Unreasonable fertilization is usually caused by unreasonable amount of fertilization, fertilization period, and fertilization methods. Common phenomena include:
1, shallow or table fertilizer application. Fertilizers are volatile, lose or hard to reach the roots of crops, and are not conducive to crop absorption, resulting in low fertilizer utilization. Fertilizers should be applied 16 to 26 cm below the seed or plant side.
2, dual chlorine fertilizer. The compound fertilizer produced with ammonium chloride and potassium chloride is called double-chlorine fertilizer, containing about 30% chlorine, easy to burn seedlings, and timely watering. Saline-alkali land and chlorine-sensitive crops cannot be treated with chlorine-containing fertilizers. Excessive application of potassium chloride to leaf (stem) vegetables not only causes the vegetables not to be tender and has many fibers, but also makes the vegetables taste bitter, has poor taste, and has low benefits.
Urine-based compound fertilizers have high nitrogen content, biuret nitrogen is also slightly higher, and easy to burn seedlings. Pay attention to the depth of watering and fertilization.
3, improper application of chemical fertilizers on crops, may cause fertilizer damage, the occurrence of burning seedlings, plant wilting and so on. For example, one-time application of too much chemical fertilizer or insufficient soil moisture after fertilization will result in excessively high concentration of soil solution and difficulty in water absorption in the crop roots, resulting in wilting and even dead plants. Excessive application of nitrogen fertilizer, the soil has a lot of ammonia or ammonium ions, on the one hand ammonia volatilization, the formation of alkaline droplets in the air droplets, burn the crop, produce spots on the leaves of burnt; on the other hand, ammonium ions in the dry The soil is easily nitrated and converted into ammonium nitrite by the action of nitrosobacter bacteria. The gasification of nitrogen dioxide gas will poison the crops. Irregular water-stained patches appear on the leaves of the crops and the veins turn white gradually. In addition, when there is too much ammonium nitrogen in the soil, the plants will absorb too much ammonia and cause ammonia poisoning.
4. Excessive use of certain nutrient elements will not only poison the crops, but also impede the absorption of other nutrient elements by the crops, resulting in deficiency of the disease. For example, excessive application of nitrogen can cause calcium deficiency; excessive nitrate-nitrogen can cause loss of molybdenum chlorosis; excessive potassium can reduce the effectiveness of calcium, magnesium, and boron; too much phosphorus can reduce the effectiveness of calcium, zinc, and boron.
5. Fresh manure should not be applied directly to vegetables. Fresh human waste contains a lot of bacteria, toxins, and parasite eggs. If it is not directly cooked, it can contaminate vegetables, cause diseases, and require high-temperature heaping fermentation or harmless treatment. Unfathered livestock and poultry manure will produce a large amount of harmful gases such as hydrogen sulfide in the process of decomposing, which will make vegetables seeds suffocate due to lack of oxygen; and generate a lot of heat, which will easily cause vegetable seeds to burn or root rot, which is not conducive to the germination of vegetable seeds. Grow.
In order to prevent the occurrence of fertilizer damage, production should pay attention to reasonable fertilization. One is to increase organic fertilizer and improve soil buffering capacity; the other is to apply fertilizer according to regulations. According to the soil nutrient level and the crop's demand for nutrient elements, reasonable fertilization, not arbitrarily increase the amount of fertilization, applying top dressing to grasp the principle of light fertilizer and ground handling; third, full-layer fertilization. The same amount of fertilizer, when applied locally, often causes a sharp increase in the concentration of the local soil solution, injuring the root system of the crop and changing it into full-layer fertilization, so that the fertilizer is evenly distributed throughout the plough layer, which can prevent the crop from harm.
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