Soil Conservation

1. Soil Conservation

2. What should you know by the end • Why is soil conservation important? • What caused the Great Dust Bowl? • What steps can we take to mitigate soil erosion? • What steps can we take to prevent soil from losing its fertility?

3. Introduction • Prairie soil = very fertile • Rich in humus because of the tall grass • Sod=thick mass of tough roots at the surface of the soil. • Sod keeps soil in place and holds onto moisture. • Prairies cover Iowa, Illinois, Kansas, Nebraska, and North and South Dakota. • Farms growing crops such as corn, soybeans, and wheat have replaced prairies.

4. The Value of Soil • Natural resource=anything in the environment that humans use. • Earth’s natural resources? Timber, minerals, oil, air, water, etc… • Soil is one of Earth’s most valuable natural resources, Why? • Plants depend on soil to live and grow. • Humans and animals depend on plants-or on other animals that depend on plants-for food. • Fertile soil is in limited supply = not much land for farming. • Takes a long time for soil to form. Why? – Talk to partner

5. Soil Damage and Loss • Human activities and changes in the environment can affect the soil. • The value of soil is reduced when soil loses its fertility and when topsoil is lost due to erosion.

6. Loss of Fertility • Soil that has lost its fertility is said to be exhausted. • Soil loss occurred in the South in the late 1800’s. • Soils in which only cotton had been grown were exhausted. • George Washington Carver developed new crops and farming methods that helped restore soil fertility in the south. • Peanuts were used to help make the soil fertile again. • Peanut plants are legumes. • Legumes have small lumps on their roots that contain nitrogen-fixing bacteria. • Nitrogen is an important nutrient for plants.

7. Loss of Topsoil • Whenever soil is exposed, water and wind can quickly erode it. • Plant cover can protect soil from erosion. • Plants break the force of falling rain, and plant roots hold the soil together. • Wind is another cause of soil loss. • Wind erosion can occur in areas with dry conditions.

10. The Dust Bowl • Great Plains = farmers settled there because of available fertile soil. • Region has 8-year drought 1931-1939. • Plowing removed the grass from the Great Plains and exposed the soil. • In times of drought, the topsoil dried out and turned to dust and blew away.

12. The Dust Bowl • By 1930, almost all of the Great Plains had been turned into farms or ranches. • Long drought turned the soil to dust. • The wind blew the soil east in great, black clouds • Dust Bowl ruined farmland in parts of the Great Plains. • Dust Bowl helped people realize the value of soil. • Farmers adopted new methods to help save soil. • Dust Bowl occurred during the Great Depression

16. Soil Conservation • Since the Dust Bowl, farmers have adopted modern methods of soil conservation • Soil conservation = management of soil to prevent its destruction. • Soil can be conserved by: • Contour plowing • Conservation plowing • Crop rotation

17. Contour Plowing • Contour plowing=farmers plow their fields along the curves of a slope. • This helps slow the runoff of excess rainfall and prevents it from washing the soil away. • http://www.teachertube.com/view_video.php?viewkey=06d988f6f73518b7ab35

18. Conservation Plowing • In conservation plowing, farmers disturb the soil and its plant cover as little as possible. • Dead weeds and stalks of the previous year’s crop are left in the ground to help return soil nutrients, retain moisture, and hold soil in place. • Also called: low-till or no-till plowing.

19. Crop Rotation • Crop rotation-a farmer plants different crops in a field each year. • Different types of plants absorb different amounts of nutrients from the soil. • Corn and cotton-absorb large amounts of nutrients. • Year after planting these crops, farmer plants crops that use fewer nutrients, such as oats, barley, or rye. • The year after that the farmer sows legumes such as alfalfa or beans to restore the nutrient supply.

20. Why is soil conservation important? • Soil provides the nutrients need to grow crops and plants • Plants depend on soil to live and grow • Humans and animals depend on plants to live • Limited supply • Soil takes along time to create

21. What caused the Great Dust Bowl? • Plowing removed the grass • Drought occurred, turning soil into dust

22. What steps can we take to mitigate soil erosion? • Cover landscape with plants, roots hold soil in place • Plant trees to break up wind • Contour plowing • Conservation plowing • (Stalks other residue left on field prevent wind and water from eroding soil

23. What step can we take to prevent soil from losing its fertility? • Crop rotation • Year 1 Corn ( Uses lots of nutrients in soil) • Year 2 oats , barley, rye ( uses less nutrients) • Year 3 the legumes (Peanuts,, alfalfa, beans - add nutrients back to soil) • Conservation plowing • (Stalks other residue left on field to decompose and add nutrients back to soil)