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Evaluation of different negligible drainage flux for field capacity estimation and its implication on irrigation depth for major soil types in Alabama, USA

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan www.asabe.org

Citation:  2021 ASABE Annual International Virtual Meeting  2100415.(doi:10.13031/aim.202100415)
Authors:   Bruno P Lena, Luca Bondesan, Brenda V Ortiz, Everton A.R. Pinheiro, Guilherme T Morata, Hemendra Kumar
Keywords:   Irrigation water use efficiency, soil hydraulic properties, soil water depletion, soil water tension.

Abstract. The objective of this study was to evaluate the impact of different negligible drainage flux on estimated ψfc using in internal drainage flux-based HYDRUS 1D simulations for major agronomic soil in Alabama state. A total of 14 sampling locations at two regions of the state were selected for the determination of the soil water retention curve. The ψ-θ relation at field capacity (ψfc and θfc, respectively) were estimated by a numerical internal drainage flux experiment for multilayered soils using HYDRUS-1D software simulations. Calculated irrigation depth based on negligible drainage fluxes (qfc) were tested to identify which qfc value most correlated with estimated corn crop evapotranspiration (ETc). Three and four qfc were tested for the soils located in the Northwest (field #1) and Southeast region of the state (field #2), respectively. Irrigation depth and ETc were selected from period between the peak of water demand for corn. For both regions, it was found an increase trend of estimated ψfc as qfc increased. The relationships between the irrigation depth and accumulated ETc was best represented by a logarithmical model for all evaluated qfc. A qfc of 0.01 and 0.025 cm d-1 for Northwest and Southeast regions, respectively, not only yielded a higher coefficient of determination, but the model also presented a closer proximity to the 1:1 relation in comparison with the other evaluated qfc values. These finding suggests that the evaluation of the impact of different qfc on the irrigation recommendation can potentially improve the assessment of an accurate qfc, and, therefore, the estimated ψfc.

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