Resumo

MARTINEZ, Juan Manuel et al. Ajustes en la estimación de carbono orgánico por el método de Calcinación en molisoles del sudoeste bonaerense. Cienc. suelo [online]. 2017, vol.35, n.1, pp.171-180. ISSN 1850-2067.

Soil organic carbon (SOC) quantification is crucial for understanding the cycling in the terrestrial ecosystems. It is important to use methodologies of easily implementation that determine the SOC properly. The aims of this study were to determine: i) the optimal temperature and time to maximize the prediction of SOC and ii) a suitable conversion factor (fc) to estimate the SOC by loss-on-ignition method (MC) in Mollisols of the southwest Buenos Aires Province (SOB). During 2010 and 2011, seventy plots under no-tillage located in the SOB, Argentina, were sampled at 0-20 cm depth. Soil organic carbon values determined by dry combustión (CS) in an elemental analyzer were considered as reference values. Soil organic matter (OM) values were determined by MC in a muffle furnace at different temperatures (360, 430, 550 and 600 °C) and times (during 2 and 4 hours). No significant interactions were detected between both factors. Significant effect of different temperatures (p<0.001), while, no significant effect of calcination time (p=0.66) were detected. Linear regressions between SOC and OM at different temperatures showed significant relationships (p <0.001) with high coefficients of determination (R² =0.91-0.95). The best prediction of SOC was found with 550 °C temperature (R² = 0.95). The fc was 2.2, which would indicate that in these soils the C content in OM was 45%. These results suggest that MC with an adequate fc, is an easily implementable protocol that provides estimation of SOC comparable with the reference CS method.

Palavras-chave : Soil organic matter; Dry combustion; Conversion factor.

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