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How many days can I water after applying urea? Watering time, matters needing attention.

How many days can I water after applying urea? Watering time, matters needing attention.

Oct 19,2020
Urea is a kind of nitrogen fertilizer. After urea is applied to the soil, it needs to be converted into ammonia nitrogen before it can be absorbed and utilized by crops. So, do you know how many days can be watered after applying urea? When is the watering time after applying urea? Let’s take a look.

You can water a few days after applying urea

It is reported that under normal circumstances it can be completed in 2 to 7 days. Based on this characteristic of urea, after topdressing urea, it must not be watered before the conversion is complete. Therefore, after fertilizing crops, it is recommended to irrigate for 2 to 3 days in summer and 4 to 7 days in winter.

Watering time after applying urea

When the temperature is 10℃, the conversion time of urea needs 7~10 days, when it takes 4~5 days when the temperature is 20℃, and it takes two days when the temperature is 30℃, all it can be converted into the ammonia needed by crops. Knowing this, you can determine the irrigation time after top dressing according to the temperature conditions.

Secondly, it is necessary to understand the soil conditions, fertile soil is faster than poor soil, and clay soil is faster than sandy soil. After topdressing urea on sticky and fertile soil, it can be irrigated earlier than barren and sandy soil. Third, it should be applied in conjunction with organic fertilizers, because organic fertilizers contain many microorganisms, which can provide better conditions for urea conversion and speed up the conversion process. It is necessary to adopt deep application and soil covering methods, which can avoid direct volatilization when exposed, and increase the chance of contact with microorganisms in the soil, which is conducive to the adsorption of ammonium carbonate or ammonium bicarbonate, which is the product of urea decomposition and transformation in the soil. Provide useful nutrients for crops.

The nitrogen content of urea is between 44% and 46%, and the biuret should be ≤0.9% to 1.5%, which is a neutral nitrogen fertilizer. Urea has a high nutrient content and is suitable for various soils and various crops. It is suitable for top dressing, especially the effect of extra-root top dressing.

When urea is applied to the soil, it can be absorbed and utilized by crops only after it is converted into ammonium bicarbonate. Due to the transformation process, the fertilizer effect is slow, and it is generally applied 4-6 days in advance. At the same time, it is also required to apply deep soil and do not irrigate immediately after application to prevent nitrogen from leaching into the deep layer and reducing fertilizer efficiency.

When urea is topdressed outside the root, especially the leaf surface, the nutrients in urea are absorbed quickly, the utilization rate is also high, and the effect of increasing production is obvious. When spraying urea, the concentration requirements are stricter. Generally, the concentration of gramineous crops is 1.5%-2%, fruit trees are about 0.5%, open-field vegetables are 0.5%-1.5%, and greenhouse vegetables are between 0.2%-0.3%. For crops in the prime of growth, or adult fruit trees, the concentration of urea can be appropriately increased.

Precautions for watering after applying urea

The thalidomide nitrogen contained in urea cannot be directly absorbed by crops. It must be converted into ammonium nitrogen through the action of microorganisms in the soil before it can be used. Therefore, the following issues should be paid attention to during the use of urea:

(1) Generally not directly used as seed fertilizer. Because urea contains a small amount of biuret, generally less than 2%, biuret is harmful to the germination and growth of seeds. If you have to make seed fertilizer, you can separate the seeds and urea into the ground. Do not soak or dress the seeds with urea.

(2) When the biuret content is higher than 0.5%, it cannot be used as an extra-root topdressing.

(3) After urea is converted into ammonium bicarbonate, it is easy to decompose and volatilize on calcareous soil, causing nitrogen loss. Therefore, deep cover soil should be applied.

Note: If you irrigate immediately after applying urea, it will be dissolved by the water. Due to the weak adsorption between soil colloid and urea, the fluidity of urea in the soil is very large, especially flooded irrigation will cause urea to drip Deeply, reduce fertilizer efficiency. Therefore, it is not advisable to irrigate immediately after top-dressing urea.