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 | 850 | Thousand metric tons of contained nitrogen | 0.00 % |
| 2009 | 850 | Thousand metric tons of contained nitrogen | 0.00 % |
