Mycorrhizae associated with brazilian coastal tablerland soils. In: Agrotrópica v. 20 p. 45-52, 2008.

Abstract

Subsoil compaction caused by anthropogenic or natural processes in coastal tableland soils (Ultisol) of Bahia, Brazil pose a great challenge to crop production - the soils at that ecosystem have a naturally compact subsoil horizon (named “coeso” layer). The role of arbuscular mycorrhiza (AM) in these soils in improving crop production is not well understood. To address this question, an experiment was undertaken in four land uses (natural forest, rubber tree plantation, pasture, and annual crops) in the cocoa-growing region of the state of Bahia, Brazil to assess mycorrhizal associations in these land use systems. Soil samples were collected from two depths (A-horizon: 0-15 cm and B-horizon: 35-50 cm). The Mycorrhizal Inoculum Potential (MIP) bioassay and AM fungal spore counts were estimated. The natural forest soil (phosphorus concentration < 0.01 mg kg-1) recorded the lowest number of AM fungal spores (18 / 100g soil, in the coeso layer) while pasture soil (phosphorus concentration 3.75 mg kg-1) showed the greatest number of AM fungal spores (168 / 100g soil, in the coeso layer). As an indicative, improvement of nutrient status of this distrophic soil may promote higher mycorrhizal association. Increased AM fungal activity and population diversity in the tableland soils, especially the coeso layers could be an important consideration to reduce the edaphologic limitations associated with those layers.