Resumo

SILVA, Eulene Francisco da et al. Labile and recalcitrant fractions of soil organic matter under integrated crop-livestock system. Pesq. agropec. bras. [online]. 2011, vol.46, n.10, pp. 1321-1331. ISSN 0100-204X.  http://dx.doi.org/10.1590/S0100-204X2011001000028.

The objective of this work was to evaluate the soil total organic carbon (TOC) and total nitrogen (TN) stocks, C and N in labile and recalcitrant fractions of the soil organic matter (SOM), and the C management index, in soils under integrated crop-livestock (ICL) system after four (ICL4) and eight years (ICL8) of settlement. For comparison purposes, other management systems were used: pasture and crop under no tillage (NT), besides native vegetation. The experiment was carried out in a completely randomized block design, with five replicates. The crop-livestock established in a period of eight years can reach a new steady state equivalent to the no-tillage with 23 years of implementation. There was accumulation in total organic carbon of 101.0 (ICL8) and 104.2 Mg ha^-1 (NT), and N total stock of 5.5 (ICL8) and 5.8 Mg ha^-1 (NT) in the 0-30 cm layer, as well as increase in the stock of labile and recalcitrant C and N fractions of SOM. For crop-livestock with eight years, the C management index of 88 was higher than other management systems, and not different from native vegetation (0-10 cm), however, it was similar to NT in the analysis of the entire profile (0-30 cm).

Palavras-chave : organic carbon; carbon management index; nitrogen; humic substances.