If the carbon to nitrogen (C:N) ratio is greater than 25:1, what happens to nitrogen (N)?

When the carbon to nitrogen (C:N) ratio in organic matter exceeds 25:1, nitrogen becomes immobilized. This process occurs because microorganisms require both carbon and nitrogen to decompose organic materials. When carbon is abundant relative to nitrogen, the microbes use up available nitrogen from the environment to balance their metabolic needs, leading to a temporary reduction in the nitrogen available in the soil.

As a result, nitrogen immobilization can lead to a decrease in nitrogen availability for plants, which may create nutrient deficiencies if significant amounts of organic matter with a high C:N ratio are incorporated into the soil. This relationship is crucial in nutrient management practices, as it underscores the importance of considering both carbon and nitrogen levels when adding organic amendments to soil.

The other possible outcomes, such as mineralization or volatilization, do not occur under conditions of high C:N ratio. In mineralization, organic nitrogen is converted into inorganic forms that plants can readily absorb, but this typically happens when the C:N ratio is lower, fostering a nitrogen release. Volatilization, on the other hand, refers to the loss of nitrogen as ammonia gas, which is a concern mainly in contexts of high nitrogen fertilizer rates, not in scenarios with high C:N ratios. Thus, nitrogen remains heavily tied