In spring, as the temperature rises, the greenhouse enters a new period of management. However, some harms in this period also gradually manifested with the advancement of management, and farmers need to focus on preventing "salt damage, drug damage and fertilizer damage." In response to these "three harms", if farmers do not pay attention, it will often cause the disease of vegetables and even dead trees. Therefore, comprehensive prevention and control should be carried out in accordance with the principle of prevention first and combination of prevention and control.
Don't underestimate "salt damage"
"Salt damage" is an important factor affecting yield in greenhouse cultivation. Therefore, it is imperative to solve the "salt damage" in melon and vegetable greenhouses. Blind excessive fertilization and the conversion of chemical fertilizers alone will inevitably lead to a rapid increase in salt accumulation in the soil, which will inevitably lead to the occurrence of fertilizer damage (salt damage). How to solve and avoid the harm caused by blind fertilization?
One is to adjust the application ratio of organic fertilizer, chemical fertilizer and microbial fertilizer in the greenhouse. Organic fertilizer accounts for 65% of the growth period of the greenhouse crops, chemical fertilizer accounts for 30% of the growth period, and microbial fertilizer accounts for 5% of the total growth period; chemical fertilizers should change the chlorine, nitrate, and Potassium and sodium-containing ingredients, microbial fertilizers must always participate in the whole process of base fertilizer, top dressing and fertilization.
The second is to increase the application of Jizhi brand soil improvement fertilizer 100 ~ 150 kg / mu in greenhouses with severe salt damage. The effect is extremely significant. The application of soil improvement fertilizer can control the occurrence and spread of soil "salt damage". Low-yield sheds have gradually become medium- and high-yield sheds, which are very popular among vegetable farmers.
The third is to choose a reasonable fertilizer type. The order of common chemical fertilizers from high to low is: ammonium chloride> potassium chloride> ammonium nitrate> potassium sulfate> urea> ternary compound fertilizer and binary compound fertilizer. The salt ability is strong. When applying in the greenhouse soil, pay attention to the amount of chloride, nitrate and sulfate fertilizers used.
Don't ignore the "drug damage"
The most common damage caused by plant growth regulators is the shrinkage of seedlings and the symptoms of fern leaf virus. In good weather, the symptoms of "drug damage" are not easy to be noticed or the symptoms are mild, but continuous rain and rain After the weather, the plants can not carry out normal photosynthesis, and there will be problems with root absorption. Therefore, the symptoms of plant poisoning will be prominent at this time. The prevention measures include the following:
First, do a good job of prevention. Grasp the correct concentration, method and location of plant growth regulators, such as gourd, use of ethephon can promote the early blooming of the main vine female flowers, but the use must be 4 to 6 true leaf stage, early use is prone to drugs harm.
Second, determine the applicable concentration. If the concentration is too low, it cannot produce the desired effect; if the concentration is too high, it will destroy the normal physiological activities of the plant and even damage the plant. The concentration effect of plant growth regulators is much more complicated than that of general pesticides. The concentration of the same plant growth regulator for different crops is very different, and it is related to the growth of crops.
Again, pay attention to the climatic conditions. If the temperature is too low, the leaf surface absorbs slowly; if the temperature is too high, the liquid of the liquid medicine will easily evaporate, which will easily cause the unabsorbed drugs to settle on the leaf surface and be harmful to the tissue. When applied in arid climate conditions, the concentration of the drug solution should be reduced; when applied in a season with sufficient rain, the concentration should be increased appropriately.
Don't let go of "fat damage"
The "fat damage" of greenhouse vegetables can be roughly divided into three types. One is that the amount of fertilization is too large or too close to the plant, and the crop is burned by high-concentration fertilizer; the second is the excessive application of a certain nutrient element, resulting in the lack of other elements; the third is the closure Under management conditions, excessive application of nitrogen fertilizer, no soil cover after application or no timely ventilation, ammonia or nitrite gas poisoning. All three types of "fat damage" must be controlled, and the focus should be on preventing and curing harmful crops such as ammonia.
The first is scientific fertilization, to prevent excessive fertilization at one time, cover soil or fully mix with the soil after applying the base fertilizer; for top dressing, it is necessary to promote deep application of soil, and irrigate water in time after application.
The second is to balance the fertilization. The potassium fertilizer should be applied in an appropriate amount, in stages or in layers; do not directly mix trace element fertilizers such as zinc and iron with phosphate fertilizers. It is best to mix them with decomposed organic fertilizers and humic acid fertilizers.
The third is that excessive application of nitrogen fertilizer will cause ammonia and nitrite gas to accumulate in the soil, so the nitrogen fertilizer should be applied in an appropriate amount and coordinated with phosphorus, potassium and other fertilizers. After the application, the soil should be covered in time or the fertilizer and soil should be fully mixed to make the nitrogen fertilizer be crop Absorb fully.
Fourth, the application of organic fertilizers, slow-release fertilizers and other nutrients that slowly release nutrients can reduce the production of harmful gases and inhibit nitrous gases. In addition to the rational application of nitrogen fertilizers, nitrification inhibitors can also be used in appropriate amounts.
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