Microbial evaluation associated with the coeso layer in brazilian coastal tableland soil. In: Agrotrópica v. 17 p. 5-16, 2005.

Abstract

This study looked at some fundamental aspects of the coeso layer of the Brazilian Coastal Tableland soils aiming to define procedures more adapted in the use and management of those soils. The Brazilian Coastal Tableland constitutes a very extensive ecosystem of great agricultural potential. Adequate knowledge of the coeso layer can bring valuable contributions to a sustainable agricultural production and environment protection. Microbial alternatives can be used associated to the current existing options (mechanical subsoiling) or plants with root system capable to grow through the coeso) to decrease the agricultural limitations of the coeso layers. The objective of this study was to evaluate the influence of different land uses on the qualitative and quantitative distribution of the microbial population of a Brazilian Coastal Tableland soil. The study was carried out at the Brazilian Wood Ecological Station and vicinity, in state of Bahia (between 16o10’ to 16o30’ S and 39o05’ to 49o40’WG). Two soil horizons (A: 0-15 cm and B: 35-50 cm) were studied in four different land use areas (natural forest, rubber tree plantation, pasture and annual crops). The soil samples were analyzed at laboratories of the Cocoa Research Center (CEPEC / CEPLAC - Bahia, Brazil) and Soil and Water Science Department at the University of Florida (Florida, USA). Specific media were used to verify the fungal and bacterial colonies of fresh and air-dried soil. Penicillium sp was the dominant fungus species for all land uses on the fresh soil samples, including the B-horizon – that represents the coeso. The dominant fungi were characterized by DNA analysis. The genetic distance showed, by trend, a little difference between the Penicillium sp from A-horizons and that ones from B-horizons. The soil under pasture presented a higher regularity on the occurrence of fungal and bacterial colonies. The relevant occurrence of bacteria and fungi into the B-horizon, in most of the studied areas, can means an interesting indicator of possibilities to the biological improvement on the coeso layers. The soil under annual crop presented a greatest diversity of fungi. The obtained information points to a correlation between microbial population and organic maters, which could be used as a possible way to improve the agro-environmental properties of the coeso’s soils.