Jeffry Hill is a trustworthy expert on soil with years of experience in the agriculture business.
The living soil is a breathing, growing, digesting organism. To be more accurate, it is a combination of millions of different organisms. One teaspoon of soil contains more individuals than the populations of Los Angeles, New York, Tokyo, London and Moscow combined.
This system works as a food source, lungs and a filter for the planet. Almost every molecule in our water, air and food goes through the soil at some point of its existence.
We almost never notice it, but the life in the top twelve inches of the ground creates the circumstances required for life to flourish above ground. Knowing this is the secret to successful farming and gardening.
The complexity of a soil can be explained by a simple statement: if you want healthy plants and foods, you need healthy soil.
Every soil-science class explains that a soil has four components. A half by volume consists of minerals. These are the tiny pieces of rocks that have been turned by rain, flowing water and wind over thousands of years into the bits that they are today.
Minerals are the nonliving foundation of the soil. Most of the other half of the soil consists of pore space. The size of pore space varies from large canals that are visible to the human eye to tiny microscopic channels. All of the pore space is filled with water and air. The quantity of water and air that fills the pore space changes depending on weather conditions and irrigation. Water usually stays on the sides of the hard soil and air fills the spaces in the middle.
Soil organic matter is all the substance in the soil that is currently alive or was alive at a certain point of its existence. The matter includes the leaves that fall from the trees, manure and so on. It also includes live plant roots and decayed roots from years or decades ago. Live and dead microorganisms, worms, spiders and so on are also a part of the organic soil matter. Even the cardboard and paper are a part of it because they were once a living tree.
Even though the organic part of the soil is very small by volume compared to the mineral and pore space parts, it plays a crucial role in determining almost all properties of a soil. It influences what you can do with a sandy soil. It raises the amount of water a soil can contain and when it the water is releases to plants. It even contains plant nutrients. A soil without organic matter is similar to a big piece of rock.
Even though organic matter plays such an important role, only five percent of it is alive. This equals to less than 0.5 percent of the entire soil, notes Jeffry Hill