Excuse me, how can we grow big white onions with thick and long stems?

Onion has been planted in China for more than 2,000 years, and its edible parts are mainly pseudobulb and tender leaves. It can be eaten raw or cooked, and it is one of the essential condiments for families. So how can we grow thick and long white onions in the process of planting green onions? Now I will talk about the cultivation techniques of green onions based on our experience in planting green onions in Gansu.

First of all, the seedlings of green onions

1. Choice of nurseries

It is advisable to choose sandy loam with fertile soil, flat terrain and convenient irrigation and drainage for green onion seedling.

2. Soil preparation and fertilization

Combined with soil preparation, 2500 kg of decomposed high-quality farm manure or 200-300 kg of commercial organic fertilizer and 20-30 kg of potassium sulfate compound fertilizer are applied.

In order to prevent soil-borne diseases, 500 grams of 40% phoxim EC can be mixed with fine sand per mu to form toxic soil. After spreading, deep ploughing should be carried out. After harrowing, the boundary shall be flat with a width of 1 m. The direction of the boundary surface should be conducive to irrigation and drainage.

Step 3: sow.

The sowing date should be suitable according to the local actual climate. In Gansu, we can divide it into spring sowing and autumn sowing, and sowing in early spring should be carried out after the soil thaws. Autumn sowing is usually in early September? Beginning of autumn? After that, before the soil is frozen, the seedlings can reach 2~3 true leaves, and the plant height is about 10 cm.

After the seeds are dried for 1~2 days before sowing, the seeds are evenly spread on the prepared border, and the amount of seeds used is generally 3~4 kg per mu, and then lightly raked and compacted after sowing.

4. Management of Welsh onion seedlings

The management of spring sowing and autumn sowing at seedling stage is different because of different seasons.

Spring seedling management: Spring seedlings enter the vigorous growth period after emergence, and the supply of fertilizer, water and fertilizer should be strengthened. Combined with the watering interval 15~20 days, 5 ~ 8kg of urea should be applied twice, and intertillage weeding should be carried out in time. Management of autumn sowing seedlings: when autumn sowing seedlings emerge, the soil should be moist to ensure that seedlings emerge completely, and frozen water should be poured before soil freezing; After turning green in spring, water and fertilize every 15~20 days, and apply 5 ~ 8 kilograms of urea per mu. Second, the management of onion colonization

1, soil preparation and fertilization

Choose fields with rich organic matter, loose soil and good drainage, and the previous crops should be non-onion and non-garlic. 2,500-3,500 kg of decomposed high-quality farmyard manure or 240-400 kg of commercial organic fertilizer, 30-40 kg of ternary compound fertilizer of potassium sulfate, 40 kg of calcium superphosphate, 0/0 kg of diammonium phosphate/kloc or 20-30 kg of ammonium nitrate are applied per mu, and after 25 cm of deep ploughing, they are harrowed.

2. Ditching and raising soil

First, dig a ditch with a depth of 15~20 cm with a hoe of about 20 cm, and then dig a ditch with a depth of 30 cm with a hoe of 10 cm, and keep the row spacing at 40~60 cm. The excavated soil will be compacted on both sides for soil cultivation in the growing period. Mix 500 grams of 40% phoxim EC with fine sand per mu, and spread it after ditching to control underground pests.

Step 3 plant

When planting, the seedlings are graded according to the size of rhizomes, and the graded seedlings are transplanted separately according to the size, which is convenient for field management in the later stage. When transplanting seedlings, the plant spacing is 3~5 cm, and the transplanting amount per mu is about 27,000 plants. When planting seedlings, keep the onion roots at the same level, shovel a small amount of fine soil, and compact the onion roots to the depth without burying the heart leaves.

Third, post-colonial management.

Generally, after the onion seedlings are planted, new roots can be sent out in 3~7 days and new leaves begin to grow. This period is a slow seedling stage, and the main management work is to promote root growth. After the slow seedling is completed, the green onion immediately enters the vigorous growth period, which is the key period for plant height, false stem fattening and onion segment enrichment. Therefore, the management of fertilizer and water should be strengthened.

1, topdressing

In the vigorous growth period, the first topdressing should be combined with soil cultivation. Spraying urea 10~ 15 kg per mu in onion ditch, followed by soil cultivation and watering; Probably enter? Summer? Season, topdressing for the second time, applying urea 10~ 15 kg and potassium sulfate ternary compound fertilizer 15~20 kg per mu, after the same fertilization, cultivating soil and watering; ? White deer? And then what? Autumn equinox? Topdressing, soil covering and watering shall be carried out respectively in seasons, and the method is the same as above. After each watering, Austria carries out intertillage weeding and cultivates 1~2 cm of soil into the ditch to prevent soil hardening and sun cracking.

Step 2 raise the soil

Soil cultivation is a process of piling soil on the furrow platform around onion roots, which can increase the height and length of onion plants and the medium amount of onion. When cultivating soil, it should be carried out as far as possible in sunny days without dew, with the core leaves not buried as the standard.

When raising soil, 1 and secondary raising soil should be shallow because the transplanted seedlings grow slowly; From the third time to the fourth time, the new roots have been firmly rooted and grow rapidly, so the soil should be deeply cultivated. Generally speaking, according to the growth of green onions, the number of times of covering soil should be no less than 4 times before harvesting.

water

When watering green onions, grasp the principle of frequent watering and watering in the morning and evening, and combine soil cultivation with topdressing. When will the solar term arrive? First frost? After that, the watering frequency should be gradually reduced, and the watering should be stopped 15 days before harvesting, which can better improve the storage time of green onions.

Fourth, the prevention and control of diseases and pests of green onions.

The field diseases of scallion mainly include downy mildew, purple spot, rust and scallion spot. The main pests are onion leaf miner, onion thrips, grubs, grubs and so on.

1, agricultural control

First, clean up the sick and disabled in the field in time to make the pathogenic bacteria overwinter without a host; Second, implement crop rotation to reduce obstacles to continuous cropping; Third, scientific and reasonable close planting; Fourth, strengthen field management and remove weeds in time; Fifth, apply more organic fertilizer and phosphorus and potassium fertilizer to improve the stress resistance of plants.

2. Pesticide control

Compliance of chemical prevention and control? Prevention first, comprehensive prevention and control? The principle of.

Downy mildew: at the beginning of the disease, chlorothalonil, mancozeb and metalaxyl were used for prevention and treatment, and the medicine was sprayed every 7~ 10 day, alternating 2~3 times. Purple spot disease: before sowing, soak the seeds in warm water at 45℃ for 65438 0.5 hours for disinfection; At the beginning of the disease, Bordeaux mixture or mancozeb was used, which was dense before and sparse after, and sprayed alternately for two or three times. Rust: Triadimefon, mancozeb and triadimefon were used at the initial stage of the disease every 10 day/time 1 3 times continuously. Liriomyza huidobrensis: Larvae preys on mesophyll, and zigzag tunnels can be seen on the leaves. In severe cases, a leaf can be preyed by more than a dozen larvae, leading to photosynthesis and yield decline. Control method: spray avermectin, dimethoate emulsion or trichlorfon/kloc-0 every 5-7 days, alternately for 2-3 times. Stop the drug before harvest 15 days. In short, in order to obtain large white onion with long stems, field management and pest control should be refined from sowing to planting, which is the premise of high yield of green onion.