Sulphur is critical to the taste and pungency of the bulb. Supplies need to be tailored to suit the desired market requirement. S can also improve skin strength and colour. Sulphur has a marked effect on the pungency of the onion through increasing the pyruvic acid content of the bulb. Therefore, it is important to exploit the right soil and use an appropriate rate and timing of sulphur that satisfies market demands.
Managing Taste and Pungency of Onion Bulbs
Taste and pungency of onions and garlic are key quality characteristics of these crops. They vary between types and cultivars. Pungency is largely due to the level of sulphur based non-protein amino acids they contain. Sweetness can be assessed by the levels of sugars in the bulb. Although measurement of these elements can be difficult, it is well known that a good nutrition is essential to manage taste and pungency of onion bulbs.
Crop Nutrition and Onion Bulb Taste and Pungency
Sulphur and Onion Pungency
Sulphur and Sugar Content
Sulphur also has a marked effect on bulb sugar content. Thus, soil type and use of sulphur as part of a nutritional program have to be carefully considered in order to meet market requirements. For example, sweet onions benefit from being grown in low sulphur soils and should have low S-fertilizer regimes with most of the S applied early season to minimize uptake into the onion bulb.
Recommended Yara Fertilizers for Onions
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YaraMila COMPLEX
12-4.8-14.9 + 8% S - Prilled NPK fertilizer which also contains magnesium and sulphur as well as micronutrients ideal for use on a wide range of arable and horticultural crops.
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YaraLiva TROPICOTE
15.5% N + 18.8% Ca - Granular calcium nitrate fertilizer for field application to a wide range of crops.
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MAINCROP S
14-5.7-17.4 + 2.2% S - A quality size matched NPK plus S size matched blended fertilizer, ideal for use for potato production due to the ratio in the of N P and K whilst including a useful amount of sulphur.
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STARTER SOLUTION PLUS
A liquid fertilizer for placement which aids rapid crop establishment, promotes efficient utilization of phosphate and improves phosphate availability.
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YaraVita BORTRAC 150
A liquid micronutrient fertilizer containing 150 g/l boron for foliar application to provide additional boron or to treat boron deficiencies in a wide range of crops.
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YaraVita BRASSITREL PRO
A flowable liquid suspension fertilizer with a combination of micronutrients including manganese, magnesium, boron and molybdenum for foliar application to oilseed rape, brassicas and legumes.