HA NOI (VNS) – While farmers in developed countries may employ more sophisticated methods to reduce water use, coffee farmers in Viet Nam have been using waste items to plan a more effective irrigation.

This helps them to save valuable water.

Local farmers in the central highlands of Viet Nam, the world's second-largest coffee producer, use empty condensed milk cans to measure rainfall and put upturned plastic bottles on the ground to measure soil moisture.

They said these tools were simple to use and low cost, almost no cost, and it's easy to scale up their use by the nation's small coffee farms.

It is one way of facing the hard truth that climate change and overuse of water in agriculture will pose a growing threat of water scarcity to farmers, households and industry.

A study co-funded by Nestlé estimated that, on average, coffee farmers use 60 per cent more water than they need during the dry season from November to April, across three to four necessary irrigation rounds.

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In Viet Nam, 2.6 million people, mostly in the Central Highlands, rely on coffee cultivation for their livelihood. Most of the coffee farms are of a small scale.

By inserting a plastic bottle upside down in the soil and observing the condensation level in the bottle, the coffee farmer is able to measure soil moisture. When the water droplets inside the bottle are few, he knows it is time for the first dry-season irrigation.