| Fertilization | Ferrous iron content (µg/g dry soil) | |
|
| BOUAKE-189 | ROK-5 |
| NPK + Urea + Ca + Zn + Mg | 0.0015a | 0.0016a |
| No fertilized | 0.00149a | 0.00143b |
| NPK + Urea | 0.0013b | 0.00142b |