Modeling drought stress and plant available water applied to soybean

• Grant number: 24/19342-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: April 01, 2025
• End date: March 31, 2027
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Quirijn de Jong van Lier
• Grantee: Karla Samylle de Queiroz Costa
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil

Abstract

The amount of water available to plants is used agronomically as an indicator of soil suitability for crop growth and biomass production, as well as in project design and irrigation management. Traditionally, total available water (TAW) is defined as the difference between water content at field capacity (FC) and wilting point (WP) whose values are very often taken to correspond to a given value of matric potential. Readily available water (RAW) is a fraction of TAW defined as the water content between FC and the limiting point (LP). Although the challenge in determining TAW and RAW lies in the correct determination of FC, LP, and WP, their values are very often taken as if they would correspond to a certain value of matrix potential. A proposal for an estimate of TAW and RAW based on the physics of the drainage process and water extraction by the root system was recently developed and tested by the research group at FISOL-CENA where this project will be developed and called "Flux-based method" (FBM). For the lower limits WP and LP, the method is based on the MFLUX root water uptake model, which predicts the extraction of water from the soil by the root system depending on the hydraulic properties of the soil and plant, and atmospheric conditions. This project aims to calibrate the MFLUX model for a soybean scenario in the State of São Paulo. The comparison with experimental data will allow us to improve the prediction of the respective lower limits LP and WP by FBM.