Resilience of soil structure of an Ultisol under different land uses, at the Zona da Mata, MG / Resiliência da estrutura em Argissolo sob diferentes usos, na Zona da Mata de Minas Gerais

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Soil structure has a great importance for agricultural production, since it exerts marked influences on carbon cycles, nutrient cycling an water behavior, as well as to soil gas which are plant development limiting factors. Thus, this work aimed to verify the resilience of an Ultisol under different land uses. The work was located in Visconde do Rio Branco, at the Zona da Mata of Minas Gerais state. There were evaluated the following uses: Orange plantation, rubber trees plantation, pasture an rain forest, as reference. Pasture and rubber trees were established 15 years ago, and orange for 6 years. Rubber trees, orange and pasture were cultivated by sugar-cane for a century, whichat accounted for soil degradation. Sampling was carried out in three replicates (soil pits) at the depths of 0 - 10, 10 - 20 and 20 - 30 cm, both undeformed and deformed sub-samples. In theses samples, attributes such as aggregate stability, aggregate morphology (through QUANTPORO program), soil density, particle density, macro and microporosity, moisture equivalent, water-dispersible clay, flocculation and dispersion degree, texture, chemical, mineralogical, micromorphological, organic carbon and humic fractions contents were evaluated. The highest degree of resilience to the original structure was observed for rubber tree plantation, followed by orange plantation and, the least recover, in the degraded pasture. Biological activity was maximum under rubber trees and orange, whereas degraded pasture shows less biological influence and greater physical exposure. Rubbe trees show greater organic carbon, humic fractions, macroporosity and water retention, with lower soil density, at the all depths. The opposite was observed for degraded pasture. There was no significant difference between the studied environments, with regard to water dispersible clay, flocculation and dispersion degree and aggregate stability at the depth 0-10 and 10-20 cm, as well as aggregate morphology, at the all depths. The micromorphological analyses has confirmed the higher structural resilience of forest, followed by rubeer-tree >orange >pasture. In the latter, there is a massive structure of welded blocks, and porosoty of fissural type, with biological channels. In the rubber tree plantation, the structure was well developed, with abundant packing voids and higher volume of intergranular porosoty, with strong biological activity and organic matter.

ASSUNTO(S)

zona da mata uso ciencia do solo densidade land use density solo zona da mata soil

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