Poor and declining soil fertility remains a major constraint on increased cereal production in sub-Saharan Africa. Input subsidy programs (ISPs) for inorganic fertilizer are a popular and expensive tool used by African governments to increase cereal yields; however, far fewer resources are devoted to promoting other soil fertility management (SFM) practices that can improve soil quality, increase cereal yield response to inorganic fertilizer, and support sustainable agricultural intensification. This article uses nationally-representative household panel survey data from Zambia to estimate the effects of the country s ISP on smallholder farm households adoption of several SFM practices: fallowing, intercropping, crop rotation, and the use of animal manure. The results suggest that Zambia s ISP induces reductions in fallowing and intercropping of maize with other crops. We also find some evidence that the program incentivizes an increase in continuous maize cultivation on the same plot in consecutive seasons but little evidence of effects on animal manure use. The changes in SFM practices induced by the ISP are likely to be detrimental to soil fertility, maize yield response to fertilizer, and returns to government expenditures on the ISP over the medium- to long-term. Overall, Zambia s ISP may have dis-incentivized sustainable intensification rather than promoted it. Acknowledgement : This research was funded by the United States Agency for International Development (USAID) through funding to the Feed the Future Innovation Lab for Food Security Policy and the USAID Mission to Zambia, and by the United States Department of Agriculture National Institute of Food and Agriculture and Michigan AgBioResearch (project number MICL02501).