Benefits of Soil Organic Matter (SOM)
1) SOM is a slow release form of nitrogen, phosphorus, and sulfur for plant nutrition and microbial growth.
2) SOM has considerable waterholding capacity and thereby helps to hold water in soil.
3) SOM buffers against changes in pH or acidity of a soil.
4) SOM's dark color enhances absorption of energy from the sun and helps to warm soils.
5) Organic materials are the cement that hold clay and silt particles together, thus contributing to the granular or crumb structure of the soil, resulting in both a more porous soil, and greater resistance to erosion, especially erosion by wind.
6) SOM binds nutrients ions (potassium, calcium, magnesium, for example) in the soil that otherwise might be leached or lost from the surface horizons.
7) Organic constituents in the humus may act as plant growth stimulants.
8) SOM is a major component of the carbon cycle estimated globally at between 1,500 and 2,000 billion metric tons. The soil pool is about twice the size as the plant atmospheric pools. Agriculture worldwide has reduced the soil carbon pool by an estimated 50 to 80 billion metric tons. Ironically, the losses have provided the space that add- ing or sequestering more carbon in soil requires.
9) SOM plays a major role in the soil's ability to tie up or absorb potential pollutants (including pesticides). This provides a safe storage place where microorganisms can degrade often toxic materials over time.
Therefore, it is essential that we build SOM levels. Without SOM, soils quickly can become degraded and lose their productivity.
Luke Baker, Ph.D.
Agronomist/Lab Specialist, Brookside Laboratories