Comparative performance of two-wheel tractor-based direct seeding and ox-drawn plough crop establishment of maize and common bean in smallholder farming systems

Abstract

Conservation agriculture (CA) is widely promoted for its potential to support agroecological intensification in sub-Saharan Africa, yet adoption among smallholder farmers remains limited, partly due to the high labour demands of manual and conventional animal draught (CAD) practices. Mechanised conservation agriculture (MCA), enabled by low-cost two-wheel tractor technologies, offers a promising solution, though comparative field evidence under smallholder conditions remains scarce. This study investigated the agronomic and labour performance of MCA systems relative to CAD-based practices, focusing on maize and common bean production in Zimbabwe. On-farm trials were conducted across 94 farms over two consecutive seasons (2018–2019 and 2019–2020) under typical smallholder management conditions. MCA significantly outperformed CAD practices across both crops. Grain yields increased by 1.26 t/ha (66%) for maize and 0.9 t/ha (82%) for common bean (P <0.001). Labour requirements were reduced by 124.6 person-hours/ha (a 5.55-fold reduction) for maize and 99.7 person-hours/ha (a 3.34-fold reduction) for common bean under MCA (P <0.001). Agronomic indicators (including crop emergence, grain yield, and labour inputs) were assessed using ANOVA and generalized linear mixed models (GLMMs) to account for variability across farms and treatments. Fuel consumption under MCA averaged 5.2 L/ha for maize and 7.1 L/ha for common bean, representing a recurrent cost. However, the value of labour saved relative to fuel expenditure favoured MCA by approximately 8:1 for maize and 5:1 for common bean, indicating strong economic viability. Capital costs of equipment nonetheless remain a barrier to individual ownership. Study limitations include its short duration and context-specific conditions, which may constrain generalisability. Long-term, multi-location research across diverse agroecological zones is needed to further validate these findings. This study provides robust field-based evidence that MCA can substantially reduce drudgery, improve crop productivity, and enhance livelihoods in African smallholder farming systems.