Soil is a short word that has many meanings.
Soil can be sweet smelling when freshly plowed and crumbly to touch . Soil can be black in color and rich in nutrients or pale brown and lacking in nutrients.
Soil has character. It is composed of mineral and organic materials in which
plants and other organisms grow. Soil is the skin of the earth that the life on
our planet depends on for sustenance. Soil is not "dirt". Soil
is a complex medium that sometimes is forgotten part of the environmental
picture. Dirt is soil out of place. Our planet depends on soil for its
lifeblood, not dirt. We must protect our soil for the future well being
of the planet just as we have protected our air and water.
"All natural resources...are soil or derivatives of soil. Farms,
ranges, crops, and livestock, forests, irrigation water and even water power
resolve themselves into questions of soil. Soil is therefore the basic natural
resource. --- Aldo Leopold (1924)
The living soil provides the mechanism for making the planet hospitable.
Green plants convert carbon dioxide, sunlight, and soil derived water into
oxygen and food (complex carbohydrates), the primary compounds of life. The
oxygen released by the plants makes the atmosphere breathable for animals.
Organism living in the soil decompose both the plant and animal remains,
releasing nutrients for new plants and more carbon dioxide for the green
plants. The cycle continues the the planet lives on as a living organism.
See more about the living planet and the Gaia hypothesis at
GAIA
Soil
Scientist
A soil scientist thinks of the soil as a natural body composed of mineral and organic matter, air, and water. This is different from the geologist who might call this loose material regolith to differentiate it from hard rock. Because the soil will be acted on by the 5 Soil Forming Factors the soil will gradually change with time and develop layers we call horizons. These soil scientists are determining the soils horizons and suitability of the soil for plant growth. Throughout the semester you may want to refer to the USDA Natural Resource and Conservation Service for information about soils and careers as a soil scientist or soil conservationist. NRCS
Greens Superintendent
Golf Greens are also often made from manufactured soil. Golf
course greens are generally made from 85 % sand and a mixture of soil and peat.
This is needed to withstand the compaction of the golfers and the mowing
equipment. To learn more about high sand content golf greens go to
Sand Golf
Greens or go the Golf Course Superintendents Association atGCSA
Green House Manager
In some instances people who use soil often need to manufacture a soil rather than use the soil made by the soil forming processes. Green house managers often build soil from peat, topsoil, and sand for use in growing flowers or vegetables. Information about green house growth media go to Green House Growth Media
Environmental Scientist
Environmental scientists work for natural resources and environmental protection departments. Federal agencies like the Environmental Protection Agency and the Natural Resources Conservation Service hire environmental scientists. Private environmental consulting firms, environmental laboratories, and corporations which discharge waste in the air, in water, or on land also hire environmental scientists to monitor discharges, assess environmental quality, and assure compliance with state and federal laws regulating pollution.
Environmental Scientist use soils information to aid them in making decisions about wetlands, environmental impacts that projects will have on the environment, and determinations to aid in the protection of soil and water resources. All these environmental concerns have a need for soils information.
Engineer
Engineers deal with soils because they want to build on soils, rather than
growing plants. Many times soils are not suited for building houses, roads or
landfills, and modification of the site can be expensive. Knowing where good
soils are located can aid in the planning of better and more environmentally
friendly communities. Soil which is suited for construction is often removed
and placed in areas where the soils are not suitable. Some information about
soil engineering can be found Soil Engineering
Soil as a medium for plant growth.
Soil for plant growth is a dynamic system. The soil acts like a sponge storing water and nutrients until both are needed by plants. Soils make up the Pedosphere which lies at at the interface between the lithosphere, biosphere, atmosphere and hydrosphere. It is therefore easy to see why soils are composed of four basic components of mineral matter, organic matter, air and water.
The composition of the mineral soil on a volume basis is considered to be 50% solids (mineral or organic) and 50% non-solids (air or water). Solids are from the weathering of rocks and minerals and the decomposition of plant and animal remains. In an "ideal" soil, the air and water are each 25%. However, the proportion will vary on an hourly, daily and monthly basis. Here two soil scientists check the water content of a soil in Alaska. The amount and type of the soils constituents vary widely from place to place which results in tremendous amounts of soil variability.
Investigation 1 in the Laboratory will give you a chance to start
working with natural and made soil. 
Go to Next Chapter ( Chapter 2)
Back to "The Materials for Making Soil"
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