Techniques of overwintering and seedling protection of spinach in North China

Autumn spinach is a winter vegetable sown in autumn and harvested in spring. It takes more than 100 days from November to early March and April of the next year in Heilongjiang and other northern areas. Therefore, under the condition of long-term low temperature, how to ensure safe winter is the key to harvest. First, pour frozen water to pour frozen water must be "certain","two appropriate". "Certain" is to decide whether to irrigate frozen water according to the amount of soil moisture. Generally, the absolute water content of sandy loam soil is less than 15%, loam soil is less than 17%, clay soil is less than 20%, frozen water should be poured. "Two suitable" means timely watering and proper watering. The suitable time for freezing water is when the soil tillage layer can thaw during the day and freeze at night. Proper watering means that the amount of frozen water cannot be too large or too small. Generally, it is appropriate to connect with the soil moisture. Second, the overwintering fertilizer can increase the soil nutrient content, play a role in winter fertilizer and spring, and promote weak and strong. Especially for the vegetable fields with less fertilizer, poor soil fertility and weak seedling situation, it is more important. Therefore, should be combined with irrigation frozen water dressing winter fertilizer, general mu application urea 10 kg or ammonium sulfate 20 kg, with water dressing. Third, the cover cold absolute low temperature in the northern cold period is very unfavorable to the safe winter of vegetable seedlings, so cover cold should be used to ensure the safe winter of seedlings. Mulching can generally be carried out after the topsoil has completely frozen. Mulch is rich in organic matter and crushed farm manure, mu sprinkle about 1000 kg.