Fertilizer use has been a key factor in boosting crop yields worldwide. At the same time, the global use of nitrogen fertilizer is associated with greenhouse gas emissions This article reviews the scope for reducing emissions associated with fertilizer use. It addresses the global scale and recent reports focused on Canada, the United States, and sub-Saharan Africa. It concludes with a review of the advantages and limitations of approaches based on managing nitrogen surplus in crop nutrient budgets and shows how a 4R approach both includes and goes beyond reducing surpluses.