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News Service

News Service:

Annette Hacker, manager,
(515) 294-3720

Office: (515) 294-4777

10-27-04

Contacts:

Andrew Manu, Agronomy, (515) 294-5510

Melea Reicks Licht, Agronomy, (515) 294-1890

Teddi Barron, News Service, (515) 294-4778

Iowa State University agronomy researcher controls erosion to save the African Sahel

AMES, Iowa -- An Iowa State University agronomy professor is using erosion control methods to restore the Sahel and Niger River in West Africa.

Andrew Manu, associate professor of soil science, has been working with the people of Niger to restore degraded lands in the Sahel, the region of West Africa that separates the Sahara Desert from the savannah. Land degradation is threatening the economic stability of the region.

"There is hope in the Sahel," Manu said. "We can restore the Sahel and make it work for the people."

Manu will present his findings at the 2004 international annual meetings of the American Society of Agronomy, Crop Science Society of America and Soil Science Society of America in Seattle, Wash., Oct. 31 to Nov. 5.

The Sahel has degraded because large human and livestock populations and increased cultivation have reduced native vegetation in the area. As a result, excessive runoff has increased erosion and decreased soil fertility. Sediment carried by the runoff is deposited into the Niger River, where it creates alluvial fans--unproductive landforms made of the transported soil and rock from the Sahel. Manu and his colleagues devised a way to prevent further erosion and sediment deposits through reforestation using microcatchments.

"Microcatchments are crescent-shaped trenches, about four feet in length, built on plateaus in the path of erosion," Manu said. "The trenches catch and hold moving water and sediment,

preventing sediment from polluting the river. We plant trees and vegetation in the trenches to use

collected water, and provide extra ground cover to further reduce erosion. People in the area also use the trees for firewood and lumber and the grasses as pasture for livestock."

Manu is working with Niger's Department of the Environment and National Agricultural Institute to promote the use of microcatchments in plateaus along the river.

While the biggest impact of his work is felt in the villages of this West African country, Manu said his research has implications in Iowa.

"The world is a global village now - whatever happens in Niger affects us here in Iowa. These solutions may be used elsewhere in the future, perhaps in Iowa, to solve similar erosion problems," Manu said.

Using archived satellite imagery and modeling technology, Manu recreated the way the Niger River looked in 1973 and 1988. He compared the previous and present conditions of the river near Niamey, the capital of Niger. Manu said the Niger River was in near pristine condition in 1973; however, by 1988, some branches of the river had been closed by sediment. Today, sediment has damaged water quality and created large unproductive alluvial fans that obstruct the river.

In addition to the use of microcatchments, Manu also suggests stricter environmental regulations to prevent people from removing erosion barriers, such as trees and soil, from affected areas. Manu plans further research to study the impact of the microcatchments on soil quality in the area.

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Note to editors: Complimentary press passes to the 2004 international annual meetings of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America are available by contacting Sara Uttech, (608) 268-4948 or suttech@agronomy.org. The meetings feature scientific sessions, symposia, and research papers/posters, in addition to a full slate of technical sessions. Visit www.asa-cssa-sssa.org/meetings/acs/ for more information on the societies' annual meetings.

Andrew Manu

Andrew Manu, ISU Agronomy associate professor, has been working with the people of Niger to stop the degradation of the Sahel, which has been severely eroding into the Niger River.
For a print quality photo contact News Service at 294-3720

West Africans look over the erosion control methods used to inhibit sediment pollution in the Niger River.
For a print quality photo contact News Service at 294-3720

Sedimentation in the Niger River has decreased soil fertility and threatens the economic stability of the region.
For a print quality photo contact News Service at 294-3720

Quick look

Andrew Manu, associate professor of soil science, has been working with the people of Niger to restore degraded lands in the Sahel, the region of West Africa that separates the Sahara Desert from the savannah. Manu and his colleagues devised a way to prevent further erosion and sediment deposits through reforestation using microcatchments.

Quote

"There is hope in the Sahel. We can restore the Sahel and make it work for the people."

Andrew Manu,
associate professor
of soil science