Soil Organic Matter Content

The mass fraction of organic compounds present in a soil sample (including decomposing plant and animal residues, humus, and living microbial biomass), expressed as a percentage or mass per unit mass of soil (e.g., % by weight or g·kg⁻¹); a material property that affects nutrient supply, water retention, soil structure and microbial-mediated nutrient cycling at the measurement depth and time.