Resíduo da colheita de eucalipto e fontes de cálcio na agregação do solo e na estabilização da matéria orgânica / Crop residue of eucalyptus and calcium sources on soil aggregation and stabilization of organic matter

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

27/07/2010

RESUMO

The interaction of organic compounds with divalent cations such as calcium (Ca) may improve soil aggregation and polymerise the organic molecules, forming metal-organic complexes more stable. The effectiveness of Ca on the aggregation in forest soils, in field conditions, and the influence of different sources of Ca in decomposing residues of eucalyptus and in the process of aggregation and stabilization of the soil organic matter (SOM) are still poorly known. Thus, the objective was to evaluate the effect of different sources of Ca associated with harvest residues of eucalyptus in the aggregation and stabilization of carbon from the SOM. Therefore, it was conducted a field study that consisted of the addition of three sources of Ca and residue of eucalyptus (leaf, twig and bark) in two regions in the extreme south of Bahia, with pluviometric indexes and amounts of clay distincts. The experimental design was in randomized blocks with five replications. The treatments consisted of no supplemental Ca and three sources of the nutrient (CaCO 3, CaSO 4 and CaSiO4) applied to the soil containing crop residues of eucalyptus (leaf, twig and bark) and an additional treatment without adding Ca and without the maintenance of the residue of eucalyptus. After 12 months of the experiment it were performed: measurement of the remaining dry matter and estimation of the half-life (t 0.05) time of eucalyptus residues deposited in the area; determination of exchangeable Ca and nonexchangeable Ca content in the soil; Separation of stable aggregates by dry and calculation of the geometric mean diameter (GMD). In the aggregate classes representing more aggregate levels were determined exchangeble Ca content, total organic C, labile C, the natural abundance of 13C from the SOM and aggregate stability obtained by the method of ultrasound. In the South and West regions the lowest amount of Ca in the residue of eucalyptus were observed for CaSO4 in relation to CaCO3 and CaSiO3. The maintenance of plant residue of eucalyptus in the area of plantation after 12 months contributed to the increase of GMD, at 0-10 cm, but no changes were found in the GMD in depth (10-20, 20-40 and 40 - 60 cm). The addition of Ca through different sources reduced the GMD in the four depths, but this effect was dependent on the source. In the South, the presence of Ca increased the stability of aggregates and the reverse was observed for the western region. The best recovery of C derived from crop residue of eucalyptus in the South, occurred on the aggregate class of 2.00 to 1.00 mm when it was applied CaSO4 and CaSiO3. In class 1.00 to 0.25mm there was no difference among treatments regarding the contribution of the C from the residue. In the western region, the contribution of C derived from the eucalyptus residue was greater in the class of 2.00 to 1.00 mm, but no difference was observed among the treatments.

ASSUNTO(S)

ciencia do solo agregação cálcio estabilidade da matéria orgânica do solo aggregation calcium stabilization of organic matter

ACESSO AO ARTIGO

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