Organic matter in soil is also known as compost. The presence of organic matter in soil is important to home gardeners and to global sustainability issues. Vegetables and flowers thrive in soil that has compost added. Global agricultural sustainability issues center on the practice of soil renewal because topsoil erosion problems affect world food supplies.
Organic matter is composed of anything that once lived. This consists of plant and animal remains in variable stages of decomposition, root and microbial exudates and humus. Decomposition of living organic matter releases nutrients needed by plants. Healthy soil is a mixture of water, air, minerals and organic matter.
Successful gardening depends on good soil. Home gardeners can improve the quality of their soil each year by continuously adding composted materials. The soil will respond by becoming porous, water retentive, alive with microorganisms and more fertile. "If you treat your soil well, it will treat your plants well" is the Golden Rule of gardening.
The University of Wisconsin Extension has defined the importance of organic matter in soil by saying that it provides energy for microbes, holds soil together, stores and supplies nutrients, holds carbon from the atmosphere, filters pollutants and improves structure and filtration.
The U.S. Environmental Protection Agency (EPA) describes compost as having the ability to clean the soil of contaminants, including chemical pollutants, wood preservatives and explosives. The application of organic matter to soils adds carbon. Carbon is an essential ingredient in the growth of beneficial bacteria, which helps create healthy plant life. Crops grown in composted soil give more abundant yields.
"Scientists have been researching the benefits of organic matter for decades," reports the United States Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS). "They have found that plant deficiency diseases are less severe in soils that are well supplied with organic matter," concludes the NRCS in its report on organic soil matter.