How should urea topdressing be applied for the highest utilization rate?
Urea is a neutral fertilizer used on various soils and crops. It is easy to store, convenient to use, and causes little damage to the soil. It is one of the most widely used fertilizers and is rich in nitrogen. However, there are still many points to pay attention to when using it. So, when using urea for topdressing, how should urea topdressing be applied for the highest utilization rate?
1. The best ways to use urea
1. According to the soil
Some soils are more fertile and some are more barren, so the amount of fertilizer used will naturally differ somewhat. For example, if the soil itself is very good and the plants growing in it are growing well, then not much urea is needed. If the soil is relatively barren and crop yields are not high, then the amount of urea can be a little more.
2. Look at crop needs
If you want the utilization rate of urea to be higher after application, the most important thing is to understand the needs of the crop. During several specific periods, its demand for nutrients is very great, and applying it at these times allows it to be absorbed better.
3. Dig trenches to fertilize
Urea contains a lot of nitrogen. If it is scattered directly on the surface, most of it will volatilize after four or five days, which is very wasteful. This is especially true when it is used on alkaline soil, where the loss is even greater. So if you want to use urea, remember to dig trenches for fertilization. The depth of the trench should be at least 10 cm or more, so that losses can be reduced more effectively.
4. Do not place it right next to the crop
Urea is rich in nitrogen, its concentration is relatively high, and it also has a certain moisture-absorbing capacity, so when using it, do not place it too close to the crop, otherwise it will burn the seedlings and affect crop growth.
5. Timing of use
After urea is applied, it cannot be absorbed by the crop immediately; it still has to go through a conversion process. Therefore, when the crop is expected to need a large amount of nitrogen, urea should be applied about one week in advance, so that it can be better utilized by the crop during the transition.
6. Do not water immediately
As mentioned at the beginning, when urea is used, it has to go through a conversion process. During this process, it is best not to water, otherwise it will cause loss of urea. Generally, water appropriately after three to five days.
2. Precautions for urea application
1. Apply urea deeply and carry fertilizer with water
In alkaline or alkaline soils, urea hydrolyzes to form ammonium nitrogen, and surface application will cause ammonia volatilization, so it should be applied deeply and covered with soil. After urea is broadcast on the surface of paddy fields, the volatilization of ammonia after hydrolysis is 10%-30%. In alkaline soil, the nitrogen lost through ammonia volatilization is 12%-60%. Under high temperature and high humidity, ammonia volatilization from urea can burn plants and accelerate the nitrification rate. Therefore, deep application of urea and carrying fertilizer with water are very important.
Because the conversion of urea in the soil can accumulate a large amount of ammonium ions, it will cause the pH to rise by 2-3 units. In addition, urea itself contains a certain amount of biuret, and when its concentration is 500 ppm, it will inhibit the young roots and young buds of crops. Therefore, urea is not suitable for use as seed fertilizer, seedling fertilizer, or foliar fertilizer. The urea content used at other application stages should also not be too high or too concentrated. After crop seedlings are harmed by biuret, chlorophyll synthesis is impaired, and the leaves develop chlorotic, yellowed, or even whitened patches or stripes.
2. Urea cannot be mixed with alkaline fertilizers
After urea is applied, it must be converted into ammonium nitrogen before it can be used by crops. Under alkaline conditions, most of the nitrogen in ammonium nitrogen will become ammonia gas and volatilize. Therefore, urea cannot be mixed with or applied at the same time as alkaline fertilizers such as plant ash, calcium magnesium phosphate fertilizer, and ammonium bicarbonate.
Urea can be used not only when applying base fertilizer, but also for later topdressing. When urea is used well during topdressing, it is very helpful for crop growth and the effect is obvious. Master the six points above to increase the utilization rate of urea, allow crops to absorb it well, and high yields and high output are no problem!