Does minimum tillage improve the livelihood outcomes of smallholder farmers in Zambia?

Minimum tillage (MT) is a farming practice that reduces soil disturbance by limiting tillage only to planting stations. MT is an integral part of Climate Smart Agriculture aimed at raising agricultural productivity, improving farmer livelihoods and building climate resilient farming systems in sub-Saharan Africa. However, there are questions on its suitability for smallholder farmers in the region. This paper assesses the impacts of MT on crop yield and crop income using an endogenous switching regression (ESR) model applied to cross sectional data from 751 fields, of which 17% were under MT in Zambia. The ESR framework accounts for heterogeneity in the decision to adopt MT or not and consistently predicts the outcomes of adopters and non-adopters had they not adopted and adopted, respectively. The results suggest that adopting MT was associated with an average yield gain for maize, groundnut, sunflower, soybean and cotton of 334 kg/ha but it had no significant effects on crop income (from sales and for subsistence) of households in the short-term. These results are partly explained by partial adoption: even among adopters, only 8% of cultivated land was under MT. In these circumstances, although MT confers some yield benefits, the gains may be insufficient to offset the costs of implementation and translate into higher incomes and better livelihood outcomes in the short-term. Additional costs associated with MT include implements, herbicides, and labor for weed control and for land preparation. Assumptions of labor saving from preparing land in the dry season and cost savings by reduced fuel use and weed pressure are aspirational because of the prevalent customary land tenure and communal grazing systems, and because mechanization and the use of herbicides to control weeds remain low among smallholders. Nevertheless, if the longer-term productivity gains from MT are large enough, these may offset the higher implementation costs of MT due to economies of scale and may eventually result in improved incomes and food security. These findings may help to explain the perceived low uptake rates for MT in Zambia and call for lowering implementation costs through extension specific to MT and by adapting MT to local contexts.