The organic material falls on the surface of the soil in the case of tops and roots, where they are in the soil. The organic matter formed from the tops is formed on the soil surface during plant decomposition. Substances such as straw for example, may take a long time to decompose. The action of burrowing animals or earthworms is important in moving organic matter into the soil where it is decomposed further. Cultivation using implements, can be important in mixing in either undecomposed or decomposed organic matter and cultivation can destroy organic matter.
Organic matter has a number of important functions in soil.
These include storage of plant nutrients and helping to maintain the structure of the soil. All nutrients are stored to some part in the organic matter. Generally, the more organic matter the greater the storage of nutrients. Soil structure is also an important feature of organic matter, as organic matter bonds hold parts of the soil together to form soil particles. These bonds can be easily broken down with excessive cultivation.