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.
The lower the C/N ratio, the easier the breakdown. With a higher C/N ratio, the breakdown of organic matter is more difficult. A high C/N does not necessarily mean something is wrong.
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 mineralization) as it encourages microbial activity. The ratio can be affected by soil management; input of straw and solid manure will eventually increase the C/N-ratio.