricultural sites as control treatment. Agricultural management with a high frequency or soybean monoculture caused COT decreases of about 30% in 0-10 cm depth. These decreases mainly affected labile fractions (particulate CO 105-2000 μm and particulate CO 53-105 μm) which decreased by 50% and 40% with respect an ASD field. These situations present the worst values in the most indices including labile fractions. However, the magnitude of the observed changes in these indices were lower in relation to those associated with the COT. The COT stratification index (0-5:5-20 cm) showed differences between treatments, which ranged from 2.0 (ASD) to 1.5 (MRR). The differential carbon input to the soil between treatments was reflected in the carbon pool index (IRC), considering a simple index to measure and sensitive to detect differences between agricultural managements. The results highlight the importance of the COT as universal indicator and the need to take into account local issues either management and/or seasonal, for the interpretation of the indices associated with the most labile fractions.

Palavras-chave : Stratification index; Soybean frequency; Labile fractions.

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