What are the potential mechanisms by which humic acid influences soil pH and nutrient buffering capacity?-February 2024-www.zdask.com

Potential Mechanisms of Humic Acid on Soil pH

Humic acid, a complex mixture of organic compounds derived from the decomposition of plant and animal matter, can influence soil pH through several potential mechanisms. These mechanisms include:

1. Buffering Capacity: Humic acid has a high buffering capacity, meaning it can resist changes in pH. It acts as a buffer by accepting or releasing hydrogen ions (H+) depending on the soil conditions. When the soil pH is too low (acidic), humic acid can release hydrogen ions to neutralize the acidity. Conversely, when the soil pH is too high (alkaline), humic acid can accept hydrogen ions to lower the pH.

2. Chelation: Humic acid has the ability to chelate or bind with metal ions in the soil. This chelation process can affect soil pH indirectly by influencing the availability of essential nutrients. For example, in alkaline soils, humic acid can chelate with iron (Fe) and other micronutrients, making them more soluble and available to plants. This can help lower the soil pH by increasing the availability of acidic cations.

See also Why is humic acid used in the restoration of degraded soils?

3. Ion Exchange: Humic acid can also influence soil pH through ion exchange processes. It can exchange hydrogen ions with other cations present in the soil, such as calcium (Ca), magnesium (Mg), and potassium (K). This exchange can help regulate the pH by replacing alkaline cations with hydrogen ions, thereby reducing the soil pH.

4. Microbial Activity: Humic acid can stimulate microbial activity in the soil. Microbes play a crucial role in nutrient cycling and organic matter decomposition. As microbes break down organic matter, they release organic acids and carbon dioxide, which can lower the soil pH. Additionally, microbial activity can enhance the release of nutrients from organic matter, further influencing the nutrient buffering capacity of the soil.

See also Humic acid and soil biodiversity promotion

In summary, humic acid can influence soil pH through its buffering capacity, chelation of metal ions, ion exchange processes, and stimulation of microbial activity. These mechanisms work together to regulate soil pH and nutrient availability, ultimately impacting plant growth and productivity.

Keywords: organic, hydrogen, exchange, mechanisms, matter, buffering, capacity, microbial, activity