Understanding Soil Quality: Its Importance and Properties
Soil Quality
Soil quality is the ability of a soil to perform functions that are essential to people and the environment. Soil quality is not limited to agricultural soils, although most soil quality work has been done in agricultural systems.
Key Features of Soil Quality
Soil quality definitions emphasize several features, such as:
- Leaching: Loss of water-soluble plant nutrients from the soil due to rain and irrigation.
- Calcification: A process in which the soil surface is supplied with calcium in such a way that the soil colloids are always close to saturation.
- Capillary Action: Manifestation of surface tension by which the portion of the surface of a liquid coming in contact with a solid is elevated or depressed, depending on the adhesive or cohesive properties of the liquid.
- Humus: The dark organic material in soils, produced by the decomposition of vegetable or animal matter and essential to the fertility of the earth.
- Soil Erosion: The washing away of soil by the flow of water.
Carolinian Life Zone
Carolinian Canada is an area in Southern Ontario found south of an imaginary line which generally runs from Grand Bend to Toronto. The Carolinian life zone is actually the northernmost edge of the deciduous forest region in eastern North America and is named after the Carolina states. The area includes some of the most significant habitats and threatened plant and animal species that can be found in Canada.
Characteristics of the Carolinian Life Zone
- Moderate climate
- Diverse plant life
- Abundant wildlife
- Presence of rare species
Soil Science and Terminology
Pedology: The science that deals with the study of soils.
Loam: A rich, friable soil containing a relatively equal mixture of sand and silt and a somewhat smaller proportion of clay.
Soil Horizons
- A Horizon: Zone of leaching
- B Horizon: Zone of accumulation
- C Horizon: The layer in a soil profile below the B Horizon and immediately above the bedrock, consisting chiefly of weathered, partially decomposed rock.
Soil Functions
Physical, Chemical, and Biological Functions
Soil performs various functions, including:
- Regulating Water: Helps control where rain, snowmelt, and irrigation water goes. Dissolved water and solutes flow over the land and through the soil.
- Sustaining Plant and Animal Life: The diversity and productivity of living things depends on soil.
- Filtering Potential Pollutants: The minerals and microbes in soil are responsible for filtering, buffering, degrading, immobilizing, and detoxifying organic and inorganic materials, including industrial and municipal by-products and atmospheric deposits.
- Cycling Nutrients: Carbon, nitrogen, phosphorus, and many other nutrients are stored, transformed, and cycled through soil.
- Supporting Structures: Buildings need stable soil for support, and archaeological treasures associated with human habitation are protected in soils.
Soil Components
Soil is composed of mineral matter, water, air, and organic matter.
Assessing Soil Quality
Visual Indicators
Soil color is a very useful indicator of soil quality and can provide an indirect measure of other more useful properties of the soil that are not so easily and accurately assessed.
The darker the color is, the greater is the amount of organic matter in the soil.
Also, soil color can be a useful indicator of soil drainage and the degree of soil aeration. In addition to organic matter, soil color is markedly influenced by the chemical form.
Physical Indicators
Physical condition of the soil in relation to plant growth. It is an integration of the following properties:
- Aggregate formation and stability
- Bulk density
- Moisture
- Aeration
- Water infiltration rate
- Drainage
- Capillary water capacity
Soil tilth plays an important role in the movement and storage of water and materials, providing structural support for plants, buildings, machines, and animals, etc.
Chemical Indicators
The acidity or alkalinity in soils have several different sources. In natural systems, the pH is affected by the mineralogy, climate, and weathering. Management of soils often alters the natural pH because of acid-forming nitrogen fertilizers or removal of bases (potassium, calcium, and magnesium).
Nitrogen, phosphorus, and potassium.
All three of these “ingredients” play a key role in the development of a plant. Soil lacking any of these three key nutrients will cause poor growth and development of the vegetation in one or all of these major areas.
Biological Indicators
Earthworms – Determine how strong and healthy the soil is.
Earthworms are miniature topsoil factories. Earthworms make soil. Eventually, all other living things pass through an earthworm on the way to becoming soil. All the soil you have ever seen has passed through the stomachs of numerous earthworms to become what it is. Earthworms are amazingly strong and can easily shift stones 60 times their own weight.
Soil Texture and Infiltration
There are several similarities that soil texture and soil infiltration tests share. Firstly, the infiltration determines the soil texture, whether it is clay, sand, or silt. Also, the capacity of the soil to hold water directly relates to the infiltration test. Lastly, the structure of the soil has a great impact on the infiltration test.