Linking innovations adoption with farm sustainability: Empirical evidence from rainwater harvesting and fertilizer micro-dosing in Tanzania

Food insecurity and poverty are of major concern for farmers and rural households in Tanzania. Innovations to increase the sustainability of households must be carefully investigated by integrating, in the analysis, the effect on crop yields with a holistic view on the overall sustainability and its components. Rainwater harvesting and fertilizer micro-dosing can increase food security, particularly in water-limited contexts, but they can also significantly increase labor requirements and the availability and use of water resources in villages and watersheds. The purpose of this study was to quantify the impacts of rainwater harvesting and fertilizer micro-dosing on environmental, social and economic sustainability of households in two regions in Tanzania - semi-arid Dodoma and semi-humid Morogoro. We selected and calculated 40 sustainability indicators for 892 households in 2013 and 2016, and we applied Difference-in-Difference Propensity Score Matching to identify relative changes in household sustainability. We show that in the dry region of Dodoma, economic sustainability increased less for adopters of the innovations in comparison to non-adopters between the years 2013 and 2016, with 6 percentage points and 11 percentage points respectively. In contrast, in the humid region, the adoption of innovations increased food security by 14 percentage points compared to 6 percentage points in the case of nonadoption. These results highlight that innovations must fit the context and should not be scaled without prior analysis of multiple impact dimensions as they may trigger significant trade-offs. By moving the focus from field to farm scale, this study contributes to providing a more rigorous assessment of the spillover effects that in-field innovations can have on the overall sustainability of households, which is a prerequisite for the advancement of sustainable intensification of agricultural production in the region.