Basic Information

Onion prefers medium textured soils with a good drainage as waterlogging causes strong root losses. The ideal pH is slightly acidic, around 6-7. Higher pH values can cause trace element deficiencies and consequently a reduction of the yield. Onion is very sensitive to the salinity of irrigation water. Therefore, it is necessary to apply fertilizers that salinize the irrigation and soil waters as little as possible. The crop requires the contribution of a high level of nitrogen. It is important to apply nitrogen in the right amount and in balance with the rest of the nutrients. Nitrogen is essential for the development of the plant. It directly influences the vegetative development, the accumulation of reserves as well as the overall development of the onion. But nitrogen should not be applied in excess as it results in delayed maturation, softer bulbs and worse storage capacity. Onion has relatively high phosphorus needs. This element is directly related to root development and therefore it is necessary to ensure an effective absorption of the remaining nutrients, thus its contribution is primarily essential at the beginning of the cultivation. The stabilized fertilizers stimulate the plant to absorp phosphorus, promoting an early development of the crop. The quality of the crop is largely determined by potassium, which makes the plant resistant to adverse environmental conditions, such as frost and drought as well as diseases and pests. A deficiency of potassium results in softer, less resistant onions and, therefore, reduces the post-harvest life. In addition to the above-mentioned advantages, the application of potassium in the form of potassium sulfate, also provides sulfur, which the onion absorbs in amounts similar to phosphorus, since it has high requirements for this nutrient. Positive responses are observed with sequential applications of the nutrient Zinc, which is a constituent of several enzymes that act in the processes of breathing, hormonal control and protein synthesis.

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