What does the C:N ratio measure in organic material?

The C:N ratio specifically measures the ratio of carbon to nitrogen in organic materials, such as plant residues or compost. This ratio is crucial because it indicates how quickly microorganisms will decompose the organic matter and how much nitrogen will be available to plants during this process. A high carbon-to-nitrogen ratio means that there is more carbon relative to nitrogen, which can slow down decomposition and nitrogen release, potentially leading to nitrogen deficiency for plants if the organic matter is incorporated into the soil without sufficient nitrogen.

The total organic matter content focuses on the overall amount of organic material present but does not provide insight into the balance of carbon and nitrogen, which is essential for nutrient cycling. The relative size of plant cells is unrelated to the C:N ratio, as this measure does not address cellular structure or function. Lastly, the ratio of nitrogen to oxygen is not relevant in the context of organic material composition, as the C:N ratio is specifically concerned with the balance between carbon and nitrogen.