Celery is suitable for applying more nitrogen fertilizer, but it is not suitable for topdressing urea. Celery requires a large number of facilities and vegetables during the whole growth period, which has the advantages of high economic efficiency and annual supply, and is therefore favored by the majority of vegetable farmers. However, in some areas where development facilities are cultivated earlier, soil salt is too high, which often results in irregular seedlings or yellowing and wilting after planting, which seriously affects the efficiency of vegetable production.
The reasons for the increase of soil salt concentration in greenhouse vegetables are as follows:
1. The greenhouse is a closed environment, which is not affected by rainfall. The soil moisture moves downwards less, and the fertilizer remaining in the soil is hardly leached. At the same time, the water rising movement is relatively strong, thus strengthening the accumulation of salt to the soil surface. To increase the salt concentration of the plough layer.
2, the amount of fertilized vegetables in greenhouses is generally far more than open field cultivation, and some even 4 to 6 times higher. In addition to the absorption of some of these fertilizers, a large amount of fertilizer remains in the soil, resulting in the accumulation of salts.
3, other cultivation measures such as shallow tillage, soil watering, surface fertilizer application, can increase the concentration of salt to the topsoil.
The prevention and control of soil salt damage in greenhouse vegetables can take the following five measures:
1. Formulated for fertilization. According to the fertilizer requirement and fertilizer utilization rate of vegetables, the fertilizer is planned, and a small number of multiple fertilization methods are adopted to prevent excessive fertilization at one time. At the same time, pay attention to the type of fertilizer, and use the chlorinated fertilizer with strong salt-producing ability in the soil.
2. Cover cultivation. Covered with soil surface to reduce water evaporation. Such as mulch film, straw and other coverings have a certain salt suppression effect.
3. Irrigation and washing of salt. For soils with high salinity, it is best to irrigate the water before transplanting the vegetables. Especially in the high temperature season, it takes about 10 days to irrigate.
4. Choose vegetables with strong salt tolerance. According to experts' observation of some vegetables, the order of salt tolerance from strong to weak is: broccoli, lettuce, spinach, eggplant, celery, tomato, sweet pepper, cucumber, and strawberry has the worst salt tolerance. Therefore, in soils with high salinity, vegetables with high salt tolerance should be planted to prevent salt damage.
5. Implement water and drought rotation in the facility. After planting the greenhouse vegetables for a period of time, the aquatic vegetables such as water spinach, white peony, medlar, sage, and wet cress can be rotated in the greenhouse. The long-term irrigation can effectively reduce the salt content of the ploughed soil.
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