As a commonly used nitrogen fertilizer, urea's absorption time by crops is not fixed, but is affected by a variety of factors. The following is a detailed analysis of the absorption time of urea by crops:
- Conversion of urea: Urea dissolves rapidly in the soil into urea ammonia, which is the first step in converting to a plant-usable form of nitrogen. Subsequently, urea ammonia is converted into ammonia gas by the action of microorganisms, and reacts with the moisture and pH in the soil to form ammonia ions (NH4+) that plants can directly absorb and utilize.
- Factors influencing the absorption time: Urea properties: Solid granular urea diffuses slowly in the soil and usually takes about 7 days to be absorbed by crops. Liquid urea, on the other hand, has a large contact area with crops due to the use of foliar fertilizer spraying, so it is absorbed relatively quickly. Crop type and growth stage: Different crops absorb urea at different rates. For example, fast-growing crops such as rice and maize, which have well-developed root systems and strong absorption capacity, may only take 3-5 days to absorb urea. For slower-growing crops, the absorption time may be longer. Soil conditions: Soil temperature, humidity and other conditions can also affect the rate of urea absorption. When the soil temperature is high and the humidity is suitable, the decomposition rate of urea fertilizer will be accelerated, which will speed up the uptake of the crop.
- Ways to improve urea utilization: In order to improve urea utilization, appropriate measures can be taken to speed up the diffusion rate of urea and increase the contact area between urea and crop roots. Another method is to add substances such as fulvic acid to urea, which can inhibit the activity of urease, thereby prolonging the duration of urea and improving utilization.
In summary, the time it takes for urea to be absorbed by crops varies depending on a number of factors. In general, solid granular urea takes about 7 days to be absorbed by crops, while liquid urea is absorbed faster due to foliar sprays. In order to maximize urea utilization and economic benefits, the appropriate fertilization method and timing should be selected according to the specific crop and soil conditions.