Soil Organic Matter

Soil organic matter is a very important factor in soil fertility. It is a reservoir of plant nutrients, has a high CEC, buffers soil pH, and chelates micronutrients. Organic matter exists in different forms in soil, ranging from living soil organisms to fresh, readily decomposed plant residues to humus that is ve[table. Living soil organisms include bacteria, fungi, actinomycetes, nematodes, earthworms, mites, and insects. They make up the soil food web, which carries out biological nutrient cycling. Plant roots are a sometimes forgotten part of the living soil biomass. Readily decomposed or active organic matter is the form of organic matter through which nutrients are actively recycled. Stable humus contributes to long-term nutrient supply and is the organic matter fraction with high CEC. Chelation is the ability of soluble organic compounds to form complexes with micronutrient metals that keep them in solution and available for uptake. In organic soils, trace metal complexes with organic matter can reduce their availability.

One of the best ways to add organic matter to the soil is to maintain fertility and grow healthy crops that add large amounts of plant residue.