Productivity and profitability of manual and mechanized conservation agriculture (CA) systems in Eastern Zambia

Climate variability and declining soil fertility pose a major threat to sustainable agronomic and economic growth in Zambia. The objective of this study was to assess crop yield, land and labor productivity of conservation agriculture (CA) technologies in Eastern Zambia. On-farm trials were run from 2012-2015 and farmers were replicates of a randomized complete block design. The trials compared three CA systems against a conventional practice. Yield and net return ha(-1) were determined for maize and legume yield (kg ha(-1)) produced by ridge and furrow tillage, CA dibble stick planting, CA animal traction ripping and direct seeding. The dibble stick, ripline and direct seeding CA systems had 6-18, 12-28 and 8-9% greater maize yield relative to the conventional tillage system, respectively. Rotation of maize with cowpea and soybean significantly increased maize yields in all CA systems. Intercropping maize with cowpea increased land productivity (e.g., the land equivalent ratio for four seasons was 2.01) compared with full rotations under CA. Maize/cowpea intercropping in dibble stick CA produced the greatest net returns (US$312-767 ha(-1)) compared with dibble stick maize-cowpea rotation (US$204-657), dibble stick maize monoculture (US$108-584) and the conventional practice (US$64-516). The net-return for the animal traction CA systems showed that maize-soybean rotations using the ripper were more profitable than the direct seeder or conventional ridge and furrow systems. Agronomic and economic benefits of CA-based cropping systems highlight the good potential for improved food security and agricultural productivity for smallholder farmers.