Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 321.200012207031 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 320 | Thousand metric tons of contained nitrogen | -0.37% |
| 2005 | 320 | Thousand metric tons of contained nitrogen | 0.00% |
| 2006 | 309 | Thousand metric tons of contained nitrogen | -3.44% |
| 2007 | 310 | Thousand metric tons of contained nitrogen | 0.32% |
| 2008 | 350 | Thousand metric tons of contained nitrogen | 12.90% |
| 2009 | 320 | Thousand metric tons of contained nitrogen | -8.57% |
| 2010 | 320 | Thousand metric tons of contained nitrogen | 0.00% |
| 2011 | 320 | Thousand metric tons of contained nitrogen | 0.00% |
| 2012 | 320 | Thousand metric tons of contained nitrogen | 0.00% |
