Bundled Sustainable Agricultural Practice Adoption and Fertilizer-Use Intensity: Agroecological and Household Decision-Making Heterogeneity among Smallholder Maize Farmers in Zambia

Abstract

Sustainable Agricultural Practices are promoted to improve productivity and environmental sustainability in smallholder farming systems, yet evidence remains limited on how bundled SAP adoption shapes fertilizer-use intensity across agroecological and household decision-making contexts. This study examined the relationship between high bundled SAP adoption and fertilizer-use intensity among smallholder maize-producing households in Senanga District (Agroecological Region I) and Mungwi District (Agroiecological Region III), Zambia. Cross-sectional survey data from 572 households were analysed using multivariable regression, interaction models, and propensity score matching.  Robustness checks included a continuous SAP intensity specification, alternative matching estimators, bootstrap inference and Rosenbaum sensitivity analysis. The results show that households adopting atleast two promoted SAPs applied significantly more fertilizer than comparable low adopters. However, the relationship was heterogeneous: the fertilizer-use response was stronger in the drier Senanga context than in Mungwi, and household farm decision-making arrangements  significantly moderated the SAP-fertilizer relationship . Robustness checks consistently supported the positive association between bundled SAP adoption and fertilizer-use intensity. The study concludes that bundled SAPs and inorganic fertilizer function as complementary technologies rather than substitutes. It recommends extension strategies that jointly promote bundled SAPs and balanced fertilizer management while adapting recommendations to local agroecological conditions and intra-household decision-making contexts.