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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?).
| Identifer | oai:union.ndltd.org:IBICT/oai:localhost:tede/317 |
| Date | 03 April 2009 |
| Creators | Fontana, Ademir |
| Contributors | Pereira, Marcos Gerv?sio, Anjos, L?cia Helena Cunha dos, Benites, Vinicius de Melo |
| Publisher | Universidade Federal Rural do Rio de Janeiro, Curso de P?s-Gradua??o em Agronomia - Ci?ncia do Solo, UFRRJ, Brasil, Ci?ncias Agr?rias |
| 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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