The Fertilizer-Food Nexus under Macroeconomic Stress: Modeling Agricultural Resilience Amid the 4F Crisis

Background. Synthetic fertilizer underpins the caloric adequacy of roughly half of humanity. Between 2020 and 2023 the fertilizer system was hit by overlapping shocks: an energy price spike, a major supplier's war, export restrictions, currency depreciation, tightening credit, and climate extremes. These were not independent events. Together they formed what this paper calls the 4F crisis: food, fuel, fertilizer, and finance. Objective. The paper examines how macroeconomic stress is transmitted through fertilizer markets to farm-level input decisions, national food availability, and household food access. It also asks what determines whether agricultural systems absorb, adapt to, or collapse under that stress. Methods. The paper uses a scoping synthesis reported in line with PRISMA-ScR principles and a PRISMA 2020 flow logic. It combines this with a transparent analytical model of fertilizer demand and yield response, extended by a stress-transmission chain covering energy prices, exchange rates, interest rates, subsidies, and trade policy. The model parameters are illustrative, not estimated. They demonstrate mechanisms and sensitivities, not forecasts. Findings. Five propositions emerge. (1) The nexus is a coupled energy-finance-trade system, not a farm-input market. (2) Price elasticity of fertilizer demand rises as application intensity falls, so low-input smallholder systems face disproportionate yield penalties from price shocks, which concentrates hunger risk where buffers are thinnest. (3) Subsidy regimes shift stress from farmers to treasuries and do not remove it. (4) Supplier concentration and the weaponization of interdependence turn commercial risk into strategic risk. (5) Resilience depends less on self-sufficiency than on diversification, efficiency, and institutional learning. Conclusion. An agenda built on nutrient-use efficiency, diversified sourcing, countercyclical financing, and crisis-learning institutions offers a more defensible route to food security than autarky or untargeted subsidy.