Promoting Sustainable Intensification of Agricultural Dryland Production and Combating Desertification in the Sahel
Four West African Sahel countries (Burkina Faso, Mali, Niger and Senegal) and two East African countries (Kenya and Tanzania) joined efforts in a cooperative venture under the IAEA regional TC project RAF/5/048 to combate desertification in dryland agriculture.
The project demonstrated using the 13C natural abundance technique in Burkina Faso and Mali that trees play a key role in the maintenance of soil organic matter in the parklands by contributing up to 50% of total soil carbon and hence have a marked influence on crop productivity in the dry savannahs of West Africa. In Niger, two commercially-available water absorbent products increased soil water storage from applied irrigation and lettuce production by 1.9- 2.4 times over the control, thus helping to boost income while conserving scarce irrigation water resources. In Mali and Tanzania, the use of soil moisture neutron probes demonstrated that tillage on contours enhanced storage of rainfall water in the soil profile (22% average increase) and increased millet biomass and grain yields by 33-50%.
In Burkina Faso, growing sorghum after peanut or cowpea crops consistently produced higher yields than cereal mono-cropping (average 0.7 t ha-1). This increase was attributed to N supply from peanut or cowpea crops as well as disease breaks, improved soil structure and water saving. A similar study with pigeon peas and maize is underway in Kenya. In Senegal, the plant availability of phosphorus from local Taiba rock phosphate was increased by composting with locally-available organic materials (phospho-compost). Under rainfed semi-arid conditions, application of this fertiliser increased millet crop yields by 29 to 57% in sandy soils with low P fertility.