Exploring options for a more sustainable crop production on the North China Plain

Chinese agriculture faces multiple challenges: guaranteeing national food security, increasing farmers' incomes, and reducing the adverse environmental effects that are associated with high input rates of agrochemicals. Smallholder farming contributes substantially to the land-use and agricultural production in China; hence, a transition in smallholder farming systems is needed to increase sustainability. In this thesis, I describe and explore crop production systems in an area of major importance for grain production in China: the North China Plain. I first conducted a farm survey in a representative county, Quzhou, to describe the diversity of current crop production systems and agricultural management practices. I compared the multi-attribute sustainability of business and smallholder farms based on their use of crop production systems and management practices. I then developed a framework incorporating farm typology, positive deviant identification and multi-objective optimization with the FarmDESIGN model to explore farm-type-specific solutions based on existing cropping systems and best management practices already used within a farming community. I found a large diversity of crop species and cropping systems in Quzhou, despite the dominance of wheat, maize and cotton. Business farms had better environmental performance than smallholder farms with equivalent gross margins per unit area but lower dietary energy yields. Reallocation of cropping systems and applying best management practices yielded the most comprehensive improvements across sustainability indicators, but at the cost of increased labour requirement. The findings emphasise the strong trade-offs between economic, environmental and social dimensions, and highlight the importance of farm type-specific interventions rather than one-size-fits-all approaches. This thesis contributes practical improvement pathways for enhancing smallholder farm sustainability on the North China Plain and advances understanding of sustainability trade-offs in smallholder crop production systems.