A salt lick to fertilize soils

Kanwa' is a mineral salt that is extracted from the subsoil in northeastern Nigeria. It is transported to the sub-humid zone of the country where it is sold to Peuhl Pastoralists who use it to supplement their cattle feed. According to a recent study of the International Livestock Centre for Africe (ILCA), ' Kanwa ' can also be used as a fertilizer. It contains a wide variety of elements, such as phosphorus and copper, which are missing in certain Nigerian soils. ILCA researchers have also analysed its effect on plant growth. Trials with plots of Stylosanthes hamata, a nitrogen-fixing forage, have been quite encouraging. Another point in favour of kanwa is its low price: between 8-10 naira (about US $ 10-12.50) per 100 kilos (220 pounds). Used in conjunction with phosphorus to fertilize nitrogen-fixing crops, it could improve agricultural productivity at less cost than commercial nitrogen fertilizers. Before promoting the use of kanwa as an inorganic fertilizer, however, research must be continued to estimate Nigeria's reserves of kanwa, to determine the optimum doses for different crops and soils, and to compare the costs and benefits of this new use of a mineral salt traditionally used to supplement cattle feed. For further information, consult: ''Kanwa cattle salt as a potential micro-nutrient fertilizer in Nigeria's Middle Belt''. ILCA Bulletin 22. P.O. Box 5689 Addis Ababa, ETHIOPIA'Kanwa' is a mineral salt that is extracted from the subsoil in northeastern Nigeria. It is transported to the sub-humid zone of the country where it is sold to Peuhl Pastoralists who use it to supplement their cattle feed. According to a recent..