Synthetic agricultural chemicals have become central to Ugandan crop production, yet their consequences for the sustainable management of land remain inadequately characterised despite mounting evidence of soil degradation and water contamination. This study examined the effect of synthetic chemicals on land use management in Njeru Municipality, Buikwe District. Adopting a positivist philosophy and a cross-sectional survey design, data were collected through enumerator administration from 246 respondents selected via multistage sampling from farming households, agro-input dealers, and agricultural extension personnel across the municipality's divisions. A structured questionnaire measured four synthetic chemical dimensions, namely intensity of application, handling and application practice, product quality and authenticity, and regulatory awareness and compliance, against land use management assessed through soil fertility maintenance, land cover and vegetation retention, water resource protection, and land use planning adherence. Data were analysed using descriptive statistics, Pearson correlation, and multiple regression in SPSS version 26. Findings revealed that intensity of application recorded the highest mean while regulatory awareness and compliance recorded the lowest. All four dimensions correlated significantly with land use management, with handling and application practice strongest (r = −0.687, p < 0.01), followed by intensity of application (r = −0.641, p < 0.01), product quality and authenticity (r = 0.573, p < 0.01), and regulatory awareness and compliance (r = 0.518, p < 0.01). The regression model was significant, F(4, 233) = 57.94, p < 0.001, explaining 49.9 per cent of variance in land use management. The findings situate within evidence that only 23 per cent of Ugandan farmers have recommended training in pesticide use (Anti-Counterfeit Network, 2022), that 30 per cent of herbicides contain less than 75 per cent of the advertised active ingredient (World Bank, 2017), and that consistent agrochemical use alters soil properties and drives fertility loss (Ssekandi et al., 2022). The study concludes that practice deficits rather than chemical use as such drive land degradation, and recommends extension investment, enforcement of the Agricultural Chemicals (Control) Act, and integrated soil fertility management.