QUALIDADE FÍSICA DO SOLO SOB DIFERENTES USOS

Abstract

Agricultural activities are fundamental for food production and balance of the Brazilian trade balance. However, the conversion of natural ecosystems into systems with conventional soil tillage, promotes negative changes in the soil structure, causing not only environmental damage, but restrictions on the productivity of these areas. Thus, the use of alternative production techniques or systems, which aim to maximize production with the least possible environmental impact, is necessary. The present work had as objective the evaluation of the soil physical quality in different systems of use, for that, visual and laboratory analyzes were carried through. The visual analysis of the soil structure (VESS) was performed by different evaluators (farmer, student and researcher) in order to understand whether the method would have reproducibility for evaluators with different levels of knowledge about the technique. The laboratory analyzes performed were soil density (Ds), soil resistance to penetration (RP), uniaxial compression test, soil porosity and pore size distribution (DPT), in order to confirm the VESS sensitivity to identify changes in structure promoted by the management, and which of the evaluators would have the score closest to the laboratory determinations. The VESS results pointed to better soil quality in the semi-deciduous forest land use systems, syntropic agroforestry system, conventional planting and degraded pasture, respectively. All evaluators agreed on this classification, however, farmers were the ones who overestimated the scores of land use systems. The laboratory results pointed to higher Ds and RP in samples collected in the degraded pasture land use system, and higher compression rates (M) and macroporosity (MA), for the semideciduous forest land use system, confirming the trend presented by VESS. When the physical attributes were correlated with the scores given by the different evaluators, only those pointed out by farmers were significantly related to the laboratory determinations. From these results, it was possible to conclude that the VESS method has sensitivity to identify structural changes promoted by land use, and can be successfully applied by operators with different levels of familiarity with the technique, and that in these cases, the practical perception is a differential. The syntropic agroforestry system has proved to be a sustainable alternative for degraded areas recovery, by improving the structural soil quality.