Application of zinc fertilizer on crops
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1. Symptoms of zinc deficiency in crops: The distribution of zinc in normal plants is the highest in the top buds, followed by the leaves, and the least in the stems. The zinc content of the whole crop is gradually increased from bottom to top. When plants are deficient in zinc, they often show lobular disease and cluster leaf disease. The content of tryptophan in plants decreases, and the amount of auxin synthesis decreases. Therefore, the plants grow slowly, short and have few leaves.
2. Characteristics of zinc absorption by crops: The sensitivity of crops to zinc is often different due to different crop types. Among the gramineous plants, maize and rice are most sensitive to zinc, and potatoes, tomatoes and beets in dicots are sensitive to zinc. Perennial fruit trees are also very sensitive to zinc. In addition to observing the symptoms from the shape, it can also be diagnosed by means of leaf analysis. The reference table for zinc content (Zn mg/kg dry matter) is as follows: Apple: Lack of <15, sufficient 16-50, high volume >50; Citrus: Lack of <15, sufficient 16-80, high volume >80; <15, sufficient 16~70, high quantity>70; corn: lack of <1O, sufficient 11-70, high quantity>70; soybean: lack of <1O, sufficient 11-70, sufficient>70; tomato: lack of <10, Sufficient 11-120, high volume >120.
3. Effective zinc in the soil: The effective zinc content in the soil is affected by many factors. Generally, the effectiveness of zinc in acidic soil is higher than that of alkaline soil. When the soil pH is 6.5, zinc deficiency may occur. The soil pH value of our county is more than 7.5, which is prone to zinc deficiency. The content of organic matter in the soil can also affect the content of available zinc in the soil, and the organic matter can release more effective zinc after decomposition. In addition, some soils with low effective zinc content, such as high effective phosphorus content or application of large amounts of phosphate fertilizer, often aggravate the symptoms of zinc deficiency in crops.
4, zinc fertilizer application technology: (1) transformation of soil conditions first to find out the effective zinc content in the soil, for some crops requiring more zinc, such as corn, soybeans, sugar beets, etc., generally apply high quality organic fertilizer per acre More than 4000 kg, improve the physical properties of the soil, so that the soil's various fertility factors - water, fertilizer, gas, heat, etc. can be coordinated. (2) Formula fertilization Under the premise of organic fertilizer, according to the principle of formula fertilization, chemical zinc fertilizer should be added as appropriate. Chemical zinc fertilizers include zinc sulfate, zinc chloride, zinc oxide, and chelated zinc, all of which are readily soluble in water. The application method is as follows: 1 base fertilizer. Apply 1-1.5 kg per mu, mix with ammonium bicarbonate and potassium sulfate as base fertilizer, but not mixed with superphosphate. 2 topdressing. For the zinc crop, the seedling stage is most sensitive to zinc, and the earlier the top dressing, the better. Corn can be applied at a distance of 7-10 cm from the seedlings. The fruit trees can be watered after being applied, and the rice can be mixed with ammonium bicarbonate. 3 spray fertilizer. When the crop has symptoms of zinc deficiency, it can be sprayed. The corn is sprayed once every 7-10 days after emergence; the rice is sprayed once in the tillering and flowering stages, and the concentration is 0.2%-0.5%. 4 soaking seeds, mixing roots, roots. The soaking concentration is 0.02%-0.05%, soaking for 12 hours. Seed dressing, use 4-8 grams of zinc fertilizer per kilogram of seed, dissolve the zinc fertilizer with a small amount of water, spray on the seeds, and mix evenly while spraying. Rice roots, 300 grams of zinc sulfate per acre, the rooting time is 30 seconds. (3) Precautions for the use of zinc fertilizer No matter which method is used to apply zinc fertilizer, it must not be excessive. Only one type of base fertilizer and top dressing can be used, and it should be applied every other year.