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Crop evapotranspiration

Guidelines for computing crop water requirements. Second edition, revised 2025

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Year of publication 2025

Place of publication Rome, Italy ;

Pages 440 p.

Author Santos Pereira, L.; Allen, R.G.; Paredes, P.; López-Urrea, R.; Raes, D.; Smith, M.; Kilic, A.; Salman, M.;

Publisher FAO ;

Product type Book (stand-alone)

Category Technical report

ISBN 978-92-5-140060-9

Series title FAO Irrigation and Drainage Paper

Series number 56 Rev.1

Edition Second edition

Revision First revision

To cite or share https://doi.org/10.4060/cd6621en

Synopsis (short abstract) The 2025 Revised Edition of Crop Evapotranspiration – Guidelines for Computing Crop Water Requirements marks a major update to FAO Irrigation and Drainage Paper No. 56, a seminal reference in agricultural water management since 1998. Building on the global uptake and proven reliability of the original guidelines—particularly the adoption of the FAO Penman-Monteith method—this new edition integrates advances in science, technology, and field practices to address the evolving challenges of agriculture in the face of climate change, water scarcity, and growing food demand.The updated guidelines reaffirm the foundational concepts while introducing enhanced methodologies for estimating crop evapotranspiration. These include the use of remote sensing, Internet of Things (IoT) applications, and improved energy balance approaches—tools that increase precision, adaptability, and scalability. The edition features updated crop coefficients, new climatic and agronomic datasets, and region-specific guidance, with particular attention to arid and semi-arid environments.Designed for a wide audience—researchers, practitioners, policymakers, and farmers—the revised guidelines support the development of more efficient and resilient irrigation practices. They enable better water allocation decisions, improved irrigation scheduling, and the implementation of water-saving strategies tailored to local contexts.By blending rigorous science with practical application, this edition remains a critical tool for sustainable agricultural planning and climate adaptation. It empowers stakeholders to optimize crop water use, reduce environmental impacts, and safeguard food security in an increasingly water-stressed world.

Last updated 06/01/2026

Cite this content as:

Santos Pereira, L., Allen, R.G., Paredes, P., López-Urrea, R., Raes, D., Smith, M., Kilic, A. & Salman, M. 2025. Crop evapotranspiration – Guidelines for computing crop water requirements. Second edition, revised 2025. FAO Irrigation and Drainage Paper, No. 56 Rev.1. Rome, FAO.

https://doi.org/10.4060/cd6621en

Language English

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