How long does ammonia last in soil?

Answered by Michael Wilson

The duration for which ammonia lasts in soil can vary depending on various factors such as soil temperature, pH, and soil moisture content. Typically, after ammonia is applied to the soil in late summer or early fall, a process called nitrification begins. During nitrification, ammonia is converted into nitrate by microbial populations present in the soil.

Initially, nitrification occurs near the surface of the soil where the ammonia has been applied. As the microbial populations rebound, the process gradually moves towards the center of the band where ammonia is present. This movement is influenced by factors like the availability of oxygen and nutrients for the microbes.

The speed at which nitrification occurs is greatly influenced by soil temperature. Warmer temperatures generally promote faster microbial activity, leading to more rapid conversion of ammonia to nitrate. Conversely, colder temperatures can slow down the process. In colder climates, it may take longer for all the ammonia to be completely converted.

Soil pH also plays a role in the duration of ammonia in soil. Nitrification is most efficient in soils with a pH range of 6-8. If the pH falls outside of this range, microbial activity may be hindered, leading to a slower conversion of ammonia to nitrate.

Additionally, soil moisture content affects the duration of ammonia in soil. Adequate moisture is required for microbial activity. If the soil is too dry, the microbial populations may be limited, resulting in a slower nitrification process. Conversely, excessively wet conditions can also hamper microbial activity.

Considering these factors, it can take approximately 2-3 months or even longer for all the ammonia applied in late summer or early fall to be converted to nitrate. However, it is important to note that this is a general estimate and can vary depending on the specific conditions of the soil.

In my personal experience, I have observed variations in the duration of ammonia in soil depending on the factors mentioned above. For example, in a relatively warm climate with optimal soil pH and moisture, I have seen ammonia being completely converted to nitrate within two months. However, in colder regions with less favorable soil conditions, the process may take longer, extending beyond three months.

To summarize, the duration for which ammonia lasts in soil can range from 2-3 months or more, depending on soil temperature, pH, and moisture content. It is important to consider these factors when applying ammonia-based fertilizers and to monitor the progress of nitrification to ensure optimal nutrient availability for plant growth.