Smallholder productivity and weather shocks: Adoption and impact of widely promoted agricultural practices in Tanzania

- There are significant complementarities among agricultural practices analyzed here.
- Most of the complementarities documented are not exploited by households.
- Maize yields remain vulnerable to rainfall and temperature shocks.
- Combined practices including soil-water conservation have robust yield benefits.
- Policies can effectively increase resilience to shocks if based on such evidence.

We investigate the impact of maize-legume intercropping, soil and water conservation practices (SWC), organic fertilizers, inorganic fertilizers and high yielding maize varieties on maize productivity under weather shocks in Tanzania using panel data. First, we estimate the determinants of adoption by applying a multivariate panel data model capturing their complementarities and/or substitutabilities. Second, after testing for their potential endogeneity, we study the impact of these practices (and combinations of them) on maize productivity controlling for weather shocks. Finally, we disaggregate results by presence/absence of seasonal rainfall and temperature shocks to explore the heterogeneous impact of adoption under weather shocks. We find strong complementarities between agricultural practices both in terms of adoption and yield impacts. Long-run variability in rainfall decreases the adoption of organic fertilizers and increases that of improved seeds. Farmers in areas where the cropping season's rainfall has been highly variable and temperature has been unexpectedly high have significantly lower maize yields. SWC emerges as one of the most important practices in increasing yields with significant benefits by itself, in combination with other practices, under average weather conditions as well as under rainfall and temperature shocks. Overall, increasing the adoption of SWC appears a promising policy option to buffer food security from increasingly frequent weather shocks in Tanzania.