Detailed Explanation of Key Techniques for Overwintering Onion Seedling Cultivation

I. Key Technical Points

     1. The seedbed site must be land that has never been planted with onions; otherwise, the death rate of overwintering seedlings increases, which is unfavorable for preserving seedlings and increasing yield;     2. For greenhouse plots, the sowing period is August 1-5, sowing rate: 17 jin/mu of seed with a germination rate above 85%. For open-field seedling cultivation, the sowing period is August 5-10, sowing rate: 15 jin/mu of seed with a germination rate above 85%. This saves the cost of building or renting a greenhouse;     3. After sowing the seeds, spray Tianbu and release water, eliminating the cost of manual weeding later;     4. The standard for lifting seedlings is a leaf sheath diameter of 6-7 mm and a fresh weight per plant of 4-6 g, which is the suitable size for seedlings. When the seedlings reach the standard for lifting, they can be lifted and stored.     5. Select a plot that has never been planted with onions for the overwintering seedling storage site, and water 4-5 days before digging trenches for storage to make the soil moist. After lifting the seedlings, use a hoe to dig trenches and bury the seedlings. The buried length is 80% of the seedling length (the heart leaf must be buried), the burial thickness is 2 cun, and a thin layer of straw curtain is placed over the seedlings (to protect against sun damage to the leaves). When the soil freezes to a depth of one chi, thicken the straw curtain to more than 1 chi. After Qingming, remove the straw curtain when the soil thaws. When the temperature is suitable, transplant to the open field (mid-April).     II. Comparison Between Winter and Spring Seedling Cultivation     1. No need for greenhouse film, saving labor and effort. Since the overwintering seedling cultivation period is from August to October, the temperature is sufficient, and no insulation treatment is needed, thus saving the cost of renting or building a greenhouse. If calculated by renting a greenhouse, the average cost per mu is reduced by 100 yuan compared with spring sowing, and it saves labor and effort.     2. Saves the cost of manual weeding in the seedbed. Since Tianbu can be sprayed after sowing overwintering seedlings, it saves the cost of 3 rounds of manual weeding that spring sowing seedling cultivation requires because herbicides cannot be sprayed. The average cost per mu is reduced by 30 yuan compared with spring sowing.     3. Saves the cost of planting seedlings during transplanting. The transplanting time for overwintering seedlings is earlier, avoiding the busy farming season when spring sowing seedlings are transplanted. The labor cost for planting is reduced by 20-60 yuan per worker compared with spring sowing seedlings. The average cost per mu is reduced by 29-87 yuan compared with spring sowing.     4. Higher selling price, more profit. Because overwintering seedlings produce larger onions that sell at a higher price, the average price per jin is 0.03 yuan higher than spring-sown onions, and the average benefit per mu is 210 yuan higher (calculated at a yield of 7,000 jin per mu).     5. Higher yield, more money. The yield of overwintering onions is about 10% higher than that of spring-sown onions. Based on a spring-sown onion yield of 7,000 jin per mu and an average price of 0.4 yuan per jin, the benefit per mu of overwintering onions is 280 yuan higher than that of spring-sown onions.     6. Good quality of overwintering seedling onions. Because overwintering onions are drought-tolerant and resistant to pests and diseases, less pesticide can be applied and the dosage can be reduced. Therefore, compared with spring sowing seedling onions, it saves both labor costs and pesticide costs while improving product quality. The average cost per mu is reduced by 20 yuan compared with spring-sown onions.           7. Early harvest, easy to sell for good money. Because overwintering onions are harvested from late July to early August, one month earlier than spring-sown onions, they can catch a good price, thus ensuring stable income, and are more favorable for intercropping other crops, enabling high and stable yields of intercropped crops, which helps increase the per-mu benefit of overwintering onions.     In summary, from the above analysis, it can be concluded that the per-mu benefit of overwintering seedling cultivation is at least 669-727 yuan higher than that of spring sowing seedling cultivation of onions. Therefore, overwintering seedling cultivation technology has very strong advantages and great development potential, and is expected to spread rapidly in the coming years. Only by reasonably combining overwintering seedling cultivation technology with spring sowing seedling cultivation technology and staggering the harvest periods of onions under the two techniques can the price advantage of onions be brought into fuller play, enabling onions, this “golden industry,” to bring greater economic and social benefits to the broad community of farmers.