Micro-basin technology in Ethiopia - is it worth the effort?

Micro-basin technologies such as tied-ridge tillage have been proposed as a means to lessen effects of high rainfall variability on crop yields. Relationships between three seasonal climate variables and maize/sorghum yields and two tillage systems were examined for a semi-arid environment in the Central Rift Valley of Ethiopia. The average yield (pooled data) was significantly higher with tied-ridge tillage compared to traditional tillage (3099 vs. 2669 kg/ha). The number of dry spells was the most important predictor for crop yield in either tillage system while total seasonal rainfall was the weakest predictor. The linear yield response to the climate variables was the same in either tillage system: yields increased by 1.85 kg/ha per mm rainfall, and decreased by 81 kg/ha for each dry spell and by 216 kg/ha for each additional dry spell event ≥ 7 days. Thus, there was no differential performance of tillage systems depending on seasonal conditions. Overall, tied-ridge tillage could be a means to improve productivity in the study environment if management-related system constraints (e.g. nutrient supply, residue management) are adequately addressed.