The proportion of nitrogen, phosphorus and potassium applied to potatoes should be appropriate.

The demand for nitrogen, phosphorus and potassium in potato is equally important. In the process of yield formation, nitrogen supply is the basis to ensure the formation of sufficient green leaf area for photosynthesis; phosphorus supply is also indispensable for tuber formation and starch accumulation; on the basis of sufficient nitrogen and phosphorus, potassium supply is necessary for carbohydrate assimilation in the early stage, aboveground to underground tuber transportation and starch accumulation in the later stage.

Field tests showed that the absorption ratio of nitrogen, phosphorus and potassium by potato was about 1 ∶ 0.5 ∶ 2.5. according to this demand, potato was called potassium-loving crop in the industry. However, in the actual fertilization decision in agricultural production, it is necessary to consider not only the supply of potato nutrients from the soil nutrient bank, but also the different supply level of soil to nitrogen, phosphorus and potassium. The application rate of nitrogen, phosphorus and potassium fertilizer is recommended on the basis of soil supply. For example, the content of available potassium in southern soil is low, so we should generally pay attention to the application of potassium fertilizer and do a good job of balanced fertilization of nitrogen, phosphorus and potassium; the content of available potassium in soil in the north is higher than that in the south, and the application of potassium fertilizer in food crops is not common, but in view of the fact that potatoes need more potassium, it is necessary to supplement potassium fertilizer appropriately. It is suggested that the average suitable ratio of nitrogen, phosphorus and potassium fertilizer is 1 ∶ 0.5 ∶ 0.6 in the north and 1 ∶ 0.4 ∶ 0.8 in the south. Assuming that the yield level of potato per mu is about 1500 kg, it is recommended that the amount of nitrogen fertilizer should be reduced to 10-12 kg / mu for pure nitrogen, 5-8 kg / mu for potash fertilizer and 3-5 kg / mu for phosphate fertilizer.

Base fertilizer and topdressing fertilizer should be used in the period, method and distribution of potato fertilization. Base fertilizer had better be combined with organic fertilizer and chemical fertilizer, which is beneficial to potato production. The distribution of nitrogen, phosphorus and potassium fertilizer in base fertilizer and topdressing fertilizer is different, and only 50% of nitrogen fertilizer, all phosphate fertilizer and most potassium fertilizer are allocated in general base fertilizer. Half of the nitrogen and potassium fertilizer can also be used as the base fertilizer, and the other half of the nitrogen and potassium fertilizer can be used as topdressing; for the fertilizer varieties of the base fertilizer, you can choose the compound fertilizer with higher phosphorus and potassium content (such as 12% Mel 15%) and appropriate nitrogen content (about 10%), or you can use the combination of simple chemical fertilizer. The elemental phosphate fertilizer had better be general calcium, and the calcium magnesium phosphate fertilizer can also be selected in the acid soil area of the south. The distribution principle of phosphate fertilizer is that most of the phosphate fertilizer is deeply applied to the bottom of the ridge according to strips or holes before ridging, and a few pieces of phosphate fertilizer are applied under the slope. The nitrogen and potassium fertilizer for topdressing should be topdressing at the budding stage at the top of the plant (that is, the formation of underground tubers), applied to the ridge side and then covered with soil and watered. The time of topdressing should not be too early, it is best to carry out when the potato block enters the expansion period, early topdressing, especially a large amount of nitrogen fertilizer, will cause the problem of small potato lumps in the upper and lower parts. In the fertilization position, the base fertilizer should be applied in ditch or hole before planting, and the depth should be about 15-20 cm. Topdressing is applied in strips or holes between rows or on the side; the fertilizer is buried at a depth of 5-8 cm and can be irrigated and covered with soil after fertilization.

In recent years, in order to obtain the high yield of potato, some farmers pay great attention to the application of nitrogen fertilizer in actual production. With the less and less amount of organic fertilizer, can not guarantee the needs of the rapid development of potato production, more and more farmers mainly rely on the application of chemical fertilizer to produce potato. Sometimes partial application of nitrogen fertilizer leads to the excessive growth of aboveground potato seedlings and the small potato cubes in the underground part. There are also many farmers have initially mastered the relevant technology. For example, in some potato producers in Gansu and Inner Mongolia, organic fertilizer is mainly mixed with low concentration compound fertilizer as base fertilizer, and then at the budding stage at the top of the plant, and then topdressing appropriate amount of nitrogen fertilizer, the results are good. It reflects the feasible technology of balanced fertilization in the whole process according to the nutritional characteristics of potato and the proportion of nitrogen, phosphorus and potassium nutrients.

In addition, potato is sensitive to trace elements such as boron and zinc, and can be supplied appropriately by means of seedbed fertilization and extra-root topdressing.