Ammonia is the primary material from which various N fertilizer products are produced. Ammonia synthesis is a major contributor to GHG emissions because of the large energy requirement for its manufacture. The Chinese Nitrogen Fertilizer Industry Association (CNFIA) surveyed 230 companies (Table S2), which account for 40% of the total N fertilizer industry in the nation, including all the large- and medium-scale plants. The survey collected information on the total energy consumption between 2002 and 2005. We have adopted the raw material consumption rate of the ammonia industry determined by this survey and classified the industry into eight categories to estimate different GHGemission factors associated with ammonia synthesis (Table S4).
GHG Emission from N Fertilizer Manufacture.