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Previous issue date: 2016-02-25 / CAPES / The Histosols are a major source of carbon storage in terrestrial environments and have high susceptibility to carbon losses when disturbed. The objective of this study was to generate pedotransfer functions (FPT) to assess the accuracy of previously published equations, applying them to predict soil bulk density (Bd) in organic soils from Brazil; to evaluate subsidence rate, and the variation of Bd and carbon of humic substances in Histosols over a period of one year; and to estimate stock and potential loss of carbon in Histosols from Rio de Janeiro State. For the first part of the study, there were used organic horizons, i.e., soil materials with total organic carbon (TOC) equal to or greater than 80 g kg-1 soil, totaling 280 horizons from different regions of Brazil. It was used the multiple linear regression technique and the equations were validated on independent data. There were tested 9 equations already published in the literature. The equations with better performance were the Hollis and FPT2, with R2 validation parameters of 0.48 and 0.49. When the clay fraction data is availlable, it is recommended to use the FPT1 equation; if there is no data on clay it is recommended the FPT2 and Hollis equations, which have only the TOC as a predictor variable. For the second part, a greenhouse experiment was carried out. For that, undisturbed samples were collected using PVC pipes, of two profiles of Organossolos Tiom?rficos, one in the neighborhood of Santa Cruz (SC Profile), city of Rio de Janeiro, and one in Mag? (Profile MG) municipality. There were evaluated 3 drainage levels, at 30, 60, and 100 cm deep, with 5 measuremts over time, being 0, 90, 180, 270, and 360 days (4 replicates). The MG profile presented the highest rates of subsidence, reaching 1.30 cm year-1 for the 100 cm drainage. Bd increased over time for both profiles, and the deeper drainage increased values in the SC profile. The deeper drainage favored the reduction of pH for both profiles. The TOC showed a decreasing trend over time. The values of carbon in the fulvic acid fraction (FAF), humic acid fraction (HAF), and humin fraction (HUM) showed no differences according to drainage levels. However, over time they showed high sensitivity to temperature changes, showing high levels of FAF and HAF at the end period and a consequent reduction in humin fraction. For the third and final section, there were used 43 soil profiles, where 18 of them did not have bulk density data, which were estimated by the FPTs. Comparisons between measured and estimated data groups was performed using the Wilcoxon test. The spatial distribution of the variables was performed using the IDW interpolation method. The average values of TOC was 228.0 g kg-1, Bd was 0.48 Mg m-3, the thickness of the profiles was 86 cm, the depth was 90 cm and the average stock TOC was 73.51 kg m-2. The spatialization showed qualitative differences for the variables in the different profile locations. The estimated TOC stock for the profiles form RJ State was 27,178,631.8 Mg. The estimated rates of loss were 10.87 kg m-2 for Histosols more recently drained and high TOC; of 7.16 kg m-2 for intermediate drained Histosols; and 1.46 kg m-2 for Histosols with longer time after drainage and low TOC. Soils with high TOC levels are more likely to have high losses TOC when disturbed. / Os Organossolos s?o uma importante fonte de estoque de carbono nos ambientes terrestres e possuem alta suscetibilidade ?s perdas de carbono quando perturbados. O objetivo do presente trabalho foi gerar equa??es, avaliar a acur?cia de equa??es j? publicadas, aplicando-as para a predi??o da densidade do solo (Ds) em solos org?nicos do Brasil; avaliar a taxa de subsid?ncia, a varia??o da Ds, e o carbono das subst?ncias h?micas em Organossolos ao longo do per?odo de um ano; e estimar o estoque e as potenciais perdas de carbono nos Organossolos do Estado do Rio de Janeiro. Para a primeira parte, trabalhou-se com horizontes org?nicos, i.e., materais de solo com teores de carbono org?nico total (COT) iguais ou maiores que 80 g kg-1 de solo, totalizando 280 horizontes em diferentes regi?es do Brasil. Foi empregada a t?cnica de regress?o linear m?ltipla e as equa??es foram validadas sobre dados independentes. Foram testadas 9 equa??es j? publicadas na literatura. As equa??es com melhor desempenho foram FPT2 e Hollis, com par?metros de valida??o R2 de 0,48 e 0,49. Em casos onde os teores de argila estejam quantificados, recomenda-se a equa??o FPT1, e na sua aus?ncia recomenda-se as equa??es FPT2 e Hollis, que possuem somente o COT como vari?vel preditora. Para a segunda parte, realizou-se um experimento em casa de vegeta??o. Foram coletadas amostras indeformadas em tubos de PVC, de dois perfis de Organossolo Tiom?rfico, sendo um no bairro Santa Cruz (Perfil SC), munic?pio de Rio de Janeiro, e outro no munic?pio de Mag? (Perfil MG). Foram avaliados 3 n?veis de drenagem, sendo de 30, 60, e 100 cm de profundidade, 5 avalia??es ao longo do tempo, sendo de 0, 90, 180, 270, e 360 dias (com 4 repeti??es). O perfil MG apresentou as maiores taxas de subsid?ncia, chegando a 1,30 cm ano-1 para a drenagem de 100 cm. A Ds aumentou ao longo do tempo para os dois perfis, e a drenagem mais profunda aumentou os valores no perfil SC. A drenagem mais profunda favoreceu a redu??o do pH para os dois perfis. Os teores de COT apresentaram tend?ncia de redu??o ao longo do tempo. Os valores de carbono da fra??o ?cido f?lvico (FAF), fra??o ?cido h?mico (FAH), e fra??o humina (HUM), n?o mostraram diferen?as de acordo com os n?veis de drenagem. No entanto, ao longo do tempo, apresentaram alta sensibilidade ?s varia??es de temperatura, mostrando elevados teores de FAF e FAH no per?odo final, e a consequente redu??o dos teores de HUM. Para a terceira e ?ltima parte do estudo, foram usados 43 perfis de Organossolos, sendo que 18 deles n?o apresentavam os dados de densidade do solo (Ds), os quais foram estimados por meio de FPTs. As compara??es entre os grupos de dados medidos e estimados foi feita pelo teste de Wilcoxon. A espacializa??o das vari?veis foi realizado atrav?s do m?todo de interpola??o IDW. Os valores m?dios de COT foi de 228,0 g kg-1, a Ds foi de 0,48 Mg m-3, a espessura dos perfis foi de 86 cm, a profundidade foi de 90 cm, e o estoque m?dio de COT foi de 73,51 kg m-2. A espacializa??o mostrou diferen?as qualitativas para as vari?veis nos diferentes locais. Foi estimado um estoque de COT de 27.178.631,8 Mg para os Organossolos do Estado do RJ. As taxas estimadas de perdas foram de 10,87 kg m-2 para Organossolos com drenagem mais recente e altos teores de COT; de 7,16 kg m-2 para Organossolos intermedi?rios; e 1,46 kg m-2 para Organossolos com menores teores de COT e longo tempo de drenagem. Solos com altos teores de COT est?o mais propensos a terem altas perdas de COT quando perturbados.
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:jspui/1987 |
| Date | 25 February 2016 |
| Creators | BEUTLER, Sidinei Julio |
| Contributors | Pereira, Marcos Gervasio, Tassinari, Wagner de Souza, Pereira, Marcos Gervasio, Garcia, Andr?s Calder?n, Loss, Arc?ngelo, Pinheiro, ?rika Fl?via Machado, Carvalho Junior, Waldir de |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Programa de P?s-Gradua??o em Agronomia e Ci?ncia do Solo, UFRRJ, Brasil, Instituto de Agronomia |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFRRJ, instname:Universidade Federal Rural do Rio de Janeiro, instacron:UFRRJ |
| Rights | info:eu-repo/semantics/openAccess |
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