Tuesday, January 05, 2010

A solar experiment

A team of scientists conducted an experiment that looks at what improvement a solar powered drip irrigation system can have on farming yields in Africa. The researchers from Stanford University just published their findings in the Proceedings of the National Academy of Sciences. They wanted to conduct the study because the effects of improved irrigation are well known for Asia, but there is very little data for Africa.

From Science Daily we read more about the experiment.

Burney and her co-authors noted that only 4 percent of cropland in sub-Saharan Africa is irrigated, and that most rural, food-insecure communities in the region rely on rain-fed agriculture, which, in places like Benin, is limited to a three- to six-month rainy season.

"On top of potential annual caloric shortages, households face two seasonal challenges: They must stretch their stores of staples to the next harvest (or purchase additional food, often at higher prices), and access to micronutrients via home production or purchase diminishes or disappears during the dry season," the authors wrote.

In November 2007, the research team began a close collaboration with local women's agricultural groups in two villages in rural Benin. In Village A, which draws surface water from a year-round stream, researchers worked with residents to install two identical solar-powered pumping systems. In Village B, which relies on groundwater irrigation, water was pumped from 25 meters (82 feet) below the surface. Each solar-powered pumping system was used by 30 to 35 women affiliated with an agricultural group. Each woman farmed her own 120-square meter (1,292-square foot) plot. The remaining plots were farmed collectively to fund group purchases and expenses.

The researchers also chose two control villages for comparison with Villages A and B. Women's agricultural groups in the control villages continued to irrigate by hand, allowing for comparison of the solar-powered drip irrigation systems to traditional methods. "Household surveys were conducted in both treatment and control villages upon installation (November 2007) and following one year of garden operation (November 2008), and included detailed questions concerning consumption and agricultural production, as well as other socioeconomic, health and general questions," the authors wrote.

Striking results

The results were striking. The three solar-powered irrigation systems supplied on average 1.9 metric tons of produce per month, including tomatoes, okra, peppers, eggplants, carrots and other greens, the authors found. Woman who used solar-powered irrigation became strong net producers in vegetables with extra income earned from sales -- significantly increasing their purchases of staples and protein during the dry season, and oil during the rainy season. During the first year of operation, the women farmers kept an average of 18 percent by weight -- 8.8 kilograms (19.4 pounds) per month -- of the produce grown with the solar-powered systems for home consumption and sold the rest in local markets.

"Garden products penetrated local markets significantly," the authors found. "Vegetable consumption increased during the rainy season (the time of greatest surplus for the women's group farmers) for the entire four-village sample of households."

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