Soil organic matter comprises a small part, usually less than 5%, of a given soil by weight. Its influence on biological, chemical and physical properties of soil is far greater than you would expect, considering the small amounts present in most soils. In earlier times the depletion of soil organic matter often resulted in a “worn out” soil. Within the last 70 years, the development of inexpensive fertilizer, large machinery, pesticides and irrigation have produced a set of agronomic practices that largely ignores soil organic matter and considers it irrelevant in modern crop production. One of the difficulties with this way of thinking is that as soil organic matter levels decrease, it is taking larger and larger amounts of more expensive inputs to “fix” the problems of fertility, disease, compaction, water availability and erosion.