In recent years, the rapid development of facilities for vegetables has played an important role in increasing farmers' income. However, due to the high temperature in the greenhouse, high humidity, poor ventilation and light transmission conditions, such as improper fertilization can easily produce fertilizer damage, reduce production and efficiency, and even serious shed damage.
First, the cause of fertilizer damage
1. Too much direct damage. Greenhouse vegetables tend to have high fertilization rates, especially for fertilizers or fast-acting organic fertilizers (human waste, cakes, etc.) that cause excessive amounts of fertilizer and can easily cause fertilizer damage. This is manifested in the difficulty of water absorption in roots of vegetables, failure to produce fresh seedlings, and deformed leaves. The vegetables are wilting and even die.
2. Injury caused by improper fertilization. Dressing acupuncture points and applying a strip from vegetable roots, or applying organic manure as a base fertilizer, the mass of the fertilizer is large, causing reverse osmosis of the vegetables. The edges of the leaves of the vegetables are burned by boiling water, and are scorched after a few days.
3. Harmful gas damage. When ammonium nitrogen fertilizer or fresh organic fertilizer is applied inside a greenhouse, the temperature inside the greenhouse is high, and it will decompose a large amount of ammonia in a short period of time, especially if the fertilizer is applied to the soil surface without covering it. When sensitive vegetables such as cucumber and tomato are damaged, they mainly show watery spots on the leaves. The cells lose water and form brown spots. In severe cases, there are massive brown spots between the veins.
4. Salt accumulation is poisonous. There are many fertilizers in greenhouses, and the soluble salt in the soil rises with the groundwater to the soil surface, resulting in the accumulation of salt in the topsoil. Due to the high salt content in the surface layer, the vegetables have physiological obstacles, such as short plants, dark green leaves, poor growth, and rimming of the leaf margin.
5. The effectiveness of nutrients is reduced. When a certain nutrient is applied in excess, antagonism may occur, resulting in a decrease in the effectiveness of other elements, and the vegetables may exhibit certain element deficiency. For example, excessive application of nitrogen causes calcium deficiency, which causes dry burning of tomato umbilical rot and cabbage. Excessive phosphorus will reduce the effectiveness of zinc, and too much potassium will reduce the effectiveness of calcium, magnesium, and boron.
Second, prevention and control measures
1. Control fertilizer usage. As long as the amount of chemical fertilizers is controlled, fertilizer damage will be greatly reduced, and mid-range levels are appropriate.
2. Master the principle of a few times. The method of deep application and stratified application in all layers is advocated, which can play a role of maintaining fertilizer, reducing volatilization losses, and reducing direct injury. It is not appropriate to spread the fertilizer on the surface of the soil and evenly distribute the fertilizer throughout the entire cultivation layer. The amount of topdressing chemical fertilizer should not be too much, and at the same time, pay attention to fertilization to properly water, keep the soil moist, reduce the concentration of the solution, to reduce or avoid injury.
3. Balanced fertilization. Must start from controlling the amount of fertilizer, according to the needs of the vegetable growth in different periods of nutrition, so that nitrogen, phosphorus, potassium balanced fertilization, to change the partial nitrogen fertilizer to reduce nitrogen, phosphorus, potassium, organic fertilizer, NPK and trace Elemental fertilizer should be applied together. Do not unilaterally pursue high yields and blindly apply fertilizer.
4. Add organic fertilizer. The application of adequately cooked organic manure can improve soil structure, improve soil buffering performance, increase soil fertility, reduce fertilizer use, and reduce salt damage. Fresh organic fertilizer can be applied only after it has been thoroughly cooked.
5 timely ventilation. When the temperature is high before and after noon, the ventilation openings should be properly opened to reduce the concentration of toxic gases caused by fertilization and reduce the damage.
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