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First, the lack of fertilizer land to increase the amount of topdressing In areas with more per capita cotton planting area, some villages still maintain a low input, low output state, planting cotton benefits are very low. Some even apply only 10 to 15 kilograms of urea or diammonium (more than 150 kilograms of seed cotton per year). Now cotton plants have shown severe lack of fertilizer. In particular, Nanpi County has already experienced heavy rains, and cotton fields have accumulated water and soil. Not many quick-acting nutrients are lost by leaching, and there is an urgent need for topdressing. If the amount of base fertilizer is small and there is no potassium fertilizer in the cotton field, 10 kg of urea should be applied and 7.5 kg of high-quality potassium fertilizer should be applied (potassium sulfate should be applied to the saline-alkali soil); if potassium fertilizer is applied to the base fertilizer, 10 to 15 kg of urea can be applied per mu. According to the test results of the Soil and Fertilizer Institute of Hebei Academy of Agricultural Sciences: in the case of a ratio of seed cotton and cotton straw of about 1:1.5, each production of 100 kg of seed cotton needs to absorb 4-5 kg ​​of nitrogen, 1.3-1.6 kg of phosphorus pentoxide, and oxidation. Potassium 4 to 5 kg. Without applying a certain amount of fertilizer, it is impossible to change the high yield of cotton. Phosphorus-deficient plots should also be added with 5 kg of diammonium. Slow-release coated urea (commonly known as controlled-release fertilizer) has a long potency and high utilization rate, and can be mixed with ordinary urea in a 1:1 ratio, which ensures the current and takes care of the future. It is not advisable to apply compound fertilizer in the flowering and bolling period. Instead, urea, potassium sulphate and other quick-acting fertilizers should be applied to make the cotton absorb and use it as soon as possible.
Second, there is a squatting block to carry out the root fertilization in the area where the rainfall is large in the previous section, such as the soil has better sensation, should pay close attention to the root fertilization, pay attention not to apply between small rows. At present, most areas still use large and small planting methods. In many areas, the line spacing is only 40 to 42 cm, and many farmers have not uncovered membranes. The small row is the least weakest place in the cotton root system. If the fertilizer is applied in a small row, it is slightly careless, such as a large amount of fertilizer, uneven fertilizer, close to the cotton tree, or light rain after application. It is easy to cause fertilizer damage to make cotton plants wilting. In many areas, the pre-emergence herbicides are improperly used or used in large amounts, and the root system is more debilitated. Therefore, it is strictly forbidden to fertilize between small rows. At the beginning of flowering, the topdressing should be carried out in the middle of the big row. Most farmers worry that the fertilizer is too far away from the cotton plant, and this fear is completely unnecessary. “Concentrated fertilization†does not mean “near fertilizationâ€. According to the observation of the researchers, the main root of cotton at the initial flowering stage has been more than 1 m deep, and the lateral extension of the lateral roots has exceeded 50 cm, and the extension speed of 0.5 to 1 cm can be maintained every day. Therefore, even if the fertilizer is applied in the middle of a large line of 1 meter wide, the cotton on both sides can be used; in addition, the cotton roots have chemotaxis, and where there is fertilizer, where the root system is more prosperous. And the deeper the better, the best is more than 10 cm, so that the loss of fertilizer is small, and the roots can be induced to tie down.
Third, when drought-resistant watering must be fertilized first, the author in the countryside to see a lot of farmers in the area did not fertilize the cotton, but after the watering, then topdressing, so that the effect of fertilizer efficiency delayed 5 to 7 days Once it has been poured, it will be delayed for a longer period of time, and it cannot exert the combined effect of water and fertilizer. Therefore, when cotton is watered during the flowering and bolling period, it must be fertilized before watering. If the land is already dry and cannot be root-dressed, it can be watered with the urea on the surface (like the wheat top dressing). Urea is very soluble in water, with a solubility of 105% at 20 ° C, twice as high as ammonium sulfate, and easily moves with water. Therefore, when urea is in contact with water, it dissolves rapidly into the water and migrates to the soil with water for use by cotton roots. Although this method of application is taboo for soil and fat scientists and cultivators, it is still a feasible method in the case of watering and dry and hard soils, and this method of fertilization is simple, labor-saving and quick. . Some people have questioned that the cultivating loose soil after watering will cause the loss of urea remaining in the upper layer of the soil, but in contrast, the fertilization method combined with this water and fertilizer has far more benefits than the shortcomings.
4. Immediately foliar spray fertilizer in cotton fields that cannot be watered and cannot be root-fertilized. Urea and potassium sulfate are the best foliar fertilizer varieties for supplementing nitrogen and potassium to cotton. The spraying concentration is 2%, and at least 0.5 kg of fertilizer is sprayed at a time. Urea and potassium sulfate can be used alone or in combination or alternately. Generally, nitrogen is added after potassium. If mixed with pesticides, the amount of fertilizer can be appropriately reduced, the interval is shorter, and the spray is several times. If combined with chemical control, it should be based on chemical control, with multiple sprays at the height of the cotton plant and less spray at the lower part.
Fish protein organic foliar fertilizer is a new type of foliar fertilizer, which is very suitable for cotton application. It can not only provide a certain amount of nitrogen, phosphorus, potassium and trace element nutrition, but also improve cotton resistance, strengthen roots and prolong Leaf function, prevention of premature aging and control of blight. When spraying, depending on the size and nutritional status of the cotton plant, the fertilizer should be used in 50-100 ml per mu, and the flowering and bolling period can be sprayed 3 times, once every 8 to 10 days. Other foliar fertilizers that have been tested by the masses for their effectiveness, reliability, and affordability can be applied.
Fifth, the high-yield cotton field flower bells need to be supplemented in the late stage. Whether cotton can be high-yield depends on the number of bells and the quality of the bells in the upper three fruit branches. In addition to the climate and pest and disease factors, nutrient supply still plays a decisive role. In the later stage, the roots of cotton became more and more aging, and the absorption function gradually decreased. The middle and lower ringing of the bells consumed a large amount of available nutrients in the soil; and after the rainy season, the available nutrients in the soil were damaged by certain leaching, so the later nutrient supply was generally satisfied. It is not necessary to solve the upper bell ringing, but also to solve it by foliar spray fertilizer; especially in the case of many bells in the middle and lower parts, the later spray fertilizer is more important.
Experience has shown that for most cotton fields, the most nutrient element in the late stage is still available potassium. The typical symptom of potassium deficiency is that the lower old leaves turn yellow or red, while the veins remain green. Generally, the potassium-deficient cotton field begins to appear after August 10, especially in the rainy years. Therefore, most cotton fields should be supplemented with potassium in the late stage, and high-quality potassium sulfate is still the first choice for spraying potassium. Any other foliar fertilizer is not as much potassium as potassium sulfate, and the price is high. Potassium dihydrogen phosphate is a traditional foliar fertilizer for cotton, but it is not suitable for potassium supplementation because it contains less phosphorus and potassium. Generally, cotton fields should be sprayed with potassium sulfate 2 to 3 times in August and mid-August. For example, in late August and early September, cotton fields were found to be prematurely debilitated due to severe potassium deficiency, and potassium supplementation was late.
Source: Hebei Science and Technology News
At present, cotton fields are entering the flowering period one after another. After that, cotton will enter the flowering and bolling period of more than 50 days, which is the peak period of cotton demand. Cotton has been flowering and ringing for more than 50 days during the flowering and bolling period. The demand for nutrients is continuous and uninterrupted, so in addition to the particularly fertile soil, it must be supplemented by top dressing. Topdressing in the flowering and boll period is an important event in the management of cotton flowering and boll period.
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