Farmers across West Africa are improving food production with a low-cost, low-tech method of irrigation that uses gravity to deliver water right where plants need it. 

Farmers in the Senegalese village of Keur-Yaba use sticks to tap thin plastic pipes running across their fields.  The tapping helps water drip slowly through holes in the pipes above green seedlings in a field of dry earth.

Amadou Diallo waters a crop of lettuce for a Senegalese employer in one of the few patches of agricultural land located within Senegal's capital, Dakar (File)It is a low-cost, low-pressure method of irrigation that is already in use in Niger, Burkina Faso, Ghana, and Benin.  By improving the efficiency of what little water is available, farmers are able to shift away from growing grains to producing fruits and vegetables - far higher-value crops that can bring 20 times the revenue.

"In order to produce those high-value crops, one needs to have a good, simple, sustainable and effective system to produce those crops," said Dov Pasternak, who heads the crops and systems diversification program forthe non-profit International Crops Research Institute for the Semi-AridTropics.  "And for this reason, I have developed a system which I call the Africa Market Garden."

Pasternak's system uses low-pressure, solar-power pumps to bring water to barrels raised on blocks.

"What I do, I elevate the water one to five meters above the field," said Pasternak.  "Using this gravity, the water goes down to the field and it irrigates the field."

In Keur-Yaba the non-governmental organization Green Senegal is using drip irrigation in a project funded by the Israeli and Senegalese governments. Each farmer tends 500 square meters of land growing onions, cucumbers, and okra.

Green Senegal's Alioune Diouf says drip irrigation has more than tripled production while reversing the exodus of farmers leaving Keur-Yaba for jobs in the city.

"Before, some farmers here were working in the city, like Dakar," said Diouf.  "But since we have the project, they come back to the village, and they do not need now anymore to go to Dakar to do another job."

Farmers in the program share responsibility for tending a plot dedicated to the local school.  Diouf says that not only improves nutrition at the school, but raises interest among children about how their food is grown.

"Children can follow once a week what is going on in the field, and if after the end of school they want to do gardening, the can do some themselves," added Diouf.

By bringing water directly to each plant, drip by drip, Pasternak's system has a water efficiency of 98 percent, compared to just 50 percent for sprinklers.

"In many places, you do not have enough water and you want to use every drop as efficiently as you can," said Pasternak.  "If you are using drip irrigation, you are giving water to the roots of the plants.  You are not spreading it over the soil and you are not wasting."

Drip irrigation has been so successful in Keur-Yaba, that farmers here plan to include eggplant, tomatoes, and watermelon in their next planting season.