The world's poorest continent could offer clues to how America's farmers might cope with a hotter, drier climate, leading agriculture experts say.
In the African Sahel -- the belt of semiarid savanna running from the Atlantic Ocean to the Red Sea -- farmers have successfully fought back an expanding Sahara and turned once dry, uncultivated scrub into highly productive farmland.
The key to their success has been allowing trees to grow, where they once cut them down, and adopting agricultural techniques that took full advantage of scarce water resources (ClimateWire, March 12). Now experts say it is time for American farmers to recognize the benefits that trees can bring to even the most arid plots of land.
"Given the situation in the U.S. Corn Belt," said Chris Reij, a sustainable land management specialist at Free University Amsterdam who has worked in Africa since 1978, "these practices might help farmers in Kansas and Iowa to adapt to more extreme weather, help make their crops more resistant to drought."
The scale and mechanization of U.S. agricultural production could not be more different than in Africa. Yet the current year's drought highlights the American sector's vulnerability to extreme heat and lack of rain -- a situation not unlike the one that plagued the African Sahel for decades.
Reij points out that trees are scattered across pastures of the Sahel and are the result of natural regeneration. That wouldn't work in the United States, where farmers and ranchers tend to cultivate or graze their herds on vast, open pastures that have been denuded of trees for as long as 200 years.
Robert Winterbottom, director of the Ecosystem Services Initiative at the World Resources Institute, concurred.
"[The Corn Belt] wouldn't look like a Sahelian landscape," he said, "but it's the principles related to more sustainable and climate-smart agriculture that were applied in the Sahel rather than the specific techniques that could be of use in the U.S."
Instead, they both explained, trees could be planted in rows between crops or bordering fields, providing many of the same benefits found in Africa: improved soil and water quality and windbreaks that keep dry topsoil from going airborne.
Experimenting in Fla.
Interest in these types of techniques -- know as agroforestry -- has been on the rise in the United States in part due to two farm bill programs promoting habitat conservation and environmental quality improvements.
Between 2008 and 2010, about 13,000 riparian forest buffers -- clusters of vegetation that protect waterways from pollution and prevent bank erosion -- were created on more than 123,000 acres. During that same period, 11,000 windbreaks running a total of 4,100 miles were established. In 2007, applications to the U.S. Department of Agriculture for funding to create silvopastures -- the technique of planting trees throughout livestock grazing areas -- totaled 770 acres. In 2010, applications totaled 8,500 acres.
George Owens farms 500 acres in the Florida Panhandle. When he inherited the land from his father in 1971, he farmed in the traditional row-cropping method. Yet his is a small farm by American agricultural standards, and the technique was not economically feasible on so few acres, he said. So in the 1980s, he turned to silvopasturing.
Owens plants slash and loblolly pines on his farm. The trees run in close, parallel rows that border 40-foot-wide pastures. Amid the rows of trees and throughout his pastures, he has planted clover and Pensacola bahiagrass on which his black Angus cows feed, shaded from the hot summer sun by an ample overstory. He sells the fast-growing pines for wood.
"Because the trees provide shade, the evaporation rate is less than if you didn't have shade," he said. "Environmentally, it's probably the best system."
The trees keep his nitrogen-rich soil moist even during dry spells. The combined income from cattle and wood makes Owen's farm more economically feasible.
The trees, he added, provide "creature comfort" for his animals. The cattle that graze in the shaded areas, he said, consume more grass because they remain cool and in turn produce more bulk -- a benefit without equal to a farmer always conscious of his bottom line.
'Change, it comes slow'
Andy Mason of the National Agroforestry Center, a joint project of the Department of Agriculture and the Forest Service, said that the application of trees in agricultural production will likely be among the most important tools in helping to create more climate-resilient agricultural lands.
"What we would like everyone to remember is that trees are hard workers," he said. "Their limbs and leaves provide shade, which can ease heat stress on animals and act as windbreaks on open fields. Their fruits and nuts can provide a source of income to the landowner and food for wildlife. And their roots are natural filters between fields and water. Of course, in a larger context, they trap carbon and help make our air cleaner."
The simple, low-cost strategy of integrating trees into agricultural production, whether in the African Sahel or in the United States, has greatly improved soil and water quality. Fallen leaves or twigs inject nutrients into the soil, reducing the need for expensive fertilizers that might also pollute nearby streams or wells. Trees cool temperatures on a local scale, and their roots can often help to keep soil moist.
In the Zinder region of Niger, 5 million hectares has been re-greened, said Reij. "For crop yields, every single hectare that has been re-greened, there has been an average of 100 kilos of extra yield," he said. "That's 500,000 tons of additional crop yield -- enough grain to feed an extra 2.5 million people."
Reij estimated that there are 200 million new trees on that 5 million acres, which have boosted economic output by $240 million.
Conflicts among farmers have decreased, said Reij, as they no longer fight over scarce crop yields and as women spend less time collecting firewood.
Regreening efforts in Senegal, Mali, Malawi, Ethiopia and Burkina Faso have had similar impacts on crop yields and economic output, said Reij. Farmers and the governments of several other African nations are considering undertaking regreening initiatives, including Nigeria, where, he said, increased crop yields could help to tamp down violence in the north.
While agroforestry in the United States occupies a small niche among farmers, advocates of its expansion see the current drought as an opportunity to rethink the way land is utilized.
"When I started using this technique in 1984, nobody from the university, nobody farming thought it would work," Owens said.
"Every forester said, 'Grow trees'; every cowman said, 'Raise cows.' I thought surely I can make this work. It's a system that should be adopted by more farmers. Change, it comes slow. You got to adopt it as a system. It may take 40 years to get it going, though."