C/N ratio
Definition
The carbon over nitrogen (C/N) ratio is a measure of the amount of nitrogen that can be released during decomposition of organic matter.
The lower the C/N ratio, the more nitrogen is released during decomposition.
Soil life is not served by low or high C/N ratio. There are no clear guidelines yet for optimal situations and how to deal with them in the advice.
Influence on decomposition
- A low C/N ratio means organic matter breaks down easily.
- A high C/N ratio means decomposition is slower and more difficult.
- A high C/N ratio does not necessarily indicate a problem, it depends on management goals and soil conditions.
Management implications
Optimal C/N ratio is, in part, dependent on your management goals. For example:
- A high C/N implies little decomposition of organic matter, and the organic matter that remains present has positively impacts workability, carbon sequestration, and water storage.
- A low C/N ratio positively impacts nutrient availability (nitrogen mineralisation) as it encourages microbial activity.
Factors Affecting the C/N Ratio
The ratio can be affected by soil management; input of straw and solid manure will eventually increase the C/N-ratio.
