Assessment of the Cambisol structure sustainability under different land uses systems in Western Amazon. / AvaliaÃÃo da sustentabilidade da estrutura de um Cambissolo sob diferentes sistemas de uso da terra na AmazÃnia Ocidental.

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

The adequate use of the soil is important for the preservation of the natural resources and for a search of a sustainable agriculture. However, itâs inadequate use promotes degradation of the soil altering its physical, chemical and biological properties. In order for the soil management happens in a sustainable way it is important to diagnose through efficient methods which impacts these managements can provoke in the soil structure from the soil physics view. Thus, this study had as objectives: a) assess the sensibility of the bulk density and total porosity to quantify the Cambisol structure alterations in different land uses systems; b) to develop a load support capacity models of a Cambisol under the use systems of young secondary forest, old secondary forest, forest, pasture, crop and agro forestry c) to determine, through the use of these models, the influence of the different use systems in the Cambisol structure in three depths and d) to determine through these models for each depth, which use systems preserved or cause degradation of the Cambisol structure. The samplings were accomplished in three depths (0 - 3, 10 - 13 and 20 -23 cm), being 10 undisturbed soil samples collected by depth in the following use systems: young secondary forest, old secondary forest, forest, pasture, crop and agro forestry. The undisturbed soil samples were used in the uniaxial compression test. It was also determined texture, particle and bulk densities and total porosity. The load support capacity models for the Cambisol are function of the preconsolidation pressure and moisture, being expressed by the equation p = 10 (a + b U). The soil bulk density and total porosity were not appropriate in the quantification of the Cambisol structure degradation. In general, in a same use system the depth 0-3 cm was the one that presented larger structure degradation. The depth of 10-13 cm was the one that suffered smaller structure degradation in the young secondary forest, old secondary forest, pasture and agro forestry (for moisture larger than 0.35 kg kg-1). The depth of 20-23 cm was the one that suffered smaller structure degradation in the forest (for moisture smaller than 0.46 kg kg-1), crop and agro forestry (for moisture smaller than 0.35 kg kg-1). In the 0-3 cm depth the use system that more degraded the Cambisol structure was pasture. In the 10-13 cm depth, in general the Cambisol structure degradation decreased in the following order: crop >old secondary forest and forest >agro forestry >young secondary forest and pasture. In the 20-23 cm depth, it was only evident the greater structure degradation of the old secondary forest and the smaller degradation of the crop (for moisture content greater than 0,40 kg kg-1).

ASSUNTO(S)

ciencia do solo degradaÃÃo da estrutura do solo. pressÃo de preconsolidaÃÃo fÃsica do solo

ACESSO AO ARTIGO

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