Onion is one of the common vegetables in China, which is rich in nutrition and is also an important seasoning vegetable in cooking.

Onion originated in continental climate zone, which has strong adaptability and belongs to long-day crops. The requirements for the growth environment and conditions are not so strict, so how should onions be fertilized?

First, the growth habits of onions

1. temperature

Onion is cold-resistant and not high-temperature, and has strong adaptability to temperature conditions. The suitable growth temperature is 13-26℃.

The required temperature varies with the growth period.

The suitable temperature for seed germination is 15-20℃, and it can germinate slowly at 3-5℃. The decrease of temperature will affect the physiological function of seeds and hinder germination.

If the temperature is too high, the seeds will not germinate; The seedlings have strong cold resistance, the suitable temperature for their growth is 12-20℃, and they can tolerate the low temperature of D6-7℃ for a short time. The suitable temperature for bulb expansion is 20-26℃. When the temperature is lower than 15℃, the bulb expansion is blocked.

When the temperature is higher than 26℃, the growth will decline and enter dormancy.

2. Moisture.

Onion has shallow roots, likes humidity, is not drought-tolerant, has weak water absorption capacity, and likes high soil moisture.

After sowing, the roots and leaves grow slowly before and after the seedlings are unearthed, and the soil should be kept moist.

Vegetative growth and bulb expansion stage are the key stages to determine the yield, which grow rapidly and need sufficient soil moisture.

The relative humidity of air is 60-70%, which is easy to cause diseases.

On the other hand, if the relative humidity is too low, it will seriously affect the bulb expansion, leading to the reduction of output, quality and efficiency.

The watering amount should be controlled before harvest 12 weeks, so as to ensure the bulb to accelerate maturity and prevent the bulb from cracking.

3. soil.

Onions are fertile, not barren, and have strong adaptability to soil environment. Suitable for planting in neutral sandy loam with loose and deep soil layer, rich nutrients, good permeability, strong water and fertility conservation and PH6-8. Low air humidity and high soil humidity can obtain ideal benefits.

4.light.

Onion is a long-day crop, which requires higher light conditions than leafy vegetables and root vegetables.

Moderate light conditions are suitable for the growth process and meet the needs of flower bud differentiation, vegetative growth and bulb formation.

If the sunshine is insufficient, it will seriously affect the yield and quality of onions.

When the temperature is high and the sunshine is long, it will enter the dormant period.

Suitable sunshine conditions can effectively promote the formation and maturity of bulbs and realize high-quality production and income increase.

Second, scientific and reasonable fertilization methods for onions

1. base fertilizer.

Soil preparation and tillage, fine harrow, flat harrow and fine harrow, and application of base fertilizer. The application of base fertilizer should be uniform and thorough, avoiding partial application, less application and missed application.

800- 1000 kg of decomposed agricultural organic fertilizer, 28-30 kg of calcium superphosphate and 0/4-15 kg of potassium sulfate can be applied per mu, and the three fertilizers can be evenly mixed and applied to the middle and upper layers of cultivated land, which is beneficial to root absorption.

2. Seedling fertilizer.

Seedling fertilization can be combined with watering at the same time.

5-6 days after sowing, apply 600-800 kg of decomposed agricultural organic fertilizer, or 0/0 kg of ammonium sulfate/kloc, 800 kg of water and 60-80 kg of phosphorus pentoxide per mu, and spread evenly.

If the soil is too sour, apply 400-500 kg of plant ash to adjust the soil properties, which is beneficial to onion growth.

3. Stem and leaf fertilizer.

After delayed emergence, in order to promote the growth of stems, leaves and vegetative organs, timely and appropriate fertilization is needed.

Combined with intertillage, loosening soil and weeding, ammonium sulfate 10 kg, 800 kg of water or 40-50 kg of nitrogen fertilizer can be applied per mu.

4. expand fat.

The stem and leaf expansion period is the key period to determine the onion yield, and it is necessary to topdress and replenish fertilizer in time.

At this stage, topdressing is usually 2-3 times.

Ammonium sulfate 10kg, potassium sulfate 5kg, water 800kg, or decomposed 50% human excrement 800kg can be applied per mu, with intertillage weeding.

It should be noted that it is necessary to grasp the good opportunity of topdressing. Premature topdressing is easy to cause white leaves on the ground and affect bulb expansion. If topdressing is too late, it will cause insufficient nutrients, affect the rapid expansion of bulbs, delay maturity and affect yield.

5. Micro-fertilizer.

Micro-fertilizer also plays an important role in onion production.

Phosphorus deficiency will lead to short plants, few leaves and poor growth; Dead spots are easy to appear between pulses when potassium is deficient; Boron deficiency is easy to cause leaf chlorosis and deformity; Calcium deficiency is easy to cause corm heart rot; Magnesium deficiency is prone to muscle rot and root rot.