Costa Rican academics are pioneering the growth of crops on freshwater lakes as a way of addressing food shortages
Ricardo Radulovich, professor of water science at the University of Costa Rica, points out that in Africa irrigation is a very limited option, due to lack of water, and rain-fed agriculture is affected by prolonged dry seasons and rainfall variability during the rainy seasons. A case in point is the Sahel in west Africa, where drought has grown increasingly frequent and where emergency aid was needed last year to forestall famine.
Yet Radulovich believes that Africa's lakes can be part of the solution to the continent's agricultural limitations. Several African countries are endowed with lakes, some very large, that occupy a surface of more than 150,000 square kilometres. Why not use that water surface to grow food and aquatic plants, and for fisheries, asks Radulovich, who began his career as an agricultural water scientist 10 years ago.
"The key issue is water," Radulovich said in a telephone interview from Costa Rica. "We have land, but water is the limiting element. You can have agriculture if you have water. If we use that lake surface to produce crops, aquatic plants, we won't waste water."
Radulovich and his team, including Schery Umanzor, have already begun prototype projects on Lake Nicaragua, where they have grown lettuce, tomato, cucumber and cantaloupe melons on floating rafts, a continuation of trials that were undertaken at sea in 2001 at the Gulf of Nicoya, on the Pacific coast. The tomato roots can trail in the water or be potted with a cotton rope dangling in the water from the pot, which draws in water to the plant.
The size of the rafts can vary, going up to six square metres, and can be made simply and cheaply, from plastic bottles, for example. Where the water is polluted by horticulture, an option is to grow flowers. One advantage of growing crops on water is that they are not as vulnerable to insects as they would be on land.
Marine agriculture offers a new solution to the problem of water scarcity
