Anhydrous ammonia is classified as a nitrogen fertilizer. It is a colorless liquid which contains 82.3% of nitrogen. The substance is used to improve plant growth when it is absorbed by soil. Anhydrous ammonia is produced by evaporating gaseous ammonia under high pressure. It is applied into the soil in the fall as well as in spring.
Physical and chemical properties
Liquid ammonia is in a gaseous state at normal atmospheric pressure and temperature. With a significant increase in temperature and pressure it turns into a liquid.
The fumes of the anhydrous ammonia have a significant elasticity therefore the tanks for transportation and storage must not be filled completely. Anhydrous ammonia destroys copper, zinc and their alloys. However, it is neutral to iron, steel and cast iron.
Application in agriculture
Anhydrous ammonia is used as a basic fertilizer and it is included into the obligatory feeding of soil.
Calendar of applying the substance to the soil:
April – the main fertilizer;
May – the preplant fertilizer;
June – feeding;
July – feeding;
August – feeding;
September – the main fertilizer.
The behavior in soil
Ammonium hydroxide is formed, when the soil is fertilized by the anhydrous ammonia, which quickly absorbs the ground moisture. Interacting with anions of soil solution, ammonium hydroxide forms various salts. It interacts with soil in a physical and chemical way and is absorbed by hard soil.
Active carbonic acid is neutralized in the soil during the first days after applying anhydrous ammonia. Thus, 12-15 days after the ammonia is absorbed it turns into nitrates. To neutralize 1 share of the anhydrous ammonia five times more calcium carbonate (CaCO3) is required.
At the same time, a temporary sterilization of soil is observed in the area with a high concentration of ammonia. This process neutralizes the nitrification of ammonium nitrogen. The usual number of microorganisms and nitrification is restored after 1-2 weeks. Under optimal conditions full nitrification is completed within a month.
The use in different soils
Anhydrous ammonia is recommended for applying on all types of soils. Heavy and rich in organic matters. However, ammonia is usually better absorbed by wet soils than dry ones and poor in humus. But, ammonia evaporates from wet soils more quickly than from dry ones.
In sandy soils absorption of ammonium is slower than in heavy soils. It leads to NH3 loss.
Anhydrous ammonia is applied up to the depth of 12-16 cm in loamy and 16-20 cm in sandy soils to avoid some extra losses. It is performed by special machines to ensure the simultaneous introduction and activation of fertilizers.
Anhydrous ammonia is also introduced with water on the surface after irrigation. In this case, however the ground processed is provided with ammonia unevenly. As a result the maturation of some crops will not be simultaneous. It is undesirable for rice and other crops which are collected by combine harvesters. However, such uneven distribution of nitrogen is not of great importance for corn. The disadvantages of this method lie in the fact that there is a possibility of significant evaporation of ammonia into the air on a sunny day.
The impact on culture
Anhydrous ammonia has a positive impact on almost all cultures.
– Cotton. Anhydrous ammonia applied before sowing is more effective for growing cotton than ammonium nitrate. It is due to the fact that during the first weeks after the introduction of ammonium nitrogen is less prone to leaching from the soil.
– Maize/corn. Introduction of anhydrous ammonia increases the yield of corn more than ammonium nitrate does.
– Oats. Productivity increases in all types of soil, especially when it is applied in the fall, in the soils poor in calcium. Applying in the same soil in the spring leads to more modest results in terms of increasing the yield.
– Wheat. The uses of anhydrous ammonia in the fall lead to deterioration in results in comparison with the introduction of ammonium nitrate. The same goes for the highly acidic soils.
– Vegetable crops. It is recommended to feed them with anhydrous ammonia three weeks before sodium nitrate or ammonium nitrate is applied.