Table 3. Effects of spraying 1 litter of fulvic acid (0.02%) twice per week in nursery pig barns and providing fulvic acid (0.02%) in drinking water in growing barns on ammonia (NH3) and hydrogen sulfide (H2S) production
| Item | Day: | Control | Fulvic acid | SEM | p-value for fulvic acid effect |
| 3 | 5 | 8 | 10 | 12 | 3 | 5 | 8 | 10 | 12 |
| Spraying | | | | | | | | | | | | |
| NH3 (mg) | 8 | 7 | 9 | 9 | 8 | 6 | 5 | 7 | 6 | 6 | 0.1 | < 0.001 |
| Drinking | | | | | | | | | | | | |
| NH3 (mg) | 5 | 8 | 4 | 6 | 12 | 4 | 3 | 4 | 6 | 8 | 0.7 | 0.129 |
| H2S (mg) | 0 | 0 | 2 | 0 | 2 | 0 | 0 | 0 | 2 | 0 | 0.5 | 0.621 |