Source: United States Geological Survey (USGS) Minerals Resources Program
Note: Check source table for details and footnotes
| Year | Production | Unit of Measure | % Change |
| 2003 | 444.399993896484 | Thousand metric tons of contained nitrogen | NA |
| 2004 | 413.399993896484 | Thousand metric tons of contained nitrogen | -6.98% |
| 2005 | 466.570007324219 | Thousand metric tons of contained nitrogen | 12.86% |
| 2006 | 495 | Thousand metric tons of contained nitrogen | 6.09% |
| 2007 | 485 | Thousand metric tons of contained nitrogen | -2.02% |
| 2008 | 490 | Thousand metric tons of contained nitrogen | 1.03% |
| 2009 | 470 | Thousand metric tons of contained nitrogen | -4.08% |
| 2010 | 380 | Thousand metric tons of contained nitrogen | -19.15% |
| 2011 | 520 | Thousand metric tons of contained nitrogen | 36.84% |
| 2012 | 470 | Thousand metric tons of contained nitrogen | -9.62% |
