Putting trees on farms fundamental to future agricultural development

Trees growing on farms will be essential to future development. As the number of trees in forests is declining every year, the number of trees on farms is increasing. Marking the launch of the International Year of Forest by the United Nations Forum on Forests (UNFF9) in New York on 29 January, Dennis Garrity, the Director General of the World Agroforestry Centre, highlighted the importance of mixing trees with agriculture, the practice known as agroforestry.

“Over a billion hectares of agricultural land, almost half of the world's farmland, have more than 10 percent of their area occupied by trees,” said Garrity, “and 160 million hectares have more than 50 percent tree cover.”

Growing trees on farms can provide farmers with food, income, fodder and medicines, as well as enriching the soil and conserving water. As natural vegetation and forests are cleared for agriculture and other types of development, the benefits that trees provide are best sustained by integrating them into agriculturally productive landscapes.

Speaking at the High Level Dialogue of UNFF9 on 3 February 2011, Garrity said, “Agroforestry is a crucial bridge between forestry and agriculture. Essentially, agroforestry is about the role of working trees in agricultural landscapes, particularly on, but not limited to, small-scale farms.”

Over the next two decades, the world's population is expected to grow on average by more than 100 million people a year. More than 95 percent of that increase will occur in the developing countries, where pressure on land and water is already intense. A key challenge facing the international community is, therefore, to ensure food security for present and future generations, while protecting the natural resource base on which we all depend. Trees on farms will be an important element in meeting those challenges. In some regions, such as Southeast Asia and in Central America, tree cover on agricultural lands now exceeds 30%.

“The transformation of agriculture into agroforestry is well under way across the globe,” said Garrity. “And there are drivers, including climate change, that ensure that this transformation will accelerate in the coming years, since agricultural systems incorporating trees increase overall productivity and incomes in the face of more frequent droughts, and agroforestry systems provide much greater carbon offset opportunities than any other climate mitigation practice in agriculture.”

In many countries, it is now quite clear that the future of forestry is on farms. In countries such as India, Kenya, and many others, the majority of the nation's wood is derived from farm-grown timber.

Practiced by farmers for millennia, agroforestry focuses on the wide range of working trees grown on farms and in rural landscapes. Among these are fertilizer trees for land regeneration, soil health and food security; fruit trees for nutrition; fodder trees that improve smallholder livestock production; timber and fuelwood trees for shelter and energy; medicinal trees to combat disease; and trees that produce gums, resins or latex products.

Reinventing agriculture

Evergreen Agriculture is a form of agroforestry that integrates trees with annual crops. “We see Evergreen Agriculture as nothing less than the radical, but entirely practical, pathway to a reinvention of agriculture,” said Garrity. “It is a vision of a future in which much of our food crops will be grown under a full canopy of trees.”

Combining fertilizer trees with conservation farming techniques is doubling and tripling cereal crop yields in many parts of the African continent. The nitrogen-fixing tree Faidherbia or Acacia albida, is increasing unfertilized maize yields in Malawi, Zambia, Tanzania, Ethiopia, and in numerous other countries. They are now being grown on millions of hectares of crop land throughout Niger, at densities of up to 200 trees per hectare, and show a tripling of yield in the crops growing beneath them. Producing food crops like maize, sorghum, and millets under these agroforests dramatically increases their drought resilience in dry years, because of positive soil moisture regimes, and a better microclimate.

This development is not happening only in Africa. The South Asia Network of Evergreen Agriculture has been launched to advance an evergreen revolution throughout the subcontinent.

Feeding the hungry

Planting trees that provide natural fertilizers on farms with poor soils helps farmers restore fertility and increase yields. Gliricidia bushes fix nitrogen in their roots and act as natural green fertilizer factories, tripling yields of maize on farms in Malawi. The prunings are fed to the animals. The bushes also reduce the risk of crop failure during droughts and prevent waterlogging when it rains too much. The nitrogen-fixing tree Faidherbia increased unfertilized maize yield four times in Zambia. The trees are being grown on over 5 million hectares of crop land in Niger.

Relieving poverty

Domesticating wild fruit trees in the Cameroon has allowed smallholder farmers to increase their earnings five times. Thousands of farmers in Tanzania are planting Allanblackia trees and earning much-needed income by selling the oil-containing seeds to companies to make margarine.

Trees grown on homestead farms, in woodlots and on communal lands are an important source of wood and other products. In humid-zone West African countries, Burundi, Rwanda and Uganda in particular, trees grown in home gardens meet most household needs for fuelwood and timber. In many cash-crop systems, trees are grown for shade and eventually provide wood – an example is Grevillea robusta in tea plantations in Kenya. In the Sudan, Acacia senegal, the source of gum arabic, is largely grown in agroforestry systems.

Accumulating carbon

Investments in agroforestry over the next 50 years could remove 50 billion tonnes of additional carbon dioxide from the atmosphere. Most of the deforestation in Africa, and in parts of Asia, is caused by agricultural expansion, largely by smallholder farmers. Agroforestry activities curb emissions of greenhouse gases by slowing the conversion of forest to farm land and holding carbon in the trees on the farms. Developing smallholder agroforestry on land that is not classified as forest could capture 30-40 percent of the emissions related to land-use change. Encouraging farmers to plant trees has the potential to increase farmers' income, sequester more carbon and benefit biodiversity.

“The International Year of Forests is a momentous opportunity to more fully recognize the tremendous importance of agroforestry and evergreen agriculture in building a better world,” noted Garrity. “Agroforestry is one of mankind's best hopes to create a climate smart agriculture, increase food security, alleviate rural poverty, and achieve truly sustainable development. And, thereby, better ensure that our world's forests can indeed be conserved far into the future.”

The World Agroforestry Centre, based in Nairobi, Kenya is the world's leading research institution on the diverse role trees play in agricultural landscapes and rural livelihoods. As part of its work to bring tree-based solutions to bear on poverty and environmental problems, centre researchers—working in close collaboration with national partners—have developed new technologies, tools and policy recommendations for increased food security and ecosystem health.