Linking agrochemicals and associated contaminants to greenhouse gas emissions in agricultural ecosystems

Agrochemicals, particularly synthetic fertilizers and pesticides, underpin modern agricultural production and food security. Their widespread use, however, has intensified environmental degradation and contributed to greenhouse gas (GHG) emissions from agricultural ecosystems. Existing evidence remains fragmented across contaminant groups, environmental settings, and farming systems, limiting mechanistic understanding of how agrochemical inputs and associated contaminants regulate GHG production and fluxes. Here, we synthesize evidence on synthetic fertilizers and pesticides together with agrochemical-associated heavy metals, microplastics, and emerging contaminants using five shared control points: substrate supply, soil aeration and redox status, pH and toxicity stress, microbial functional guilds, and contaminant co-exposure. Our synthesis indicates that GHG responses are more consistently interpreted through shared control points than through contaminant class alone. Fertilizers most consistently affect N2O through reactive nitrogen availability, acidification, and microbial nitrogen cycling, whereas responses to pesticides, heavy metals, microplastics, and emerging contaminants vary more strongly with toxicity, soil structure, hydrology, dose, and co-exposure. Persistent knowledge gaps remain in multi-contaminant interactions, long-term field observations, and climate–contaminant feedbacks. Addressing these gaps through mechanistic experiments, long-term monitoring, and integrated mitigation will improve prediction and management of agricultural GHG emissions.