What happens as fresh organic matter decomposes in the soil and forms humus?
As fresh organic matter is decomposed in the soil some of the energy rich carbon compounds are oxidized to provide energy to the decomposing organism. This carbon ends up as CO2. H2O is also a by-product. Some of the carbon ends up in the tissue of the decomposing organism. Some of the nutrients in the organic matter are utilized by the decomposing organism and the rest end up in the soil usually in forms available to higher plants. The residue from this process is called humus. Humus is composed of living and dead microbes, partially decomposed organic matter and any residue formed in the decomposition process.
