A Dose–Response Analysis of Rice Yield to Agrochemical Use in Ghana

In recent years, Ghanaian agriculture has witnessed a surge in the use of agrochemicals, with the likely consequence that nonoptimal levels of application could cause environmental damage and economic losses. We identify the factors that affect the adoption of agrochemicals and the intensity of use in Ghanaian rice farming. We estimate the average treatment effects of chemical fertilizer and herbicide adoption using a Dose–Response Model (DRM). Our results show that a wide range of socioeconomic factors, including education, asset ownership, extension service, off-farm income, and land ownership affect adoption and use intensity of agrochemicals. On average, chemical fertilizer usage is associated with a 10% increase in the average treatment effect; low levels of chemical fertilizer have a negative impact on rice yield, and the result turns positive with more intensive use. Similarly, herbicide treatment generates a 7% increase in the average treatment effect, but higher herbicide levels will have negative causal effects on rice yield, and the result worsens with more herbicide treatment. Both agricultural technologies were designed to be used together, hence the appropriate mix of levels and intensity is crucial to achieve greater benefits. The DRM accounts for heterogeneity in the sample and is a useful tool to develop guidance on optimal levels of agrochemicals.