干旱区生态环境知识资源中心

Food security is a concern in many parts of the tropics, but it is an acute problem in a band of countries bordering the Sahara desert on the south-Sub- Saharan Africa. Crop productivity and production, stability, and resilience to adverse events seem to be diminishing with time. Low productivity is related to both adverse soil conditions and insufficient rainfall amounts and distribution. Portions of the region receive substantial amounts of rainfall, yet much is lost during intense storms. A rainfall capturing technology "Amenagement en courbes de niveau’’ (ACN), a variant of closely spaced, narrow-base terraces, has been developed in Mali and has proven beneficial in several West African countries. A field where ACN had been installed was instrumented to quantify the effects of ACN on soil/water availability. Capacitance probes were installed to 160 cm so that soil moisture measurements could easily be taken two to three times a week during 2 years-2003 and 2004. Soil moisture profiles indicated that substantially more water was retained in soils where the ACN technology was installed than where it was not present. The ACN technology led to increased soil moisture during the first month of rains. However, the differences in soil moisture were greatest at the end of the rainy season when soil moisture of the subsoil was much greater where the ACN technology had been implemented. Moisture contents were greater in the soil profile 80-160 cm with values ranging 0.18-.21 cm(3) cm(-3) compared to 0.15 in the No-ACN plots.