UC Berkeley Professor’s Research 
Allows for Increased Crop Yield 

AMANDA PAUL / Daily Cal 15mar02

New Methods Target Soil of Sub-Saharan Africa

After 10 years of researching the causes of low crop turnout in Sub-Saharan Africa, UC Berkeley professor Pedro Sanchez has made huge strides in the fight for hunger.

Sanchez's findings, published today in Science magazine [Soil Fertility and Hunger in Africa Science v.295, n.5562, 15mar02], are the result of his research in Nairobi at the International Center for Research Agroforestry. He is teaching in the Department of Environmental Science, Policy & Management.

Sanchez discovered that the low crop yield in Africa is the result of low levels of phosphorus and nitrogen in the soil. He proceeded to implement three widely accessible methods of soil replenishment, which significantly increased crop yield.

For 10 years, Sanchez traveled throughout Africa collecting data that overwhelmingly substantiated his claims that low levels of phosphorus and nitrogen caused the depleting food supply. Collaborating in the research are UC Berkeley professors Gary Sposito and David Zilberman.

Sanchez said the soil in Sub-Saharan Africa lacks nitrogen and phosphorous because farmers cannot afford to restore the nutrients the crops naturally consume. Fertilizers which would restore the soil are expensive, Sanchez said.

Poor road infrastructure compounds the problem by making fertilizers difficult to transport. In addition, the government does not offer adequate funding for soil maintenance, he said.

According to Sanchez's article, three main methods of soil replenishment are used in combination or individually to get successful results.

The first method involves interplanting leguminous trees with young maize crop. The trees grow at a slow pace, so they do not inhibit the growth of the corn.

After harvesting the corn, the farmers leave the trees to grow and get nitrogen from the air to replenish the soil. Then they cut the trees, leaving the remnant nitrates to absorb into the soil.

The second method uses abundant amounts of crushed rock phosphates found in eastern and southern Africa to restore the soil.

The third method transfers pieces of the Mexican sunflower shrub Tithonia diversifolia along with the crops.

The effects of these methods, which many farmers in the sub-Sahara have adopted since his intervention, have shown significant improvement.

"They tell me they are not hungry anymore, and that they can help their neighbors," he said.

But there are several limitations to these methods, such as the limited availability of rock phosphate and the incompatible strains of T. diversifolia.

"We have seen improvement among the 100,000 to 500,000 farmers that have used these soil replenishment programs, but we need to be affecting the millions," Sanchez said.

The Kenyan and Zambian governments have contributed funds to benefit agriculture, but they have not been sufficient, he said. Sanchez is hopeful that wealthy nations like the United States will contribute to the effort, based on the effectiveness of his discovery.

Currently, Sanchez is teaching a sociology class that explores trends and determinants of poverty with an urban focus.

source: http://www.dailycal.org/article.asp?id=8042 15mar02