Water

• Although water is important to plants, too much standing water can easily kill plants. Soil that drains water too quickly does not allow plants to get enough water, and soil that is too heavy allows water to pool and plants can be killed from overwatering. Organic matter mixed into the soil breaks up the soil and absorbs water. In fact, organic matter can absorb six times its weight in water, according to the University of Minnesota. The water is released to plants when needed but is pulled away from the plant and held in the organic matter, preventing pooling and soggy soil.
  
  

Bacteria and Aeration

• Fertile soil needs bacteria for healthy plants. Bacteria feed on organic matter. Because of the texture that organic matter adds to soil, the soil will not compact around the roots of plants. This adds aeration to the soil. The soil texture also reduces erosion.
  
  

Minerals

• Water can leach nutrients and minerals out of the soil and away from plants. Organic matter absorbs minerals. Even if water does not leach the minerals out of soil, the soil might not always have enough nutrients and minerals to support healthy plants. Organic matter allows the minerals to be slowly released to plants and back into the soil.
  
  

Soil pH and Nutrients

• Plants require specific pH ranges to grow properly. Organic matter changes soil's pH because of the nutrients it releases when it is decomposed. Organic material releases nitrogen, magnesium, calcium, potassium, phosphorus and sulfur, and lime can be added to further adjust soil pH. Each of these nutrients, and the pH they provide, help plants grow strong, healthy root systems, promote chlorophyll production, encourage plant bloom and growth and help plants resist disease. Copper, boron, iron, chloride, manganese, zinc and molybdenum are also found in organic matter, according to www.agr.state.nc.us.
  
  

Disease

• When plants are not healthy, either from under or overwatering or improper nutrition, they are much more susceptible to disease. When organic matter is added to the soil, the plants have the aeration, water and nutrition they need to grow healthy.