2 The three systems humans depend on for their food supply Croplands (77%) – land used for planting crops; vegetables, fruits, and grainsRangelands (16%)- Land used for grazing livestock; meat productsOcean fisheries (7%) - shellfish/fish (6% of protein in human diet)
4 Human Population Growth and Food Production 9 billion humans by 2054More food than has been produced in last 10k yrsIs current technology capable?Environmental degradation?PollutionWater supply (irrigation)OvergrazingOverfishingEcological services (matter; energy)
5 Lack of Diversity in Food 30,000 edibleplant species3 grain crops that provide “more than ½ of the calories people consume”.But 90% of all food only comes from15 plants [esp. wheat, rice, corn] and8 animals- [esp. beef, pork, chicken]Fish-1% energy6 % protein
6 Major Types of Agriculture Traditional subsistence (20%, 44% pop.)Low-input, human labor, "just enough"Shifting cultivation; nomadic livestockTraditional intensiveHigher input, "more than enough"PlantationMonoculture cash crops (bananas, coffee, sugarcane, etc)Industrialized (high-input)25% of all cropland, developed nations
7 Industrialized agriculture Shifting cultivationPlantation agricultureNomadic herdingIntensive traditional agricultureNo agricultureFig. 12.2, p. 263
8 The Green Revolutionincreased production of food per unit of area of cropland; planting monocultures, increase use of pesticides, water, fertilizers, etc.Since 1950Develop & plant monocultures (ie. corn)Input fertilizer, pesticides, waterMultiple cropping on plot of landSince 1967Fast growing dwarf varieties of rice and wheatMore food on less landIncrease use of fossil fuels, fertilizers, pesticides, irrigationAge 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… Farm more land =Increase crop yield / land areaHigh-yieldmonocultures=selective breedinggenetic engineering (GMO’s)High Input=high energy input (8% world oil)fertilizers, pesticides, waterHigh intensityfrequency ofcropping=dwarf varieties- 3-5x yieldmulticropping (2-3/year)
10 Wheat monoculture in Washington MonoculturesIntensified 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 WashingtonFigure 9.4a
11 Green revolution: Environmental impacts Intensification of agriculture causes environmental harm:Pollution from synthetic fertilizersPollution from synthetic pesticidesWater depleted for irrigationFossil fuels used for heavy equipmentHowever, without the green revolution, much more land would have been converted for agriculture, destroying forests, wetlands, and other ecosystems.
12 First green revolution (developed countries) Second green revolution (developing countries)Major International agriculturalresearch centers and seed banks
13 Energy Use in Food Production: Industrial Agriculture (United States) Since1940’s: 2x production on the same amount of landAgribusiness- 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 exportsPutting food on the table utilizes 17% of US commercial energy, mostly from oilFood 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 cookPlants 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 landMost traditional farmers use INTERPLANTING - growing several crops on a single plot of land.Types of interplanting-Polyvarietals - varieties of 1 cropIntercropping - 2+ different on same plot (legumes/grain)Agroforestry/alley cropping - crops/trees togetherPolyculture - many plants maturing at different times on same plotAdvantages include: < energy input, erosion/weather protection, pest/herbicides not needed
16 Soil Erosion and Degradation Causes: water, wind, and peopleLand 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 agricultureFigure 8.2
19 Desertification A loss of more than 10% productivity due to: • Erosion• Soil compaction• Forest removal• Overgrazing• Drought• Salinization• Climate change• Depletion of water resourcesWhen severe, there is expansion of desert areas, or creation of new ones, e.g., the Middle East, formerly, “Fertile Crescent”.
23 Preventing soil degradation Several farming strategies to prevent soil degradation:• Crop rotation• Contour farming• Intercropping• Terracing• Shelterbelts• Conservation tillage
24 Soil conservationAs 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 districts worked with farmers to disseminate scientific knowledge and help them conserve their soil.
25 Crop rotationAlternating the crop planted (e.g., between corn and soybeans) can restore nutrients to soil and fight pests and disease.Figure 8.16a
26 Contour farmingPlanting along contour lines of slopes helps reduce erosion on hillsides.Figure 8.16b
27 IntercroppingMixing crops such as in strip cropping can provide nutrients and reduce erosion.Figure 8.16c
29 TerracingCutting 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 ShelterbeltsRows of fast-growing trees around crop plantings provide windbreaks, reducing erosion by wind.Figure 8.16e
31 Conservation tillageConservation 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 Reduces erosionSaves fuelCuts costsHolds more soilwaterReduces soilcompactionAllows several cropsper seasonDoes not reducecrop yieldsReduces CO2release from soilCan increaseherbicide use forsome cropsLeaves stalks thatcan harbor croppests and fungaldiseases andincrease pesticideuseRequiresinvestmentin expensiveequipmentDisadvantagesAdvantagesTrade-OffsConservation Tillage
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 soilsEvaporation in arid areas draws water up through the soil, bringing salts with it. Irrigation causes repeated evaporation, bringing more salts up.
37 Global fertilizer usages Fertilizer use has risen dramatically in the past 50 years.Figure 8.19b
38 Inorganic Commercial Fertilizers Trade-OffsInorganic Commercial FertilizersAdvantagesDisadvantagesDo not add humus to soilReduce organic matterin soilReduce ability of soil tohold waterLower oxygen content ofsoilRequire large amounts ofenergy to produce,transport, and applyRelease the greenhousegas nitrous oxide (N2O)Runoff can overfertilizenearby lakes and kill fishEasy to transportEasy to storeEasy to applyInexpensive to produceHelp feed one of everythree people in theworldWithout commercialinorganic fertilizers,world food output coulddrop by 40%
39 OvergrazingWhen 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 OvergrazingOvergrazing 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 securityHowever, 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 (causes numerous diseases, esp. in developing world) 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 malnourishedCommon nutritional deficiency diseases:Marasmus and KwashiorkorM = diet low in calories and proteinK = severe protein deficiency
45 Feedback loop Poverty Malnutrition Decreased resistance to disease High deathrate forchildrenenergyabilityto learnto workShortenedlifeexpectancyFeedback loopFig. 12.9, p. 269
46 Environmental effects of food production Biodiversity LossLoss and degradation of habitat fromclearing grasslands and forests anddraining wetlandFish kills from pesticide runoffKilling of wild predators to protectlivestockLoss of genetic diversity fromreplacing thousands of wild cropstrains with a few monoculture strainsSoilErosionLoss of fertilitySalinizationWaterloggingDesertification
47 Air Pollution Water Greenhouse gas emissions from fossil Fuel issue Other air pollutants from fossil fuel usePollution from pesticide spraysWaterWater wasteAquifer depletionIncreased runoff andflooding from land clearedto grow cropsSediment pollution fromerosionFish kills from pesticiderunoffSurface and groundwaterpollution from pesticidesand fertilizersOverfertilization of lakesand slow-moving riversfrom runoff of nitratesand phosphates fromfertilizers, livestockwastes, and foodprocessing wastes
48 Human Health Nitrates in drinking water Pesticide residues in drinking water,food, and airContamination of drinking andswimming water with diseaseorganisms from livestock wastesBacterial contamination of meat
49 Pesticide usePesticide 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 controlSynthetic 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.”)
51 Biological control Biocontrol has had success stories. Bacillus thuringiensis (Bt) = soil bacterium that kills many insects. In many cases, seemingly safe and effective.Cactus moth, Cactoblastis cactorum (above), was used to wipe out invasive prickly pear cactus in Australia.Figure 9.7
52 But biocontrol is risky Most biocontrol agents are introduced from elsewhere.Some may turn invasive and become pests themselves!Cactus moths brought to the Caribbean jumped to Florida, are eating native cacti, and spreading.Wasps and flies brought to Hawaii to control crop pests are parasitizing native caterpillars in wilderness areas.
53 Integrated pest management (IPM) Combines biocontrol, chemical, and other methodsMay involve:• Biocontrol• Pesticides• Close population monitoring• Habitat modification• Crop rotation• Transgenic crops• Alternative tillage• Mechanical pest removal
54 Genetic modification of food Manipulating and engineering genetic material in the lab may represent the best hope for increasing agricultural production further without destroying more natural lands.But many people remain uneasy about genetically engineering crop plants and other organisms.
55 Some GM foods Golden rice: Enriched with vitamin A. But too much hype? FlavrSavr tomato: Better taste?But pulled from market.Ice-minus strawberries: Frost-resistant bacteria sprayed on.Images alarmed public.Bt crops: Widely used on U.S. crops.But ecological concerns?Figure 9.12
57 Scientific concerns about GM organisms Are there health risks for people?Can transgenes escape into wild plants, pollute ecosystems, harm organisms?Can pests evolve resistance to GM crops just as they can to pesticides?Can transgenes jump from crops to weeds and make them into “superweeds”?Can transgenes get into traditional native crop races and ruin their integrity?
58 Socioeconomic and political concerns about GM products Should scientists and corporations be “tinkering with” our food supply?Are biotech corporations testing their products adequately, and is outside oversight adequate?Should large multinational corporations exercise power over global agriculture and small farmers?
59 Europe vs. AmericaEurope: has followed precautionary principle in approach to GM foods. Governments have listened to popular opposition among their citizens.U.S.: GM foods were introduced and accepted with relatively little public debate.Relations over agricultural trade have been uneasy, and it remains to be seen whether Europe will accept more GM foods from the U.S.
60 Genetically Modified Food and Crops ProjectedDisadvantagesNeed less fertilizerNeed less waterMore resistant to insects,plant disease, frost, anddroughtFaster growthCan grow in slightly saltysoilsLess spoilageBetter flavorLess use of conventionalpesticidesTolerate higher levels ofpesticide useHigher yieldsAdvantagesTrade-OffsGenetically Modified Food and CropsIrreversible andunpredictable geneticand ecological effectsHarmful toxins in foodFrom possible plant cellMutationsNew allergens in foodLower nutritionIncreased evolution ofPesticide-resistantInsects and plantdiseaseCreation of herbicide-Resistant weedsHarm beneficial insectsLower genetic diversity
61 Preserving crop diversity Native cultivars of crops are important to preserve, in case we need their genes to overcome future pests or pathogens.Diversity of cultivars has been rapidly disappearing from all crops throughout the world.
62 Seed banks preserve seeds, crop varieties Seed banks are living museums of crop diversity, saving collections of seeds and growing them into plants every few years to renew the collection.Careful hand pollination helps ensure plants of one type do not interbreed with plants of another.Figure 9.14
63 Animal agriculture: Livestock and poultry Consumption of meat has risen faster than population over the past several decades.Figure 9.15
64 Feedlot agricultureIncreased meat consumption has led to animals being raised in feedlots (factory farms), huge pens that deliver energy-rich food to animals housed at extremely high densities.Figure 9.16
65 Feed lotsMore production of livestock in smaller, condensed spaces; Produce more using less space and energyIncreases need for antibiotics due to enclosed spaces; leads to issues of cruelty to animalsHormones given to produce larger animals for more meat= more $!
66 Feedlot agriculture: Environmental impacts Immense amount of waste produced, polluting air and water nearbyIntense usage of chemicals (antibiotics, steroids, hormones), some of which persist in environmentHowever, if all these animals were grazing on rangeland, how much more natural land would be converted for agriculture?
67 Food choices = energy choices Energy is lost at each trophic level.When we eat meat from a cow fed on grain, most of the grain’s energy has already been spent on the cow’s metabolism.Eating meat is therefore very energy inefficient. - Hence, the “Eating Green” Challenge! Feb. 28- March 7
68 Grain feed input for animal output Some animal food products can be produced with less input of grain feed than others.Figure 9.17
69 Land and water input for animal output Some animal food products can be produced with less input of land and water than others.Figure 9.18
70 AquacultureThe raising of aquatic organisms for food in controlled environmentsProvides 1/3 of world’s fish for consumption220 species being farmedThe fastest growing type of food production
71 Benefits of aquaculture Provides reliable protein source for people, increases food securityCan be small-scale, local, and sustainableReduces fishing pressure on wild stocks, and eliminates bycatchUses fewer fossil fuels than fishingCan be very energy efficient
72 Environmental impacts of aquaculture Density of animals leads to disease, antibiotic use, risks to food security.It can generate large amounts of waste.Often animals are fed grain, which is not energy efficient.Sometimes animals are fed fish meal from wild-caught fish.Farmed animals may escape into the wild and interbreed with, compete with, or spread disease to wild animals.
73 Catching and Raising More Fish FisheriesFishing methods (See Fig p. 299)Sustainable yieldOverfishing- decreased biodiversity; affects aquatic food chains; bycatch; loss of foodCommercial extinctionAquaculture- collectively involves fish farming and ranching;salmon and shrimp
74 Environmental impacts of aquaculture Transgenic salmon (top) can compete with or spread disease to wild salmon (bottom) when they escape from fish farms.Figure 9.20
75 3 methods used to catch fish: aquaculture3 methods used to catch fish:trawl bagdrift netpurse-seine
76 Trade-Offs Aquaculture Highly efficientHigh yield in smallvolume of waterIncreased yieldsthrough cross-breeding and geneticengineeringCan reduce over-harvesting ofconventional fisheriesLittle use of fuelProfit not tied to priceof oilHigh profitsAdvantagesLarge inputs of land, feed,And water neededProduces large andconcentrated outputs ofwasteDestroys mangrove forestsIncreased grain productionneeded to feed somespeciesFish can be killed bypesticide runoff fromnearby croplandDense populationsvulnerable to diseaseTanks too contaminated touse after about 5 yearsDisadvantagesTrade-OffsAquaculture
77 More Sustainable Aquaculture Reduce use of fishmeal as a feed to reduce depletion of other fishImprove pollution management of aquaculture wastesReduce escape of aquaculture species into the wildRestrict location of fish farms to reduce loss of mangrove forests and other threatened areasFarm some aquaculture species (such as salmon and cobia) in deeply submerged cages to protect them from wave action and predators and allow dilution of wastes into the oceanSet up a system for certifying sustainable forms of aquacultureSolutionsMore Sustainable Aquaculture
78 Sustainable agriculture Agriculture that can practiced the same way far into the futureDoes not deplete soils faster than they formDoes not reduce healthy soil, clean water, and genetic diversity essential for long-term crop and livestock productionLow-input agriculture = small amounts of pesticides, fertilizers, water, growth hormones, fossil fuel energy, etc.Organic agriculture = no synthetic chemicals used. Instead, biocontrol, composting, etc.
79 Organic farming Small percent of market, but is growing fast 1% of U.S. market, but growing 20%/yr3–5% of European market, but growing 30%/yrOrganic produce:Advantages for consumers: healthier; environmentally betterDisadvantages for consumers: less uniform and appealing-looking; more expensive
80 Conclusions: Challenges Chemical pesticides pollute, and kill pollinators, and pests evolve resistance.GM crops show promise for social and environmental benefits, but questions linger about their impacts.Much of the world’s crop diversity has vanished.Feedlot agriculture and aquaculture pose benefits and harm for the environment and human health.
81 Conclusions: Challenges Organic farming remains a small portion of agriculture.Human population continues to grow, requiring more food production.Soil erosion is a problem worldwide.Salinization, waterlogging, and other soil degradation problems are leading to desertification.Grazing and logging, as well as cropland agriculture, contribute to soil degradation.
82 Conclusions: Solutions Biocontrol and IPM offer alternatives to pesticides.Further research and experience with GM crops may eventually resolve questions about impacts, and allow us to maximize benefits while minimizing harm.More funding for seed banks can rebuild crop diversity.Ways are being developed to make feedlot agriculture and aquaculture safer and cleaner.
83 Conclusions: Solutions Organic farming is popular and growing fast.Green revolution advances have kept up with food demand so far. Improved distribution and slowed population growth would help further.Farming strategies like no-till farming, contour farming, terracing, etc., help control erosion.Government laws, and government extension agents working with farmers, have helped improve farming practices and control soil degradation.Better grazing and logging practices exist that have far less impact on soils.
84 Sustainable Agriculture High-yield polycultureOrganic fertilizersBiological pest controlIntegrated pestmanagementIrrigation efficiencyPerennial cropsCrop rotationUse of more water-efficient cropsSoil conservationSubsidies for more sustainable farming andfishingIncreaseSoil erosionSoil salinizationAquifer depletionOvergrazingOverfishingLoss ofbiodiversityLoss of primecroplandFood wasteSubsidies for unsustainablefarming and fishingPopulation growthPovertyDecreaseSolutionsSustainable Agriculture
85 Sustainable Agriculture Waste les foodReduce or eliminate meat consumptionFeed pets balanced grain foods instead of meatUse organic farming to grow some of your foodBuy organic foodCompost your food wastesWhat Can You Do?Sustainable Agriculture
87 QUESTION: ReviewIntegrated pest management may involve all of the following EXCEPT… ?a. Close population monitoringb. Biocontrolc. Exclusive reliance on pesticidesd. Habitat modificatione. Transgenic cropsAnswer = c
88 QUESTION: Review What do seed banks do? a. Lend money to farmers to buy seedsb. Pay farmers to store seedsc. Buy seeds from farmersd. Store seeds to maintain genetic diversitye. None of the aboveAnswer = d
89 QUESTION: Review Which is NOT a benefit of aquaculture? a. Provides a reliable protein sourceb. Reduces pressure on natural fisheriesc. Produces no wasted. Uses fewer fossil fuels than commercial fishinge. All of the above are benefitsAnswer = c
90 QUESTION: Weighing the Issues Can we call the green revolution a success?a. A huge success; it has saved millions from starvation because it increased food production to keep pace with population growth.b. Not a success; its environmental impacts have outweighed its claimed benefits.c. A success; its environmental impacts are balanced by the fact that it saved huge areas from deforestation.Answer = personal opinion
91 QUESTION: Interpreting Graphs and Data With 500 kg of water, you could produce … ?a. 2 kg of protein from milkb. Protein from 50 chickensc. 750 kg of protein from beefd. 15 eggsAnswer = aFigure 9.18b
92 QUESTION: ViewpointsShould we encourage the continued development of GM foods?a. Yes; they will bring many health, social, and environmental benefits.b. No, we should adopt the precautionary principle, and not introduce novel things until we know they are safe.c. Yes, but we should proceed cautiously, and consider each new crop separately.Answer = personal opinion
93 QUESTION: Review Which statement is NOT correct? a. Soil consists of disintegrated rock, organic matter, nutrients, and microorganisms.b. Healthy soil is vital for agriculture.c. Soil is somewhat renewable.d. Soil is lifeless dirt.e. Much of the world’s soil has been degraded.Answer = d
94 QUESTION: Review The A horizon in a soil profile… ? a. Is often called the “zone of accumulation.”b. Is often called “topsoil.”c. Contains mostly organic matter.d. Is the lowest horizon, deepest underground.Answer = b
95 QUESTION: Review Erosion occurs through… ? a. Deforestation. b. Excessive plowing.c. Overgrazing rangelands.d. Two of the above.e. All of the above.Answer = e
96 QUESTION: ReviewDrip irrigation differs from conventional irrigation in that … ?a. It is much less efficient.b. It can cause salinization.c. Water is precisely targeted to plants.d. About 40% is wasted.Answer = c
97 QUESTION: Weighing the Issues You are farming an extremely steep slope that is sunny and very windy. What strategies would you consider using?a. Crop rotationb. Contour farmingc. Intercroppingd. Terracinge. Shelterbeltsf. No-till farmingAnswer = personal opinion, but d & e would be first priority
98 QUESTION: Interpreting Graphs and Data Grain produced per person has… ?a. Risen steadilyb. Fallen sharplyc. Increased since 1983d. Decreased since 1983Answer = dFigure 8.3
Your consent to our cookies if you continue to use this website.