2. Soil Organic Matter

• The organic matter (OM) consists of a variety of (Bacteria, Fungi, Algae, Actinomycetes, etc.), animal life (Earthworms, Nematodes, Protozoa, Mites, Beetles, Moles, etc.), their excretions, debris of dead bodies decomposed to various extents.
• It ranges from less than 1% in many soils in the plains to 3-4% in forest and mountain soils.
• Average composition of OM is 47% C, 44% O, 7% H, 2% N and traces of other elements.
• It is the storehouse of nutrients, affects cation exchange, water retention, and fixation and release of nutrients.