Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 873.5 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 856.5 | Thousand metric tons of contained nitrogen | -1.95% |
| 2005 | 860 | Thousand metric tons of contained nitrogen | 0.41% |
| 2006 | 850 | Thousand metric tons of contained nitrogen | -1.16% |
| 2007 | 850 | Thousand metric tons of contained nitrogen | 0.00% |
| 2008 | 830 | Thousand metric tons of contained nitrogen | -2.35% |
| 2009 | 830 | Thousand metric tons of contained nitrogen | 0.00% |
| 2010 | 830 | Thousand metric tons of contained nitrogen | 0.00% |
| 2011 | 830 | Thousand metric tons of contained nitrogen | 0.00% |
| 2012 | 830 | Thousand metric tons of contained nitrogen | 0.00% |
