Scallion fertilizers have good quality of reducing nitrogen and potassium

Case: Welsh onion is a favorite storage seasoning vegetable and it is loved by people. The scallions produced in Zhangqiu, Shandong Province are particularly well-known. In recent years, local farmers have been willing to invest more in water and fertilizer for high yields. For example, pure onion species can produce up to 40-50 kilograms of pure nitrogen per acre, and pure phosphorus is about 10-15 kilograms per mu. However, investment in potash fertilizer is not universal, and some farmers do not apply potassium fertilizer or use less fertilizer. Such fertilization habits have begun to receive attention. For example, Wang Fengying, an onion farmer of the previous year, under the guidance of agricultural technicians, made adjustments to the fertilization arrangement of his 20-acre green onion, and the result was that yield and quality of welsh onion had improved at the autumn harvest. Zhuangli people asked her how to adjust the fertilization this year. Wang Fengying summed up the experience: The main adjustment of scallion fertilization is to reduce nitrogen and potassium, pay attention to organic fertilizer and chemical fertilizer application, so that each will have a good effect. Why should we pay attention to the reduction of nitrogen and potassium in the cultivation of onion?

Experts: From the introduction of the situation, the past scallion fertilization has obvious defects, that is, excess nitrogen and a small amount of potassium form a serious imbalance of nitrogen and potassium nutrition. In this regard, according to the principles of formula fertilization and nutrient balance, agricultural technicians proposed adjustments for reducing nitrogen and potassium on the onion fertilization, and saw the effect.

First, onion is a long-lived Liliaceae vegetable crop. In some parts of northern China, autumn sowing is generally adopted - spring planting - summer harvesting small shallots - planting autumn harvesting white onions. During this period, it is necessary to experience different stages of growth, such as seedling stage, leaf stage, and onion formation stage. In general, the output of scallion is high and can reach a level of 6,000 to 10,000 pounds per mu. The ratio of N, P, and K nutrient uptake by Welsh onion is approximately 1 : 0.4:1.3 or so, it can be seen that green onions have more potassium and nitrogen, and phosphorous second. Therefore, in the proportion of fertilization, we must pay attention to the balanced supply of nitrogen and potassium fertilizers. Especially in the conditions of high yield cultivation and no application of organic fertilizer, pay more attention to potassium supplementation. As for the specific amount of potassium, the proportion of nitrogen and potassium fertilizers, mainly depends on the following three aspects: First, the ability of the soil itself to supply potassium, such as the ability of the sandy soil to provide low potassium, to increase the amount of potassium fertilizer; Second, depends What is the target output of green onions? In high-yielding levels, such as 10,000 metric tons per mu, on-season output of scallions produces more potassium from the soil, so potassium should be increased accordingly; thirdly, other fertilizer applications, such as the amount of returning straw and the amount of nitrogen fertilizer. If you put a lot of organic fertilizer, you can use less potassium fertilizer; in particular, the amount of chemical nitrogen fertilizer should be appropriate, and it must be balanced with the corresponding potash fertilizer to have a good effect. Otherwise, the blind investment will not only be of no benefit to the high yield of green onions, but it will also cause the quality of green onions to be low, such as the small proportion of light blue, leafy, and not rich onions.

Second, the general scallion at a higher level of production under the recommended amount of nitrogen is about net nitrogen 20-26 kg / acre, the case of partial application of too much nitrogen, coupled with a large amount of water, not only a waste of nitrogen, increased costs, and production Out of the onion is not resistant to storage, quality decline, but also because of the loss of available nitrogen, has a negative effect on the environment, so the amount of nitrogen fertilizer should be appropriate. In the selection of nitrogen fertilizer varieties, the most common is urea, but the best suitable nitrogen fertilizer is ammonium sulfate, because the onion is a sulfur-loving crop.

Third, on the scallion fertilization method also pay attention to. Full fertilization should be divided into two parts: base fertilizer and top dressing. It is best to apply some organic fertilizer in the basal fertilizer and adopt methods of spreading and ploughing. Fertilizer base fertilizer should be applied to all phosphate fertilizers, 40% nitrogen fertilizer and 60% potassium fertilizer, and the varieties can be compound fertilizer or single fertilizer. When selecting compound fertilizer, general or special type can be selected, but it is not suitable for high nitrogen type compound fertilizer. The application depth of basal must be about 15 cm. The top-dressing of green onions can be performed in 2-3 times, and the remaining 60% of nitrogen and 40% of potassium in the base fertilizer are applied as top-dressing in the mid-to-middle period of the Shengye period and light blue period, respectively. The top-dressing method should have a good effect of water-fertilizer blending. Avoid large-water and large-nitrogen flushing, which will not only reduce the fertilizer utilization rate, but also spread urea on the surface in summer. The loss of nitrogen volatilization will cause smoked leaf burning problems.