Estrutura de solos em manejo conservacionista: diagnóstico visual, laboratorial, caracterização e inter-relações

Abstract

The visual analysis of soil structure can be a useful and practical tool for monitoring soil physical condition in conservation management systems. Thus, the objective of this work was to analyze the relationship between visual and laboratorial diagnosis of soil structure, in a conservation management system. We utilized completely randomized experimental design in a factorial double was used, the factors being soil classes (Haplic Cambisol, Red Latosol and Haplic Nitosol), evaluated at different depths (pille [-0.05-0.15 m]; 0.05-0.15 m; 0.25-0.35 m and 0.45-0.55 m) in triplicate. The evaluation was based on the visual appearance of the structure of the soil after five years of implementation of a management system considered conservationist, being analyzedresistance, consistency, porosity and presence of roots in the structural units of the soils, categorized by five visual scores (Ev) used in quality grading structure, ranging from Ev = 1 (best quality) at Ev = 5 (worst quality). In order to evaluate the physical attributes of the soil (macroporosity, microporosity, pore distribution by size and soil density), undisturbed samples were collected and submitted to matrix potentials -2, -4, -6, -10 kPa in the suction units, and -33, -100, -500, -1500 kPa in the Richards chamber. The aggregation was evaluated by the geometric mean diameter. We observed in the depths of 0.25-0.35 and 0.45-0.55m, the Latosol presented visual score lower when compared to Nitosol and Cambisol, indicating its better structural condition in these depths, comparative form to other soils analyzed. The increase of the visual scores is related to the loss of the structural porosity (inter aggregates) and increase of the textural porosity (intraaggregates). The principal component analysisdemonstrated that quantification of the attributes density, microporosity, silt content and the pore diameter class < 0.6 μm helped to justify the increase in Ev.