By Paul Stapleton, allafrica.com, December 6, 2011
The fertiliser tree, Faidherbia albida, is inter-cropped with maize in southern Tanzania.
Climate-smart agriculture seems to be a buzz term at the U.N. climate change talks this year, and there is considerable discussion about how agriculture (a large emitter of greenhouse gases) now has to be part of the solution to climate change, and not just part of the problem.
For Dennis Garrity, Drylands Ambassador for the United Nations Convention to Combat Desertification (UNCCD) and former Director-General of the World Agroforestry Centre, this is welcome news. For several years now he has been championing the term "Evergreen Agriculture" as a viable science-based approach to increasing smallholder productivity under a more variable climate, and at low marginal costs to poor farming families.
Garrity's vision is of a future where much of our annual food crop production occurs under a full canopy of trees. And in a number of countries in Africa, this vision is on its way to being realised, with extremely encouraging results in terms of higher food crop yields and restoration of degraded soils.
The challenge that lies ahead is to extend these practices to millions of other poor farmers who desperately need homegrown solutions to their food production problems.
Through Evergreen Agriculture, particular types of trees are intercropped in annual food crop and livestock systems. As with most forms of agroforestry, the trees offer multiple benefits to farmers. They can provide sources of green fertiliser to build healthier soils and enhance crop production, increase soil fertility by fixing nitrogen in their roots, and provide fruits, medicines, livestock fodder, timber and fuelwood.
Additionally, trees grown on farms have environmental benefits in the form of shelter, erosion control, watershed protection, water retention and increased biodiversity. Carbon storage both above-ground and below-ground is greatly enhanced compared to conventional agriculture, thus improving opportunities for rewards in the form of agricultural carbon offsets for farmers. Agroforestry can also enhance resilience to climate variability and climate change.
FERTILISER TREES
In Africa, the most promising results of Evergreen Agriculture are coming from the integration of fertiliser trees into cropping systems. These trees improve soil fertility by drawing nitrogen from the air and transferring it to the soil through their roots and leaf litter. Scientists have been evaluating various species of fertiliser trees for many years, including Sesbania, Gliricidia, Tephrosia and Faidherbia.
The indigenous African acacia (Faidherbia albida) is perhaps the most remarkable of these fertiliser trees. Faidherbia sheds its nitrogen-rich leaves during the early rainy season and remains dormant throughout the crop-growing period. The leaves grow again when the dry season begins. This makes it highly compatible with food crops, because it does not compete with them for light, nutrients or water during the growing season: only its bare branches spread overhead while the food crops grow to maturity.
In Niger, satellite imagery shows close to 5 million hectares of land covered by Faidherbia albida. Millet and sorghum production has been significantly enhanced on these fields where up to 160 trees are grown per hectare.
In Malawi, maize yields have increased up to 280 percent when they are grown under the canopy of Faidherbia trees. In Zambia, 160,000 farmers have extended their conservation farming practices to include the cultivation of food crops within agro-forests of Faidherbia trees. Extensive observations have indicated that growing maize in the vicinity of the trees dramatically increases production, and the health of the soils is improved.
RE-GREENING THE SAHEL
As scientists, development practitioners and farmers seek innovative solutions to transform the way agriculture currently operates, there is increasing attention on practices like Evergreen Agriculture. And during Agriculture and Rural Development Day at COP17, Garrity and co-hosts from the African Development Bank (AfDB) and the International Fund for Agricultural Development (IFAD) shared the latest findings on its performance.
In western Africa, farmer-managed natural regeneration of indigenous trees on farmlands is spreading across semi-arid farmlands in the region, especially in Niger, where medium-to-high density systems of Faidherbia albida and annual crops occupy over five million hectares, and are diffusing rapidly across the country.
"Farmers are also using the approach in Burkina Faso, Mali and other countries," said Garrity. Its clear impact has stimulated a new commitment to the re-greening of the Sahel among donors and countries.
Evergreen Agriculture is emerging as an affordable and accessible science-based practice which is both climate-smart and able to increase smallholder food production. There is an urgent need to refine, adapt and extend this approach, not just in addressing climate change, but also to drastically improve the incomes and livelihoods of smallholder farmers and help meet the challenge of feeding the world's projected population of 9 billion by 2050.
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