The faidherbia albida is a species of tree native to Africa. For thousands of years it has been recognised in countries such as Ethiopia and in West Africa as a very beneficial tree and now appreciation of this tree has spread to Zambia and Malawi.
Although many species show promise in agroforestry, Faidherbia albida, an indigenous acacia-like tree is particularly beneficial in two ways. At the recommended planting density of 100 trees per hectare, mature Faidherbia albida trees supply equivalent 300kg of complete fertiliser and 250kg of lime, which result in an estimated 250-400% yield in increase in maize under a tree canopy. In addition, Faidherbia display the unusual trait of reverse phenology. This means that they leaf up in the dry season and defoliate in the rains, the reverse of the common growth pattern and thus reducing competition for sunlight with rain-fed crops (such as maize, a common crop in countries like Zambia) which are grown underneath the trees so as to benefit directly from improved soil fertility.
For more on the faidherbia albida tree: http://www.plantzafrica.com/plantefg/faidalb.htm
For more on agroforestry and its use for environmental sustainability: http://www.worldagroforestry.org/newsletter_?news=7
Green Musing 