A Critical Review of the Water Balance and Agronomic Effects of Conservation Tillage under Rain‐fed Agriculture in Ethiopia

About 80% of Ethiopia's population is involved in rain‐fed agriculture. Moisture stress coupled with traditional tillage with breaking ard plough, locally known as ‘Maresha’ are the major limiting factors for agricultural production. Soil erosion, low infiltration and decline agricultural productivity because of conventional tillage implement have been frequently reported. In order to curve this situation and meet the huge food demand of the growing population, different conservation tillage systems have been implemented. However, there is limited information about the impacts of the practices. This review paper therefore aimed at providing adequate information concerning the impacts of the practices on water balance and crop yield. Systematic, best evidence and narrative review techniques were used. Results revealed that the application of conservation tillage had brought significant improvement on water balance and agricultural production. Researchers found over 50% decreased in surface runoff, 9 to 40% improvement in water productivity and good crop transpiration (T = 53 mm season−1), compared to conventional tillage T = 49 mm‐season−1 because of conservation tillage implement. Moreover, doubled grain yield was obtained from ridging, subsoiling and wing plough (1076, 1044 and 1040 kg ha−1, respectively) compared to traditional tillage which resulted in 540 kg ha−1. Improving water balance and agricultural production in rain‐fed agriculture need to reduce evaporation and surface runoff through improving moisture retention and transpiration. This could be achieved by the adoption of conservation tillage which can improve on‐farm water balance, yields and water productivity among smallholder farmers in Ethiopia. Copyright © 2016 John Wiley & Sons, Ltd.