Retention Curve with Application of Mathematical Models for the Evaluation of Hydraulic Conductivity in Soil Samples Under Different Structural Conditions

• Grant number: 24/16799-2
• Support Opportunities: Scholarships in Brazil - Master
• Start date: February 01, 2025
• End date: February 28, 2026
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Paulo Leonel Libardi
• Grantee: Ana Laura Haddad Bistane
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

For soil and water management and conservation, it is very important to understand the soil physical and hydraulic properties, which are essential to the processes of water retention and movement in the soil. Although the retention curve is a well-studied hydraulic property of the soil, issues related to the methodology for its determination using Richards chambers are not fully understood, particularly regarding: a) the use of undisturbed samples for tensions equal to or greater than 400 kPa, and b) the time of permanence of sample in the chamber for these higher tensions. Therefore, the objectives of this study are: a) to determine the complete retention curve (water tension ranging from 0 to 1500 kPa) of three soils with distinct textures (sandy, medium, and clayey) using disturbed and undisturbed samples, with Haines funnels (0 a 10 kPa) and Richards chambers (0 a 10 kPa), and, from it, to evaluate the pore size distribution based on capillarity theory and the relative hydraulic conductivity as a function of water content, Kr(0), using the van Genuchten model; b) to assess the hydraulic conductivity as a function of water content, K(0), by the product of Kr(0).Ko, where Ko is the saturated soil hydraulic conductivity, which will be determined by the constant head permeameter method, and c) to verify the possibility of reducing the time of the samples in the Richards chamber for high tensions. The retention curves will be subjected to analysis of variance (ANOVA) and compared using confidence intervals.