Sub-Saharan Africa

In Sub-Saharan Africa, one of the major reasons for declining per capita food production has been low fertilizer use. Agriculture, as practiced by small farmers, has primarily been of a subsistence nature, and continuous cropping without adding any fertilizers has left the soil depleted of organic matter and nutrients. From many studies, it has been concluded that the small family farms in Africa can produce a sizable surplus of food grains such as maize, sorghum, cowpea, and soybean through additions of phosphorus and other nutrients. Several projects set out to demonstrate just that potential, for example :

	Fertilizer investment for soil fertility restoration in west africa
	Etude du phosphore naturel du togo - brut et partiellement attaqué - en région maritime, des plateaux et centrale
	Influence de l'apport de paille et de composés organiques modèles, sur l'assimilabilité des ions po4 dans différents types de sol: conséquences sur la fertilisation phosphatée

The use of rock phosphates as phosphate sources for growing Zebu cattle in Sahelian rangelands has been evaluated.

Rock Phosphates as a phosphorus source for growing Zebu Cattle in Sahelian Rangelands

Mineral deficiencies are serious constraints to animal health and livestock productivity in sub-Saharan regions of West Africa. To overcome those negative effects, prevention plans require ruminants to have mineral supplementation using good quality mineral supplements, but these are not often available in production sites.

Although potentially toxic and of variable quality, rock phosphates appear to be natural mineral sources, locally available, and can be explored for improvement of calcium and phosphorus levels in ruminants diets. The nutritional efficiency of these rock phosphates is tested in the Ferlo area in the Sahel. Large variations in phosphate quality were observed, suggesting a great diversity between mines. Characterization of existing phosphate mines in Senegal, of potential toxicity of their rock phosphates and of possible use of this rock as phosphorus supplement in cattle feed were the objectives of the study conducted on Gobra Zebu bulls raised in the experimental station of the semi-arid rangelands of Senegal.

The cattle showed good tolerance to intake of phosphate rock at the applied diet. Bone storage and urinary elimination of fluorine appeared to be the major physiological mechanisms of cattle for resisting any fluorine toxicity that may be associated with rock phosphates intake. Accordingly, cattle daily consumption of phosphate rock, up to 50g of Taiba and 200g of Thiès, did not have any harmful effects on male Gobra Zebu.

The prescribed diets of rock were not dangerous to zebu cattle raised on the station and under good conditions. The results suggest rock phosphate diets need to be tested on traditionally- raised herds over a longer period of time to demonstrate any beneficial effect of rock phosphates intake on animal performance.

IMPHOS started on-farm trials on 144 dairy cows to demonstrate the beneficial effects of mineral supplements fed to dairy cows in Sahelian rangelands of Senegal.

Four mineral recipes were tested :
Rock phosphate + Salt
Rock phosphate + Salt + micronutrients
Rock phosphate + Salt + micronutrients + molasses
Rock Phosphate + Salt + micronutrients + molasses + urea

Three formulations, powdery, granule or licking blocks, were also compared.
The following promising results were obtained:
Phosphate rock supplements to animal feed didn't cause any visible health damage.
Several factors affected the consumption of mineral supplements, which include form of supplement, animal status, grazing period and grazed lands. But mineral supplements were well consumed by most of the tested animals.
Overall, supplementation with phosphate rock resulted in positive effects on animal's survival and milk production, which continued during almost the whole dry season. Inversely, extensively raised dairy cows without mineral supplement stopped producing milk few weeks after the onset of the cold dry season. Continuous milk production of during the cold dry season is therefore a worthwhile improvement in dairy cows performance under the Sahelian conditions.
Mineral supplementation also improved animal reproduction rate, as each cow bears one calf every year.

To help the marketing of the developed mineral formulas, the above promising results were disseminated through appropriate audiovisual media. In addition, frequent meetings were held between livestock farmers and their technical advisors in order to review annually the results from the conducted experiments, including:

Development of 4 diet formulas that had positive effects on animal survival, reproduction and milk production rates in the Ferlo region.
Production of a documentary aired through the Senegalese TV.
Training of 36 livestock farmers on mineral supplementation techniques. These trainees constitute the first small group that will be asked to contribute to disseminating the mineral supplementation technology developed by the project.