Fertilizers produced during fertilization are difficult to identify and sometimes confused with pesticide phytotoxicity. Therefore, it is necessary to distinguish between different situations and identify common fats. The following are two types of fertilizer types and identification methods.
Burn type fat damage. Fertilizer is applied in the orchard. If dry application is applied, urea, ammonium bicarbonate and ammonium sulfate are applied alone, and the water is not diluted with water. The fruit trees such as citrus are prone to burn-type fertilizer. As a result, the main branches and side branches of the orange tree are often badly damaged, the bark is chlorotic and brown, and the small branches are dehydrated or even die. Some orange trees start to lose water and turn yellow and dry coke from the mature tip of the base branch, and then quickly fall off, but the new leaves on the top of the branches are not falling on the tree, and some fruit farmers mistakenly believe that root rot harm causes rotten roots. Dead tree. Therefore, fertilization in citrus and other orchards should pay attention to the application of compound fertilizer and superphosphate, etc., the above situation rarely occurs. When applying single fertilizer, the hole should be poured into the water. If it is in dry weather, apply fertilizer, especially digging. When the hole is applied dry, it will rain for a long time after fertilization, and the fat will come faster and more seriously.
Poisonous fertilizer. Some fertilizers are toxic, such as lime nitrogen, also known as calcium cyanamide, a dark gray powdery or fine-grained nitrogen fertilizer, and the only slow-acting nitrogen fertilizer with water-insoluble characteristics, in addition to being used as fertilizer. It can also be used as a herbicide, a bactericide, a defoliant, and a snail. However, lime nitrogen has strong toxicity. After being applied to the soil, it needs to be absorbed by the crop through a series of transformations. However, some toxic substances will be poisoned during the transformation process, causing damage or death. Therefore, it should be used as a base fertilizer when using, and it is not suitable for top dressing or seed fertilizer, and the application amount is strictly controlled. The crops sensitive to it are rapeseed, potato, etc., which are generally not suitable for application.
In addition, inferior chemical fertilizers such as superphosphate and its superphosphate-containing compound fertilizer, the free acid exceeds the standard, and it is easy to burn the seedlings after being applied to the soil. When the fresh manure is directly applied, and the amount is large, the fertilizer produces a large amount of organic acid and heat during the decomposition process, which easily causes the root of the crop to be injured and forms a fertilizer.
(Cao Dihuan)
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