The Makeup of Soil

What is soil? Layer on the earth’s crust that provides a combination of resources.

How does soil help support life? Oxygen—needed for adequate root growth. Temperature—determined by the amount of heat the soil absorbs from the sun and the amount it loses to the atmosphere. Temperatures within a particular range are needed for plant growth and seed germination.

How does soil help support life? Water—utilized for growth of plants. Carbon—utilized in the form of organic matter in the soil. Nutrients—provided as minerals. Nitrogen is one mineral made available and recycled through decaying material in the soil.

Soil Components Solid portions (50 percent of soil volume) ▫ Mineral matter  45 percent of the soil  Inorganic material originating from rock.  Determine the soil’s ability to hold water and provide nutrients  Sand, silt, and clay ▫Organic matter  5 percent of the soil  Partially decomposed plant and animal matter  Contributes to the soil’s fertility as well as improved aeration and water-holding capacity  Gives soil its dark color

Soil Components Pore space (50 percent of soil volume) ▫Air  25 percent of the soil ▫Water  25 percent of the soil  When it rains, water will enter the soil or flow off the soil’s surface. There is a constant fluctuation in the amount of air and water found in the soil.

Living Organisms Found in Soil Forms of life in soil include: Earthworms Insects Bacteria Fungi Other organisms

Bacteria and Fungi Break down organic matter and release nutrients Have symbiotic relationships with plants. ▫Symbiosis is the living together of unlike organisms where both organisms benefit.  fungi get glucose and sucrose from plant roots  plants are assisted in the absorption of water and minerals

Animals and Insects Earthworms, ants, crawfish, moles, and other organisms improve the soil tilth (the ease with which soil can be worked). ▫create openings in the soil as they tunnel ▫enhances drainage and improves air exchange