For the old greenhouses, the most prominent problem is the soil salinization, and the most prominent cause of soil salinization is long-term, large-scale use of fertilizer by vegetable farmers. Older sheds are poor in heat insulation, and they are prone to rooting after winter. Therefore, in the selection of red fertilization in winter, the old greenhouse should pay attention to the selection of microbial fertilization or humic acid, total water-soluble fertilizer and other fertilizers, both to alleviate soil salinization but also help to increase the temperature. Select biological fertilizer. Biofertilizer can release nitrogen, phosphorus and potassium fixed in the soil and promote soil fertility. The use of biological fertilizers in older greenhouses is more effective. In order to ensure that vegetables absorb enough nutrients, it is recommended that vegetable growers use bio-fertilizers and compound fertilizers in rotation. Choose humic acid fertilizers. Because of the high nutrient content of N, P and K in the soil of old greenhouses, humic acid fertilizer can increase the utilization of P and K and some trace elements in the soil. Humic acid fertilizers have a synergistic effect on phosphorus and potassium. Based on the application of humic acid fertilizers, the amount of chemical fertilizers can be appropriately reduced, and generally it can be reduced by about 1/3. The humic acid fertilizers commonly used in vegetable production include nitrohumic acid, ammonium humate, sodium humate, potassium humate, potassium nitrohumuvate, diammonium fulvic acid, phosphoric acid fulvic, etc. Friends can choose to apply. Select all water soluble fertilizers. The total amount of water-soluble fertilizer is small, and only 10-15 pounds of greenhouses can be used for an acre of land, and the utilization rate is as high as 85%. It can supplement the nutrients needed for crops, and it is worthwhile to promote the use of biological bacteria in winter. Fertilizer way. Lactobacillus Fermentum,Fermentum Lactobacillus,Lactobacillus Fermentum Powder,Lactobacillus Fermentum Probiotic Jiangsu Biodep Biotechnology Co. ,Ltd. , https://www.mbioda.com