Urea has high nitrogen content and its aqueous solution is neutral. In addition to the basic fertilizer used in crops, the vast majority of crops are used for top dressing. So, how can we increase the effect of urea dressing? The main points should be as follows:
First, determine the amount of topdressing fertilizer based on soil fertility Practice has proved that increasing the amount of fertilizer applied to the middle and low-yielding fields can significantly increase production. For high-yielding fields, the general level of fertilization can be maintained.
Secondly, the key to improving the utilization of chemical fertilizers in top-dressing crop nutrients is to grasp the critical period and maximum efficiency period for nutrient absorption by various crops. Try to achieve top-dressing in the nutrient-rich period of crops in order to increase fertilizer utilization. .
Third, to do deep-buried soil practice has proved that the application of urea in the ground surface at room temperature for 4 to 5 days, most of the nitrogen will be volatilized ammonia, its utilization is only about 30%, especially in the calcareous and alkaline soil On the surface, the volatilization loss of ammonia is more serious. Therefore, when urea is used to top-dress dry farm crops, it is better to grind the pits or deepen the ditch for less than 10 cm, so that the urea can be contained in the moist soil, which is conducive to the conversion of urea and is also conducive to the ammonia fertilizer. Adsorption reduces volatilization losses.
Fourth, to maintain a certain distance with the crop because of high urea nitrogen content, nutrient concentration, has a great hygroscopicity. Therefore, when topdressing, it is necessary to prevent urea from being applied near the roots of crops, and it is even more important not to drop urea into the heart of the crop so as not to burn the seedlings and affect the growth. Therefore, it must be kept at a certain distance from the crop.
V. Pre-application Because urea is a low-molecular organic compound, it must have an ammoniated process after it is applied to the soil, and it can be converted into a highly volatile ammonium carbonate before it can be absorbed by the crop root system. Therefore, using urea to topdress crops should be applied about 7 days earlier than other nitrogen fertilizers.
Sixth, do not mix urea with alkaline fertilizer is a neutral fertilizer, fertilizer and alkaline fertilizer should not be mixed application, to prevent the reduction of fertilizer efficiency. If non-mixed application with alkaline fertilizer is not possible, it is also necessary to stagger the fertilization date, usually every 3 to 5 days. However, when urea is mixed with potassium chloride, phosphate rock powder, and superphosphate, the effect of increasing production is significant.
7. Immediately after topdressing, it is not appropriate to apply urea immediately after it is applied to the soil. It must not be absorbed by the soil before it is converted and transformed. If you fill water immediately after chasing, it will cause a large loss of urea. Soil water shortage, non-irrigation can not be time, but also to do small ground irrigation, avoid flooding irrigation. When topdressing rice, it should be considered that urea has a greater fluidity before transformation, and even after topdressing, it is not possible to immediately apply water. Generally, it is advisable to fill small water once every 3 to 5 days after recovery.
Eight, should be done outside the root dressing urea damage to the crop leaves is relatively small, but also easily soluble in water, strong diffusion, easy to be absorbed by the leaves, after entering the leaves is not easy to cause the phenomenon of plasmolysis, it is very suitable for the top dressing. However, high quality urea with a biuret content of no more than 2% should be used to prevent damage to the leaves. The concentration of urea as the topdressing fertilizer varies depending on the type of crop. The concentration of the top dressing outside the crop is 1.5% to 2%; the concentration of top dressing outside the double leaf crop is 1%, and the concentration during the flowering phase of the crop It should also be smaller. Generally, the amount of topdressing fertilizer outside the urea root per mu is 0.5 to 1.5 kg. The spraying time is appropriate around 4:00 pm, when the evapotranspiration is small, the leaf pores gradually open, and the diluted urea solution can be absorbed completely at one night, which greatly improves the utilization of urea.
Dingmin Pharmaceutical supply Velpatasvir API and Velpatasvir Intermediates with high purity and best price. The main products CAS No are as follows: 1377049-84-7, 1378388-16-9, 1335316-40-9, 1438383-89-1. Sample can be sent if you request.
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Cas 1335316-40-9,Velpatasvir Intermediates,11-Dihydro-5H-Dibenzo
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