Is It Dirt or Soil?
What do you call the material you grow plants in? Is it soil or dirt? The two words are often interchanged depending on the location of the material. There is often much discussion about the choice of terms used especially if a soil scientist is nearby. One suggestion is to think of soil as a thin diverse living skin that covers the land. It is a dynamic community and changing over time and space.
Dirt may be thought of as dead soil and is often washed away with soap and water. Some consider dirt to have lost the characteristics to support life. Dirt is also defined as soil where you do not want it. If a plant out of place is called a weed, then perhaps a definition of dirt could be considered soil out of place.
The capability of soil to support plant life is vital to life on earth. Farmers and gardeners frequently recognize that there is a difference between soil and dirt. Crop production and yields definitely vary in different soils. The mixture in soil varies but each shovel full holds more living things that all the human beings ever born.
Healthy soil supports life and is alive. It contains many insects (alive and dead), worms as well as particles of clay, silt and sand, that come from rock. The organic part of soil is made from dead or decaying organisms. These microscopic creatures have their own jobs in the web of life. Scientists study them to see what role they play to keep soil alive. Air and water are also important in good soil as are billions of microorganisms including fungi and bacteria.
One group of microbes helps to prevent plant diseases. Plants can be harmed when “bad” microbes, called pathogens, attack their roots and cut off their water supply. Good microbes in the rhizosphere can protect plants from those pathogens. They can directly kill the pathogen and turn it into a nutrient soup or the microbes also can encourage the plant to protect itself by growing thicker cell walls.
Soil is also considered to perform many critical functions in an ecosystem. These include serving as the media for growing plants and modifying the atmosphere by absorbing gases and dust. Soils provide the habitat for animals and organisms. Soils absorb, hold, release, alter, filter and purify most of the water in the systems. Nutrients are recycled in soil so they can be used over and over. Soils also serve as engineering material for construction of foundations, roads, buildings and dams. They can destroy or preserve artifacts of our endeavors.
In a rural community, perhaps we have a better understanding of the value of soil.