Smallholder farming systems in Ghana face significant challenges related to resource management and economic viability. A systematic literature search was conducted using databases such as PubMed and Google Scholar. Studies were selected based on relevance to smallholder farming systems in Ghana, with emphasis on empirical applications of DiD models in environmental and economic analyses. The analysis revealed that the DiD model has been applied effectively across various contexts but faces challenges related to data availability and temporal consistency. Despite these challenges, the DiD model remains a robust tool for assessing cost-effectiveness in smallholder farms. Future research should focus on improving data collection methods and enhancing temporal alignment of studies. Researchers are encouraged to adopt standardised methodologies and share their findings openly to facilitate peer review and validation. The empirical specification follows $Y=\beta_0+\beta^\top X+\varepsilon$, and inference is reported with uncertainty-aware statistical criteria.