Nitrous Oxide

Figure Data

Estimated U.S. anthropogenic emissions of nitrous oxide in 2004 totaled 353.7 MMTCO₂e, or 1.2 MMT nitrous oxide. Nitrous oxide emissions represented 5.0 percent of total U.S. greenhouse gas emissions in 2004 and were 5.5 percent above the 2003 level of 335.2 MMTCO₂e. Most of the increase from 2003 can be attributed to increased emissions from agricultural sources, which rose by 17.4 MMTCO₂e in 2004 and represented 94 percent of the overall increase in nitrous oxide emissions (18.5 MMTCO₂e) from 2003. The 2004 level marks the first year since 2000 in which U.S. emissions of nitrous oxide have been higher than the 1990 level of 337.0 MMTCO₂e (Table ES5 and Figure ES5).

Agriculture

Agricultural sources, at 265.2 MMTCO₂e, accounted for 75 percent of total U.S. nitrous oxide emissions in 2004. Agricultural emissions in 2004 were 7.0 percent above the 2003 total of 247.8 MMTCO₂e, primarily as the result of an increase of 9.5 percent (17.7 MMTCO₂e) in emissions from the nitrogen fertilization of agricultural soils. Emissions from nitrogen fertilization, at 204.3 MMTCO₂e, accounted for 77 percent of nitrous oxide emissions from agriculture in 2004. Emissions from the solid waste of domesticated animals, at 60.3 MMTCO₂e, made up 23 percent of agricultural nitrous oxide emissions in 2004, and burning of crop residues produced another 0.6 MMTCO₂e. Total U.S. emissions of nitrous oxide from agriculture sources have increased by 6.4 percent since 1990.