The moisture & temp play a key role for vitalization of ammonia in soil the moisture/Temp are inversely proportional to depth of the soil, means above portion of soil moisture is less and temp is more vitalization is more and below moisture less votalization is less because the moisture is more and temp is less. and others factors as following also depends vitalization.

The rate of ammonia volatilization (FNH3, mg N m−1 h−1) is approximately calculated as

FNH3=f/D (C0-Ci)

Where f (L h−1) is the air flow rate through the tunnel, D (m) is the enclosed length of the urea band (2 m) and c i and c o (mg NH3-N L−1) are the NH3 concentrations of the air entering and leaving the tunnel, respectively. Ammonia volatilization occurs as NH4 is converted to NH3 gas at the soil surface and transported to the atmosphere.

Factors affecting ammonia volatilization

Soil factors the extent of NH3 volatilization is influenced by soil pH, type (or texture), cation exchange capacity (CEC), soil organic matter (SOM), temperature, and moisture content of the soil.

1. Soil pH

In general, alkaline soils (pH >7.0) are more susceptible to NH3 volatilization, while neutral to acidic soils (pH 5.0–7.0) result in reduced NH3 volatilization losses. During urea hydrolysis, the initial soil pH increases surrounding the fertilizer .

2. Soil physical and chemical properties

Ammonia volatilization largely depends on the texture of a soil along with its buffering capacity. Generally, soil texture is an important indicator of CEC since clay content is positively correlated with CEC

3. Soil temperature

Increased soil temperature increases the solubility of urea and thus, the rate of NH3 volatilization. Generally, the risk of NH3 volatilization is increased at soil temperatures over 21-22degree C

4. Soil moisture

Soil moisture plays a critical role in determining the fate of applied fertilizer N. For example, urea applications to a wet soil surface result in increased NH3 volatilization as the rate of hydrolysis is increased and movement into the soil is decreased due to the amount of water-filled pore spaces. Similarly, prolonged contact of fertilizer granules with a damp soil surface promote N loss

5. Environmental factors

Urea needs to be hydrolyzed before NH3 can be volatilized and the rate of the hydrolysis process can be affected by certain environmental conditions such as soil temperature and humidity.

https://www.google.com/url?sa=i&url=https%3A%2F%2Fcdnsciencepub.com%2Fdoi%2Ffull%2F10.4141%2Fcjss2012-095&psig=AOvVaw2dAQNY_3ZOkuPw59gWm0WA&ust=1654331978304000&source=images&cd=vfe&ved=0CAwQjRxqFwoTCICijIrxkPgCFQAAAAAdAAAAABAD

If the soil pH is alkaline the shorter the diffusion distance the greater will be the loss of NH3 prior to oxidation

Dear Gulderay,

I will go with both

Dear Gulderay,

I have little confusion with your question. Is it the free ammonia available in the soil or the amount of ammonia that has escaped from the soil through volitilization. However, answers for both the cases will cover almost same factors.

I will go with both the answers given by the two experts. While increased moisture content and reduced temperature are two important factors which influence volatilization of ammonia. On the other hand, alkaline pH induces formation of free ammonia from ammonium. You may find the answer yourself by studying the ammonium and ammonia contents of several soils along with their moisture, temperature and pH values at different depths.

Dear Gulderay,

I have little confusion with your question. Is it the free ammonia available in the soil or the amount of ammonia that has escaped from the soil through volitilization. However, answers for both the cases will cover almost same factors.

I will go with both the answers given by the two experts. While increased moisture content and reduced temperature are two important factors which influence volatilization of ammonia. On the other hand, alkaline pH induces formation of free ammonia from ammonium. You may find the answer yourself by studying the ammonium and ammonia contents of several soils along with their moisture, temperature and pH values at different depths.

Dear Gulderay,

I have little confusion with your question. Is it the free ammonia available in the soil or the amount of ammonia that has escaped from the soil through volitilization. However, answers for both the cases will cover almost same factors.

I will go with both the answers given by the two experts. While increased moisture content and reduced temperature are two important factors which influence volatilization of ammonia. On the other hand, alkaline pH induces formation of free ammonia from ammonium. You may find the answer yourself by studying the ammonium and ammonia contents of several soils along with their moisture, temperature and pH values at different depths.

Sorry, my inputs to the question has inadvertently been sent before finalizing it with some constructional errors. Request to ignore the mistakes.