Manejo da matéria orgânica do solo e estoques de carbono em cultivos de frutas tropicais

Abstract

The main objective of this study was to investigate changes in carbon dynamics and stocks in agricultural soils. Soil samples were collected at 0-10 cm and 10-30 cm depths in two agricultural areas (cultivated with banana (Musa spp.), and cultivated with citrus (Citrus sinensis). A native forest soil was used as a reference and to determine the carbon pool management index. Organic matter was physically fractionated into particulate organic matter (> 53 µm) and complexed organic matter (< 53 µm). Analysis of total organic carbon was run to characterize soil organic matter. Comparing to the native forest soil, the banana cultivation increased the total soil organic carbon content (TOC) in approximately 14% while citrus cultivation reduced the TOC content in about 38%. The cultivated soils reduced the particulate organic matter fraction in more than 50%, showing a higher decomposition rate of the organic residues. The Carbon Management Index values were lower than 1 in all treatments, however the best results were observed for the citrus orchard (116.5). Overall, the change in land use from native forest to fruit crops reduced soil organic matter content, especially its labile fraction, and reduced soil quality.Manejo da matéria orgânica do solo e estoques de carbono em cultivos de frutas tropicais R E S U M OCom este trabalho objetivou investigar as mudanças na dinâmica e no estoque de carbono em solos agrícolas. Amostras de solo foram coletadas de 0-10 cm e 10-30 cm, em duas áreas agrícolas (cultivo de banana (Musa spp) e cultivo de citros (Citrus sinensis). Um solo em floresta nativa foi utilizado como referência e para determinação do Índice de Manejo de Carbono (IMC). A matéria orgânica do solo (MOS) foi fracionada fisicamente em particulada (MOP, > 53 µm) e complexada (MOC, < 53 µm). O carbono orgânico total (COT) foi analisado para caracterizar a MOS. Comparando com o solo em mata nativa o cultivo da banana aumentou o teor de carbono orgânico do solo (TOC) em aproximadamente 14% enquanto o cultivo de citros reduziu o teor de TOC em cerca de 38%. O cultivo de fruteiras reduziu a fração particulada em mais de 50% mostrando uma velocidade de decomposição maior dos resíduos orgânicos. Os valores do Índice de Manejo de Carbono foram menores que 1 em todos os tratamentos; entretanto, foram observados os melhores resultados para o pomar de citros (116,5). No geral, a mudança no uso da terra de mata nativa para culturas de frutas reduziu o teor de matéria orgânica do solo, especialmente sua fração lábil, e a qualidade do solo.

The temperature sensitivity of soil organic carbon decomposition is greater in subsoil than in topsoil during laboratory incubation

“…Firstly, fresh organic matter derived from residues, root secretions, and/or organic fertilizer is often concentrated in the surface layer 36 , leading to a higher POXC in the TL than in the SL (Table 1). Secondly, the differences bwtween R 20 in the TL and the SL may be caused by differences in soil microbes.…”

Organic Matter Fractions in a Quartzipsamment Under Cultivation of Irrigated Mango in the Lower São Francisco Valley Region, Brazil

“…Soil tillage leads to degradation of organic matter and causes losses in OC, in spite of the annual deposit of organic residues from the fruit orchards (Bernardi et al, 2007). Evaluating the impact of banana and citrus orchards in relation to native vegetation (remaining from the Atlantic Forest) in the Plateau of Neópolis, Sergipe, Brazil, Guimarães et al, (2014) observed that an irrigated banana plantation resulted in a 14 % increase in the OC content in the and higher c stocks in the heavy and light sOM fraction in comparison to native caatinga, especially in the uppermost soil layer. Many studies have evaluated the SOM dynamic under annual crops in regions with high rainfall (Freixo et al, 2002;Carneiro et al, 2009).…”

“…They observed that the OC stocks were inversely proportional to the depth evaluated. In a study carried out in Sergipe, Brazil, evaluating the impact of eight years of banana growing on the SOM of an Argissolo (Ultisol) in relation to native forest, Guimarães et al (2014) observed that growing irrigated banana resulted in a 14 % increase in the OC content. The greater OC contents found in the area of the banana plantation compared to the native forest area arise from the incorporation of crop residues (leaves and pseudostem) and of the plant material cleared off the area itself, together with the contribution of plant matter from herbaceous species.…”

“…Consequently, fractionation of SOM may be an important tool for detecting changes in the SOM stocks in the short term and for directing research with a focus on studying SOM (Benites et al, 2010). In a study carried out in the Plateau of Neópolis, SE, evaluating the impact of eight years of banana and citrus orchards on the soil organic matter fractions in relation to the Atlantic Forest, Guimarães et al, (2014) did not observe a difference in the OC content in the 10-30 cm depth layer when comparing the banana plantation to native forest. In contrast, in this same layer, particulate organic matter was 29 % greater in the soil under native forest when compared to the banana orchard, and this fraction may be used as an indicator of soil quality.…”

Initial Recovery of Organic Matter of a Grass-Covered Constructed Soil after Coal Mining

“…The CMI has been estimated from particle-size fractions (Vieira et al, 2007;Schiavo et al, 2011;Guimarães et al, 2014;Zhao et al, 2014). Recently, Conceição et al (2014) found a high correlation (r = 0.92; p<0.01) between CMI estimated from these fractions and from density fractions (separated with SPT solution).…”