Faixa ótima do conteúdo de água para avaliação visual da estrutura do solo

Abstract

The Visual Evaluation of Soil Structure, VESS, is a widely used method for monitoring soil structural quality. It is a simple and efficient tool that aids in making sustainable decisions related to soil management. Although θ does not directly change the criteria of the method, its influence on the soil consistency can lead to misinterpretations of the hand test and increase the subjectivity of the analysis, especially in the range closest to saturation. Facing this issue, the objective of this research was to determine the most suitable range of soil water content for applying the Visual Evaluation of Soil Structure (VESS) methodology in a very clayey soil. The evaluations were carried out over 11 days, at regular intervals of 24 hours, starting 24 hours after soil saturation. Soil samples were collected daily for laboratory analysis. The VESS method and matric potential were determined in the field, while physical attributes, such as soil penetration resistance, soil density, and water content, were determined in the laboratory. From these data, the penetration resistance and water retention curves were obtained. Soil penetration resistance varied inversely with water content and positively with soil density. The ideal range for the VESS method corresponded to penetration resistance values between 2.50 and 3.00 MPa. The results indicated that the ideal range of water content for visual analysis occurred between the fifth and seventh day, corresponding to a water content between 0.38 and 0.36 m3 m-3, equivalent to a matric potential between -15.33 to -16.67 kPa, and located near the inflection point of the soil water retention curve.