oil organisms play a vital role in the degradation of organic matter and subsequent soil humusformation. When plants die, leaves are dropped onto the soil surface where microorganisms can “attack” and decay plant tissue. The organic matter is used as an energy source for microorganisms, increasing their population in the soil. These organisms utilize easily digestible materials (like simple sugars and carbohydrates) found in the plant material, leaving more resistant materials (such as fats and waxes) behind. The material left behind is not easily decomposed; it comprises the humus found in soil. Humus acts as a gluing agent, essentially holding primary soil particles (sand, silt, clay) together to form secondary aggregates or ‘peds’. These organisms and the humus they help create aid in the soil development and the formation of soil horizons.