Chapter 14: Food & Soil Resources

1. Chapter 14: Food & Soil Resources

2. The three systems humans depend on for their food supply Croplands (77%) – land used for planting crops; vegetables, fruits, and grains Rangelands (16%)- Land used for grazing livestock; meat products Ocean fisheries (7%) - shellfish/fish (6% of protein in human diet)

3. Human Food Supply Fisheries Croplands Rangelands Major increase in food production post-1950 High-TechGear &Electronics FeedlotsFeed Pens Tractors Farm Equip. i n p u t Irrigation GrowthHormones Aquaculture CarefulBreeding FertilizersPesticides

4. Human Population Growth and Food Production 9 billion humans by 2054 More food than has been produced in last 10k yrs Is current technology capable? Environmental degradation? Pollution Water supply (irrigation) Overgrazing Overfishing Ecological services (matter; energy)

5. Lack of Diversity in Food 30,000 edible plant species 3 grain crops that provide “more than ½ of the calories people consume”. But 90% of all food only comes from 15 plants [esp. wheat, rice, corn] and 8 animals- [esp. beef, pork, chicken] Fish- 1% energy 6 % protein

6. Major Types of Agriculture Traditional subsistence (20%, 44% pop.) Low-input, human labor, "just enough" Shifting cultivation; nomadic livestock Traditional intensive Higher input, "more than enough" Plantation Monoculture cash crops (bananas, coffee, sugarcane, etc) Industrialized (high-input) 25% of all cropland, developed nations

7. Plantation agriculture Industrialized agriculture Nomadic herding Shifting cultivation Intensive traditional agriculture No agriculture Fig. 12.2, p. 263

8. The Green Revolution increased production of food per unit of area of cropland; planting monocultures, increase use of pesticides, water, fertilizers, etc. Since 1950 • Develop & plant monocultures (ie. corn) • Input fertilizer, pesticides, water • Multiple cropping on plot of land Since 1967 • Fast growing dwarf varieties of rice and wheat • More food on less land • Increase use of fossil fuels, fertilizers, pesticides, irrigation Age of Genetic Engineering • >2/3 of products on U.S. grocery store shelves contain ingredients from GE crops!

9. Green-Revolution- increasing global food production… selective breeding genetic engineering (GMO’s) high energy input (8% world oil) fertilizers, pesticides, water dwarf varieties- 3-5x yield multicropping (2-3/year) = = = Farm more land = Increase crop yield / land area High-yield monocultures High Input High intensity frequency of cropping

10. Monocultures Intensified agriculture meant monocultures, vast spreads of a single crop. This is economically efficient, but increases risk of catastrophic failure (“all eggs in one basket”). Wheat monoculture in Washington Figure 9.4a

11. Green revolution: Environmental impacts Intensification of agriculture causes environmental harm: Pollution from synthetic fertilizers Pollution from synthetic pesticides Water depleted for irrigation Fossil fuels used for heavy equipment However, without the green revolution, much more land would have been converted for agriculture, destroying forests, wetlands, and other ecosystems.

12. Second green revolution (developing countries) First green revolution (developed countries) Major International agricultural research centers and seed banks

13. Energy Use in Food Production:Industrial Agriculture(United States) Since1940’s: 2x production on the same amount of land Agribusiness- big companies and large family farms own 75% of US food production - 2% pop.= farmers; 9% pop.= involve in production - Agriculture provides18% US GNP; 19% jobs (private sect); 0.3% world's labor - 17% of world’s grain is produced in the US; ½ the world’s corn & soybean exports • Putting food on the table utilizes 17% of US commercial energy, mostly from oil • Food production uses 3 units of fossil fuel energy for 1 unit of food energy obtained. Units of energy take in to account the energy used to grow, store, process, pack, process, refrigerate, and cook • Plants involve > energy out than in; Livestock involve > energy in, than out.

14. Energy Use in Food Production: Traditional and Traditional Intensive • 20% of world food on 75% cultivated land • Most traditional farmers use INTERPLANTING - growing several crops on a single plot of land. Types of interplanting- • Polyvarietals - varieties of 1 crop • Intercropping - 2+ different on same plot (legumes/grain) • Agroforestry/alley cropping - crops/trees together • Polyculture - many plants maturing at different times on same plot Advantages include: < energy input, erosion/weather protection, pest/herbicides not needed

15. Intercropping Polyculture Polyvarietals Agroforestry

16. Soil Erosion and Degradation Causes: water, wind, and people • Land degradation- when natural or human induced processes reduce the future ability of land to support crops, livestock or wild species. (i.e. soil erosion due to flowing water or wind) • Erosion of topsoil leads to loss of soil fertility and increase sediment in nearby surface waters which can block sunlight, kill fish, and clog irrigation ditches, channels, etc.

17. Causes of soil degradation Most soil degradation is caused by: • livestock overgrazing • deforestation • cropland agriculture Figure 8.2

18. Types of soil erosion Splash erosion Rillerosion Gully erosion Sheet erosion Figure 8.11

19. Desertification A loss of more than 10% productivity due to: • Erosion • Soil compaction • Forest removal • Overgrazing • Drought • Salinization • Climate change • Depletion of water resources When severe, there is expansion of desert areas, or creation of new ones, e.g., the Middle East, formerly, “Fertile Crescent”.

21. The Dust Bowl Drought and degraded farmland produced the 1930s Dust Bowl. Storms brought dust from the U.S. Great Plains all the way to New York and Washington, and wrecked many lives. Figure 8.14

22. Desertification Consequences Causes Overgrazing Deforestation Erosion Salinization Soil compaction Natural climate change Worsening drought Famine Economic losses Lower living standards Environmental refugees

23. Preventing soil degradation Several farming strategies to prevent soil degradation: • Crop rotation • Contour farming • Intercropping • Terracing • Shelterbelts • Conservation tillage

24. Soil conservation As a result of the Dust Bowl, the U.S. Soil Conservation Act of 1935 and the Soil Conservation Service (SCS) were created. SCS:Local agents in conservation districtsworked with farmers to disseminate scientific knowledge and help them conserve their soil.

25. Crop rotation Alternating the crop planted (e.g., between corn and soybeans) can restore nutrients to soil and fight pests and disease. Figure 8.16a

26. Contour farming Planting along contour lines of slopes helps reduce erosion on hillsides. Figure 8.16b

27. Intercropping Mixing crops such as in strip cropping can provide nutrients and reduce erosion. Figure 8.16c

28. (c) Alley cropping

29. Terracing Cutting stairsteps or terraces is the only way to farm extremely steep hillsides without causing massive erosion. It is labor-intensive to create, but has been a mainstay for centuries in the Himalayas and the Andes.

30. Shelterbelts Rows of fast-growing trees around crop plantings provide windbreaks, reducing erosion by wind. Figure 8.16e

31. Conservation tillage Conservation tillage is not a solution for all crops everywhere. • It often requires more chemical herbicides (because weeds are not plowed under). • It often requires more fertilizer (because other plants compete with crops for nutrients). No-till and reduced-tillage farming leaves old crop residue on the ground instead of plowing it into soil. This covers the soil, keeping it in place. Here, corn grows up out of a “cover crop.” But legume cover crops can keep weeds at bay while nourishing soil, and green manures can be used as organic fertilizers. Figure 8.16f

32. 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

33. Central Case: No-Till Agriculture in Brazil Southern Brazil’s farmers were suffering falling yields, erosion, and pollution from agrichemicals. They turned to no-till farming, which bypasses plowing. Erosion was reduced, soils were enhanced, and yields rose greatly. No-till methods are spreading worldwide.

34. Irrigation The artificial provision of water to support agriculture 70% of all freshwater used by humans is used for irrigation. Irrigated land globally covers more area than all of Mexico and Central America combined. Irrigation has boosted productivity in many places … but too much can cause problems.

35. Waterlogging and salinization Overirrigation can raise the water table high enough to suffocate plant roots with waterlogging. Salinization(buildup of salts in surface soil layers) is a more widespread problem. Salt in soils decreases the osmotic potential of the soil so that plants can't take up water from it. The salts can also be directly toxic, but plant troubles usually result primarily from inability to take up water from salty soils Evaporation in arid areas draws water up through the soil, bringing salts with it. Irrigation causes repeated evaporation, bringing more salts up.

36. Solutions 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)

37. Global fertilizer usages Fertilizer use has risen dramatically in the past 50 years. Figure 8.19b

38. 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

39. Overgrazing When livestock eat too much plant cover on rangelands, impeding plant regrowth. The contrast between ungrazed and overgrazed land on either side of a fenceline can be striking. Figure 8.22

40. Overgrazing Overgrazing can set in motion a series of positive feedback loops. Figure 8.21

41. Global food production World agricultural production has risen faster than human population. Figure 9.1

42. Global food security However, the world still has 800 million hungry people, largely due to inadequate distribution. Considering soil degradation, can we count on food production continuing to rise? Global food security is a goal of scientists and policymakers worldwide.

43. Nutrition Undernourishment = too few calories (especially developing countries) Overnutrition= too many calories (especially developed world) Malnutrition = lack of nutritional requirements (causes numerous diseases, esp. in developing world) Figure 9.2

44. Food Production, Nutrition and Environmental Effects ~ 1 in 6 people in developing nations are chronically undernourished or malnourished Common nutritional deficiency diseases: Marasmus and Kwashiorkor M = diet low in calories and protein K = severe protein deficiency

45. Decreased resistance to disease High death rate for children Poverty Malnutrition Decreased ability to learn Decreased ability to work Shortened life expectancy Decreased energy Feedback loop Fig. 12.9, p. 269

46. Environmental effects of food production Biodiversity Loss Soil 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 Erosion Loss of fertility Salinization Waterlogging Desertification

47. Air Pollution Water Water waste Aquifer depletion Increased runoff and flooding from land cleared to grow crops Sediment pollution from erosion Fish kills from pesticide runoff Greenhouse gas emissions from fossil Fuel issue Other air pollutants from fossil fuel use Pollution from pesticide sprays 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

48. 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

49. Pesticide use Pesticide use is still rising sharply across the world, although growth has slowed in the U.S. 1 billion kg (2 billion lbs.) of pesticides are applied each year in the U.S. Figure 9.5

50. Biological control Synthetic chemicals can pollute and be health hazards. Biological control (biocontrol) avoids this. Biocontol entails battling pests and weeds with other organisms that are natural enemies of those pests and weeds. (“The enemy of my enemy is my friend.”)