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News Release

January 6, 2010


Mark Shwartz, Woods Institute for the Environment: (650) 723-9296,

Ashley Dean, Program on Food Security and the Environment: (650) 723-4920,

Solar-powered irrigation systems improve diet and income in rural sub-Saharan Africa, Stanford study finds

Solar-powered drip irrigation systems significantly enhance household incomes and nutritional intake of villagers in arid sub-Saharan Africa, according to a new Stanford University study to be published in the Proceedings of the National Academy of Sciences (PNAS). The  study found that solar-powered pumps installed in remote villages in the West African nation of Benin provide a cost-effective way of delivering much-needed irrigation water, particularly during the long dry season. The results are scheduled to be published the week of Jan. 4 in the online edition of PNAS.

"Our case study on women's farming groups in rural Benin revealed solar-powered drip irrigation – a clean, cost-competitive technology – significantly improved nutrition and food security as well as household incomes in one year," said lead author Jennifer Burney, a postdoctoral scholar with the Program on Food Security and the Environment at Stanford.

"Solar-powered drip irrigation systems break seasonal rainfall dependence, which typically limits farmers to a three- to six-month growing season, and support the production of diversified, high-value crops in rural Africa," Burney added.

She and her co-authors noted that much of sub-Saharan Africa's rural population is considered "food insecure," surviving on less than $1 per person per day. "And whereas most are engaged in agricultural production as their main livelihood, they still spend 50 to 80 percent of their income on food, and are often net consumers of food," they wrote.

Benin pilot project

In 2007, with support from Stanford's Woods Institute for the Environment, Burney and her colleagues partnered with the nonprofit Solar Electric Light Fund (SELF) on a pilot irrigation project in rural Benin. SELF financed and led the installation of three solar-powered drip irrigation systems in two villages in Benin's Kalalé district. Each system is used by a local women's agricultural group, which typically consists of 30 to 35 women who share the maintenance costs of the new irrigation technology.

"In Kalalé, 80 percent of the villagers live on less than $1.25 per day, which is representative of a number of poor, rural communities in Africa," said study co-author Rosamond Naylor, director of the Program on Food Security and the Environment and a professor of environmental Earth system science at Stanford.

In rural Benin, women and girls traditionally are responsible for hauling water by hand, often from very long distances. The solar-powered irrigation systems were designed to free them from hauling water to grow vegetable crops, particularly during the dry season.

To measure the impact of the solar-powered drip irrigation technology, the researchers monitored the agricultural groups using the new irrigation systems, as well as two "control" villages where women continued growing vegetables in traditional hand-watered gardens. Household surveys were conducted at the start of the project in November 2007 and again in November 2008.

Nutrition and income

The results were striking. "In just one year, we saw that photovoltaic drip irrigation systems had important implications for food and nutrition security, as well as household income," Burney said.

The three solar-powered irrigation systems supplied on average 1.9 metric tons of produce per month, including such high-valued crops as tomatoes, okra, peppers, eggplants and carrots. In villages irrigated with solar-powered systems, vegetable intake increased to three to five servings per day – the U.S. Department of Agriculture's Recommended Daily Allowance for vegetables – with most of the improvement taking place during the long dry season. In a world where 20 to 25 percent of global disease burden for children is due to malnutrition, such improvements could have a large impact over time, Burney said.

"Seventeen percent of project beneficiaries reported feeling less food insecure, demonstrating a remarkable effect on both year-round and seasonal food access," Naylor added.

As for household income, the authors found that women who used solar-powered irrigation became strong net producers of vegetables and earned extra income from sales, allowing them to significantly increase their purchases of high-protein food and other staples during the dry season.

Project benefits quickly spread to other community members, Burney said. For example, an elementary school curriculum was developed to help village children learn about the benefits of solar drip technology. "There was an overwhelming sense of pride in the new system by teachers, children and women participating in the farmer groups," she added.


Each solar-powered drip irrigation system is about 1.24 acres (0.5 hectare) in size, costs approximately $18,000 to install and requires about $5,750 a year to maintain, the authors said. Based on the projected earnings of the farmers, the system should pay for itself in about 2.3 years, they concluded. And despite higher up-front costs, the durable solar systems should be more economical in the long run than less expensive irrigation systems that use gasoline, diesel or kerosene pumps, with the added benefit of being emissions free, they added.

Focusing on novel irrigation technologies for farmers could be the needed tool for escaping poverty in sub-Saharan Africa, according to Burney. "The photovoltaic irrigation drip system could potentially become a 'game changer' for agricultural development over time," she added.

"Solar-powered irrigation provides a cleaner source of energy that is less susceptible to global price fluctuations," Naylor said. "Improved agricultural productivity in the developing world can play a critical role in global poverty alleviation, and productivity-enhancing technologies provide a sense of hope for persistently poor households."

Other co-authors of the PNAS study are Lennart Woltering and Dov Pasternak of the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in Niger and Marshall Burke of the Department of Agricultural and Resource Economics at the University of California-Berkeley.

The research was supported by an Environmental Ventures Projects grant from the Woods Institute for the Environment at Stanford. The Program on Food Security and the Environment is jointly run by the Woods Institute and the Freeman Spogli Institute for International Studies at Stanford.

Ashley Dean is communications manager at the Program on Food Security and the Environment at Stanford University.




Jennifer Burney, Program on Food Security and the Environment: (650) 721-6684,

Rosamond Naylor, Program on Food Security and the Environment: (650) 723-5697,

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