Soil-Water Management and the

Spontaneous Regeneration of Absent Species in the Sahel

Goro Uehara

Soil Management CRSP

University of Hawaii

The Soil Management CRSP and partner institutions in Mali, Senegal and The Gambia have achieved important results in the conservation of water in the rain-fed agriculture of the Sahel. The technology, originally called amenagement en courbes de niveau (ACN), loosely translated as ridge tillage, is a holistic, landscape approach to managing water and capturing rainfall. The ACN consists of points of the same levels in a given farmer's field connected to form permanent ridges (ADOs). Smaller ridges are annually drawn between the ADOs to complete the system.

The increased capture of rainfall has produced five important results:

1. Reduced drought risk to food crops,

2. Increased crop yields

3. Increased carbon sequestration.

4. Ground water recharge resulting in more reliable drinking water supplies, and

5. Increased biodiversity

Spontaneous regeneration of Faidherbia albida (Acacia albida), Adansonia digitata (boabab), Vitellaria paradoxa (shea butter), Parkia biglobosa (nere), Ficus plantyphylla (negaba), Cordyla pinnata (dugura), Terminalia albida (wolojii) and many other declining species has been observed by farmers and documented by researchers.

Because water is a major limiting biological factor in the Sahel, its redirection from surface runoff to infiltration into soils is causing unanticipated changes in the hydrology and biology of the Sahelian landscape. Scaling up of the ridge tillage systems from farms, to villages, to provincial and regional scales is underway.