Chapter 8 - Water and Soil Conservation Benefits of Living Organisms for Water and Soil 1. plants break fall of rain and reduce damage to the soil 2. plant materials on the soil provide a rain absorbing layer on the surface 3. decayed plants improve soil structure and nutrient content 4. plants move water around by taking it up in their roots and releasing it in the atmosphere The interdependence of plants and animals for food constitutes what is known as a food chain. Food Chain - A sequence of organisms showing what eats what. Producer Primary Consumer (Herbivore) Secondary Consumer (Carnivore or Omnivore) Decomposer Producers Manufacture their own food supply chemically (photosynthesis). This means that they are autotrophic. They start the food chain (usually a plant). Consumers Feed on other organisms. They are heterotrophic (cannot make their own food). Herbivores: consumers that feed on plants Carnivores: consumers that feed on animals Omnivores: consumers that feed on both plants and animals. Decomposers Feed on dead organisms. They are saprotrophic. They clean up and recycle matter in an ecosystem. Bacteria and fungi.
Earth s Water Supply Of all the water on Earth, only a small amount is available for us to use. 97.2% of the Earth's water supply is salt water, leaving only 2.8% as fresh water of the total supply of water on Earth: 0.6% is groundwater (we can use some of this water) 0.01% is in lakes and streams (we can use some of this water) 2.2% is in glaciers and icecaps 0.001% is water vapor The Water Cycle The cycling of water between the water sources, atmosphere, and the surface areas is called the water cycle.
Types of Pollution Point Source Pollution Pollutants that are discharged from, and can be traced back to, an identifiable point or source. Example: Factory s discharge pipe or sewage ditch. Nonpoint Source Pollution When the source of a pollutant cannot be identified; it could have come from many places. Examples: runoff from agricultural fields containing fertilizers or pesticides motor oil filtering from urban areas sediments from eroded stream banks Conserving Water and Improving Water Quality 1. Save clean water 2. Dispose of household products carefully 3. Care for lawns, gardens and farmland carefully 4. Practice sensible pest control 5. Control water run-off keep soil covered with plants no-till planting crops without plowing or disking alternate strips with close growing crops with row crops contour farming plant cover crops 6. Control soil erosion 7. Avoid spillage or dumping of gasoline, fuel or oil in the ground 8. Keep chemical spills from seeping away 9. Properly maintain your septic system
Relationships of Land and Water Precipitation Land as a Reservoir land serves as a container for water water soaks down into the soil and forms a water table water below the table may run out to the surface in the form of springs, creating river, bays and oceans Types of Ground Water saturated soil has water occupying all of its pores water that drains out of wetted soil is gravitational water capillary water is held loosely against soil particles and can be absorbed by plant roots hygroscopic water is held tightly by soil and is unable to be absorbed by plants. Soil Important Soil Properties: 1. Soil is a limited, renewable resource that is used in many ways. Soil is the foundation for life. 2. Soil is the loose material covering the surface of the earth which has been created by natural processes. Soil supports plant and animal life. 3. Soil is made up of 4 parts: mineral matter (45%) air (25%) water (25%) organic matter (5%) Mineral Matter o What you can see and feel. o Soil texture or particles size distribution refers to the proportions of sand, silt, and clay particles which make up the mineral component in a particular soil. o On PEI, the agricultural soil types are loams to fine sandy loams. They are high in silt and fine, but low in clay. o Air and Water o Should contain even amounts of air and water. o The amount of air and water space is referred to as the soil porosity. Organic Matter o Composed of anything that lives or once lived. o Humus helps the soil store water and nutrients and reduces erosion.
Land erosion and soil conservation caused by: o wind and rain o Deforestation o slash and burn method of farming Trees help to prevent soil erosion It takes about 300-500 years for nature to develop 1 inch of soil from bedrock. Functions of Soil 1. Medium for plant growth A source of nutrients Provides ventilation for plants root systems Absorb rainwater and hold it where it can be used by the plants roots. Has insulating properties (protects the deep root systems from extreme temperatures). 2. Regulator of water supplies Soil filters and regulates water supply by storing water after a precipitation event. 3. Habitat for organisms Small quantities of soil can house whole food chains These organisms decompose organic matter and convert minerals and nutrients into usable forms. 4. Recycler of raw materials Turns this waste into humus Converts the mineral into forms used by plants and animals Returns the carbon to the atmosphere as carbon dioxide 5. Engineering medium For structures (roads, causeways, foundations for buildings and bridges). Establishment of forestry and agriculture crops.
Soil Forming Processes 1. Chemical weathering Decomposition from chemical reaction of minerals in the rock and oxygen, water, or other chemicals. Example oxidation (rusting). 2. Physical weathering Also known as disintegration, when larger rocks are broken down into smaller pieces. Examples glacier movement, temperature changes (frost wedging), moving water. 3. Biological weathering Organisms help breakdown rocks to form soil. Examples tree roots, burrowing animals Most soils are a combination of sand, silt and clay called loams. Good growing soil contains 20% clay, 40% silt, and 40% sand. PEI s Provincial soil is sandy loam. Remember It takes thousands of years for soils to develop. A soil that is destroyed now will not be replaced within our lifetime. Prevention and Reduction of soil erosion Most methods are based on: reducing raindrop impact reducing or slowing the speed of wind or water moving across the land. securing the soil with plant roots. increasing absorption of water. carrying run-off water safely away. Ways to reduce or prevent wind and water erosion include: keep soil covered when growing plants cover the soil with mulch. use strip cropping on hilly lands rotate crops increase organic matter in soil correct balance of lime and fertilizer avoid overgrazing by animals.