Particulate organic matter (POM) includes steadily decomposing plant litter and animal faeces, and the detritus from the activity of microorganisms. Most of it continually undergoes decomposition by microorganisms (when conditions are sufficiently moist) and usually has a turnover time of less than 10 years. Less active parts may take 15 to 100 years to turnover. Where it is still at the soil surface and relatively fresh, particulate organic matter intercepts the energy of raindrops and protects physical soil surfaces from damage. As it is decomposes, particulate organic matter provides much of the energy required by soil organisms as well as providing a steady release of nutrients into the soil environment.
The decomposition of POM provides energy and nutrients. Nutrients not taken up by soil organisms may be available for plant uptake. The amount of nutrients released (mineralized) during decomposition depends on the biological and chemical characteristics of the POM, such as the C:N ratio. In addition to nutrient release, decomposers colonizing POM play a role in improving soil structure. Fungal mycelium entangle soil particles and release sticky, cement-like, polysaccharides into the soil; ultimately forming soil aggregates 
Soil POM content is affected by organic inputs and the activity of soil decomposers. The addition of organic materials, such as manure or crop residues, typically results in an increase in POM. Alternatively, repeated tillage or soil disturbance increases the rate of decomposition by exposing soil organisms to oxygen and organic substrates; ultimately, depleting POM. Reduction in POM content is observed when native grasslands are converted to agricultural land. Soil temperature and moisture also affect the rate of POM decomposition. Because POM is a readily available (labile) source of soil nutrients, is a contributor to soil structure, and is highly sensitive to soil management, it is frequently used as an indicator to measure soil quality.