Rice is the staple food for over half of the global population and accounts for about 35 % of the total agricultural share of irrigation water consumption.
AWD can significantly cut water use and methane emissions in irrigated rice without reducing yields, yet adoption remains limited.
The International Rice Research Institute (IRRI) has introduced the field water tube, a simple but effective tool to monitor water depth and schedule irrigation.
However, implementation has remained extremely low in the Philippines, with current estimates showing only 12 per cent of the national irrigation system area practicing it.
This low adoption of AWD in the Philippines was investigated by researchers from the IRRI, the Philippine Rice Research Institute, the University of the Philippines, and the University of Queensland.
Layers of barriers
A major reason AWD is difficult to implement in gravity‑fed irrigation systems was the uneven land and soil conditions.
With hundreds of farmers relying on the same water source, small differences in elevation and clay content determine how quickly fields dry, said the study.
Low‑lying plots and those with heavier soils hold water far longer than higher‑elevation plots, making it nearly impossible for farmers to synchronise drying periods.
The study also highlighted how top‑down water management further limits AWD adoption.
In gravity‑fed systems, water is released according to fixed rotation schedules rather than real‑time field needs, leaving farmers with little control over timing.
Socio‑economic conditions add another layer of complexity.
About two‑thirds of the fields are farmed by tenants who often lack the authority or risk tolerance to adopt AWD, fearing potential yield loss could jeopardise their lease.
The study found that farmers were more willing to use AWD during the wet season, when rainfall provides a safety buffer against drying stress.
An urgent need
According to the study, the Philippines was among the pioneers of AWD research.
Rice is central to the country’s food supply and economic growth, yet the sector is under mounting pressure from water scarcity and heavy irrigation demand.
It also grapples with role as the country’s largest source of agricultural methane.
High temperatures and widespread continuous flooding make the Philippines the top emitter of methane per hectare of rice land, a problem now intensified by more frequent El Niño events and increasingly erratic water availability.
These pressures underscore the urgent need for more sustainable water management in the country.
The researchers argued for tailored interventions such as more flexible irrigation governance, stronger incorporation of farmer feedback, and alignment of water delivery schedules with site‑specific agro‑environmental conditions.
It also recommended introducing advanced monitoring technologies, such as IoT‑enabled water-level systems, to reduce information delays.
Gio Karlo Evangelista, Kristine Samoy-Pascual, Romeo J. Cabangon, Manuel J. Regalado, Yuji Enriquez, Rubenito Lampayan, Arnel Rala, Sudhir Yadav Why AWD isn’t taking off: Understanding barriers and pathways for scaling in gravity-fed irrigation systems in rice landscape Agricultural Systems, Volume 231, 2026 https://doi.org/10.1016/j.agsy.2025.104491
