Causal Effects of Crop-Environment Interactions Adaptation on Yield Stability in Uganda: A Difference-in-Differences Design

Agricultural adaptation to environmental variability is widely promoted as a means of stabilising yields, yet credible evidence on its causal effects in smallholder systems of sub-Saharan Africa remains scarce. The central problem is that adaptation is not randomly assigned: farmers who adapt differ systematically from those who do not, and the environmental shocks that motivate adaptation also affect yields directly. The proposed design exploits temporal variation in the onset of adaptation combined with spatial variation in exposure to environmental stressors, using a composite spatial index of drainage density, rainfall intensity, soil permeability and related criteria to define treatment intensity. The article formalises the identifying assumptions, examines their plausibility in the Ugandan context, and specifies a suite of robustness checks including parallel-trends diagnostics and placebo tests. The contribution is a transparent, replicable research protocol that clarifies what evidence would be needed to support causal claims about adaptation and yield stability, and that guards against the over-interpretation of observational associations common in the adaptation literature.