March 18, 2013
Maize grows under a full canopy of Faidherbia albida in Tanzania. Credit: World AgroForestry Centre
Evergreen agriculture integrates trees into crop systems, helping farmers protect against drought, conserve water, improve soil fertility, and fight climate change.
Around the globe, agriculture is facing a daunting challenge: How can farmers significantly increase yields to feed the world’s burgeoning population while growing crops in depleted soils with scarce water resources and at the same time avert a 4°C warmer world?
In Africa, where soils are often degraded and most smallholder farmers cannot afford commercial fertilizers, food production needs to double by 2050 to avoid widespread starvation, even as climate change threatens to decrease crop yields by up to 50 percent.
To address these challenges, CGIAR, a consortium of 15 research centers supported by the World Bank, pursues climate-smart solutions that can sustainably reduce poverty and food insecurity. One area of that research involves evergreen agriculture — the integration of trees into crop and livestock systems. The practice is already helping millions of poor, small-scale farmers across Africa protect themselves against drought and hunger, while reducing greenhouse gas emissions, conserving water, and improving soil fertility.
The power of an acacia
The most promising results in evergreen agriculture come from the integration of Faidherbia albida trees, an indigenous African acacia, with food crops. These trees improve soil fertility by drawing nitrogen from the air and transferring it to the soil through their roots and leaf litter.
Unlike most trees, Faidherbia sheds its nitrogen-rich leaves during the early rainy season, making it highly compatible with food crops because it does not compete with them for light, nutrients, or water during the growing season. The leaves grow again when the dry season begins, after the crops have been harvested.
African farmers who have adopted evergreen agriculture are reaping impressive results without the use of costly fertilizers. Crop yields often increase by 30 percent and sometimes more. In Zambia, for example, maize yields tripled when grown under Faidherbia trees.
"I used to get about 10 bags of maize from my field," said Mary Sabuloni, a widow and mother of eight in Malawi who started planting fertilizer trees with her maize. “Now I get at least 25 bags." This has made a huge difference in her children’s lives. "In the past, we often went hungry," she says, "but now I can feed my family all year round.”
Fighting climate change
In addition to increasing farmers’ productivity and incomes, the practice of evergreen agriculture has other benefits, including:
- increasing rainwater use efficiency by up to 380 percent,
- capturing and storing up to 4 tons of carbon per hectare annually, and
- reducing up to 3.5 tons of CO2 -equivalent emissions per hectare per year.
Within the context of climate change, an increasing global population, reduced landholdings, and declining soil productivity, evergreen agriculture is not only an effective solution to complex agriculture challenges, but it is also an affordable way to achieve the triple win of increased productivity, incomes, and food security; improved resilience; and greater climate change mitigation.
In recognition of its success, research conducted on evergreen agriculture by the World Agroforestry Centre, a member of the CGIAR Consortium, recently won a UK Climate Week Award.