1. The Soil Texture Triangle Creates classes which break the distribution of particle sizes (soil textures) into 12 categories: clay, sandy clay, silty clay, sandy clay loam, clay loam, silty clay loam, sand, loamy sand, sandy loam, loam, silt loam, silt.

2. To Use: 1.Place the edge of a ruler at the point along the base of the triangle that represents the percent of sand in your sample. Position the ruler on the line that slants in the direction that the numbers are facing for percent sand. 2.Place the edge of a second ruler at the point along the right side of the triangle. Position the ruler on the line which slants in the direction that the numbers are facing for percent silt.

3. To Use: 3.Place the point of a pencil at the point where the two rulers meet. Place the top edge of one of the rulers on the mark, and hold the ruler parallel to the horizontal lines. The number on the left should be the percent of clay in the sample. Note: The sum of the percent of sand, silt, and clay should add up to 100. 3.The descriptive name of the soil sample (textural class) is written in the shaded area where the mark is located. If the mark should fall directly on a line between two descriptions, record both names.

4. An additional Soil Texture Triangle Practice Worksheet is available online.

5. Soil Degradation The breakdown of our most important resource. Wednesday, November 18 th, 2015

6. Soil: The Final Frontier Soil is a vital part of the natural environment. –Habitat It controls the flow of water and chemical substances between the atmosphere and the earth Acts as both a source and store for gases (like O and CO 2 ) in the atmosphere.

7. Soils not only reflect natural processes but also record human activities both at present and in the past. –They are therefore part of our cultural heritage. –The modification of soils for agriculture and the burial of archaeological remains are good examples of this.

8. What would we do without it?! Soil helps to provide much of the food that humans consume. –Only 25% of the Earth’s surface is made up of soil and only 10% of that soil can be used to grow food. Without it, we cannot support primary producers.

9. World Soil Conditions Soils are becoming degraded in many regions.

10. Major Causes of Soil Degradation Overgrazing 34% Deforestation 30% Cropland Agriculture 28% Other Causes 8%

11. Erosion and Deposition Erosion = removal of material from one place and its transport elsewhere (by wind/water) Deposition = arrival of eroded material at a new location –These processes are natural, and can build up fertile soil. –But where artificially sped up, they are a big problem for farming.

12. Erosion is commonly caused by: Overcultivating, too much plowing, poor planning Overgrazing rangeland with livestock Deforestation, especially on slopes

13. Deforestation is the removal of trees. –Without trees to stabilize the soil, it erodes.

14. Erosion from flooding Floodplains and tropical rain forests are areas where there is a lot of erosion. –Most concerns about erosion are related to accelerated erosion, where the natural rate has been significantly increased mostly by human activity

15. Soil Exhaustion Agricultural systems disrupt natural mineral cycling. –The soil may become mineral deficient and lose fertility. –Plants need minerals to grow and thrive such as nitrates, phosphates and sulfates.

16. Desertification Desertification is the expansion of dry lands due to poor agricultural practices, improper soil moisture management, salinization and erosion, forest removal, and climate change. –Overuse of agricultural lands is the cause. –10% of the world’s land has been desertified. –25% is at risk. –In Mali, the Sahara desert has expanded more than 650 km in less than 20 years.

18. Desertification A loss of more than 10% productivity due to: Erosion Soil compaction Forest removal Overgrazing Drought Salinization Climate change Depletion of water resources etc.

20. Soil degradation on drylands is caused mostly by erosion

22. Chemical Problems Chemical emissions: Industrial processes and vehicles release toxic substances which are heavier than air and settle on the soil. Toxic Seepage & Chemical contamination: improperly disposed chemicals seep into soil

23. Pesticides that are applied to fields can also destroy beneficial organisms in the soil. –Bacteria that fix nitrogen, organisms that break down soil (worms) –Bioaccumulation causes the concentrations of these pesticides to increase up the food chain.

24. Salinization Salinization is a gradual increase in salt (ionic compounds) in soil. –Irrigation in areas where the bedrock contains high salt levels will cause these aqueous salts to be brought to the surface –Irrigation water contains dissolved salts when evaporates, leave behind in soil Leaching

25. Desalination Desalination is used to remove ions from water. –The Middle East has the least amount of freshwater than any other area on the planet and desalination is used to provide freshwater for agricultural and household purposes. This prevents salinization of the soil through agriculture.

26. Soil Conservation Techniques that can be applied before a parcel of land is prepared for agricultural land use. Starts with the identification of areas that should not be planted. Considerations to be included are slope, soil type, existing waterways, critical endemic plant and animal habitat.

27. Prevention Methods Conservation tillage –Residues from previous year’s crops are left in place to prevent soil erosion Crop rotation –Planting a series of different crops in the same field over a period of years

28. Contour plowing –Plowing around hill instead of up/down Strip cropping –Alternating strips of different crops along natural contours Terracing –Creating terraces on steep slopes to prevent erosion

29. Preserving Soil Fertility Organic fertilizers –Animal manure, crop residue, bone meal & compost –Nutrient available to plants only as material decomposes Inorganic fertilizers –Manufactured from chemical compounds –Soluble Fast acting, short lasting Mobile: Easily leach and pollute groundwater

30. Soil Reclamation Two steps 1.Stabilize land to prevent further erosion 2.Restoring soil to former fertility Best way to do this is shelterbelts –Row of trees planted to reduce wind erosion

31. Soil Conservation Act 1935 –Authorized formation of Soil Conservation Service, now called Natural Resources Conservation Service (NRCS) –Assess soil damage and develop policies to improve soil Food Security Act (Farm Bill) 1985 –Farmers with highly erodible soil had to change their farming practices –Instituted Conservation Reserve Program Pays farmers to stop farming highly erodible land Soil Conservation Policies