Food & Soil

1. Food & Soil Chapter 14 & 16

2. Perennial crops • Return yearly • No need to prepare soil • Advantages-less labor; reduces soil erosion; deeper roots mean less need for irrigation; less pollution from chemical fertilizers & pesticides

3. Land Institute in Kansas • Experimenting with ecology approach to agriculture • Polyculture- perennial grasses, legumes, sunflowers, grain crops, & plants that provide natural insecticides

4. Food Providers • Croplands – grains • Rangelands – meat • Ocean fisheries

5. Most important crops • Wheat • Rice • Corn

6. Industrialized agriculture • High-input • Uses large amounts of fossil fuel energy, water, commercial fertilizers, pesticides • Monoculture

7. Plantation Agriculture • Form of industrialized • Tropical developing countries • Cash crops (bananas, coffee, soybeans, sugar cane, cocoa, vegetables) • Monoculture

8. Traditional Subsistence Ag • Uses human labor or draft animals • Produces enough crops or livestock for family

9. Traditional Intensive Ag • Increased input of human & draft labor, fertilizers, & water • Produces food for family & to sell for income

10. Green Revolution • Develop & plant monocultures- selectively bred or genetically engineered key crops (rice, wheat, corn) • Produce high yields by high inputs of fertilizers, pesticides, water • Multiple cropping- increase number of crops grown per year on a plot of land

11. 1st Green Revolution- high input approach 1950 – 1970 • 2nd Green Revolution- since 1967, fast-growing dwarf varieties of rice & wheat

12. More Food, Less Land • Saves large areas of forests, grasslands, wetlands, & easily eroded mountain terrain from being used to grow food

13. Agricultural Industry • Superfarms- big companies & larger family-owned farms control 75% of US food production • Production has doubled since 1950 • More efficient- input decreases, output increases • US farm products cost 1/3 less than in 1910 • Energy- 10 units / 1 unit of food on the table

14. Interplanting • Practice of growing several crops on the same plot http://www.endtimesreport.com/album.html

15. Polyvarietal Cultivation • Plot contains several varieties of same crop

16. Intercropping • 2 or more different crops at the same time on a plot

17. Agroforestry • Alley cropping • Crops & trees are grown together

18. Polyculture • Different plants maturing at various times are planted together

19. Advantages • Of low-input polyculture • Less need for fertilizer • Less need for water • Protection from erosion • Less need for insecticides • Less need for herbicides • Insurance against profit loss

20. Africa • Soil replenishment & crop growth • Plant corn & trees at start of growing season • Cut trees at start of 2nd growing season • Add phosphate rock • Plant leaves & stems (waste) of Mexican sunflower – provides nutrients

21. Soil Erosion • Movement of soil components (surface litter & topsoil) • Causes: • Farming, logging, construction, overgrazing, off-road vehicles, deliberate burning • Effects: • Loss of soil fertility • Sediment in surface water

22. Global – erodes 38% faster than topsoil is produced • US- 16% higher

23. Farm Act • Food Security Act 1985 • Subsidy for taking erodible land out of production • Replant with grass or trees for 10-15 years

24. Dust Bowl • Wind erosion • Crop failure • Extensive drought • Started soil conservation practices

25. Desertification • Conversion of usable land to desertlike land • 1/3 of all land • 70% of drylands • Prevention (or slowing)- reduce overgrazing, deforestation & destructive forms of planting, irrigation, & mining

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

27. Irrigation Issues • Salinization- accumulation of salts in upper soil layers from annual applications of irrigation water • Reduces yield on 1/5 of cropland • Waterlogging- saturation of soil with irrigation water • Water table rises closer to surface • Reduces yield on 1/10 of cropland

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

29. Soil Conservation • Using methods to reduce soil erosion & restore soil fertility • Conventional tillage farming- farmers plow, break up, then smooth soil for planting surface • Often leaves soil bare

30. Conservation tillage farming- disturbs soil as little as possible while planting crops • Minimum tillage- soil not disturbed over winter • No till- special planting machines inject seeds, fertilizers, & weed killers into thin slits in unplowed soil, cut is smoothed over

31. Figure 14-13 Trade-Offs Conservation Tillage Disadvantages Advantages 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 Reduces erosion Saves fuel Cuts costs Holds more soil water Reduces soil compaction Allows several crops per season Does not reduce crop yields Reduces CO2 release from soil

32. Reducing Soil Erosion • Terracing- cutting series of steps into a hillside • Retains water at each level = controls runoff

33. Control farming- plowing/planting crops across slope (instead of up & down) • Each row holds soil & slows water runoff • Strip cropping- plant alternating strips of a row crop (cotton/corn with grass/legume) • Cover crop traps soil = slows erosion & spread of pests/disease

34. Contour plowing & strip cropping

35. Alley cropping (agroforestry)- several crops plants in strips between trees & shrubs (used for fruit or fuel wood)

36. Windbreaks (shelter-belt)- tall row of trees surround plot

37. Land classification- identify easily erodible land • Suitable/unsuitable for cultivation

38. Fertilizers • Organic fertilizer- using plant/animal materials to restore nutrients • Commercial inorganic fertilizer- produced from minerals

39. Trade-Offs Inorganic Commercial Fertilizers Disadvantages Advantages 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% 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 (N2O) Runoff can overfertilize nearby lakes and kill fish Figure 14-15Page 286

40. Organic Fertilizers • Animal manure- dung & urine of cattle, horses, poultry, other farm animals • Adds organic nitrogen • Stimulates soil bacteria & fungi • Green manure- freshly cut or growing green vegetables plowed into soil • Increases organic matter & humus • Compost- formed when (oxygen &) microorganisms in soil break down organic matter (leaves, food wastes, paper, wood)

41. Spores of mushrooms- (puffballs & truffles) take in moisture & nutrients • One application lasts all year

42. Crop Rotation • Plant areas with nutrient-depleting crops then legumes the next year • Restores nutrients • Reduces erosion by keeping soil covered • Reduces crop losses to insects

43. Nutrition Problems • Chronic undernutrition- cannot grow or buy enough food to meet basic energy needs • Mental retardation • Stunted growth • Susceptible to infectious diseases (diarrhea, measles) • Malnutrition- results from deficiencies of protein & key nutrients

44. From Malnutrition • Marasmus- diet low in calories & protein • Nursing infants of malnourished mothers • Children who don’t get enough food after being weaned • Thin, shriveled (looks like a very old miniature starving person) • Effects can be reversed with balanced diet

45. Kwashiorkor- severe protein deficiency in infants & children (1-3) • New baby deprives them of breast milk • Diet changes to grain or sweet potatoes (enough calories, not enough protein) • Bloated belly, reddish-orange hair, discolored/puffy skin • Effects can be cured with balanced diet • EXCEPT- mental retardation & stunted growth • 825 million- 95% in developing countries • 5.5 million premature deaths

46. Reducing Deaths • Immunize children • Encourage breast feeding • Prevent dehydration (from diarrhea) • Prevent blindness in children (Vitamin A) • Family planning services • Increase education for women

47. Deficiencies • Vitamin A- blindness, death • Iron- anemia, fatigue, increased chances of infection, increased chance of dying in childbirth, infant- increased chances of death due to infection • Iodine- stunted growth, mental retardation, goiter (enlargement of thyroid gland that can lead to deafness)

48. Overnutrition • Food energy intakes exceed energy use & causes excess body fat • Harmful effects: • Lower life expectancy • Greater susceptibility to disease & illness • Lower productivity • Lower life quality • 2/3 of US adults are overweight • 1/3 obese

49. China’s Food Problems • Falling grain production • Rise in meat consumption • Large (potential) food supply deficit

50. Figure 14-19Page 292 Trade-Offs Genetically Modified Food and Crops Projected Advantages 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 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