Land resources
- 1. Lokhesh Mithuna Maran Mogan Prasad Mohamed Abbas Nandhakumar Nandhini Priyanka E.V.S Project B.Arch (1st year) Section ‘B’
- 8. Soil, a limited resource we depend upon, but take for granted
- 9. Soil Erosion What causes soil erosion? How serious of a problem is it? Good news and bad news from the U.S. What is desertification? How do salts degrade the soil?
- 10. CAUSES OF SOIL EROSION Wind WHY CARE about Water #1 soil erosion? People
- 12. Impacts of Soil Erosion Loss of soil fertility Sediment runoff causes problems in surface water (pollution, clog ditches, boat channels, reservoirs) #1 source of U.S. water pollution Renewable only on LONG timeframes (200-1,000yrs. for 1 inch)
- 13. Soil Erosion On Ag. land in U.S. today, soil is eroding 16 times faster than it is created
- 14. Global Soil Erosion Areas of serious concern Areas of some concern Stable or nonvegetative areas Fig. 14-7 p. 280
- 15. Causes of Desertification Overgrazing Deforestation Erosion Salinization Soil Compaction Natural Climate Change
- 16. World Desertification Fig. 14-9 p. 282
- 17. Desertification: causes and consequences. •Occurring on 1/3 of world’s land
- 18. SALINIZATION 1. Irrigation water contains small amounts of dissolved salts 2. Evaporation and transpiration leave salts behind 3. Salt builds up on soil
- 20. Reducing and Cleaning Up Salinization Reduce irrigation Switch to salt-tolerant crops Flush soils Not growing crops for 2-5 years Install underground drainage
- 21. Soil Degradation on Irrigated Land Salinization Evaporation Evaporation Transpiration Waterlogging 1. Precipitation and irrigation water percolate downward 2. Water table rises Waterlogging 3. Bad for roots Less permeable clay layer Fig. 14-11 p. 283
- 24. What controls soil productivity? Water -infiltration, drainage, storage Nutrients/toxins (12/17) Gas Exchange -CO2 out, O2 in Strength/rooting volume Waste Disposal Seed/seedling nursery
- 25. Where is the best soil?
- 26. Where are the productive soils? We see what we know. The more we know, the more options we realize we have w/ the world’s soils.
- 27. What are some threats? Finite arable land: 1.1 billion hectares 1961 0.32 ha/p; today 0.15 ha/p; 2050 0.12 ha/p Erosion – today 12-40 Mg/ha 30% agricultural lands irreversibly damaged. Desertification – e.g., 27% China affected w/ new 2500 km2/yr. Salinization- affects 20% of world’s 250+ million hectares of irrigated lands. Contamination w/ heavy metals. Urbanization and other competing uses. Problematic off-site issues & competing uses.
- 28. Threats? Think little things. Compaction or loss of porosity. Loss soil organic matter. Loss CEC other buffering potential. Doolittle Prairie – e.g., 10% reduction in pore volume = 152 m3/ha = 2200 ft3/ac -less gas exchange, water storage, root volume; poorer nursery. -water quality & quantity, air quality
- 29. Soil Conservation What is soil conservation and how does it work? What are some methods for reducing soil erosion? Inorganic versus organic fertilizers
- 30. Soil Conservation Involves many ways of reducing soil erosion and restoring fertility to soil.
- 31. Conventional Tillage Farmers plow the land and then break up and smoothes soil to make a planting surface Leaves soil vulnerable to erosion Midwest tillage often down in fall (winter bare)
- 32. Conservation Tillage Disturbing the soil as little as possible while planting crop Not tilling over winter Planting without disturbing soil Special equipment “inject” soil with seed, fertilizer etc. In 2003 45% of U.S. farms
- 37. Contour planting Planting crops in rows across the slope Strip Cropping Cover Crops: can be planted Alternating right after harvest to hold onto crops from soil during winter row crops and crops that
- 39. Alley Cropping: several cops planted together in rows (alleys) Increases shade (less water) Provide windbreaks
- 40. Windbreaks
- 41. SOIL RESTORATION Organic fertilizer Animal manure Compost Crop rotation Commercial inorganic fertilizer
- 42. Organic Fertilizer Has decreased in the U.S. due in part because most farmers no longer raise livestock and it costs too much to transport Poop Factory and Phillies Soil Inorganic fertilizers have taken off
- 43. Inorganic Fertilizers Nitrogen, Phosphorous, Potassium Grown in usage worldwide Credited with increasing crop yields (1/4 of world crops) W/o could only feed 2-3 billion people Many problems associated (see next slide)
- 44. “Conservation is a state of harmony between men and land.” - Ibid. “What greater grief than the loss of one's native land.” -Euripides “The land belongs to the future” -Willa Cather