Skillful management and protection of growing onions in spring

Scientific fertilization after turning green in spring, the first fertilization should be carried out to supplement nutrition for the growth of onion roots and lay a foundation for the vigorous growth of aboveground parts in the future. Fertilization should be based on fully mature organic fertilizer, with 1000 kg per mu, with 20 kg of superphosphate and 10 kg of potassium sulfate in the middle. Plastic film mulching is generally only combined with watering with 15 kg of diammonium sulfate and 10 kg of potassium sulfate per mu.

When the onion plant grows to 8-10 true leaves and the bulb begins to become fat, the head-promoting fertilizer is applied for 2 times, and 10-20 kg of ammonium sulfate can be applied per square meter, focusing on the middle stage of bulb expansion. When the bulb begins to expand, do not apply too much nitrogen fertilizer, lest the plant be greedy. In the bulb expansion period, potassium sulfate should be added when fertilizing, the dosage is 5 kg ~ 10 kg per mu, because the lack of potassium in onions will lead to poor storability.

Timely watering onions planted before winter should be watered back to green water in spring and timely. Early watering will lower the temperature of the soil, which is not conducive to the growth of onions. Too late will also inhibit the growth of plants, resulting in the phenomenon of dry tip of leaves.

When onion bulbs begin to expand, water squatting seedlings should be controlled, and squatting time should be flexibly controlled according to soil, climate and plant growth status. When sandy soil or climate is dry, the squatting seedling period should be shortened appropriately. Clayey soil, low-lying and rainy soil should appropriately prolong the squatting seedling period. The aim is to promote the transformation from onion growth to bulb expansion, which usually takes about 10 days. It is generally believed that the mature tubular leaves of onions turn dark green, the mesophyll is thick, the waxy surface of the leaves increases, and the color of the heart leaves deepens, which is the sign of squatting seedlings at the end of this period. After squatting seedlings, generally watering every 5 days to promote the rapid expansion of the bulb, when there is a part of the plant lodging in the field, stop watering to avoid the bulb not resistant to storage after harvest.

When the onion is not covered with plastic film, it must be ploughed before squatting seedlings. The number of times of ploughing in clayey soil is more than that in sandy soil, and the depth of intertillage should be controlled within 3 cm, shallower near the plant and deeper away from the plant. After the plant is closed, stop ploughing. While ploughing, soil cultivation can be carried out appropriately.

The harvest is stored in southern Shandong and is usually harvested in mid-June. The main sign of onion bulb maturity is that in the later stage of bulb expansion, there are no new leaves to enrich the leaf sheath, the pseudostem is hollow, and the plant is dumped from the base of the pseudostem. The maturity of the bulb is related to the characteristics of onion varieties, planting time and climatic conditions. The varieties with short dormancy period and poor storability should be harvested early and start harvesting when half of the plants are lodging, while the harvest time of the mid-late maturity varieties is relatively late, and 70% of the plants should be harvested when lodging.

Harvest should be carried out on sunny days, and it is best to have several sunny days in a row. Pull out the whole plant during harvest and spread out for 2-3 days. When drying, only the leaves, not the head, the bulbs should be covered with leaves, which can promote the post-ripening of the bulbs and dry the outer skin. Then remove the soil, cut off the whisker roots, withered leaves can be stored. There are also some who do not remove leaves after harvest, but directly weave petals or bundle them for storage.