How to maximise onion dry matter content

The majority of onion crops are grown for the fresh market so it is important to maximise dry matter. Nitrogen and potassium are the most important nutrients influencing dry matter content of onion bulbs. Bulbs should be sufficiently dry for the intended purpose. Most common bulb onions have 10-12% dry matter. Onions grown for dehydration require higher dry matters of 17-20%.

Nitrogen form influences onion dry matter

Effect of nitrogen source on onion dry matter

Trials confirm that a balance between nitrate and ammonium-N is most effective at promoting onion leaf and bulb growth. However, during later stages of growth, nitrate forms provide higher dry matters in the bulb.

Effect of nitrogen source on onion dry matter

Potassium increases onion dry matter

Potassium is particularly important where high N rates have been applied (if high yielding systems). In these situations, increasing dry matter and sugar accumulation in the bulb helps maintain yield.

Effect of potassium on onion bulb dry matter

Onion agronomy and fertiliser advice
Onion agronomy and fertiliser advice

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