First, scientific fertilization
The first fertilization will be carried out after the return of spring in spring to supplement the growth of the onion root system and lay the foundation for the vigorous growth of the aboveground parts. Fertilization should be based on fully decomposed organic fertilizers, with 1,000 kg applied per 667 square meters, followed by 20 kg of superphosphate and 10 kg of potassium sulfate. The mulching film generally applies 15 kg of diammonium sulfate and 10 kg of potassium sulfate per 667 square meters.
When the onion plants grow to 8 to 10 true leaves and the bulbs begin to grow into size, they begin to apply the head fertilizer and apply it for 2 to 3 times. Each square meter can be applied with 10-20 kg of ammonium sulfate. Fertilizer is applied in the middle of bulb expansion. The emphasis is on the amount of fertilizer to be applied. When the bulb begins to swell, do not apply too much nitrogen to prevent the plant from "greediness." During bulb expansion, potassium sulfate should be added during fertilization at an amount of 5 to 10 kilograms per 667 square meters because potassium deficiency from onions can result in poor storage stability.
Second, timely watering
Spring water should be poured back to Qingshui, pouring green water should be timely, premature watering will reduce the temperature of the soil, is not conducive to the growth of onions, will inhibit the growth of plants too late, the occurrence of leaf tip phenomenon. When the onion bulbs begin to expand, the length of the seedlings must be controlled according to the soil, climate, and plant growth conditions. When the sandy soil or the climate is dry, the seedling stage should be shortened appropriately; the clay soil, low-lying, It is necessary to appropriately extend the seedling stage during the rainy season. The purpose is to promote the expansion of onion growth into bulbs, which generally takes about 10 days.
It is generally believed that the mature tubular leaves of onions turn dark green, the leaves are hypertrophied, the waxiness of the leaves is increased, and the color of the heart leaves is deepened, which is the sign of the end of the seedlings in this period. After the seedlings are planted, they are generally poured with water every 5 days to promote the rapid expansion of the bulbs. When the plants in the field are partially lodged, watering is stopped to avoid storage after the bulbs are harvested.
Third, harvest storage
Onions in Laizhou are generally harvested in mid-June. The main sign of maturity of onion bulbs is that in the late stage of bulb expansion, no new leaves are filled with leaf sheaths, and the pseudo stems are hollow, and the plants are dumped from the base of the false stems. The sooner or later of bulb maturity period is related to the characteristics of onion varieties, planting time and climatic conditions. The species with short dormancy and poor storability should be harvested as early as possible. When half of the plants fall down, they can start harvesting, while the late-maturing varieties have late harvest, and 70% of the plants should be harvested when lodging.
Harvesting should be carried out on a sunny day, with several sunny days being best. The whole plant will be pulled out at the time of harvest and spread for 2 to 3 days. When drying, only dry leaves, no sunning, bulbs should be covered with leaves, which can promote the ripening of bulbs and dry the skin. Then remove the soil and cut the fibrous roots and dead leaves to store them. Some of them do not go to the leaves after harvest, and they are directly compiled or bundled and stored.
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