Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 726.431030273438 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 705.317993164063 | Thousand metric tons of contained nitrogen | -2.91% |
| 2005 | 654.786010742188 | Thousand metric tons of contained nitrogen | -7.16% |
| 2006 | 726.968994140625 | Thousand metric tons of contained nitrogen | 11.02% |
| 2007 | 726 | Thousand metric tons of contained nitrogen | -0.13% |
| 2008 | 726 | Thousand metric tons of contained nitrogen | 0.00% |
| 2009 | 726 | Thousand metric tons of contained nitrogen | 0.00% |
