Iron deficiency made worse by
- High pH
 - Water logged soils
 - Calcareous soils
 - High copper, manganese or zinc soils
 
Iron is important for
- Chlorophyll formation and photosynthesis
 - Improved yield and quality
 - High requirement
 
Yara recommended fertilizers for Iron
YaraVita® FERRICHEL NINETY™
Onions: 1 to 3 lb/acre from 2 weeks after transplanting or as soon as there is sufficient leaf cover to intercept the spray. Repeat as necessary at 10 to 14 day intervals. Note: Final application to be made at least one month before harvest. Water rate: 20 gallons/acre.
Read more about YaraVita® FERRICHEL NINETY™