Understanding Onion Nutrition

Transplanting: At transplanting, the crop will require phosphorus to maximize root development and to supply reserves for season long growth and good bulbing. Nitrogen and potassium are also required to promote strong early growth. Potassium will also help the crop withstand abiotic stresses. Sulphur is a vital nutrient in onions for flavor and will also be required in the early stages. Micronutrients such as boron, manganese and zinc are necessary to ensure good root and shoot growth.

Vegetative growth: During this stage, sufficient nitrogen is required to ensure optimal development of the crop in preparation for formation of the onion bulbs. Insufficient nitrogen supply will result into stunted weak plants with very little small bulbs. It is important to ensure that the crop receives enough phosphorus at this stage to drive the growth of new shoots and provide the energy required for growth. Potassium will be required to ensure continued growth and development. Other nutrients such as calcium, sulfur and magnesium will also be required to maintain vigorous, healthy leaf growth and to build plant supplies prior to bulbing

Bulb formation: At this stage the growth of the leaves reduces and the plant focusses on the development of the bulb. Nitrogen will be required to maintain strong plant structure but excess nitrogen at this stage may cause poor quality bulbs. Phosphorus will be required to provide the energy required to initiate and support bulb development. For potassium, this is the peak stage at which high amounts are required for high yield and quality bulbs. Calcium is very crucial at this stage to ensure good supply to the bulb to maximize eventual storage quality. Insufficient calcium will result into bulbs that rot quickly after harvest.

Bulb expansion: At this stage, nitrogen will be required in lower quantities to maintain dry matter production and not compromise bulb quality. Sufficient levels of phosphorus will drive maturity and bulb size while potassium will maximize the bulb size and weight. Calcium will maintain bulb firmness and quality while Sulphur will ensure desired pungency of the onion. Micronutrients will improve the storage and skin finish quality.

The Yara Onion Nutrition program has been developed to provide complete and balanced nutrients for high yields and uniform bulbs. It is designed to ensure better nutrient management at each stage with micronutrients that are deficient in most soils. Additionally, the Yara program is designed with bulb storability in mind.

The bulbs can stay in good quality for up to 6 months thus attracting better prices.