Air harm ammonia easily enters from stomata and water holes in the leaves of vegetables and causes alkaline harm in the plants. The leaves of the victim crops were initially immersed in water and gradually turned to light brown. The young shoots or growing points were atrophic and black. When the leaves were severe, they were scorched and the whole plant died of physiological water loss. There are four causes of harm: one is the application of insufficiently decomposed manure; the second is the fermentation of cake fat or chicken manure in a greenhouse; third is the application of fertilizer to the ground during top dressing; four is uneven fertilization, such as sudden high temperature weather, easy to induce concentration Ammonia damage.
Fertilizer application to the soil of a single chemical fertilizer or excessive application of chemical fertilizers, commercial organic fertilizer, resulting in excessive concentration of soil solution, resulting in reverse osmosis, leading to the inhibition of vegetable root development, plant wilting or leaf margin charred, there is a deficiency of disease .
One of the phytotoxicity is dominant phytotoxicity, and the symptoms are obvious; the second is hidden phytotoxicity, and the symptoms lurk or extend to the lower jaw. After a phytotoxicity occurs, the leaves of the vegetables lose their green or produce spotted spots, perforation, fallen leaves, fallen flowers, fallen fruits, or even the whole plant withered. There are four causes of harm: one is that the pesticide species is not on the road or misuse of herbicides; the second is that the application concentration is too large; the third is the purchase of inferior pesticides; and the fourth is the use of drugs at high temperatures.
Drought and drought are not only affecting the sowing of vegetables and seedlings, but also affect the growth and development of vegetables, and bring difficulties to fertilization. There are three causes of harm: First, improper site selection and lack of water sources; Second, poor water quality; Third, ditches, irrigation and drainage facilities are not matched, and water is difficult to draw.
Harmful damage means that the same or similar vegetables are planted in the same shed in the annual or seasonal season, and the yield and quality of the crop are decreasing year by year. There are three causes of harm: First, the same or similar vegetables prefer a certain kind of nutrient elements. When the needed elements are not added in time, it will cause harm; Second, the accumulation of soil pathogens causes disease; Third, the root exudates lead to imbalance of soil microbial community structure. , Soil aging.
There are four countermeasures:
Before selecting a suitable shed site to improve the site selection of water system supporting sheds, full consideration should be given to whether there are sufficient and excellent water sources. To open a ditch, easy to divert water, drainage. Wherever conditions permit, one faucet can be installed in each greenhouse, and sprinkler facilities can be used in high standards.
Rational fertilization promotes healthy vegetables Firstly, it is necessary to apply sufficient organic manure in farmland all year round; second, use refined high-energy commodity organic fertilizers, bio-organic fertilizers, and bio-organic compound fertilizers; and third, use N and P for nitrogen and phosphorus stabilization. , Potassium fertilizer, and microelement fertilizer; Fourth, fertilize in appropriate amount; Fifthly, if fertilizer damage occurs, it can spray 0.01% of bait (brassica lactone) or erythrosine (microbial agent) 800 times solution 2 ~ 3 times.
Scientific use of drugs to ensure the safety of vegetables First, when a minor injury occurs, fertilizer and water management can be strengthened to restore the normal growth of vegetables; Second, use of pesticides, especially herbicides should be used with caution; Third, the dose and concentration of good pesticides should be avoided. Repeated application of a pesticide; four is not allowed to mix pesticides; five is to avoid high temperatures; six herbicide applied equipment can be reused after cleaning.
Rotation of crop rotation to adjust the cultivation environment First, eggplant, tomatoes, melons and other susceptible vegetables, to change planting varieties in different seasons or seasons; Second, prone to disturbances in greenhouses to increase the application of organic fertilizer to improve the soil; The soil retting agent inhibits the bacteria; the fourth is the lack of nutrients in response to the lack of soil. (Yu Hongzhang)
Link: Fertilizer in Winter Shelter "Seven Don't"
Many vegetable farmers in greenhouse vegetable cultivation often blindly fertilize and use fertilizers. Not only do they fail to produce high yields, but they also cause harm to the soil and crops. Recently, scientists used greenhouses to scientifically use fertilizers. The reporter interviewed the Gansu Academy of Agricultural Sciences for soil and fertilizer. Director of the Institute of Water-saving Agriculture Che Zongxian.
Do not apply ammonium thiosulfate as a physiological acid fertilizer. After application, it will increase the acidity of the soil, destroy the soil structure, and adversely affect the growth of vegetables.
Do not use uncomminuted cakes and cakes with low carbon-nitrogen ratios and rapid decomposition. Locally, high temperature and high concentrations of ammonia and organic acids are easily generated and roots are easily burned. Cakes should be broken and used after high temperature fermentation.
Do not fertilize vegetables under drought conditions is hi water crops, fertilization when the soil is dry, not only can not fully play the effect of fertilizer, but also a sudden increase in soil solution concentration, easy to make vegetables root. Therefore, the fertilization of vegetables should be combined with irrigation. Fertilization can be carried out. Fertilizer can be filled with fertilizer and then watered, or the water can be applied directly.
Do not use too much diammonium phosphate vegetable requires a lot of nitrogen and potassium, and relatively less phosphorus. Phosphorus fertilizers are not suitable for dispersing in vegetable greenhouses. Phosphorus is easily absorbed and solidified by the soil and loses its fertilizer efficiency. Therefore, phosphate fertilizers are suitable as basal fertilizers or concentrated in root-dense soil layers in the early stage of vegetables. It should be noted that diammonium phosphate should not be mixed with alkaline fertilizers such as grass ash so as to avoid ammonia volatilization and ammonia damage.
Do not use chloride-containing chemical fertilizers. Chloride ions can reduce the starch and sugar content of vegetables. The quality of vegetables will be degraded and the yield will be reduced. Moreover, chloride ions will remain in the soil, which can lead to acidification of the soil and easily cause decalcification of the soil.
Do not apply iron fertilizer to the soil. Iron is easily converted into insoluble compounds by the soil and loses its fertility. Iron does not flow easily on the leaves. Foliar sprays should be used. Diluted ferrous sulfate solution can be sprayed evenly on the leaves of vegetables. Face.
Do not apply the rare earth micro-fertilizer directly to the soil rare earth fertilizer solution can be sprayed on the leaves of vegetables, spraying about 60 kilograms per acre.
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