Decomposição de resíduos da colheita e transferência de carbono para o solo em plantações de eucalipto

• Ano de defesa: 2012
• Autor(a) principal: Souza, Ivan Francisco de
• Orientador(a): Barros, Nairam Félix de
• Banca de defesa: Paiva, Haroldo Nogueira de , Soares, Emanuelle Mercês Barros
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Viçosa
• Programa de Pós-Graduação: Mestrado em Solos e Nutrição de Plantas
• Departamento: Fertilidade do solo e nutrição de plantas; Gênese, Morfologia e Classificação, Mineralogia, Química,
• País: BR
• Palavras-chave em Português: Solos; Teor de carbono; Resíduos vegetais; Eucalipto; Dióxido de carbono; Humus
• Palavras-chave em Inglês: Soils; Carbon; Vegetable waste; Eucalypt; Carbon dioxide; Humus
• Área do conhecimento CNPq: CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO
• Link de acesso: http://locus.ufv.br/handle/123456789/5484

In Brazil, eucalyptus is planted in regions with different climate and soil conditions, which affect harvest residue decomposition and the rate of carbon transference fromresidues (Cres) to the soil, hence influencing soil organic matter (SOM) content. SOM is considered one of the most important indicators of soil quality and forest production sustainability. Debarking the trunk of the tree during forest harvesting contributes to increase the amount of residues left in the site, but it may impair residues decomposition due to the large C:N ratio of the material. However, very little is known about bark influence on eucalypt residue decomposition and its role on SOM formation under the Brazilian conditions. It is a common practice the use of low rates of N fertilizers in eucalypt plantations in Brazil, which would contribute to slower microbial activity in the decomposition process. Leaving the residues on the surface without incorporating them into the soil would also help to limit Cres to SOM. Hence, this study has the objective to determine the influence of leaving on soil surface eucalypt bark and slash in site after harvesting operations as wells as the effect of nitrogen fertilizer addition on the rates of residue decomposition and Cres to the SOM, and how climate and soil characteristics affect these processes. The experiment was installed in four sites (Eunápolis, Aracruz, Virginópolis and Belo Oriente) belonging to the Atlantic Forest biome and six (João Pinheiro, Três Marias, Curvelo, Itamarandiba e Luiz Antônio) belonging to the Cerrado (savanah type of vegetation), all varying in climate and soil characteristics. In each site the 12 treatments (3 slash handling systems, i.e., complete removal, left in the site with trunk debarking or not; 2 slash disposal systems, i.e., left on soil surface or incorporated into the soil; and 2 rates of N, i.e., zero or 200 kg ha-1) were laid out in random blocks with 4 replications. The remaining dry matter was quantified at 0, 3, 6, 12 and 36 months later, and estimated the decomposition constant (k) and half life time (t0,5) of the residues. Residue Ct to SOM was assessed 12 months after starting the trial, by soil physical fractionation to separate particulate organic matter (POM) and organic matter associated to soil minerals (MAM). The influence of climate and soil characteristics on t0,5 and Cres was estimated by linear multiple regression. Residue incorporation into the soil favored both the decomposition and Cres. Decomposition was enhanced by debarking but less Cres was detected. Nitrogen addition had little effect on the residues decomposition rate and SOM stabilization. Residues t0,5 was shorter in sites with higher rainfall regimes and mean annual temperatures and residues incorporation, mainly in sandy soils. The mean residue t0,5 was 1.28 year. Cres is reduced with increasing mean temperature and soil acidity and enhanced by increased clay content and deficit of C saturation of the soil. In average, the rate of C recovering was 15 % from the decomposed residues, in 12 months.