Symptoms of fertilizer damage occur during nursery and field planting, especially in the south. It is no less harmful than pests. There are two types of traumatic and internal injuries. Traumatic fertilizers are caused by external damage to the fertilizer, causing damage to the roots, stems, and leaves of rape. For example, excess ammonia can cause watery spots, transmission of tissue necrosis, and black and brown spots on the stems of Katsura, which will not last long or die. Internal injury is the improper use of fertilizer, resulting in physiological damage caused by the destruction of the ion balance in the plant. For example, excessive absorption of ammonia results in the collapse of the mesophyll tissues, the disintegration of chlorophyll, the failure of normal photosynthesis, and the death of the plants, affecting the yield and quality.
The first cause is gas poisoning. When the concentration of ammonia gas in the seedbed or field is higher than 5mg/kg, the stems and leaves of rapeseed and other leafy vegetables are stained with water, causing cells to lose water. When the ammonia concentration is higher than 40mg/kg, Acute injury, transmission of tissue necrosis, chlorophyll disintegration, obvious black spots or massive lesions between stems and leaves. The production of ammonium bicarbonate, ammonia, and urea can occur. Urea is an amide nitrogen fertilizer that is hydrolyzed to ammonium bicarbonate in the soil under the action of uremic enzymes, and then decomposed to produce gaseous ammonia. In case of high temperature conditions, the soil moisture content is less than 20%. At this time, gaseous ammonia is easily deposited on the seedbed or Soil surface, causing gas poisoning. Concentration, deposition time and damage are positively correlated. Second, the concentration of damage caused by excessive use of chemical fertilizers or organic fertilizers will cause concentration damage. When the salinity concentration in the soil is higher than 3000 mg/kg, the functions of the plant to absorb nutrients and moisture are inhibited, the cell infiltration resistance is large, and the symptoms of concentration injury appear. Fertilizer production on the production, excessive organic fertilizer or not fully fermented, these fertilizers in the air, water,
Under the action of temperature, a large amount of organic acids and heat are decomposed, and the roots of Chinese cabbage vegetables such as rape cannot withstand the effects of high acid and high heat and cause fertilizer damage. In particular, the excessive application of nitrogen caused the overload of soil available nitrogen and the concentration was too high, which caused grain seed and burning seedlings. Some have caused the accumulation of nitrous acid and caused poisoning. Third, over-application of potassium fertilizer by antagonism will cause more potassium in the soil, which will hinder the absorption of calcium, magnesium, boron and other trace elements and the occurrence of deficiency syndrome.
Prevention methods (1) Based on practical, practical, practical principles to reform fertilization methods. Promote the use of enzyme composted compost and decomposed organic fertilizers, using stratified application or full-layer deep casting. The fertilizer required for the production of manure in the lower part of the crop will be applied to the soil in 60%-80% of the total amount during the soil preparation. The total amount of fertilisers and fertilization planned in the year may also be used. Technology, to grasp the three elements of nitrogen, phosphorus, potassium and trace elements formula, after application according to the degree of soil moisture to determine whether to water, generally to keep the soil moist, so that the full maturity of fertilizer. Do not sow or plant immediately after dry application. (2) Apply chemical fertilizers scientifically. The standard amount of 667m2 for each vegetable field is 25kg of ammonium bicarbonate, 15kg of ammonium sulfate and 10kg of urea. The weather, soil, seedlings, physical and chemical properties of fertilizers must be taken into account during the application, and they should be grasped according to local conditions so that they can fully exert their fertilizer efficiency and save energy. Cost, effectively prevent the occurrence of fertilizer damage. Conditions to minimize the amount of chemical fertilizers to produce nitrate-free vegetables. Promote the application of coated urea, long-term ammonium bicarbonate, controlled release fertilizers, wrapped fertilizers, silicate bacteria, biological potash and so on. (3) Advocate the combination of biological fertilizers and chemical fertilizers to reduce the use of chemical fertilizers in the production of long-term use of chemical fertilizers, soil microorganisms will also cause decomposition of organic matter blocked, not only easy to lose nutrients, while reducing the utilization of organic fertilizer and other resources. Therefore, the combination of biological fertilizers and chemical fertilizers can improve the long-term application of chemical fertilizer soil, not only to make up for the shortcomings of lack of nitrogen in biological fertilizers, but also to make the chemical fertilizers not lost. The vegetable field can apply 50-80kg of green biological fertilizer per 667m2 or spray Application of "Yi Yi" microbial active organic fertilizer 300 times. (4) If necessary, apply Huimanfeng, Fengbao, Baofengzao and other multi-element foliar fertilizers. When Huimanfeng is applied, the dosage of 667m2 is 250-500ml, diluted 400-600 times, or administered with Fengbao Active Liquid Fertilizer I 400-500 times.
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