Nitrogen has greatest effects on onion yield although too much nitrogen softens the bulb and increases storage rot diseases. However nitrogen can also influence quality by helping to increase skin thickness.
Phosphorus has a positive effect on storage quality of onions and garlic, especially when high rates of nitrogen have been used.
The use of potassium allows growers to maintain high rates of nitrogen for yield with reduced risk of storage problems such as rots or sprouting.
Calcium is particularly important for bulb density, integrity and long-term storage with minimal disease problems. Magnesium also has a role to play in improving storage quality characteristics.
Boron has been shown to improve storage quality, which could be associated with the micronutrient’s role in improving calcium accumulation in the bulb.