Seventy percent of the world’s freshwater is used for irrigation and global water resources are drying up as climate change takes hold and population growth continues. Sixty percent of the world’s hungry people live in South Asia and sub-Saharan Africa — most of them on small farms — where they do not have a reliable source of water to produce sufficient yields. Only 4% of the cultivated land in sub-Saharan Africa is currently equipped for irrigation — 95% of cropland in the region depends on rain and climate scientists predict that rainfall on the continent will decline in the coming decades. But there is great potential to expand irrigation with small-scale solutions.
Nourishing the Planet recommends three models for effective water management that have the potential for getting “more crop per drop”:
The foot-operated treadle pump enables 2.3 million farmers in the developing world — some 250 000 in sub-Saharan Africa — to boost crop productivity, improve harvest reliability and raise incomes. The original $35 version can irrigate 0.2 hectares with ground water; newer models can irrigate up to 0.8 hectares and cost no more than $140 installed. These devices already generate $37 million a year in profits and wages. In Zambia, International Development Enterprises worked with farmers to determine the most effective type of pump. The Mosi-O-Tunya pump is manufactured locally and delivers 25% more water a second than older versions.
A suite of low-cost drip irrigation technologies is helping farmers use limited water supplies more efficiently, often doubling water productivity. These systems deliver water directly to the plant roots through perforated pipes or tubes and can come in the form of $5 bucket kits, $25 drum kits or $100 shiftable drip systems that irrigate up to 0.2 hectares. Solar-powered micro-irrigation drip systems are also making their debut in West Africa. One study found that after a year of using these systems, villagers in Benin had higher incomes and protein in their diets. Children attended school more often since they no longer needed to spend their day collecting water.
More effective use of rainfall
Conservation tillage methods that leave the soil intact; timely weeding and mulching and planting vegetative barriers all help to maximise green water or rainwater stored in the soil and plants as moisture. Rainwater harvesting using small earthen dams and other methods also helps maximise rainwater utility. Supplementing these practices with irrigation may produce optimal results. In Kenya, Maasai women are working with the UN Environment Programme and the World Agroforestry Centre to build rooftop catchment tanks, which provide water for their households and save women time collecting water.
Satisfying the water requirements of the future, while also coping with population growth, increasing consumption, persistent poverty and a changing climate, will take a commitment well beyond what has materialised to date. Support — and research and investment — from governments, development agencies and international and national NGOs can help make such technologies more accessible to smallholder farmers.
Crossposted from the Worldwatch Institute’s Nourishing the Planet.