Irrigation is going to have to feed an ever-increasing proportion of the world’s growing population – but supplies of fresh water are dwindling. Much of the increase in food production will need to come from smallholder farmers in low to middle-income countries. VIA’s innovation is designed for these farmers and has been shown to work. The company developed a soil water sensor – buried in the ground and attached to a light – that shows blue when the plants have plenty of water, green when things are ok and red when they need a drink.

Farmers were hungry for this kind of information, quickly changed their irrigation practices and substantially increased their yields. Almost all farmers who grew more food used less water to do so. Over-irrigating leaches nutrients out of the soil, wastes energy and causes environmental problems such as waterlogging and salinity. The sensors can be bought for less than USD10 and by using colours as indicators for action are easily understood by farmers regardless of language or literacy. 40,000 are already in use across 20 countries but the innovation is applicable to around 200 million of the poorest farming households in the world.