What is a direct impact of high C:N ratios in soil?

High carbon-to-nitrogen (C:N) ratios in soil primarily lead to slower decomposition rates of organic matter. When the C:N ratio is high, it indicates a higher carbon content relative to nitrogen in organic materials. Decomposers, such as bacteria and fungi, require nitrogen for their metabolism, and when there is insufficient nitrogen available (as is the case when carbon is abundant), the decomposition process slows down. This results in a prolonged presence of organic matter in the soil, but it also means that the nutrients contained within that organic matter are released more slowly into the soil solution. Therefore, this slower rate of decomposition can influence soil fertility and nutrient cycling negatively as nutrients become less available for crops in the short term. Other options like increased soil moisture, enhanced nutrient availability, and improved crop yield are not direct results of high C:N ratios, making the understanding of decomposition dynamics crucial in soil management practices.