Extra-root topdressing technology in soybean production

In soybean production, paying attention to extra-root topdressing is an important measure to increase yield and income. Therefore, it is necessary to grasp the characteristics of fertilizer requirements of soybean at different growth stages and supplement nutrition in time to meet the needs of soybean growth and development, so as to achieve the purpose of increasing production and income. Principles of fertilization: suitable for phosphorus and potassium, less nitrogen, micro-application of molybdenum. Because there are symbiotic nodules in the roots of soybean, which can fix nitrogen in the air, the demand for external nitrogen application of soybean is relatively less, while the demand for phosphorus and potassium is relatively more. In addition, when soybean is deficient in molybdenum, it can hardly form root nodules, which will lead to the adverse consequences of less clamping and low 1000-grain weight, which will affect the yield. Fertilization time: should choose cloudy and windless weather, sunny days should be carried out before 10:00 and after 4 p.m. Spraying requirements: soybean is a dicotyledonous plant, the stomata on the back of the leaf are more than the surface of the leaf, and the spongy tissue on the back of the leaf has strong water absorption capacity, so both the positive and negative sides of the leaf should be sprayed when spraying leaf fertilizer. But the concentration of liquid fertilizer should be appropriate to avoid causing fertilizer damage. First, the seedling stage: mainly spraying phosphate fertilizer, especially in the land where there is no base fertilizer. The critical period of phosphorus nutrition of soybean is in the seedling stage, so the supply of adequate phosphorus nutrition at this time is beneficial to the growth and development of soybean and enhance stress resistance. In the seedling stage, the spray concentration is 2%-4%, and the superphosphate leaching solution is sprayed once every 10-15 days, twice in a row. Second, vegetative growth period: before flowering, soybean vegetative growth is the most exuberant period, mainly stem and leaf growth. Nitrogen is not only an indispensable component of protein and nucleic acid metabolism in crops, but also an indispensable element in chlorophyll synthesis, but if nitrogen is not applied properly, it is also easy to cause plant crazy growth, lodging and vulnerable to diseases and insect pests. Therefore, nitrogen should be applied according to the principle of more application in weaker plots and less application in more prosperous plots. Potassium can increase crop cellulose, grow tough stems, enhance the ability of disease and insect resistance and lodging resistance, but also enhance the ability of cells to absorb water, which is conducive to drought resistance. Molybdenum can promote nitrogen metabolism and enhance the nitrogen fixation ability of soybean. During the vegetative growth period, the foliar surface should be evenly sprayed with the proportion of 1% urea, 0.3% potassium dihydrogen phosphate, 0.5% potassium dihydrogen phosphate and 0.01% sodium molybdate. Once every 7 to 10 days, spray for 2 times in a row. The period from the first flowering to the clipping stage of soybean is the period of both vegetative growth and reproductive growth, and the branches and leaves are more exuberant. The mixed application of 0.1% photosynthetic micro-fertilizer and 1% soybean king plus 5% 25 mg / kg "920" can enhance the photosynthesis of soybean, prevent falling flowers, promote pinch and bulge, increase yield and improve quality.