Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 264.399993896484 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 332.299987792969 | Thousand metric tons of contained nitrogen | 25.68 % |
| 2005 | 320 | Thousand metric tons of contained nitrogen | -3.70 % |
| 2006 | 319 | Thousand metric tons of contained nitrogen | -0.31 % |
| 2007 | 320 | Thousand metric tons of contained nitrogen | 0.31 % |
| 2008 | 320 | Thousand metric tons of contained nitrogen | 0.00 % |
| 2009 | 320 | Thousand metric tons of contained nitrogen | 0.00 % |
