1. timely sowing: onion seeding should be sown about 40 days before the local average temperature drops to 15 ℃. Generally in mid-September sowing. Each acre of onion land need to build a seedbed 35 square meters, sowing 120-150g, seed bed width should be slightly equal to the arm length of about 1-1.2m, easy to operate.
Sowing method: first sieve the soil with a fine sieve, ready for mulch, and then in the whole nursery bed watering the bottom of the water, water seepage is complete, in the bed evenly sown seeds, covered with 1cm thick mulch. Before germination, the seeding furrow is covered with an old straw mat or straw to prevent the seedbed from drying out. 8-9 days after sowing when the beds show buds, remove the cover (should be removed in the evening, so as not to avoid seedlings burned by the sun) and watering.
2. Inter-seedling, seedling: when the onion seedlings have 2 true leaves, the general seedling growth to about 5cm, to carry out 2 inter-seedling. Seedling density is too large, the lack of light between plants, difficult to form strong seedlings. In order to make a single plant to get full light, sowing each seedling should occupy the last 3cm2 seedbed, strip sowing should be made through the inter-seedling spacing of 1-1.5cm, should be combined with the inter-seedling weeding in a timely manner.
Second, field cultivation techniques
1. Fertilization: (1) Border formation: After the soil is plowed and harrowed, make a 120cm 4-row border. The beds should be well fertilized.2) Mulching: Before mulching, the ground is finely tilled, well fertilized, and watered to create moisture. Spraying herbicides: wait until all the water in the beds seeps through, and spray when the soil is moist. Use 33% weed killer 100ml per mu, evenly sprayed on the bed, mulching film compaction.
2. Transplanting period and seedling age: (1) The transplanting date is generally in mid-November. (2) transplanting before the seedling requirements are: seedling age 50-55 days, because at this time the seedling is easy to root, transplanted back to upright fast; seedlings do not grow, because the seedling grows back to upright slow; seedling thickness of 6-8mm, seedling height of 25cm, the seedling weight of about 4-6g; no insect pests and weeds; branching more leaves are not damaged.
3. transplanting: before transplanting holes in the film, row spacing 20cm, plant spacing 15cm. seedlings, should be transplanted immediately, transplanting can not make the roots exposed to the ground surface, but also should not be too deep, generally 2-3cm deep can be. After transplanting, each hole watering or irrigation in the border to promote its survival.
4. Moisture management: immediately after the end of planting irrigation slow seedling water, and then appropriate water control, to promote the development of new roots. Timely irrigation of antifreeze water to ensure the safe overwintering of seedlings. Timely irrigation of green water, promote the early development of seedlings green. Bulb expansion before the water control "squatting" 1 week, when the leaf color dark green, wax increased, leaf thickening when the end of the "squatting", start irrigation. After bulb expansion, diligent irrigation, promote bulb growth, generally 7-10 days 1 time, until 1 week before harvest, stop irrigation, promote bulb maturity, and favorable storage.
5. Fertilization: (1) good fertilization, early March when the onions began to return to the green, with urea 10kg per acre. (2) heavy application of bulb expansion fertilizer, April 15-20 timely application of full expansion of fertilizer, 15kg per acre with diammonium phosphate, urea 10kg. (3) spray a good foliar fertilizer, bulb expansion in the middle of the early stage, spraying foliar fertilizer. Specific method is: respectively in late April and early May with potassium dihydrogen phosphate 0.15kg per mu FengYanLing (or FengYanSu) 1