Onion cultivation requires high quality and high yield, and it is the key to reducing nitrogen and potassium on fertilization. The specific fertilization method is now described as follows:
1. Welsh onion is a long-growing Liliaceae crop. In the Huang-Huai River basin, we generally use the nursery from September to October, transfer from February to March in the following year, harvest onion or shallot from May to June, or from March to April. , Transplanting in June, and planting patterns of white shallots in autumn and winter. The output of Welsh onion is relatively high. Generally 667 square meters (1 mu) produce 3,000 to 6,000 kilograms, and the ratio of N, P and K nutrient absorption is about 1:0.4:1.3. The demand for potassium and nitrogen is higher, and the demand for phosphorus is higher. Less, so the proportion of fertilization should pay attention to the balanced supply of potash, especially in the case of high-yield cultivation and no application of organic fertilizer, pay more attention to potash fertilizer. The specific proportion of nitrogen, phosphorus, and potassium fertilizers depends on the following three aspects: The first is the ability of the soil itself to supply potassium. For example, for sandy soils with low potassium capacity, it is necessary to appropriately increase the use of potash fertilizer. Second, what is the target output of green onions? Under the conditions of high-yielding cultivation, the amount of potassium taken away from the soil by scallion production in each season is also greater, so the application amount of potash fertilizer should be increased accordingly. The third is the application amount of other fertilizers, such as the amount of returning straw and the amount of nitrogen fertilizer. If you put in a large amount of organic fertilizer, you can use less potassium fertilizer. In particular, the amount of chemical nitrogen fertilizer should be appropriate, and it should be balanced with the corresponding potash fertilizer before it has a good effect of increasing production. Otherwise, the blind application of chemical nitrogen fertilizer is not only not conducive to the high yield of green onions, but also will cause the quality of green onions, such as small proportion of light blue, leafy, not strong onion, and even bitter.
2. In general scallion at a higher yield level, the recommended amount of nitrogen fertilizer is about 667 square meters of pure nitrogen 20 to 26 kg. The excessive application of nitrogenous fertilizer, coupled with the large amount of water, not only waste nitrogen fertilizer, increase the cost, but also produce green onions are still not resistant to storage, quality decline, and will have a negative effect on the environment due to nitrogen loss. Therefore, the amount of nitrogen fertilizer to be appropriate, in the selection of nitrogen fertilizer varieties, the most common is urea, but the most suitable type of nitrogen fertilizer is ammonium sulfate, because the green onion is sulfur-like crops.
3. Fertilization methods are stressful. The onion fertilizes the base fertilizer and the dressing fertilizer in two parts. The best 667 square meters of basal fertilizing 4,000 to 5,000 kilograms of high-quality organic fertilizer is used for spreading and ploughing into the soil. The fertilizer base fertilizer should be applied to all phosphate fertilizers, 40% nitrogen fertilizer and 60% potassium sulfate fertilizer. Fertilizer or single fertilizer. In the selection of compound fertilizer, sulfur-based general-purpose or special-purpose type can be used, and high-nitrogen type compound fertilizer should not be applied. The base fertilizer application depth must be about 15 cm. The top dressing of green onions can be divided into 2 to 3 times, and the remaining 60% of nitrogen fertilizer and 40% of potassium fertilizer of the base fertilizer can be applied as top dressing in the mid-to-middle period of the Shengye period and the light green period. Composting method: It is required that the effect of water-fertilizer blending be good. Avoid large-water and large-nitrogen flushing. Otherwise, it will not only cause low fertilizer utilization rate, but also spread urea on the surface in the summer, and nitrogen volatilization will also cause smoked leaf to burn seedlings.
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