Abstract

VASQUEZ, José Rafael; MACIAS, Felipe  and  MENJIVAR, Juan Carlos. Soil respiration as a function of its use and relationship with the carbon fractions in soils in the province of Magdalena, Colombia. Bioagro [online]. 2013, vol.25, n.3, pp.175-180. ISSN 1316-3361.

Land-use and soil management affect labile and humified fractions of soil organic matter, thus reducing the biological activity. The objective of this study was to evaluate the effect of land-use on soil respiration and its relationship to some carbon forms (Ct: total carbon: Cox: oxidized carbon; Cnox: non-oxidized carbon; Cp: humic fraction carbon; Cdox: non-easily oxidized carbon). Six sites located in the province of Magdalena, were studied, and according to the respiration rate, they could be differentiated into two main groups. The first one, characterized by an annual rainfall higher than 1200 mm and neutral soils, showed respiration rates of 3.08 to 4.00 mg C-CO₂·h^-1·g^-1 soil or 124.3 to 280.1 mg C-CO₂·h^-1·g^-1 Cox. The second group, whose precipitation does not exceed 880 mm and exhibits alkaline soils, showed rates of 0.91 to 1.93 mg C-CO₂·h^-1·g^-1 soil or 65.9 to 93.3 mg C-CO₂·h^-1·g^-1 Cox. The soil respiration as a function of the Cox showed differences within land-uses, being higher in agricultural soils as compared to forest soils (27.4 mg C-CO₂·h^-1·g^-1 Cox lower in forest). Soil respiration correlated positively with all studied C forms, except the non-oxidized C, which confirms the recalcitrance of this C fraction. The higher respiration rate in agricultural soils confirms that improper handling of cultivated soils can significantly increase CO₂ emissions to the atmosphere.

Keywords : Carbon forms; carbon sinks and sources.

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