Relações entre a mineralogia, fertilidade, acidez e macrofauna em latossolos do cerrado sob pastagem

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The Cerrado region occupies approximately 24% of Brazilian territory, making it the second biggest biome in South América, exceeded only by the Amazon Rainforest. The majority of the soils of the region were described as being acid, with a low capacity for cation exchange and high saturation by aluminium. Pastures cover 117 million hectares, of which 54 million are cultivated pastures. The most dramatic and typical effects of aluminum toxicity on plants have already been demonstrated by various researchers. However, in most of these studies there are indications that the exchangeable aluminum or the total level of AI of the solutions are not sufficient indicators of the toxicity of the aluminium, highlighting the importance of evaluating the truly toxic species. Another important point is the effect of toxic aluminum on organisms within the soil since the principal processes of nutrient recycling, maintenance of physical structure and hydraulic properties, are regulated by the organisms within the soil. The objective of this work was to analyse the role of biodiversity on the functioning of the soils under pasture in the Cerrado region characterizing the relationships between the characteristics of the soil (minerology, constituents, chemical fertility, aluminium speciation) and its fauna (diversity and abundance). Samples of soil were collected from different locations of the Cerrado region for chemical and minerological characterization. The experiment was carried out in test-tubes, with the aim of studying the solutions of soils under pasture and determining aluminum speciation. The soil macrofauna in different conditions of chemical fertility and different levels of kaolinite and gibbsite was evaluated. The results allowed us to conclude that the majority of the pasture of the Cerrado region presents unsatisfactory levels of macronutrients for good development. Zn is the micronutrient most frequently limiting the development of the pasture of the Cerrado region. The kaolinitic soils present greater acidification potential than the gibbsites, where the levels of exchangeable AI are always very low. The greatest concentration of soil macrofauna under pasture of the Cerrado region occurs in the superficial layer of 0?10 cm of depth. The predominance of Isoptera (termites) is more accentuated in soils of low chemical fertility. There is greater density of Oligochaetas in the kaolinitic soils.

ASSUNTO(S)

solos - teor de alumínio solos - mineralogia fauna do solo soils - aluminum content soils - mineralogy soil fauna

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