Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 475.100006103516 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 531.799987792969 | Thousand metric tons of contained nitrogen | 11.93 % |
| 2005 | 525 | Thousand metric tons of contained nitrogen | -1.28 % |
| 2006 | 480 | Thousand metric tons of contained nitrogen | -8.57 % |
| 2007 | 460 | Thousand metric tons of contained nitrogen | -4.17 % |
| 2008 | 460 | Thousand metric tons of contained nitrogen | 0.00 % |
| 2009 | 460 | Thousand metric tons of contained nitrogen | 0.00 % |
