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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Water Management and Systems Research » Research » Publications at this Location » Publication #369988
Research Project: Improving the Sustainability of Irrigated Farming Systems in Semi-Arid Regions

Location: Water Management and Systems Research

Title: Utilizing digital image processing and two-source energy balance model for the estimation of evapotranspiration of dry edible beans in western Nebraska

Author
item LIANG, WEI-ZHEN - University Of Nebraska
item QIAO, XIN - University Of Nebraska
item POSSIGNOLO, ISABELLA - University Of Nebraska
item IRMAK, SUAT - University Of Nebraska
item HEEREN, DEREK - University Of Nebraska
item RUDNICK, DARAN - University Of Nebraska
item DeJonge, Kendall

Submitted to: Irrigation Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2020
Publication Date: 3/18/2021
Citation: Liang, W., Qiao, X., Possignolo, I., Irmak, S., Heeren, D., Rudnick, D., DeJonge, K.C. 2021. Utilizing digital image processing and two-source energy balance model for the estimation of evapotranspiration of dry edible beans in western Nebraska. Irrigation Science. 39:617-631. https://doi.org/10.1007/s00271-021-00721-7.
DOI: https://doi.org/10.1007/s00271-021-00721-7

Interpretive Summary: In this study, Two-source energy balance (TSEB) model was used to estimate crop evapotranspiration of dry edible beans in western Nebraska. Digitally-captured canopy images were used to calculate input parameters for the TSEB model. The proposed methods in this study, by uniting digital image processing and TSEB models, have great potential to be automated and used in field-scale for various irrigation management scenarios of many crops.

Technical Abstract: Having an accurate yet simple method to estimate crop evapotranspiration (ETC) is a vital component of reliable irrigation scheduling. In this study, Two-source energy balance (TSEB) model: the TSEB model with the Priestley-Taylor equation (TSEB-PT) and the Penman-Monteith equation (TSEB-PM) were used to estimate ETC of dry edible beans in western Nebraska. Compare with previous studies, this study is unique that a Visual Basic software was developed to process digitally-captured RGB canopy images to obtain necessary canopy input parameters for the TSEB model. The software estimated canopy cover (CC) percentage was closely correlated with commercial leaf area index meter derived CC with R2 of 0.96. Additionally, software estimated leaf shape factor was closely correlated with measured leaf shape factor with R2 of 0.99. Both TSEB-PT and TSEB-PM models were able to estimate ETC well for fully-irrigated dry edible bean. The root mean square error (RMSE) of ETc from TSEB models versus ETC from FAO56 ranged from 0.95 to 1.63 mm/day in 2018, and 0.75 to 1.35 mm/day in 2019. Furthermore, ETC from TSEB-PT and TSEB-PM were compared with neutron probe derived ETC and the RMSE ranged from 2.03 to 9.65 mm in roughly one-week period under four different irrigation settings. The proposed methods in this study, by uniting digital image processing and TSEB models, have great potential to be automated and used in field-scale for various irrigation management scenarios of many crops.