What are the soil organic matter pools composed of?

The composition of soil organic matter pools is categorized into three main types: stable, moderately stable, and easily decomposable organic matter. These categories reflect the various stages of decomposition and transformation that organic materials undergo in the soil environment.

Stable organic matter, often referred to as humus, consists of well-decomposed materials that resist further breakdown and contribute to soil structure and nutrient retention over long periods. Moderately stable organic matter includes compounds that have been partially decomposed and still provide some nutrient value while also contributing to soil structure. Easily decomposable organic matter consists of fresh plant materials and microbial biomass that are readily broken down by soil microorganisms, rapidly cycling through the ecosystem and contributing to immediate nutrient availability.

This tripartite pool structure enhances soil health by providing a reservoir of nutrients, improving soil structure, water retention, and increasing microbial diversity. The fusion of these different organic matter pools is essential for maintaining soil fertility and supporting plant growth. Thus, the understanding of these organic matter types is critical for effective soil management and conservation practices.