Tesis
Substâncias húmicas em solos de diferentes feições geomorfológicas no rebordo do planalto do Rio Grande do Sul
Fecha
2008-12-16Registro en:
MENEZES, Fábio Pacheco. Humic sbstances in soils from differentes geomorfhologic feature in the edge of Rio Grande do Sul plateau. 2008. 112 f. Dissertação (Mestrado em Agronomia) - Universidade Federal de Santa Maria, Santa Maria, 2008.
Autor
Menezes, Fábio Pacheco
Institución
Resumen
In spite of the great importance of the soil organic matter for the sustainability of the
natural systems and of agricultural production, its study remains incipient in the area
of the Edge of the Rio Grande do Sul Plateau, where different research have been
reporting negative aspects of the inadequate soil use. In that sense, the carbon
distribution evaluation among the chemically separated fractions can supply
subsidies to analyze the effects of land use on those sites. Besides that, it is
important to know the role carried out by the different geomorphological features
present in the area, once that the variation of the soil attributes can be different in
each segment of the landscape. The purpose of this research was to evaluate the
influence of the land use on the soil organic matter fractions, chemical attributes and
aggregates distribution in different soil depths and landscape positions, analyzing
three topossequences of soils of hillsides areas of the Edge of the Plateau. Soil
characteristics such morphological, environmental, chemistries and physical, were
analyzed for each soil horizon and layer. The chemical fractionation of the soil
organic matter was realized to quantificate the carbon amount of the humic fractions
and to determinate the amount of Fe+3 and Al3+ co-extracted with the humic
substances. The results allowed to verify that the chemical and physical attributes of
the soil were effected by the land use, and the position of the profile in the landscape
has an important effect in the distribution of the materials in the studied
topossequences. The forest showed the largest indexes of aggregation of the soil in
the superficial layer and in the top of the landscape, where the larger amount of total
organic carbon was verified. The amount of carbon in the fractions extracts of the soil
organic matter was different for each land uses. The acid fraction carbon showed low
amount in relation to the other extracts. The humina fraction corresponded to the
most sensitive indicator to the change of use of the soil. Most of the soil organic
matter was distributed in the alkaline-soluble fractions. However, higher values were
observed at the forest due to the soil litter. Among the alkaline-soluble fractions, the
humic acids were predominant, but they showed variations according to the position
in the landscape. This fraction associates preferentially with Fe+3, while Al+3 showed
larger affinity for the fulvic acids.