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vol.70 número5Contribution of nitrogen from sugarcane harvest residues and urea for crop nutritionSoil and crop residue CO2-C emission under tillage systems in sugarcane-producing areas of southern Brazil índice de autoresíndice de assuntospesquisa de artigos
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Scientia Agricola

versão impressa ISSN 0103-9016

Resumo

SEGNINI, Aline et al. Carbon stock and humification index of organic matter affected by sugarcane straw and soil management. Sci. agric. (Piracicaba, Braz.) [online]. 2013, vol.70, n.5, pp.321-326. ISSN 0103-9016.  http://dx.doi.org/10.1590/S0103-90162013000500006.

The maintenance of sugarcane (Saccharum spp.) straw on a soil surface increases the soil carbon (C) stocks, but at lower rates than expected. This fact is probably associated with the soil management adopted during sugarcane replanting. This study aimed to assess the impact on soil C stocks and the humification index of soil organic matter (SOM) of adopting no-tillage (NT) and conventional tillage (CT) for sugarcane replanting. A greater C content and stock was observed in the NT area, but only in the 0-5 cm soil layer (p < 0.05). Greater soil C stock (0-60 cm) was found in soil under NT, when compared to CT and the baseline. While C stock of 116 Mg ha-1 was found in the baseline area, in areas under CT and NT systems the values ranged from 120 to 127 Mg ha-1. Carbon retention rates of 0.67 and 1.63 Mg C ha-1 year-1 were obtained in areas under CT and NT, respectively. Laser-Induced Fluorescence Spectroscopy showed that CT makes the soil surface (0-20 cm) more homogeneous than the NT system due to the effect of soil disturbance, and that the SOM humification index (HLIF) is larger in CT compared to NT conditions. In contrast, NT had a gradient of increasing HLIF, showing that the entry of labile organic material such as straw is also responsible for the accumulation of C in this system. The maintenance of straw on the soil surface and the adoption of NT during sugarcane planting are strategies that can increase soil C sequestration in the Brazilian sugarcane sector.

Palavras-chave : Laser-Induced Fluorescence Spectroscopy; sugarcane replanting; crop residues; no-tillage; soil organic matter.

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