1. SOIL LAB: Land Resources and Management

2. US land area: 9,161,966 km 2 3,537,454.85 square miles US arable land: 1,650,070 km 2 637,095,589 square miles US irrigated land: 223,850 km 2 86,429 square miles Water used for irrigation per year: 195.57 km 3 = 51,664,128,300,000 gallons Land Resource Management– Some Numbers

3. Images courtesy Dr. Sam Atkinson & UNT Remote Sensing Image Library Denton County Population aerial pictures… Circa 2004 Circa 1984

4. Urban Sprawl Urban sprawl, also known as suburban sprawl, is the spreading out of a city and its suburbs over rural land at the fringe of an urban area. Residents of sprawling neighborhoods tend to live in single-family homes and commute by car.

5. Urban Sprawl Low population density is an indicator of sprawl. Urban planners emphasize the qualitative aspects of sprawl such as the lack of transportation options and pedestrian friendly neighborhoods. Conservationists tend to focus on the actual amount of land that has been urbanized by sprawl

6. Forest Concepts 1/5 th of world covered by forest (depending on how you define a forest) Clear Cutting- taking of all trees Seed-Tree Cutting- leave the mature Shelterwood Cutting- harvest mature trees over 2 or 3 years Selective Cutting- only a few trees taken every few years.

7. Resource Management Forests cut down for Agriculture, Development.- 38% of arable land During 19 th Century 25 million acres of wetlands were turned into farmland. Pastureland for grazing livestock uses ¼ of the Earth’s land surface.

8. Soil Formation Climate- warmer wetter ones speed it up Organisms- more decomposers more soil formation Topographic relief- mountains and valleys have different exposure to sun, water, wind.

9. Soil Formation Parent material – what type of bedrock is below the topsoil. Time – in general we won’t see the formation of new soil in our lifetime. (90 years is just not long enough!)

10. Soil Type of Mineral Particle Size Range Sand 2.0 - 0.06 millimeters Silt 0.06 - 0.002 millimeters Clay less than 0.002 millimeters

11. Soil Triangle We used the pyramid to find out what type of soil we had. All soils are made up of sand, soil, and clay – typical percents are 40% sand, 40% silt and 20% clay.

12. Soil Horizons Eluviation Movement of humus, chemical substances, and mineral particles from the upper layers of a soil to lower layers by the downward movement of water through the soil profile.

13. Soil Horizons Illuviation: Deposition of humus, chemical substances, and fine mineral particles in the lower layers of a soil from upper layers because of the downward movement of water through the soil profile.

14. Soil

15. Soil Nutrients Plants need nutrients to grow Levels of Nitrogen (N), Phosphorous (P) and Potassium (K) are important for excellent crop growth Farmers add fertilizer to the soil to increase the levels of Nitrogen, Phosphorous and Potassium

16. Soil Erosion Many places are experiencing desertification because of over plowing from monoculture Erosion can be natural – wind and water but it is accelerated by humans in our over tilling/plowing. No-tilling, terracing, drip ground irrigation and polyculture farming will slow down erosion.

17. We are dependant on soil Soil erosion vs. formation is a losing battle at the present because soil formation takes a LONG time to renew! Not all soils are equal for agriculture There is a great deal of variation in soils Take Home Message