More than 4 billion microorganisms can be found in a teaspoon of organic fertile soil. Fertile soil provides the necessary nutrients for vegetable and fruit health. The University of California at Davis reports that tomatoes grown on organically fertile soil have almost twice the bioflavinoid content as tomatoes grown in other types of soil. Soil fertility is a major focus of sustainable agriculture.
Organic soil contains both fresh organic plant and animal residue and decayed residue. Tiny microorganisms, insects and worms ingest the organic content of the soil and create nutrient recycling. Nutrient recycling is the process of nutrient transfer from plant waste to soil to microorganisms and again to the plant. Organic soil fertility depends on the constant addition of organic matter to feed nutrient recycling.
Organic matter is added to soil by growing cover crops, utilizing the no-till method and by adding composted plant and animal residues. Cover crops increase soil stability and add nutrients as they decompose. The no-till method is recommended by The American Dahlia Society as a safeguard against erosion and as a method of increasing soil fertility.
Organic soil fertility also depends on soil structure. Roots need to hold onto soil particles to develop and soil must be able to retain water easily. Loosely structured sandy soil does not retain water and heavy claylike soil does not provide enough oxygen for growing plants. Organic matter incorporated into both types of soil improves structure and increases fertility.
Soil that has lost its fertility can be rehabilitated by adding compost as an amendment, a side dressing and mulch. Compost has been found by the U.S. Environmental Protection Agency to be effective in transmuting toxic poisons in the soil and returning it to a higher level of fertility. It is easy to start a compost pile in the backyard for a constant supply of nutrient-rich soil amendment.
Soil Fertility Programs
Organic soil fertility is a major focus in global and national sustainable agriculture programs. University of Florida’s research suggests that “Crop nutrient management programs in organic systems are ultimately site-specific. There is no 'cookbook' approach to designing an organic fertility program.” Soil fertility in the home garden can be managed with the addition of compost, the use of mulch and by refraining from contaminating the soil with pesticides and synthetic materials.