Water (Jun 2022)

Simple ET<sub>o</sub>-Based Rules for Irrigation Scheduling by Smallholder Vegetable Farmers in Laos and Cambodia

  • John McPhee,
  • Jochen Eberhard,
  • Alice Melland,
  • Jasim Uddin,
  • Lucinda Dunn,
  • Sarith Hin,
  • Vanndy Lim,
  • Veasna Touch,
  • Phimmasone Sisouvanh,
  • Inthong Somphou,
  • Tounglien Vilayphone,
  • Phaythoune Mounsena,
  • Stephen Ives

DOI
https://doi.org/10.3390/w14132010
Journal volume & issue
Vol. 14, no. 13
p. 2010

Abstract

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Hand-held hoses and watering cans are widely used by smallholder farmers to irrigate vegetables in Cambodia and Laos. Overwatering is common. Technology change (e.g., low-pressure drip irrigation) has been used to improve irrigation efficiency but can be unaffordable for many smallholder farmers. The purpose of this study was to identify an appropriate method of predicting crop water demand, develop and field-test improved irrigation schedules for smallholder leafy vegetable farming based on that method, and then develop extension tools to communicate the schedules to smallholder farmers. Improved irrigation schedules for leafy vegetables were developed based on a crop water use prediction technique that is well established (the Penman–Monteith method) but beyond the capacity of smallholder farmers to implement without access to simple aids. Compared to conventional practice, the method approximately halved water and labour use and improved irrigation water productivity 2–3 fold in field research and demonstration trials. Simplified extension tools to assist smallholder farmers with practice change were developed. This work showed that significant efficiencies could be gained through improved irrigation scheduling without changing application technology.

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