Made available in DSpace on 2016-04-26T19:39:32Z (GMT). No. of bitstreams: 1 2009 - Ademir Fontana.pdf: 2160169 bytes, checksum: fd6ae828d8a9c078041d2b180e5bd9b9 (MD5) Previous issue date: 2009-04-03 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / The importance of soil organic matter in pedology and especially soil classification studies can be substantiated by the use of attributes such as organic carbon content, degree of organic matter decomposition from the fibers content. Recent studies in Brazil with humic substances report establishment of standards that could be used to differentiate soil horizons (diagnostic attributes), soil horizon classification and the relationship with properties that connote soil fertility. This study had as objectives: to characterize humic substances and humic acids of different diagnostic soil horizons of Brazilian soils; b) to propose the utilization of attributes related to humic substances in the characterization of the lower hierarchical levels (family and series) of the Brazilian System of Soil Classification (SiBCS). The soil material utilized material from 169 diagnostic horizons or epipedons, identified as: 13 O histic, 30 H histic, 42 A mollic, 39 A umbric, and 45 B spodic horizons. In these horizons there were evaluated the chemical properties: TOC, pH, H+, SB (sum of bases), CEC and V% (base saturation); physical properties: sand, silt and clay contents; quantitative fractionating of humic substances: fulvic acid fraction (C-FAF), humic acid fraction (C-HAF) and humin (C-HUM), C-HAF/C-FAF, C-AE/C-HUM, and C-AE/COT ratio (C-AE = C-FAF + C-HAF), and the %FAF, %HAF, %HUM and %AE. In the purified humic acid (HA) spectroscopic analyses were performed on visible and infrared regions, elemental composition and termogravimetric analyses; in addition to that the alkaline extract (AE) was analyzed by spectroscopy on visible region. The quantitative fractionating of humic substances showed differential distribution between the types of diagnostic soils horizons, highlighting the O and H histic horizons, where the predominance of humin showed average around 53% and 39%, respectively, and followed by humic acids. Also, for the H histic horizon there were high values of the C-HAF/C-FAF ratio (average of 5.6). On the mollic epipedon it was observed predominance of humin with average around 71%, and low values of C-AE/C-HUM ratio (average of 0.2), and on the umbric epipedon humin predominance averaging 47%, followed by humic acids. On the spodic horizon there was predominance of fulvic and humic acids with average around 30% and 44%, respectively. On this horizon, the values of the C-HAF/C-FAF ratio were high, with average around 9.9 (most of them higher than 1.0), and the C-AE/C-HUM ratio averaged 16.5 (majority higher than 2.0). The evaluation of variables related to visible and infrared spectroscopic, elemental composition and termogravimetric of HA, and visible region for AE, showed similar characteristics and absence of a pattern independent ly of soils genesis. According to the distribution of humic substances the following differential characteristics were proposed to the SiBCS: Stable Organic Matter (surface mineral horizons) C-AE/C-HUM = 0.5, Iluvial Organic Matter (subsurface mineral horizons) - C-AE/C-HUM = 2.0, and Leaching Potential (system or soil) - C-HAF/C-FAF and C-AE/C-HUM = 1.0. Also, the establishment of classes according to humic substances was efficient to identify distinct groups based on their chemical properties. This result validates the proposal of using these variables to classify these horizons on the family and series levels, and contribute to structure the SiBCS in the lower hierarchical levels (5th and 6th). / A import?ncia da mat?ria org?nica do solo nos estudos de pedologia e em especial na classifica??o de solos pode ser constatada pela utiliza??o de atributos como os teores de carbono org?nico e grau de decomposi??o da mat?ria org?nica a partir do teor de fibras. Alguns trabalhos desenvolvidos recentemente no Brasil com subst?ncias h?micas em solos buscaram estabelecer padr?es que poderiam ser utilizados na separa??o de horizontes (atributo diagn?stico), classifica??o dos horizontes ou mesmo rela??es com propriedades ed?ficas que conotam fertilidade dos solos. Este trabalho teve como objetivos: caracterizar diferentes horizontes diagn?sticos de solos por meio das subst?ncias h?micas e dos ?cidos h?micos; e propor o uso de atributos relacionados ?s subst?ncias h?micas na categoriza??o dos n?veis hier?rquicos inferiores (fam?lia e s?rie) do SiBCS. Foram utilizados materiais de solo de 169 horizontes diagn?sticos, sendo: 13 O h?stico, 30 H h?stico, 42 chernoz?mico, 39 A h?mico, 45 B esp?dico. Foram avaliadas as propriedades qu?micas: COT, pH, SB, H+, Al3+, CTC e V%; propriedades f?sicas: areia, silte e argila; fracionamento quantitativo das subst?ncias h?micas: fra??o ?cidos f?lvicos (C-FAF), fra??o ?cidos h?micos (C-FAH) e fra??o humina (C-HUM), rela??es C-FAH/C-FAF, C-EA/C-HUM e C-EA/COT (C-EA = C-FAF + C-FAH) e a %FAF, %FAH, %HUM, % EA. Em ?cidos h?micos (AH) purificados foram realizadas an?lises espectrosc?picas na regi?o do vis?vel e infravermelho, composi??o elementar e termogravim?trica; al?m de, no extrato alcalino (EA) an?lise espectrosc?pica na regi?o do vis?vel. O fracionamento quantitativo das subst?ncias h?micas apresentou distribui??es diferenciadas entre os tipos de horizontes diagn?sticos de solos, destacando-se no O h?stico e H h?stico o predom?nio da humina com m?dia de 53% e 39%, respectivamente, seguido dos ?cidos h?micos e ainda para o ?ltimo, altos valores da rela??o C-FAH/C-FAF (m?dia de 5,6). No A chernoz?mico observou-se o predom?nio absoluto da humina com m?dia de 71% e baixos valores da rela??o C-EA/C-HUM (m?dia de 0,2) enquanto no A h?mico houve predom?nio da humina (m?dia de 47%), seguida dos ?cidos h?micos. No B esp?dico o predom?nio dos ?cidos f?lvicos e h?micos com m?dia de 30% e 44%, respectivamente, e altos valores da rela??o C-FAH/C-FAF com m?dia de 9,9 (maioria superiores 1,0) e C-EA/C-HUM com m?dia de 16,5 (maioria superiores 2,0). Pela avalia??o das vari?veis relacionadas ? espectroscopia do vis?vel e infravermelho, composi??o elementar e termogravimetria dos AH, e na regi?o do vis?vel para o EA, observou-se caracter?sticas semelhantes e aus?ncia de padr?o diferencial independente da g?nese dos solos. Com base na distribui??o das subst?ncias h?micas foram feitas as seguintes propostas de caracter?sticas diferenciais no SiBCS: Mat?ria Org?nica Est?vel (horizontes minerais superficiais) - C-EA/C-HUM = 0,5, Mat?ria Org?nica Iluvial (horizontes minerais subsuperficiais) - C-EA/C-HUM = 2,0 e, Potencial de Lixivia??o (sistema ou solo) - C-FAH/C-FAF e C-EA/C-HUM = 1,0. O estabelecimento de classes com os valores das subst?ncias h?micas tamb?m foi eficiente para individualizar grupos pela compara??o das propriedades qu?micas, o que valida a proposta de utiliza??o dessas vari?veis para a classifica??o desses horizontes nos n?veis de fam?lia ou s?rie e podem contribuir para a estrutura??o do SiBCS nos n?veis hier?rquicos inferiores (5? e 6?).