ABSTRACT
Living organisms also produce and excrete extracellular substances, such as enzymes and other organic compounds that facilitate nutrient uptake and microbial mobility (e.g., microbial mucilages), as well as metabolic by-products (wastes). Biochemical compounds are also released to the extracellular environment through the death and decay of organisms (cell lysis) and material derived from higher plant residues (leaf litter), sloughing cells from plant roots, and animal excrement. All of these mechanisms add to the innumerable array of biochemical compounds in the soil environment that make up the soil biomass carbon pool.
