Healthy Soil for Life
Soil health, also referred to as soil quality, is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans. This definition speaks to the importance of managing soils so they are sustainable for future generations. To do this, we need to remember that soil contains living organisms that when provided the basic necessities of life - food, shelter, and water - perform functions required to produce food and fiber.
Only "living" things can have health, so viewing soil as a living ecosystem reflects a fundamental shift in the way we care for our nation's soils. Soil isn’t an inert growing medium, but rather is teaming with billions of bacteria, fungi, and other microbes that are the foundation of an elegant symbiotic ecosystem. Soil is an ecosystem that can be managed to provide nutrients for plant growth, absorb and hold rainwater for use during dryer periods, filter and buffer potential pollutants from leaving our fields, serve as a firm foundation for agricultural activities, and provide habitat for soil microbes to flourish and diversify to keep the ecosystem running smoothly.
Soil Biological Fertility
Soils are alive! A variety of soil organisms live in the soil. These include bacteria, fungi, microarthropods, nematodes, earthworms and insects. These organisms live on soil organic matter or other soil organisms and perform a number of vital processes in soil. Other organisms are involved in transformation of inorganic molecules. Very few soil organisms are pests.
The role of soil organisms in soil fertility may involve the following:
• helping soil to form from original parent rock material,
• contributing to the aggregation of soil particles,
• enhancing cycling of nutrients,
• transforming nutrients from one form to another,
• assisting plants to obtain nutrients from soil,
• degrading toxic substances in soil,
• causing disease in plants,
• minimizing disease in plants,
• assisting or hindering water penetration into soil.
Soil Chemical Fertility
Soil chemistry is concerned with the availability of elements for plant uptake as well as the presence in soil of elements and chemical compounds that might be present at levels that are detrimental to plants and soil organisms. Some elements in the soil are nutrients and are essential for plant growth. Other elements are not essential and may be toxic to plants. The availability of elements for plant uptake is affected by soil pH and reactions of the elements with soil particles and organic matter.
Soil chemical fertility is affected by:
• composition and parent material of the soil,
• soil pH,
• element adsorption to clay surfaces and organic matter,
• soil salinity.