Soil fulfills many functions. It recycles dead materials, it supports roads and buildings, it gives animals a place to live, and it provides the environment for growing food. There are beneficial types of soil for each activity and there are specific ways to nourish and treat each type so it remains productive and viable. Degradation of soil from detrimental agricultural practices has caused many people to take a second look at soil’s characteristics.
Soil is a mixture of minerals, air, water, and decaying plant and animal residues.These are called “organic matter." It includes fungi, earthworms, bacteria and other micro-organisms. There can be 900 of earthworms, 2,400 pounds of fungi, 1,500 pounds of bacteria, 133 pounds of protozoa, 890 pounds of arthropods and algae and various small mammals in one acre of topsoil, according to the National Sustainable Agricultural Information Center.
Topsoil is the uppermost 2 to 8 inches of soil. It is the productive layer of soil that is responsible for the nutrient content of vegetables and fruit. The health of topsoil is directly related to the health of people who eat its crops. Agricultural practices that do not nourish, replenish and tend topsoil health cause soil degradation and infertility. Synthetic fertilizers, pesticides and excessive tilling practices destroy the natural biological life processes in soil.
Soil Minerals and Health
Soil contains 45 percent minerals, 25 percent air and water, and two to five percent organic matter. The minerals in healthy soil are the same ones needed by our bodies for good health. They include potassium, chloride, sodium, calcium, phosphorus, magnesium, zinc, iron, manganese, copper, iodine, selenium and molybdenum. The Nutrition Security Institute reports that health problems have increased as the mineral content of topsoil has decreased.
Soil erosion is a primary concern in organic gardening and worldwide sustainable agriculture programs. “In the last 40 years, 30 percent of the world’s arable land has become unproductive,” according to the Center for Earth Leadership. Recent studies have shown that soil can be nutritionally regenerated and crop production increased with organic soil rejuvenation practices. Home gardeners can do this easily by applying compost and using mulch.
Reasons to Compost
Soil improvement with backyard composting is more than a way to recycle kitchen waste efficiently. Compost increases the organic matter content of garden soil. Higher organic matter content in soil increases its nutrient content and therefore improves health. The nutritional value of tomatoes grown on organically managed soil increases significantly, according to a 2007 study at the University of California at Davis.