Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 3529 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 3875.30004882813 | Thousand metric tons of contained nitrogen | 9.81% |
| 2005 | 5187.39990234375 | Thousand metric tons of contained nitrogen | 33.86% |
| 2006 | 5110.5 | Thousand metric tons of contained nitrogen | -1.48% |
| 2007 | 5129.2998046875 | Thousand metric tons of contained nitrogen | 0.37% |
| 2008 | 5100 | Thousand metric tons of contained nitrogen | -0.57% |
| 2009 | 4945.89990234375 | Thousand metric tons of contained nitrogen | -3.02% |
| 2010 | 5553.2421875 | Thousand metric tons of contained nitrogen | 12.28% |
| 2011 | 5444.2998046875 | Thousand metric tons of contained nitrogen | -1.96% |
| 2012 | 4466 | Thousand metric tons of contained nitrogen | -17.97% |
