How does decomposition timing vary for different materials?

The time it takes for substances to decompose varies greatly, depending on the nature of the compounds. Simple modifications are often fleeting, while large, complex compounds like proteins and carbohydrates can persist for many years. Temperature, moisture, and bacterial activity all contribute to the rapid breakdown of the substances. An understanding of this will enable us to work more effectively in our composting and soil creation.

Molecular Complexity establishes the basic rates of decomposition. Simple structures require little processing, whereas more complex ones require special enzymes. Sugars and starches break down rapidly, followed by protein and cellulose. Lignin and waxes are the most resistant to decomposition.

Environmental factors can significantly impact the rate at which materials decompose. Warm temperatures greater than 60°F increase microbial activity. Moisture is also necessary for enzymatic activity, allowing the breakdown of substances. Aerobic conditions allow for a more rapid breakdown of materials than anaerobic conditions. I have found that decomposition may be twice as fast in the summer months as in winter.

Lignin and charcoal are the most resistant materials. These polymers are complex structures that enzymes cannot degrade because of their cross-linked nature. Microbes gradually oxidize surfaces over time, and complete oxidation may take decades. They are the most stable materials, making them good candidates for long-term carbon storage in soils.

The practical application is balancing compost ingredients. For example, mix fast-decomposing scraps from the kitchen with slower yard waste. Turn your piles regularly to sustain aerobic conditions. The information shared in the second section can help a farmer time the termination of a cover crop to benefit the soil the most.

Read the full article: Soil Organic Matter: The Essential Guide