A tree that is almost perfectly complementary to crop growing, doubles and even triples crop yields, and thrives in dry areas, is being rolled out across Kenya in a drive to use the ‘fertiliser tree’ to regenerate soils so poor they are damaging agricultural output and human health. In Zambia, where over 160,000 farmers are using the Faidherbia Albida tree over an area of 300,000 hectares, unfertilised maize yields are averaging 4.1 tonnes per hectare when planted near the tree, compared to 1.3 tonnes per hectare for those grown away from the tree’s canopy. Now, some 2,200 farmers from Eastern and Western Kenya are piloting the planting of the tree, which also conserves soil moisture and provides fodder feed for livestock. (...)

The article:
http://www.businessdailyafrica.com/-/539444/1171952/-/122lfrcz/-/

Basic information:
http://en.wikipedia.org/wiki/Faidherbia_albida
http://it.wikipedia.org/wiki/Faidherbia_albida
http://www.plantzafrica.com/plantefg/faidalb.htm
http://www.worldagroforestrycentre.org/sea/Products/AFDbases/AF/asp/SpeciesInfo.asp?SpID=1