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Limitations to evapotranspiration in water transfer through the soil-plant-atmosphere continuum: revisiting the crop coefficient

Grant number: 20/07294-3
Support Opportunities:Scholarships in Brazil - Doctorate
Effective date (Start): January 01, 2022
Effective date (End): April 27, 2024
Field of knowledge:Agronomical Sciences - Agronomy - Soil Science
Principal Investigator:Quirijn de Jong van Lier
Grantee:Marina Luciana Abreu de Melo
Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
Associated scholarship(s):22/03770-0 - Calibrating an upscaled microscopic root water uptake model by inverse modeling, BE.EP.DR


Traditionally, the Soil-Vegetation-Atmosphere Transfer (SVAT) is considered limited by demand (sink-limited) when there is no restriction in the water supply from the soil. In this condition, the crop coefficient (Kc) should be determined. However, there is evidence that the SVAT can be limited by soil (source-limited) or by crop (crop-limited), even when the soil water content is high. Mechanistic root water uptake (RWU) models allow simulating the processes involved based on physical principles. The objective of this project is to investigate the SVAT and whether it is sink, source or crop-limited, as well as to improve the estimate of crop evapotranspiration (ETc), through a mechanistic RWU model, associated with a hydrological model. The calibration of a physical RWU model included in the SWAP eco-hydrological model will be performed for some observed scenarios of soil, water demand, and root properties. Then, scenarios with different combinations of soil and plant hydraulic properties, water condition, and atmospheric demand will be simulated by the SWAP model to elucidate whether and when the SVAT is sink, source, or crop-limited. The ETc estimated by the model will be compared to the ETc calculated based on the Kc associated with the available water capacity (AWC). Finally, an improvement of the Kc-AWC approach will be proposed under source and/or crop-limited conditions. With this pioneering study, we hope to clarify the sink, source, or crop-limited scenarios and improve the determination of Kc and ETc, with implications for irrigation management.

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Scientific publications
(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
DE MELO, MARINA LUCIANA ABREU; VAN LIER, QUIRIJN DE JONG. FluxPAW: A standalone software to calculate flux-based plant available water. SOFTWARE IMPACTS, v. 15, p. 4-pg., . (22/00853-2, 20/07294-3)

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