Table 4.
Percent contribution based on median calibrated parameters for different sources of dissolved inorganic nitrogen export for the Mississippi River Basin and major sub-basins
| 2002HIST | Mississippi River Basin (%) | Arkansas-Red River Basin (%) | Missouri River Basin (%) | Ohio-Tennessee River Basin (%) | Upper Mississippi River Basin (%) |
|---|---|---|---|---|---|
| Tile-drained agriculture | 47 | 1 | 18 | 46 | 68 |
| Non-tile drained agriculture | 28 | 48 | 45% | 27 | 18 |
| Atmospheric deposition | 10 | 19 | 13 | 12 | 5 |
| Human sewage | 10 | 21 | 16 | 10 | 8 |
| Background | 5 | 12 | 9 | 5 | 1 |
| 2022BASE | |||||
| Tile-drained agriculture | 46 | 1 | 17 | 45 | 68 |
| Non-tile drained agriculture | 28 | 52 | 43 | 28 | 17 |
| Atmospheric deposition | 8 | 15 | 11 | 9 | 5 |
| Human sewage | 12 | 20 | 20 | 12 | 9 |
| Background | 6 | 13 | 9 | 6 | 1 |
| 2022CROP | |||||
| Tile-drained agriculture | 45 | 1 | 16 | 45 | 67 |
| Non-tile drained agriculture | 28 | 52 | 43 | 28 | 17 |
| Atmospheric deposition | 8 | 15 | 11 | 9 | 5 |
| Human sewage | 12 | 20 | 20 | 13 | 9 |
| Background | 6 | 13 | 9 | 6 | 1 |