One by one, Ali Kassim pulls out the weeds that have grown in his rice paddy. It's surprisingly rare in Africa, but he is cultivating African rice - once close to extinction after it was pushed aside centuries ago for a higher-yield imported Asian variety.

Researchers hope to see more and more farmers like Kassim, who is 32 and among about 100 people in Togo's central Atakpamey region to take part in an experimental programme led by the Africa Rice Centre (AfricaRice), based in neighbouring Benin.

In the small west African country, experts are seeking to change the farming habits of a whole continent by reintroducing African rice, or Oryza glaberrima, in the hope of scaling down food crises.

Cultivated for about 3,500 years and then close to extinction, African rice was abandoned by most farmers in favour of the Asian variety, Oryza sativa, which has a higher yield and has been imported for about 450 years.

But the local rice is more nutritious and researchers are currently working on ways of producing a strain with a higher yield that could enable an increase in production across the continent, which imports most of its rice.

"The principal objective (...) is to achieve self-suffiency in Africa in the matter. We are therefore giving priority to the yield, so that the new African rice can be more competitive against its Asian kin," said Moussa Sie, head of the research programme.

With production largely outdone by growing demand, Africa imports 40 percent of the rice it consumes, at the cost of 3.6 billion dollars (2.8 billion euros) in 2008, according to the Africa Rice Centre report for that year.

Africa's dependency poses risks such as during the global food crisis of 2008, when a hike in the prices of basic commodities caused food shortages and riots all over the world.

"The basic ingredients exist for another episode like the one in 2008," warned Papa Abdoulaye Seck, director general of AfricaRice, in an interview last April. "Global rice stocks are low, and El Nino threatens rice production in countries like Thailand and the Philippines."

"Moreover, despite significant increases in domestic cereal production in many countries during 2008 and 2009, Africa continues to depend heavily on food aid and global cereal markets for its leading food staples, rice and maize," he added.

- 'A revolution for our agriculture' -

Nevertheless, according to AfricaRice, this cereal is now the main source of food in west Africa, where its consumption has grown annually by 4.5 percent from 1961 to 2006.

The new African rice, which researchers are now testing in experimental paddies, is a mixture of the two, with a majority of African genes, according to Moussa Sie.

"The main complaints that were made against African rice were laying, which is a tendency of the plants to lie down when the grains were ripe, and shedding, when ripe grains fall off at maturity," explains Marie Noelle Ndjiondjop, a geneticist at AfricaRice.

"The idea of these experimental fields is to try out different cultures in order to assess the successes and limits of our research in the field," she added.

According to Moussa Sie, "only spreading the culture of the new African rice can provide an appropriate response to the famine which is raging in our region."

Niger is currently hit very hard by a food crisis, with millions of people struck by drought, who have lost their harvests and their cattle, according to agencies of the United Nations.

The Africa Rice Centre pays farmers for taking part in its programme and gives them seed.

For rice-grower Ali Kassim, the first results already seem satisfactory.

"What we see is that this gives a great deal," he said. "The rice that comes out after the harvest, when it's sent to the mill to be husked, it doesn't break.

"That's the reason why we think this is a revolution for our agriculture," he said.