Organic matter is also referred to as humus when in a finished composted state. Actually, you can never get too much of a good thing when it comes to incorporating organic matter into garden soil, says Musgrove. The primary reason for adding organic matter to the garden is to improve drainage and improve soil structure. Soil is made up of a mixture of different sized particles, which include clay, sand and silt. Roots must grow and move in the soil to obtain water and air.
Organic matter builds a better soil structure for roots to forage for water, nutrients and air.
Organic matter also helps bind soil particles together in sandy soil. This helps prevent water from flowing through too quickly. There are several types of organic matter that can be added to garden soil. The best, easiest, and most economical and available organic matter is compost from your own back yard. Commercially packaged sources of organic matter include manures, peat and composted materials.