(I) Soybean Fertilization Technology 1 Soybean demand for major nutrients Soybeans have relatively high economic value in grain and oil crops. Soybeans require a large amount of nitrogen, but they can fix nitrogen through root nodules. Generally, they can obtain 5-7.5 kg/mu from the atmosphere, which is about 40% to 60% of that required for soybeans. For each 100 Kg of soybean produced, 1.8-10.1 Kg of nitrogen (N), 1.8-3.0 Kg of phosphorus (P2O5), and 2.9-3.0 Kg of potassium (K2O) should be absorbed from the soil. The ratio of nitrogen, phosphorus, and potassium needed was 1:0.17-0.23:0.39-0.41. It absorbs much more nutrients than rice, wheat and corn. 2 soy absorption law Soybean growth is divided into seedling stage, branching stage, anthesis stage, crust stage, granule stage and maturity stage. The whole growth period is 90-130 days. The law of sucking fertilizer is: (1) Nitrogen absorption rate. The emergence and branching period accounted for 15% of the total amount of nitrogen absorbed during the whole growth period, 16.4% from branching to full flowering, 28.3% from flowering to stalking, and 24% from drum bean. Flowering to grain size is the peak period of soybean nitrogen uptake. (2) Phosphorus absorption rate. The seedling stage accounted for 17% of the initial flowering period, 70% of the early flowering period to the drum bean period, and 13% of the drum grain to the mature period. Phosphorus is needed most in the mid-growth stage of soybean. (3) The rate of potassium absorption. Accumulative potassium absorption accounted for 43% before flowering, flowering to account for 39.5% of the granule phase, and still required to absorb 17.2% of potassium from drum grain to maturity. From the above, it can be seen that the flowering to pedicel stage is not only the peak period of soybean dry matter accumulation, but also the peak period of absorbing N, P, and K nutrients. 3 Technical points of fertilization of soybean Soybean fertilization system is generally composed of basal fertilizer, seed fertilizer and topdressing fertilizer. The principle of fertilization is to ensure that soybeans have sufficient nutrition, but also to play a role in nitrogen fixation of rhizobia. Therefore, whether in the early or late growth stage, nitrogen should not be used in excess so as not to affect the growth of Rhizobium or cause lodging. On the other hand, it is also necessary to correct the misconception that "there is no need for nitrogenous fertilizer for rhizobia." Fertilization should be done with a reasonable mix of N, P, K, trace elements such as boron and molybdenum, and combination of slow-acting and quick-acting fertilizers. The summary is as follows: 3.1 Base fertilizer application of organic fertilizer is the key measure to increase soybean production. Organic fertilizers can be applied to the former crops on the crop rotation, while soybeans use their subsequent effects. It is conducive to nodulation and nitrogen fixation and increases soybean production. Soybeans can be grown on low-fertility soils, and 10Kg of calcium phosphate and potassium chloride can be added as basal fertilizer, which is beneficial to soybean production. 3.2 Seed Fertilizer Generally, 10Kg-15Kg superphosphate or 5Kg diammonium phosphate is used as seed fertilizer per acre, and boron-deficient soil is added with 0.4-0.6Kg borax. Because soybeans are dicotyledonous crops, seedlings are difficult to top soil at the time of emergence. Seed dressings are best applied to the lower or lateral parts of seeds, and must not be in direct contact with fertilizers. In addition, Huaibei and other places in our province with 1-2% ammonium molybdate seed dressing, the effect is also very good. 3.3 Top dressing proved that In the soybean seedling stage, when the root has not yet formed nodule, or when the nodule activity is weak, proper application of nitrogen fertilizer can make the plant grow robustly. It is also necessary to apply a small amount of nitrogen fertilizer at the flowering stage as appropriate. The amount of nitrogen fertilizer is usually urea 7.5-10Kg. In addition flowering spraying with 0.2-0.3% potassium dihydrogen phosphate aqueous solution or with 2-4Kg per acre with 100Kg of superphosphate water spray, can increase the nitrogen content of grain, there is a significant increase in production; according to data, flowering spray 0.1% borax, copper sulphate, manganese sulphate aqueous solution can promote full grain, increase soybean oil content. (B) Sweet Potato Fertilization Technology 1 Sweet potato requirements for major nutrients Sweet potatoes are food and vegetables that are used as food and have high nutritional value. It is also a raw material for industrial production. In recent years, more and more attention has been paid to planting. The roots of sweet potato are deep and wide, stems can be rooted, and the ability to attract fertilizers is strong. A certain amount of production can also be obtained on barren soil, which often leads people to believe that sweet potatoes do not need to be fertilized. Practice has proved that sweet potato is a crop that requires fertilization. According to the study, the production area of ​​fresh potatoes per mu of about 3500-5000Kg, every production of 1000Kg of sweet potato to absorb 3.5Kg of nitrogen (N), 1.8Kg of phosphorus (P2O5), about 5.5Kg of potassium (K2O) from the soil. The ratio of N, P and K is 1:0.51:1.57. Sweet potato is a good potassium crop, and increasing potassium fertilizer has a significant effect on both yield and quality. Sweet potato is not chlorine, when the application of ammonium chloride, potassium chloride and other chlorinated fertilizers containing more than a certain amount, will not only reduce the starch content of potato block, and the potato block is not resistant to storage. 2 Fermentation Law of Sweet Potato Sweet potato absorbed less nutrients at the seedling stage. From the branching and potato stage to the vigorous growth stage of stems and leaves, the absorption rate of nutrients increased, and the absorption amount increased. It gradually decreased in the late period, and the absorption of nitrogen and phosphorus decreased during the period of rapid expansion of the tuber. The absorption of potassium remains high. 3 sweet potato fertilization technical points The fertilization of sweet potato should be based on the climate, soil characteristics and plant growth and development stages to take appropriate fertilization methods. The summary is as follows: 3.1 Basal fertilizer Basic fertilizer is the main measure for sweet potato fertilization. Basal fertilizer should be based on high-quality organic fertilizers. Sand land, good permeability, large temperature difference between day and night, poor water retention and fertility, semi-mature organic fertilizer should be used as a base fertilizer; clay should be applied to mature organic fertilizer. Part of the nitrogen fertilizer and all phosphorus and potassium fertilizers can also be applied simultaneously with the base fertilizer. 3.2 Topdressing If the amount of nitrogen applied to the basal fertilizer is insufficient, it should be top-dressed in stages, but mainly in the medium-term. The specific top dressing period should be flexible. If the soil is dry, the temperature is low, and the potato seedlings are thin and weak when they are planted, the seedlings can be raised early. In the branching and potato stage, the branches are late, the growth of stems and leaves is not prosperous, and the leaves are small. If the plant grows normally, it can be applied less or not. Into the rapid expansion period of the tuber, if the stems and leaves premature decline, the leaf area index decreased rapidly, the leaf rate increased, the nitrogen fertilizer can be traced 1-2 times, the amount according to climatic conditions and seedlings set. When the soil cracks and the tubers swell, in the event of drought, the stems and leaves turn yellow earlier and the number of yellow leaves increases. If the soil is moist and there are many autumnal rains, when the stems and leaves turn yellow, the ash can be used more. If it is clear and rainy for a long time, it can be 1-2 times, and vice versa. In short, the principle of fertilization of sweet potato is that the amount of sand dressing should be a small number of times, the frequency of topdressing should be reduced, and the amount of topdressing can be appropriately increased. With adequate water supply and good water conditions, the amount of nitrogen fertilizer should be controlled so as not to cause stems and leaves to grow in length. Tuber growth, otherwise it will reduce production, fertilizer efficiency is not high. Ningbo DOKEE Medical Technology Co., Ltd. , https://www.dokeemedical.com