Answer: About 30 days after turning green onions in autumn, the leaf growth period begins, and the fertilizer requirement increases, and 15-20 kg of ammonium sulfate is applied per mu. 50 to 60 days after turning green, the bulbs start to swell, which is also a key period for top dressing. Apply 20 to 25 kilograms of ammonium sulfate per mu, mix with a suitable amount of potash fertilizer, or irrigate dilute manure with water. Bulbs are in full bloom, fertilize as needed. For mid-to-late varieties, when the bulbs have the size of walnuts, ammonium sulfate can be applied down the water, 15-25 kg per mu to ensure that the bulbs continue to expand. Spring-planted onions were topdressed after slow seedling growth, leaf growth period, initial bulb expansion and bulb expansion phase. Disclaimer: Some articles of this website are transferred from the Internet. If the legal rights of third parties are involved, please inform this website for processing. phone As a professional supplier of medical apparatuses and instruments, Suzhou Medtion International Trade Co., Ltd. is located in Zhangjiagang City, Jiangsu Province. We are wholly owned subsidiary of Jiangsu Redleaf Medcial Equipment Co., Ltd who is a professional Medical equipment producer for 30 years. We specialize in developing and producing stretchers,anti-coronavirus products, first-aid product, Funeral Products, ward products, Diagnosis Device, emergency rescue product and so on. We supply one stop purchasing of Medical Equipment for all overseas customers. Our products can be made in accordance with customers' requirements. With advanced technology, scientific production equipment, reliable product's quality, conform contract, stable credit and excellent service, we have got the production aptitude and passed all quality authentications successfully. We warmly welcome you to cooperate with us. Oxygen Concentrator,Advanced Oxygen Concentrator,Medical Oxygen Generator,Home Use Oxygen Concentrator Medton Medical , https://www.medton.cn