Conservation Agriculture Effects on Crop Productivity and Soil Properties in Ethiopia

Conservation agriculture (CA) is common globally but not in tropical Africa, including Ethiopia. Conservation agriculture was evaluated at Bako (short-term CA study) and Melkassa (medium-term CA study) in Ethiopia for effects on crop yield and soil properties. Results showed the rate of water infiltration was 16% more at Bako and 15% less at Melkassa for conventional practice (CP) (tillage plus crop residue removal) compared with CA (no tillage plus residue retention). Time-to-pond was doubled and soil penetration resistance was 7 kP less for the 0-0.1 m depth with CA maize (Zea mays L.)-dry bean (Phaseolus vulgaris L.) rotation compared to CP maize monoculture at Melkassa. Soil organic C for the 0-0.05 m soil profile was 16 g kg(-1) with CA compared with 12 g kg(-1) for CP and early maize growth was slower with CA compared with CP at Melkassa. Maize stover yield was 10.14 Mg ha(-1) for CP compared with 9.01 Mg ha(-1) for CA in 2015 at Bako, but maize yields were greater with CA at Melkassa in 2016. Monoculture and inter-crop dry bean, respectively, had 40 and 32% more grain yield with CA compared to CP in 2016 at Melkassa. It was concluded that medium-term beneficial effects of CA on soil properties and crop productivity can be expected at Melkassa, but any short-term benefits of CA at Bako were uncertain.