Estabilização do carbono orgânico em função de biomassas de diferentes qualidades aplicadas em um solo enriquecido com cálcio

Abstract

Making carbon available to the soil through pruning residues of legumes cultivated in alley crop systems is a promising alternative to the traditional cultivation system. The modified alley system in the experimental area had already established legumes, where a native species (Clitoria fairchildiana), three exotics (Acacia mangium, Leucaena leucocephala and Gliricidia sepium) and a forage species (Panicum maximum, Mombasa) were used. The effect of mixing legume biomass with different residue qualities on soil carbon stabilization, biological activity, soil resistance to penetration and cation content was evaluated. Maize was planted intercropped with legumes and crop productivity served as an indicator of the quality and stability of soil C in the different treatments. The design used was randomized blocks, with four replications. The treatments were organized from the application of pruning residues of the following forage and legumes: Mombasa (M); Sombreiro + Leucaena (S+L); Acacia + Leucaena (A+L); Leucaena + Gliricidia (L+G); Acacia + Gliricidia (A+G); Sombreiro + Gliricidia (S+G); and Control, with bare ground. The application of biomass residues of different qualities positively influenced the content of calcium and magnesium in the layer surface of the soil, as well as the levels of organic carbon and microbiological activity of the soil in most of the analyzed variables, with statistical differences in relation to the control. Most of the treatments in alleys showed higher productivity results when compared to the control, mainly the S+G treatment (Sombreiro + Gliricidia). The Mombasa grass did not present statistical differences in relation to the control in all the studied variables.