What is Erosion? The word "erosion" is derived from the Latin "erosio", meaning to "to gnaw away".

Erosion The first five pictures of this presentation are of the same rock, just in different time periods. Pay attention to the dates on the side of the pictures and see what the water did to this rock. 1890                                                                       

Erosion Still the same rock. 1910                                                                        

Erosion Still the same rock. 1920                                                               

What is Soil Erosion? In general terms soil erosion implies the physical removal of topsoil by various agents, including  rain, water flowing over and through the soil profile, wind, ice or gravitational pull.

Types of Soil Erosion Wind erosion: the removal soil particles by the force and kinetic energy of the wind. These soil particles are transported and deposited when the wind energy drops. Water erosion: caused by the kinetic energy of rain falling on the soil surface and by the mechanical force of runoff. Gravity erosion: Mass movement of soil occurs on steep slopes under the influence of gravity. The process involves the transfer of slope-forming materials from higher to lower grounds due to self weight.

Causes of Soil Erosion Climatic Factors Land use – by man Soil itself Hydrology (how water flows) Landform and topography

Climatic Factors The two most important climatic factors having a direct effect on erosion are precipitation and wind velocity. Other climatic factors have an indirect effect on soil erosion, such as water balance, temperature and relative humidity.

Land Use Humans play a major role in soil erosion through their use and abuse of natural resources, for example deforestation, grazing, arable land use, faulty farming systems, high crop intensity, housing construction, and mining.

Soil Itself The susceptibility of a soil to erosion is influenced by its physical, hydrological, chemical and mineralogical properties as well as its soil profile characteristics. Important soil physical and hydrological properties that affect the resistance of a soil to erosion include texture, structure, water retention and transmission properties. AKA some soil can erode quicker than other soils (think clay verses sand)

Topography Slope gradient, slope length and shape of slope are the important variables of landform that affect erosion processes for all types of soil erosion, e.g., splash, sheet, rill, and gully erosion.

FORESTRY PRACTICES Forests are logged by two different methods: CLEAR CUTTING – every tree is cut down whether it has value or not and the unnecessary trees are left SELECTIVE CUTTING – only certain trees are cut down depending on what they are needed for ( firewood, paper, furniture or lumber)

(a) Selective cutting Clear stream Major tree harvesting methods. If you were cutting trees in a forest you owned which method would you choose and why? (a) Selective cutting Figure 9.6: Major tree harvesting methods. Question: If you were cutting trees in a forest you owned, which method would you choose and why? Clear stream Fig. 9-6, p. 182

(b) Clear-cutting Muddy stream Figure 9.6: Major tree harvesting methods. Question: If you were cutting trees in a forest you owned, which method would you choose and why? Muddy stream Fig. 9-6, p. 182

(c) Strip cutting Cut 1 Uncut year ago Dirt road Cut 3–10 years ago Figure 9.6: Major tree harvesting methods. Question: If you were cutting trees in a forest you owned, which method would you choose and why? Clear stream Fig. 9-6, p. 182

EVALUATING A CLEAR-CUT Company’s point of View 1. Less expensive – provide timber or pulp at a more competitive price 2. safer for workers 3. Company can choose which trees to plant – get better price for when the area is logged again in the future.

EVALUATING A CLEAR-CUT Ecological Point of View 1. Soil erosion and runoff into local streams increases – increasing growth of algae 2. Eroded soil forms sediment in streams, affecting spawning areas of fish. 3.Removal of vegetation on the ground exposes the soil, increasing the warming of the area in summer and cooling in winter Exposure also increases water loss from the soil.

EVALUATING A CLEAR-CUT Clear-cut creates completely different abiotic and biotic conditions in the area. Ecosystem must change – therefore the community must change. Loss in forest plants – loss of forest animals Ecotones are also created between the remaining forest and the newly cut area.

DEFORESTATION Is any removal of trees from the area of land. Deforestation affects the environment in many ways: 1. Erosion – tree roots hold soil in place during heavy rains 2. Nutrient Loss – nutrients are washed away with the rain instead of being absorbed by the trees Cont…

DEFORESTATION 3. Temperature Change – the ground will absorb more energy (albedo effect?) and affect organism functions 4. Carbon Cycle Change - no trees to take in CO2 and to make O2 5. Food Web Changes – less producers at the beginning of food chains 6. Habitat loss – nesting areas and ground cover disappears

What can help prevent erosion?

Techniques Modern techniques include - contour plowing - terracing - crop rotation - shelter belt

Ways of Preventing Erosion Prevent soil erosion by planting vegetation, trees, ground cover, shrubs and any other plants. The roots from these plants will help hold the soil in place. Soil will not be easily blown away by wind or washed away by the rain. Create windbreaks, which are Hedges or fences of trees designed to reduce erosion, especially wind erosion. Plant them on different plots of lands.

Ways of Preventing Erosion Part 2 Grow crops on farm lands. When land is not being used, use cover crops because they help prevent soil erosion by wind or rain. Beans are often used as cover crops. Apply mulch, which is; a protective covering of rotting vegetable matter spread to prevent soil erosion. The topsoil is will not be likely washed or blown away, when it’s covered by mulch.

Plants can help prevent erosion. Look at the roots on these grasses Plants can help prevent erosion! Look at the roots on these grasses. Roots help hold the soil in place so that it doesn’t wash away. Plant roots

Engineering Project You always dreamed of being a farmer, so you left the city and bought an old farm in Kentucky. However, the more you learn about farming, the more you regret purchasing this farm. It has laid barren for 5 years and the top soil is beginning to erode away. If you want to save your investment, you must act quickly. The bank has agreed to increase your loan, but every penny you spend, you must pay back with interest.

The picture below is your main field.

Design Criteria/ Constraint Matrix Designs Criteria and Constraints (Rate 0-3) Totals Last on Steep Land Protect Against Water Erosion Readily Available Cost Efficient A Ex: Mulch 1 2 3 9 B C D

Engineering project What is your question/ problem? What were some soil conservation methods you learned about today? (research) Which idea fits the constraints of your field the best? Write the steps you would have to take in order to save your field. Sketch your final design.

Evaluate Switch design plans with your table partner and evaluate their plan. List AT LEAST one thing they did well on. List AT LEAST one thing they could improve upon. (Focus on the design, procedure steps, and sketch.)

Refine Working with a group, refine your designs. You may combine them or choose one that you like best. You will now create a mini-poster with your design. Include a decision matrix, sketch, and reasoning. Imagine you have to present this to a stranger who knows nothing about soil erosion. Make sure your poster explains using text and graphics.