Yield effects of conservation farming practices under fall armyworm stress: The case of Zambia

Abstract

Conservation farming (CF) aims to achieve increased agricultural productivity while ensuring environmental sustainability through a system of agronomic practices, including minimum soil disturbance (MSD), crop residue retention (RR), and crop rotation (CR). Although inconclusive, there is some evidence that CF can improve crop yields in smallholder farming systems of sub-Saharan Africa (SSA). In this article, we examined whether the implementation of CF practices (either separately or in tandem) can offset the negative yield effects of fall armyworm (FAW), a new invasive pest that is causing devastating effects on maize in SSA. We used data from 1048 smallholder maize plots across the major maize-producing agro-ecological zones of Zambia. Results showed that 86% of the plots had at least one of the CF practices, but only 26% of the plots were under the full CF package. Factors that consistently influenced the use of the various CF packages included agro-climatic conditions, land tenure security, livestock raising and credit constraints. We found suggestive evidence that CR, when adopted in isolation or in combination with RR, can increase maize yield by up to 360 kg/ha (28%) under FAW stress. On the other hand, none of the MSD-related practices (including the full CF package) had a significant effect on maize yield. Overall, our analyses suggest that certain components of CF can mitigate short-term yield loss, but high-rainfall environments and the use of modern inputs (improved seeds and agrochemicals) are the most robust determinants of smallholder maize yields in the face of FAW invasion.