Sustentabilidade de sistemas de uso da terra em Mato Grosso do Sul

Abstract

This study was developed with the aim to evaluate the sustainability of land use systems based on physical, chemical and biological attributes, on two soils of Mato Grosso do Sul. Were evaluated six land use systems at Lagoa Grande settlement, Itahum district, Dourados-MS, on Quartz-sand Neosol: three agroforestries systems, named SAF 1, 2 and 3; cultivated pasture of Brachiaria decumbens Stapf.; conventional tillage system (SPC) and area with scrap of Native Cerrado Biome. In Distrofic Oxisoil, at Embrapa Agropecuária Oeste, also in Dourados-MS, were studied four systems of use: agroforestry system (SAF); cultivated pasture of Brachiaria decumbens Stapf.; conventional tillage system (SPC) and scrap of native vegetation from Semideciduous Forest (Mata). Firstly, were evaluated physical and chemical attributes on three soil depths (0-5, 5-10 e 10-20 cm), in both places of study. The physical attributes evaluated were soil density, macroporosity, microporosity, total porosity, geometric average diameter, weighted average diameter and texture. The chemical attributes studied were organic matter, aluminium, calcium, magnesium, potassium, phosphorus, pH CaCl2, potential acidity, sum of bases, CTC (T), CTC (t), aluminium saturation (m%) and bases saturation (V%). For analysis of these data were applied statistical techniques of multivariate analysis, among them, the factorial analysis based on principal components and the cluster analysis. Each study local, based on mentioned attributes, resulted on chapters 1 and 2 of the dissertation. Afterwards, the systems seated on the two kinds of soils were stitch together on chapter 3 for evaluation of edaphic mesofauna, which were determined Shannon-Weaner (H') diversity indexes, Simpson (Is) diversity and Pielou (J') equitability. Into each chapter there are conclusions, however, on a resumed way can be quoted the following conclusions: a) in soils of sandy texture, low increments on clay contribute to improve the physical and chemical sustainability of land use systems. The bigger content of soil organic matter presents on SAF 2 contributes for its chemical quality, also observed on the other systems due to the presence of exchangeable bases. All the systems, exception SAF 2, are similar to Native Vegetation as soil physical attributes and, therefore, sustainable on this aspect, except on depth of 0-5 cm, due human effects. In relation to soil biological quality, the bigger sustainability is gained by SAF 1 and SAF 3; b) among the evaluated systems on Distrofic Oxisoil, Pasture, although with the worst indicators of physical quality, is sustainable as chemical quality, featuring its tenors of soil bases, while SPC, as SAF are less sustainable on these aspects. However, as edaphic mesofauna diversity, SPC presents itself more diverse, being SAF less sustainable; c) the contribution of more complex land use systems, as Agroforestries systems, is more significant for physical, chemical and biological sustainability on Quartz-sand Neosol, given that its bigger limitations of use when compared to Distrofic Oxisoil.