Onions and garlic have a relatively low nutrient uptake efficiency, due to their shallow root system characterised by thick roots with very few and short hairs. So to achieve optimum yields it is important to apply nutrients as close as possible to the rooting zone frequently and in readily available forms.
Macronutrient uptake in onions
Major nutrient removal figures show that nitrogen and potassium are the nutrients needed in relative greatest quantities in onion and garlic crops. They are fundamental for achieving high marketable yields.
High rates of nitrogen are needed to satisfy crop demand. However it is important not to over-apply nitrogen, particularly in bulb onions, as this can delay maturity, soften bulbs and lead to storage rots.
Micronutrient uptake in onions
While much lower levels of micronutrients are needed to satisfy yield and quality onion crop production, the correct balance of these trace elements is essential.
The key micronutrients needed in greatest quantities are boron, and iron. These have an influence on yield and quality. Zinc also pays a role in seed germination.
