We introduce a world fertilizers model that is capable of producing fertilizer demand projections by crop, by country, by macronutrients, and by year. For each crop, the most relevant countries in terms of production, consumption, or trade are explicitly modeled. The remaining countries are modeled, for each crop, within a regional aggregate. The nutrient coverage includes nitrogen (N), phosphorous (P), and potassium (K). In this report we present the data and procedures used to set up the model as well as the assumptions made. The fertilizer model interacts with the yield equations of the FAPRI-ISU model (Food and Agricultural Policy Research Institute at Iowa State University), and by means of a set of production elasticities, projects each nutrient’s application rate per hectare for each commodity and each country covered by the FAPRI-ISU model. Then, the application rates and the areas projected by FAPRIISU are used to obtain projections of fertilizer demand from agriculture on a global scale. With this fertilizer module, policies that directly affect fertilizer markets, such as input taxes or subsidies, quantity use restrictions, and trade restrictions, can now be explicitly formulated and evaluated. The effects of these policies on global agricultural markets and on greenhouse gas emissions can be evaluated with the FAPRI-ISU model and the Greenhouse Gas in Agriculture Simulation Model (GreenAgSiM). Also, any other policy affecting commodity markets such as input and output price shocks, biofuels mandates, and land-use change can now be evaluated with regard to its impacts on the world fertilizer markets.