1. Soils and agriculture

2. Soils  Origins  Importance  Maturity and Horizons  Variations with Climate and Biomes  Variations in Texture and Porosity  Origins  Importance  Maturity and Horizons  Variations with Climate and Biomes  Variations in Texture and Porosity

3. Soil isn’t dirt! Soil is a complex mixture covering most of Earth’s land surfaces Soil is a complex mixture covering most of Earth’s land surfaces –Eroded rock –Mineral nutrients –Decaying organic matter –Water –Air –Community of organisms Is the basis for life and food Is the basis for life and food

4. Soils have layers Soils have horizontal layers called Horizons Soils have horizontal layers called Horizons Top 2 layers teem with plant roots and complex food webs Top 2 layers teem with plant roots and complex food webs –O Horizon Surface litter layer Surface litter layer Freshly fallen partly decomposed leaves etc Freshly fallen partly decomposed leaves etc –A Horizon Topsoil: Most important layer for agricultural purposes Topsoil: Most important layer for agricultural purposes –Humus: partially decomposed organic matter –Holds water and nutrients taken up by plants –Inorganic particles –Decomposers (bacteria, fungi) breakdown organinic matter releasing nutrients usable by plants –Color: Dark = Nutrient rich, Light = Nutrient poor

5. Soils have layers Lower horizons contain most of a soil’s inorganic material (broken down rock) Lower horizons contain most of a soil’s inorganic material (broken down rock) –B horizon Subsoil Subsoil Varied mixture of sand, silt clay and gravel Varied mixture of sand, silt clay and gravel –C Horizon Parent material Parent material Lies on top of bedrock Lies on top of bedrock

6. Soil and hydrology Pore spaces in soil trap water and air needed by plant roots Pore spaces in soil trap water and air needed by plant roots –Infiltration: downward movement of water into spaces within the soil –Leaching: Dissolution of organic matter and nutrients in upper layers which carries these materials down to the lower layers

7. Soil texture and porosity Soil texture Soil texture –Determined by relative amounts of clay, silt, sand and gravel in the soil mixture Texture determines soil porosity and permeability Texture determines soil porosity and permeability –Porosity: The volume of pore space in a soil Larger particles = more pore space Larger particles = more pore space Smaller particles = less pore space Smaller particles = less pore space –Permeabilty: Rate at which water and air move from the top layers to the lower layers of soil

8. Soil Profiles in Different Biomes Fig. 4-27, p. 75 Why do we use grasslands for agricultural purposes?

9. To feed the world…. Conservation of matter Conservation of matter –Available resources limit agricultural production –Nutrients used by plants Nitrates: Protein and DNA Nitrates: Protein and DNA Phosphates: DNA, RNA, ATP Phosphates: DNA, RNA, ATP –Soil degraded as nutrients removed by harvest Conservation of Energy Conservation of Energy –Trophic level energy loss Vegetarian vs Carnivorous diets Vegetarian vs Carnivorous diets Green revolution Green revolution –Increase yield per acre –Monoculture –Intensive tillage = soil erosion –Requires Energy: Emissions and oil Energy: Emissions and oil Fertilizers and pesticides: Toxic pollution, soil salinization Fertilizers and pesticides: Toxic pollution, soil salinization Irrigation: Water rights and usage Irrigation: Water rights and usage

10. 2,000 1,500 1,000 500 0 Grain production (millions of tons) 1950196019701980199020002010 Total World Grain Production Year

11. 400 350 300 250 150 Per capita grain production (kilograms per person) 1950196019701980199020002010 World Grain Production per Capita 200 Year

12. Calories per day per person 3,700 3,500 3,300 3,100 2,900 2,700 2,500 2,300 2,100 19601970 1980 1990 200020102030 Year Developed countries World Developing countries

13. Figure 14-3 Page 276 Croplands Help maintain water flow and soil infiltration Provide partial erosion protection Can build soil organic matter Store atmospheric carbon Provide wildlife habitat for some species Ecological ServicesEconomic Services Food crops Fiber crops Crop genetic resources Jobs Natural Capital Croplands Ecological Services Economic Services Help maintain water flow and soil infiltration Provide partial erosion protection Can build soil organic matter Store atmospheric carbon Provide wildlife habitat for some species Food crops Fiber crops Crop genetic resources Jobs

14. Biodiversity Loss Loss and degradation of habitat from clearing grasslands and forests and draining wetland Fish kills from pesticide runoff Killing of wild predators to protect livestock Loss of genetic diversity from replacing thousands of wild crop strains with a few monoculture strains Soil Erosion Loss of fertility Salinization Waterlogging Desertification

15. Air Pollution Greenhouse gas emissions from fossil Fuel issue Other air pollutants from fossil fuel use Pollution from pesticide sprays Water Water waste Aquifer depletion Increased runoff and flooding from land cleared to grow crops Sediment pollution from erosion Fish kills from pesticide runoff Surface and groundwater pollution from pesticides and fertilizers Overfertilization of lakes and slow-moving rivers from runoff of nitrates and phosphates from fertilizers, livestock wastes, and food processing wastes

16. Human Health Nitrates in drinking water Pesticide residues in drinking water, food, and air Contamination of drinking and swimming water with disease organisms from livestock wastes Bacterial contamination of meat

17. 4%2%6%5% 17% of total commercial energy use CropsLivestockFood processingFood distribution and preparation Food production

18. Figure 14-10 Page 283 Consequences Causes Worsening drought Famine Economic losses Lower living standards Environmental refugees Overgrazing Deforestation Erosion Salinization Soil compaction Natural climate change

19. Figure 14-12 Page 283 Reduce irrigation Switch to salt- tolerant crops (such as barley, cotton, sugar beet) Prevention Flushing soil (expensive and wastes water) Not growing crops for 2-5 years Installing under- ground drainage systems (expensive) Cleanup Solutions Soil Salinization

20. Figure 14-13 Page 284 Reduces erosion Saves fuel Cuts costs Holds more soil water Reduces soil compaction Allows several crops per season Does not reduce crop yields Reduces CO 2 release from soil Can increase herbicide use for some crops Leaves stalks that can harbor crop pests and fungal diseases and increase pesticide use Requires investment in expensive equipment Disadvantages Advantages Trade-Offs Conservation Tillage

21. Figur e 14- 14a Page 285 (a) Terracing

22. Figur e 14- 14b Page 285 (b) Contour planting and strip cropping

23. Figur e 14- 14c Page 285 (c) Alley cropping

24. Figur e 14- 14d Page 285 (d) Windbreaks

25. Trade-Offs Inorganic Commercial Fertilizers Advantages Disadvantages Do not add humus to soil Reduce organic matter in soil Reduce ability of soil to hold water Lower oxygen content of soil Require large amounts of energy to produce, transport, and apply Release the greenhouse gas nitrous oxide (N 2 O) Runoff can overfertilize nearby lakes and kill fish Easy to transport Easy to store Easy to apply Inexpensive to produce Help feed one of every three people in the world Without commercial inorganic fertilizers, world food output could drop by 40% Figur e 14- 15 Page 286

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27. Table 23-1 Page 520 Table 23-1 Major Types of Pesticides Type Insecticides Chlorinated hydrocarbons Organophosphates Carbamates Botanicals Microbotanicals Examples DDT, aldrin, dieldrin, toxaphene, lindane, chlordane, methoxychlor, mirex Malathion, parathion, diazinon, TEPP, DDVP,mevinphos Aldicarb, carbaryl (Sevin), propoxur, maneb, zineb Rotenone, pyrethrum, and camphor extracted from plants, synthetic pyrethroids (variations of pyrethrum), rotenoids (variations of rotenone), and neonicotinoids (variations of nicotine) Various bacteria, fungi, protozoa Persistence High (2–15 years) Low to moderate (1–2 weeks), but some can last several years Low (days to weeks) Biologically Magnified? Yes No

28. Table 23-1 Page 520 Table 23-1 Major Types of Pesticides Type Herbicides Contact chemicals Systemic chemicals Soil sterilants Fungicides Various chemicals Fumigants Various chemicals Examples Atrazine, simazine, paraquat 2,4-D, 2,4,5-T, Silvex, diuron, daminozide (Alar), alachlor (Lasso), glyphosate (Roundup) Tribulan, diphenamid, dalapon, butylate Captan, pentachlorophenol, zeneb, methyl bromide, carbon bisulfide Carbon tetrachloride, ethylene dibromide, methyl bromide Persistence Low (days to weeks) Mostly low (days to weeks) Low (days) Most low (days) Mostly high Biologically Magnified? No Yes (for most)

29. Figur e 23- 4 Page 523 600 500 400 300 200 100 1950 Number of genetically resistant insect species Year Neonicotinoids (1995) Pyrethroids (1978) Carbamates (1972) Organophosphates (1965) DDT/cyclodienes (1946)

30. Figure 23-7 Page 528

31. MH JH MH JH MH Pupa Eggs Larva Black

32. Producing and eating meat Land use issues Land use issues –More land needed More land needed for grazing than grain production More land needed for grazing than grain production Acre of grain for human consumption feeds more than an acre used for grazing Acre of grain for human consumption feeds more than an acre used for grazing Land needed to grow forage AND raise animals: Housing, food storage and waste disposal Land needed to grow forage AND raise animals: Housing, food storage and waste disposal

33. Producing and eating meat Energy issues Energy issues –Eating at a lower trophic level More solar energy available to humans, less lost through trophic transfer More solar energy available to humans, less lost through trophic transfer –Storage of grain less energetically expensive than processing and storing meat Transport, slaughter and refrigeration Transport, slaughter and refrigeration –Energy costs associated with meat production Producing grain for livestock Producing grain for livestock –Fertilizers, irrigation, pesticides, farm machinery Animal waste management Animal waste management –Pumping, treatment, transport, disposal Animal care and round up of free range livestock Animal care and round up of free range livestock

34. Problems and consequences Problem Problem –Overgrazing –Water Pollution Slaughter Slaughter Wastes Wastes Riparian grazing Riparian grazing –Land use Fencing, deforestation Fencing, deforestation –Uses more water Consequence Consequence –Desertification, erosion nutrient loss –Groundwater contamination, ^BOD, Eutrophication, etc –Habitat loss & fragmentation, decreased biodiversity –Water shortages / depletion

36. Eating less meat: Pro and Con Advantages Advantages –Reduced risk of disease Cholesterol Cholesterol –Clogged arteries –Hypertension –Heart disease –Reduced chemical exposure Hormones Hormones Steroids Steroids Antibiotics Antibiotics Pesticides (Biomag!) Pesticides (Biomag!) –Reduced exposure to disease Mad Cow Mad Cow Salmonella/ E. coli Salmonella/ E. coli Parasites Parasites Disadvantages Disadvantages –Meat an excellent source of protein Essential amino acids –Rice and Beans! Difficult to get enough protein without meat –Nutritional deficiencies Kwashikor: Protein Blindness: Vit. A Pollegra: Vit. B Anemia: Iron Inadequate essential fats balance

37. Spotter airplane Fish farming in cage Trawler fishing Purse-seine fishing sonar trawl flap trawl lines trawl bag Long line fishing lines with hooks Drift-net fishing fish caught by gills floatbuoy fish school

38. 100 80 60 40 20 0 195019701960200019901980 Catch (millions of metric tons) Year Total World Fish Catch

39. 25 20 15 10 5 0 195019701960200019901980 Per capita catch (kilograms per person) Year World Fish Catch Per Person

40. 800 600 400 200 0 19601970198019902000 Year 80 70 60 50 40 30 20 Harvest (thousands of metric tons) Abundance (kilograms/tow) Abundance Harvest 10

41. Highly efficient High yield in small volume of water Increased yields through cross- breeding and genetic engineering Can reduce over- harvesting of conventional fisheries Little use of fuel Profit not tied to price of oil High profits Advantages Large inputs of land, feed, And water needed Produces large and concentrated outputs of waste Destroys mangrove forests Increased grain production needed to feed some species Fish can be killed by pesticide runoff from nearby cropland Dense populations vulnerable to disease Tanks too contaminated to use after about 5 years Disadvantages Trade-Offs Aquaculture

42. What are GMOs and how are they produced Online activities

43. Projected Disadvantages Need less fertilizer Need less water More resistant to insects, plant disease, frost, and drought Faster growth Can grow in slightly salty soils Less spoilage Better flavor Less use of conventional pesticides Tolerate higher levels of pesticide use Higher yields Projected Advantages Trade-Offs Genetically Modified Food and Crops Irreversible and unpredictable genetic and ecological effects Harmful toxins in food From possible plant cell Mutations New allergens in food Lower nutrition Increased evolution of Pesticide-resistant Insects and plant disease Creation of herbicide- Resistant weeds Harm beneficial insects Lower genetic diversity