What should be noted when using urea?
How is urea applied? Here is an introduction to the field application methods of urea: it can be used as a base fertilizer and as a top dressing, but is not suitable as a seed fertilizer. When urea is used as a base fertilizer, two points should be noted. First, it should be applied deeply and covered with soil; do not irrigate immediately after application, to prevent the urea from leaching into deeper layers. When urea is used as a base fertilizer on dryland, be sure to apply...
What should be noted when using urea? Please advise.After urea is applied to the soil, it can only be absorbed and used by crops in large amounts after it is converted into ammonium bicarbonate. Because a conversion process is involved, its fertilizer effect is relatively slow, and it is generally necessary to apply it 4-6 days in advance. At the same time, deep application with soil coverage is also required, and do not irrigate immediately after application, to prevent nitrogen from leaching into deeper layers and reducing fertilizer efficiency.
When urea is used as a foliar top dressing, especially when sprayed on leaves, the nutrients in the urea are absorbed very quickly, the utilization rate is also high, and the yield-increasing effect is obvious. When spraying urea, the concentration requirements are relatively strict. Generally, the concentration for gramineous crops is 1.5%-2.0%, for fruit trees about 0.5%, for open-field vegetables 0.5%-1.5%, and for greenhouse vegetables between 0.2%-0.3%. For crops in the vigorous growth stage, or for mature fruit trees, the concentration of urea applied can be appropriately increased.
The following issues should be noted when using urea:
(1) Generally, it is not used directly as a seed fertilizer. This is because urea contains a small amount of biuret, generally less than 2%, and biuret is harmful to seed germination and growth. If it must be used as a seed fertilizer, the seeds and urea can be placed into the ground separately; never soak or dress seeds with urea.
(2) When the biuret content is higher than 0.5%, it must not be used as a foliar top dressing.
(3) After urea is converted into ammonium bicarbonate, it easily decomposes and volatilizes on calcareous soil, causing nitrogen loss. Therefore, it should be applied deeply and covered with soil.
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