Healthy Soil
By Gerry Hernandez, UC Master Gardener
Have you ever looked; I mean really looked at your soil? What do you see? Do
you see critters such as earthworms? Have you looked at your soil under a microscope? There are many components to soil. Soil is a big subject, pun intended.
We will only be able to scrape the surface in this article, yes, pun intended.
Dirt and soil are NOT the same thing.
Dirt is a lifeless mixture of minerals, air, and water. Soil includes minerals and air, as well as animals and other living things, and eventually their waste and/or decaying bodies.
What is Soil?
Soil is a naturally occurring mixture of inorganic and organic ingredients with a
definite form, structure, and composition that varies from one location to another.
Soil is vital to anchor plant roots, supply water and air to those roots, and furnish nutrients for plant growth.
Soil also absorbs rainfall and mitigates flooding; removes pollutants and cleanses water; stores water for plants, wildlife, and people; provides habitat for organisms, such as microscopic bacteria and earthworms; and stores atmospheric carbon.
The quality of the soil directly affects its ability to carry out each of these
important tasks.
Healthy soil is loose, friable, and welldrained, approximately 45% minerals,
25% water, 25% air, and 5% organic matter, has good structure and texture, plenty of nutrients and a pH between 5.5 and 7.5 and has large numbers and types of organisms.
The living component of soil is referred to as the “soil food web” and includes
microscopic bacteria, algae, fungi, and protozoa; more complex life forms like
nematodes and micro-arthropods, and visible creatures such as earthworms, insects, and small vertebrates.
The main factors that impact the health of the soil are the soil structure and texture, soil chemistry, organic matter content, soil biology and water infiltration, retention, and movement.
Healthy soil has a good combination of all these factors; unhealthy soil has a
problem with at least one of them.
What does healthy soil do? Healthy soil cycles nutrients, making them available to plants; provides a healthy rooting environment; creates habitat for diverse
plants, animals, and microbes living in and above the soil; minimizes leaching of nutrients into ground and surface water; minimizes run-off and erosion; maximizes water-holding capacity so water enters the soil and is available for plant growth; absorbs and filters excess nutrients and pollutants so water does not carry contaminants to groundwater or surface water; and provides a stable foundation for structures.
Do you have healthy soil? There are many indicators of healthy soil, such as:
productive, good-looking plants, earthworms, water that penetrates easily and
soil that is easy to work.
At the Donna Critchfield demonstration garden, we have been working toward
healthy soil by adding compost. We now have good working soil that is productive, supports earthworms and is becoming easy to work
Source: University of California
Agriculture and Natural Resources. Visit
cecolusa.ucanr.edu or ipm.ucanr.edu