1. Land preparation and fertilization

Ten days before sowing, plow the land and apply fully decomposed, mashed and sieved farmyard manure. The amount of fertilizer per acre should not exceed If it exceeds 2000kg, it must be plowed twice to a depth of about 20cm or more to fully mix the fertilizer with the soil, and then use a flat rake to level the border surface in preparation for sowing.

There are two types of border specifications: one is a small high border, with a border width of 1.6m, a furrow width of 0.2m, a furrow depth of 0.1m, and 8 rows of transplants per border. This border is suitable for clayey soil. Or fields with small gaps. The second is the flat border: the border width is 2m, the border width is 0.27m, the height is 0.2m, and 10 rows are planted in each border. Flat borders are suitable for sandy soil.

2. Transplanting and density

The transplanting period can be divided into:

1) The suitable transplanting period for film-mulched fields is November 15th to Tuesday. Ten days (around the beginning of winter).

2) The suitable transplanting period for unmulched fields is October 20 (before and after frost). The regular density should be increased or decreased according to the soil fertility, fertilization level and management level. Generally, the planting row spacing is 20cm, the plant spacing is 16~17cm, and the density per acre is about 20,000 plants.

In order to prevent bolting, it is generally appropriate to use moderately sized seedlings with a leaf sheath diameter of 6 to 7 mm and a fresh weight of 4 to 6 grams per plant. Eliminate large, weak and inferior seedlings. Before planting, small and large seedlings should be planted separately and managed at different levels to increase production in a balanced manner.

Extended information:

Growing environment:

1. Temperature

Onions have strong adaptability to temperature. Seeds and bulbs can germinate slowly at 3 to 5°C and start to accelerate at 12°C. The suitable growth temperature for seedlings is 12 to 20°C, for leaves is 18°C ??to 20°C, and for bulbs is 20°C to 26°C. Strong seedlings can withstand ~6 to 7 ℃ low temperature. Bulbs require higher temperatures to expand. Bulbs cannot expand below 15°C and grow best at 21-27°C. If the temperature is too high, growth will decline and it will enter dormancy.

2. Light

Onions are long-day crops and require more than 14 hours of long-day conditions during the bulb expansion and bolting and flowering stages. Under high temperature and short day conditions, only leaves will grow and onions will not form. The suitable light intensity for onions is 20,000 to 40,000 lux. ?

3. Water

Onions should be supplied with sufficient water during the germination period, seedling growth period and bulb expansion period. However, water should be controlled during the seedling stage and before overwintering to prevent the seedlings from growing too long and suffering from freezing damage. Irrigation should be controlled 12 weeks before harvest to enrich the bulb tissue, accelerate maturity and prevent bulb cracking. Onion leaves are drought-tolerant and suitable for humidity of 60% to 70%. High air humidity is prone to disease.

4. Soil and nutrition

Onions have strong adaptability to soil. Fertile, loose, neutral loam with good ventilation is suitable. Sandy loam is easy to obtain high yields, but The bulbs in clay loam soil are plump, good in color and resistant to storage. The onion root system has a weak ability to absorb fertilizer, so sufficient nutritional conditions are required to achieve high yields.

Each 1,000 kilograms of onions need to absorb 2 kilograms of nitrogen, 0.8 kilograms of phosphorus, and 2.2 kilograms of potassium from the soil. The application of copper, boron, sulfur and other trace elements can significantly increase production.

Baidu Encyclopedia - Onion