AP Environmental Science Ch 14 Food Resources © Brooks/Cole Publishing Company / ITP.

AP Environmental ScienceAP Environmental Science

Ch 14Ch 14

Food ResourcesFood Resources

© Brooks/Cole Publishing Company / ITP

SoilSoil

Soil FormationSoil Formation

Soils develop in Soils develop in response to:response to: ClimateClimate Parent MaterialParent Material TopographyTopography TimeTime Living and dead Living and dead

organismsorganisms

ClimateClimate Climate (temperature and moisture) affect:Climate (temperature and moisture) affect:

Weathering processesWeathering processes Microenvironmental conditions for soil organismsMicroenvironmental conditions for soil organisms Plant growthPlant growth Decomposition ratesDecomposition rates Soil pHSoil pH Chemical reactions in the soilChemical reactions in the soil

Destructional -WeatheringDestructional -WeatheringLandscapes broken down by chemical & physical Landscapes broken down by chemical & physical

processes & erosionprocesses & erosion

PhysicalPhysical Includes temperature Includes temperature

changes (freezing and changes (freezing and thawing, thermal thawing, thermal expansion), crystal expansion), crystal growth, pressure, growth, pressure, plant roots, burrowing plant roots, burrowing animalsanimals

Causes disintegration Causes disintegration of parent material and of parent material and facilitates chemical facilitates chemical weatheringweathering

ChemicalChemical Always in waterAlways in water Includes hydration, Includes hydration,

hydrolysis, oxidation, hydrolysis, oxidation, reduction, carbonation reduction, carbonation

Parent MaterialParent Material Parent material-Parent material- refers to the rock and refers to the rock and

minerals from which the soil derives.minerals from which the soil derives. The nature of the parent rock has a direct The nature of the parent rock has a direct

effect on the soil texture, chemistry and effect on the soil texture, chemistry and cycling pathways.cycling pathways.

Parent material may be native or transported Parent material may be native or transported to area by wind, water or glacier.to area by wind, water or glacier.

TopographyTopography

Topography-Topography- physical physical characteristics of characteristics of location where soil location where soil is formed.is formed. DrainageDrainage Slope directionSlope direction ElevationElevation Wind exposureWind exposure

TimeTime

O horizonO horizonLeaf litterLeaf litter

A horizonA horizonTopsoilTopsoil

B horizonB horizonSubsoilSubsoil

C horizonC horizonParentParent

materialmaterial

Mature soilMature soil

Young soilYoung soil

BedrockBedrockBedrockBedrock

Immature soilImmature soil

• Soil horizons• Soil horizons • Soil profile • Soil profile • Humus • Humus

Organisms in SoilOrganisms in Soil Bacteria—fix nitrogenBacteria—fix nitrogen Worms and insects-aerate and Worms and insects-aerate and

fertilize the soilfertilize the soil Trees, plants, etc. provide stability Trees, plants, etc. provide stability

against erosion and organic material against erosion and organic material HumusHumus--decomposed, organic matter --decomposed, organic matter

Decreases erosion and retains waterDecreases erosion and retains water Provides nutrients Provides nutrients Improves porosity so makes root growth Improves porosity so makes root growth

easier.easier. Temperate deciduous forests and Temperate deciduous forests and

grasslands have very rich soilgrasslands have very rich soil

Soil PropertiesSoil Properties Infiltration/permeabilityInfiltration/permeabilityPorosityPorosityLeachingLeachingTextureTexturepHpHEtc.Etc.

100%clay100%clay

IncreasingIncreasingpercentage siltpercentage silt

IncreasingIncreasingpercentage claypercentage clay

00

2020

4040

6060

8080

8080

6060

4040

2020

00100%sand100%sand 8080 6060 4040 2020 100%silt100%silt

Increasing percentage sandIncreasing percentage sand

Water Water

High permeability Low permeability

Fig. 10.17, p. 224

SoilSoil PropertiesProperties

TextureNutrient InfiltrationWater-Holding Aeration Capacity Capacity

____________________________________________________Clay Good Poor Good Poor

Silt Med Med Med Med

Sand Poor Good Poor Good

Loam(mix) Med Med Med Med

Soil ChemistrySoil Chemistry Acidity / Alkalinity – pH Acidity / Alkalinity – pH Most abundant element in soil is oxygen Most abundant element in soil is oxygen

in the form of SiOin the form of SiO22

Major NutrientsMajor Nutrients NitrogenNitrogen Phosphorus (phosphates)Phosphorus (phosphates) Potassium (potash)Potassium (potash)

Acidity / Alkalinity – pHAcidity / Alkalinity – pH pH directly affects the availability of plant food pH directly affects the availability of plant food

nutrientsnutrients Too acidic or basic will not: Too acidic or basic will not:

Allow compounds to dissolveAllow compounds to dissolve Allow presence of certain ionsAllow presence of certain ions

Best if between pH 6 – 8 (except for acid loving Best if between pH 6 – 8 (except for acid loving plants)plants) Too acidic, add ground limestoneToo acidic, add ground limestone Too basic, add organic material like steer manureToo basic, add organic material like steer manure

Nitrogen ContentNitrogen Content ImportanceImportance

N is component of proteins and N is component of proteins and DNADNA

Stimulates growth and Stimulates growth and produces rich green colorproduces rich green color

Quality and protein content of Quality and protein content of fruit fruit

Taken up by plant as NHTaken up by plant as NH44++

(ammonium) and NO(ammonium) and NO33- -

(nitrate)(nitrate) Replenished naturally by:Replenished naturally by:

Rhizobacteria on legume roots Rhizobacteria on legume roots (beans, alfalfa) that fix nitrogen (beans, alfalfa) that fix nitrogen gas for plant usegas for plant use

Fertilizer from manure or Fertilizer from manure or inorganic sourcesinorganic sources

Phosphorus for GrowthPhosphorus for GrowthAbundance causes:Abundance causes:

Strong root systemStrong root system Increases seed yield and fruit developmentIncreases seed yield and fruit development Parts of root involved in water uptake (hair)Parts of root involved in water uptake (hair)

Major role in transfer of energy--ATPMajor role in transfer of energy--ATP Taken up by plant as HTaken up by plant as H22POPO44

-- and HPO and HPO44-2 -2

Fertilizer is made from rock phosphateFertilizer is made from rock phosphate Banned in laundry detergentsBanned in laundry detergents

in some states due to in some states due to eutrophication of lakes eutrophication of lakes from runoff.—IN is onefrom runoff.—IN is one

Potassium ContentPotassium Content ““Potash”Potash” Important in vigor and vitality Important in vigor and vitality

of plantof plant Carries carbohydrates through Carries carbohydrates through

the plantthe plant Improves quality of fruitImproves quality of fruit Promotes vigorous root systemsPromotes vigorous root systems Offsets too much NOffsets too much N

Found naturally in feldspar and Found naturally in feldspar and micasmicas

Improving Soil NutrientsImproving Soil Nutrients

Organic fertilizer-Organic fertilizer- from plant and animal from plant and animal materials (i.e. green manure, cow manure)materials (i.e. green manure, cow manure)

Commercial inorganic fertilizer-Commercial inorganic fertilizer- produced produced from various minerals.from various minerals.

HumusHumusCrop rotationCrop rotation-by planting crops that use a -by planting crops that use a

lot of nutrients, like corn, and the next lot of nutrients, like corn, and the next year plant those that return nutrients, like year plant those that return nutrients, like legumes. legumes.

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 ofenergy to produce,transport, and apply

Release the greenhouse gas nitrous oxide (N2O)

Runoff can overfertilizenearby lakes and kill fish

Easy to transport

Easy to store

Easy to apply

Inexpensive to produce

Help feed one of every three people in theworld

Without commercialinorganic fertilizers,world food output coulddrop by 40%

Food ProductionFood Production

Generalized locations of the world’s principal types of food production.

Fig. 12–2© Brooks/Cole Publishing Company / ITP

Food ProductionFood Production Food systemsFood systems

Croplands-mostly produce grain; Croplands-mostly produce grain; provide 77% of the worlds foodprovide 77% of the worlds food

Rangelands and Confined Animal Rangelands and Confined Animal Feeding Operations (CAFOs)-Feeding Operations (CAFOs)-produce meat; provide 16% of produce meat; provide 16% of world’s foodworld’s food

Ocean fisheries-produce 7% of Ocean fisheries-produce 7% of worlds foodworlds food

14 plants & 8 terrestrial 14 plants & 8 terrestrial animal species supply animal species supply approximately 90% of the approximately 90% of the world’s caloric intakeworld’s caloric intake

Wheat, rice, and corn Wheat, rice, and corn provide more than ½ the provide more than ½ the calories humans consume-calories humans consume-annuals!annuals!

Food ProductionFood Production Technological advances caused a huge increase Technological advances caused a huge increase

in food production due to growing/raising plants in food production due to growing/raising plants and animals closer together than ever beforeand animals closer together than ever before Competition within species minimizedCompetition within species minimized For plants: farm machinery, irrigation, inorganic For plants: farm machinery, irrigation, inorganic

fertilizers, pesticides, high yield varietiesfertilizers, pesticides, high yield varieties For animals: antibiotics, food additives, growth For animals: antibiotics, food additives, growth

hormones, enclosed animal pens.hormones, enclosed animal pens.

Figure 14-3Figure 14-3Page 276Page 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 Services Economic 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

Types of Food ProductionTypes of Food Production Industrialized agriculture-Industrialized agriculture- high high

input, high output form of input, high output form of farming, usually consisting of farming, usually consisting of monocultures made possible monocultures made possible b/c of cheap energyb/c of cheap energy OIL OIL Large amounts of fossil fuel, Large amounts of fossil fuel,

water, water, commercial fertilizers, and commercial fertilizers, and pesticides.pesticides.

10 units 10 units nonrenewables/1unit food nonrenewables/1unit food (on table)(on table)

Mostly used in developed Mostly used in developed countriescountries

Plantation agriculture-Plantation agriculture- Cash Cash crops in the tropicscrops in the tropics

Green RevolutionsGreen Revolutions First “Green” Revolution since First “Green” Revolution since

19501950 Haber-Bosch process was Haber-Bosch process was

developed, which fixes nitrogen, a developed, which fixes nitrogen, a limiting factor to plant, and limiting factor to plant, and therefore animal, growth.therefore animal, growth.

Process uses fossil fuels Increased yields per unit area of

cropland. Diverse family farms became

monocultures of GM, high–yield crops Large inputs of fertilizer, pesticides,

and water Increased the intensity and frequency

of cropping. 2nd Green Revolution since

1967 Introducing fast-growing, higher

yield dwarf varieties of rice and wheat to developing countries

Types of Food ProductionTypes of Food Production Traditional agriculture- Traditional agriculture- low low

input form of farminginput form of farming 1 unit nonrenewable 1 unit nonrenewable

resource input =1unit foodresource input =1unit food Traditional subsistence-Traditional subsistence-

human labor & draft human labor & draft animals to produce animals to produce enough crops or livestock enough crops or livestock for a family’s survival.for a family’s survival. Shifting cultivation and Shifting cultivation and

nomadic livestock herdingnomadic livestock herding

Types of Food ProductionTypes of Food Production

Traditional Traditional intensive-intensive-increased increased inputs inputs of labor, fertilizer, of labor, fertilizer, and water to and water to achieve achieve higher yields for higher yields for sale.sale.

Growing TechniquesGrowing Techniques Growing techniques in traditional agricultureGrowing techniques in traditional agriculture InterplantingInterplanting – growing several crops on the – growing several crops on the

same plot so diversity reduces water loss same plot so diversity reduces water loss and risk due to misfortunesand risk due to misfortunes 1. Polyvarietal cultivation1. Polyvarietal cultivation – planting several – planting several

varieties of the same crop.varieties of the same crop. 2. 2. IntercroppingIntercropping – two or more different crops – two or more different crops

grown at the same time on a plot.grown at the same time on a plot.

Growing TechniquesGrowing Techniques 3. Agroforestry-3. Agroforestry-crops and trees grown on same crops and trees grown on same

plot.plot. 4. 4. ***Polyculture***Polyculture – different plants that mature – different plants that mature

at different times at different times Low input, less fertilizer and water due to varying Low input, less fertilizer and water due to varying

root systems, wind and water erosion protection, less root systems, wind and water erosion protection, less insecticideinsecticide higher yields! higher yields!

Interplanting video clip

Soil Erosion and DegradationSoil Erosion and Degradation Soil erosion- Soil erosion- movement of soil movement of soil

components, especially litter and components, especially litter and topsoil, from one place to topsoil, from one place to another.another. Makes soil less fertile and less able Makes soil less fertile and less able

to hold waterto hold water Takes typically 200–1000 years to Takes typically 200–1000 years to

form 2.5 centimeters (1 inch) of form 2.5 centimeters (1 inch) of topsoiltopsoil

Eroding faster than it forms in about Eroding faster than it forms in about one–third of the world's croplandone–third of the world's cropland

In the U.S. is being eroded 16x In the U.S. is being eroded 16x faster than it is being formedfaster than it is being formed

Moving water is the prime cause Moving water is the prime cause of erosion.of erosion.

Major areas of Major areas of the world are the world are threatened by threatened by serious soil serious soil erosion.erosion.

Soil Erosion and DegradationSoil Erosion and Degradation

1930s- a combination of 1930s- a combination of drought and poor soil drought and poor soil conservation led to conservation led to severe wind erosion of severe wind erosion of topsoil in what is known topsoil in what is known as the Dust Bowl of the as the Dust Bowl of the Great Plains.Great Plains.

1935 Soil Erosion Act-1935 Soil Erosion Act- SCS (Soil Conservation SCS (Soil Conservation Service) promoted Service) promoted sound soil conservation sound soil conservation practicespractices

Soil Erosion Video


Soil Erosion and Soil Erosion and DegradationDegradation

Causes:Causes: OvergrazingOvergrazing Deforestation and Deforestation and

devegetationdevegetation Surface miningSurface mining Poor irrigation Poor irrigation

techniquestechniques Salt buildupSalt buildup Farming on unsuitable Farming on unsuitable

terrainterrain Soil compaction by farm Soil compaction by farm

machinery.machinery.


Problems with Problems with irrigationirrigation Salinization-Salinization- results in results in

irrigated cropland irrigated cropland where salts build up to where salts build up to levels that decrease levels that decrease yields or prevent yields or prevent cultivation.cultivation.

Waterlogging-Waterlogging- results results when excess irrigation when excess irrigation water raises the water water raises the water table and lowers crop table and lowers crop productivity.productivity.

Soil ConservationSoil Conservation Soil conservation involves Soil conservation involves

reducing soil erosion and reducing soil erosion and restoring soil fertility.restoring soil fertility. Conservation–tillage farming-Conservation–tillage farming- use use

of special tillers or of special tillers or no–till no–till methodsmethods that inject seeds, that inject seeds, fertilizers, and herbicides into fertilizers, and herbicides into unplowed soil. Soil not disturbed unplowed soil. Soil not disturbed over winter in temperate zones.over winter in temperate zones.

WindbreakingWindbreaking- use of vegetation - use of vegetation surrounding a plot of land to surrounding a plot of land to reduce wind erosionreduce wind erosion

Use of cover crops during the off-Use of cover crops during the off-season (i.e. winter wheat can be season (i.e. winter wheat can be grown in some areas.)grown in some areas.)

Stalks and stem remains of Stalks and stem remains of harvest can be left in field over harvest can be left in field over winterwinter

Soil ConservationSoil Conservation Other methods:Other methods:

Terracing-Terracing- protects steep slopes protects steep slopes Contour farming-Contour farming- plowing at right angles to the plowing at right angles to the

slopesslopes Strip croppingStrip cropping maintains strips of different maintains strips of different

vegetation between cropsvegetation between crops Alley croppingAlley cropping grows crops between rows of grows crops between rows of

treestrees AgroforestryAgroforestry

Erosion Control video clipErosion Control video clip

TERRACING CONTOUR PLANTING AND STRIP CROPPING

ALLEY CROPPINGAGROFORESTRY

WINDBREAKING

World Food SupplyWorld Food Supply Enough food is produced to feed all Enough food is produced to feed all

people, but it is unevenly distributed.people, but it is unevenly distributed. LDCs are undernourished or malnourished LDCs are undernourished or malnourished

Undernutrition- Undernutrition- can’t meet basic energy needscan’t meet basic energy needs Malnutrition-Malnutrition- energy needs met, but not energy needs met, but not

enough proteins and vitamins (“mal” = bad)enough proteins and vitamins (“mal” = bad) Still growing exponentially Still growing exponentially

MDCs are over nourished and wasteful.MDCs are over nourished and wasteful. More grain is going to livestock and cars, so More grain is going to livestock and cars, so

the price of grain b/t 2006-2008 roughly the price of grain b/t 2006-2008 roughly tripled, setting record highs. tripled, setting record highs.

Recently been buying or leasing lands in LDCs Recently been buying or leasing lands in LDCs to grow cropsto grow crops

World Food SupplyWorld Food Supply Carrying capacity of Earth is reliant on both Carrying capacity of Earth is reliant on both

food and freshwater suppliesfood and freshwater supplies Our food supply is based on limited freshwater, as Our food supply is based on limited freshwater, as

well as nonrenewable fossil fuels.well as nonrenewable fossil fuels. Many tracts of land are being use to grow corn or Many tracts of land are being use to grow corn or

sugar cane for fuel instead of food.sugar cane for fuel instead of food. The number of people Earth can support The number of people Earth can support

depends on the following:depends on the following: Cultural carrying capacity/person (habits, diet, Cultural carrying capacity/person (habits, diet,

etc.)etc.) Sustainability of future food productionSustainability of future food production Percentage of the population eating meat (higher Percentage of the population eating meat (higher

trophic level…remember 2trophic level…remember 2ndnd law of law of thermodynamics!)thermodynamics!)

World Food SupplyWorld Food Supply Per capita food Per capita food

production slowingproduction slowing Freshwater crisesFreshwater crises Salinization of soil and Salinization of soil and

erosionerosion Drought and flooding due Drought and flooding due

to climate changeto climate change World population World population

increasingincreasing Increasing demand for Increasing demand for

food in industrializing food in industrializing countries, especially meatcountries, especially meat

Degradation and loss of Degradation and loss of croplandcropland

Decrease in grain stores Decrease in grain stores which have been kept which have been kept since ancient timessince ancient times

Increasing Food Production?Increasing Food Production? To increase crop yieldsTo increase crop yields

Genetic engineeringGenetic engineeringRaise the share of Raise the share of

photosynthetic product photosynthetic product in the seedin the seed

Develop strains of Develop strains of plants resistant to plants resistant to disease, insects, and disease, insects, and drought.drought.

Increase inputs of water, Increase inputs of water, fertilizer, and pesticidesfertilizer, and pesticidesEventually these Eventually these

additions produce no additions produce no additional increase in additional increase in crop yields.crop yields.

Figure 14-19Figure 14-19Page 292Page 292

ProjectedDisadvantages

Need less fertilizer

Need less water

More resistant to insects,plant disease, frost, anddrought

Faster growth

Can grow in slightly saltysoils

Less spoilage

Better flavor

Less use of conventionalpesticides

Tolerate higher levels ofpesticide use

Higher yields

ProjectedAdvantages

Trade-OffsGenetically Modified Food and Crops

Irreversible andunpredictable genetic and ecological effects

Harmful toxins in foodFrom possible plant cellMutations

New allergens in food

Lower nutrition

Increased evolution ofPesticide-resistantInsects and plant disease

Creation of herbicide-Resistant weeds

Harm beneficial insects

Lower genetic diversity

Increasing Food ProductionIncreasing Food Production Investigate new types of Investigate new types of

foodfood Cultivation of less widely Cultivation of less widely

known plants that may be known plants that may be found in seed banks or found in seed banks or elsewhereelsewhere

Cultivation of perennial Cultivation of perennial plants reduce inputs of plants reduce inputs of water, fertilizer, and water, fertilizer, and energy – reduce soil energy – reduce soil erosionerosion

Yummy insects: Yummy insects: microlivestockmicrolivestock

Increasing Food ProductionIncreasing Food Production Cultivating more landCultivating more land

Clear tropical forestsClear tropical forestsNutrient–poor soils will likely Nutrient–poor soils will likely

make agriculture make agriculture unsustainableunsustainable

Removal of valuable carbon sinkRemoval of valuable carbon sinkLoss of biodiversityLoss of biodiversity

Irrigate arid landsIrrigate arid landsExpensive damsExpensive damsDepletion of groundwater Depletion of groundwater

A major economically profitable A major economically profitable and environmentally sustainable and environmentally sustainable expansion of cropland is unlikely expansion of cropland is unlikely over the next few decades. over the next few decades.

Turning to the OceansTurning to the Oceans

Fisheries and fish harvestsFisheries and fish harvests 11 of the world’s 15 major oceanic fishing areas 11 of the world’s 15 major oceanic fishing areas

have been fished at or beyond their estimated have been fished at or beyond their estimated maximum sustainable yield for commercially maximum sustainable yield for commercially valuable species and are in a state of decline. valuable species and are in a state of decline.

Why?Why? Growing demand for seafoodGrowing demand for seafood Efficient, large–scale industrial fishing fleetsEfficient, large–scale industrial fishing fleets Degradation and destruction of coastal wetlandsDegradation and destruction of coastal wetlands Pollution of coastal watersPollution of coastal waters

Turning to the OceansTurning to the Oceans Aquaculture—the Blue Aquaculture—the Blue

RevolutionRevolution Fish farming and fish ranchingFish farming and fish ranching

Produce high yields in a small Produce high yields in a small volume of watervolume of water

Increase yields by Increase yields by crossbreeding and genetic crossbreeding and genetic engineeringengineering

Supplies 1/3 of the Supplies 1/3 of the commercial fish harvestcommercial fish harvest

Aquaculture – the limitationsAquaculture – the limitations Conversion of coastal Conversion of coastal

wetlands to fish farmswetlands to fish farms Genetic pollution of natural Genetic pollution of natural

fish populations by escapeesfish populations by escapees Contamination of nearby Contamination of nearby

waters with waste and waters with waste and chemicalschemicals

Environmental ImpactsEnvironmental Impacts

General considerationsGeneral considerations World population increase will demand greater World population increase will demand greater

food productionfood production Further application of green revolution Further application of green revolution

techniques will increase food production, but techniques will increase food production, but these techniques have limitations and these techniques have limitations and environmental consequencesenvironmental consequences

Industrialized agriculture has a greater harmful Industrialized agriculture has a greater harmful impact on air, soil, water, and biodiversity impact on air, soil, water, and biodiversity resources than any other human activity!resources than any other human activity!


Fig. 12–11 a and b



Fig. 12–11 c and d



Fig. 12–11 e© Brooks/Cole Publishing Company / ITP

Environmental ImpactsEnvironmental Impacts Focus on meatFocus on meat

More than 1/2 of the world’s cropland is used to More than 1/2 of the world’s cropland is used to produce livestock feedproduce livestock feed

Overgrazing is the major cause of desertification of Overgrazing is the major cause of desertification of arid and semi–arid landsarid and semi–arid lands

Cattle produce the GHG, methane (CH4) primarily Cattle produce the GHG, methane (CH4) primarily when belching, which is 25X’s more potent GHG than when belching, which is 25X’s more potent GHG than CO2CO2

Cattle in feedlots require large doses of antibiotics: Cattle in feedlots require large doses of antibiotics: 70% of all U.S. antibiotics in U.S. goes in meat 70% of all U.S. antibiotics in U.S. goes in meat productionproduction

50% of all water withdrawn from rivers and aquifers 50% of all water withdrawn from rivers and aquifers used for meat production each year.used for meat production each year.

1 cow’s waste = 16 humans’!1 cow’s waste = 16 humans’! Meatrix Video--5 minMeatrix Video--5 min

Kilograms of grain needed per kilogram of body weight

Beef cattle

Pigs

Chicken

Fish (catfishor carp)

7

4

2.2

2

© 2004 Brooks/Cole – Thomson Learning

The Ultimate QuestionThe Ultimate Question Do we feed people at the expense of the Do we feed people at the expense of the

environment?environment? Worldwide we already have enough food, it just has to be Worldwide we already have enough food, it just has to be

distributed evenlydistributed evenly Many cases in scientific research have shown that when Many cases in scientific research have shown that when

food sources increase, so do species’ populations…food sources increase, so do species’ populations…positive feedback loop…possibly furthering positive feedback loop…possibly furthering environmental damage.environmental damage.

Humans have one thing that other species do not: Humans have one thing that other species do not: RESTRAINTRESTRAINT

Possibly turn to population controls instituted with Possibly turn to population controls instituted with promised food aid?promised food aid?

In the meantime, people are dying and this can’t be In the meantime, people are dying and this can’t be ignored.ignored.

Sustainable AgricultureSustainable Agriculture

Some ways to reduce environmental Some ways to reduce environmental impactimpact Reduce water waste in irrigationReduce water waste in irrigation Emphasize Emphasize biologicalbiological pest control and pest control and

integrated pest managementintegrated pest management Increase use of organic fertilizersIncrease use of organic fertilizers Increase use of soil conservation Increase use of soil conservation

techniques.techniques. Increase use of polyculture: less water, Increase use of polyculture: less water,

fertilizers, herbicides, insecticides, and fertilizers, herbicides, insecticides, and greater biodiversity.greater biodiversity.

Eat less meatEat less meat Bill Nye: Dinner (14 min)Bill Nye: Dinner (14 min)

High-yield polyculture

Organic fertilizers

Biological pest control

Integrated pestmanagement

Irrigation efficiency

Perennial crops

Crop rotation

Use of more water-efficient crops

Soil conservation

Subsidies for more sustainable farming and fishing

Increase

Soil erosion

Soil salinization

Aquifer depletion

Overgrazing

Overfishing

Loss of biodiversity

Loss of primecropland

Food waste

Subsidies for unsustainable farming and fishing

Population growth

Poverty

Decrease

Solutions

Sustainable Agriculture

•Waste less food

•Reduce or eliminate meat consumption

•Feed pets balanced grain foods instead of meat

•Use organic farming to grow some of your OWN food

•Buy organic food

•Compost your food wastes

What Can You Do?

Sustainable Agriculture

Pesticides: Types and UsesPesticides: Types and Uses

Pest –Pest – any species that any species that competes with humans for competes with humans for food, invades lawn and food, invades lawn and gardens, destroys wood in gardens, destroys wood in houses, invades ecosystems, houses, invades ecosystems, causes disease, or is a causes disease, or is a nuisance.nuisance.

100 species of plants (weeds), 100 species of plants (weeds), animals (mostly insects), fungi animals (mostly insects), fungi and microbes (infect plants and microbes (infect plants and animals) cause 90% of and animals) cause 90% of damage to the crops we growdamage to the crops we grow

Geographic range of five major pests in the lower 48 state of the United States

Types of PesticidesTypes of Pesticides

Pesticides-Pesticides- chemicals used to kill chemicals used to kill undesirable organismsundesirable organismsInsecticides-Insecticides- insect killers insect killersHerbicides-Herbicides- plant killers plant killersFungicides-Fungicides- fungus killers fungus killersNematocides-Nematocides- round–worm killers round–worm killersRodenticides-Rodenticides- rat and mouse killers rat and mouse killers

Types of PesticidesTypes of Pesticides

11stst generation pesticides generation pesticides Mostly natural substances obtained from plantsMostly natural substances obtained from plants Examples: pyrethrum and rotenoneExamples: pyrethrum and rotenone

2nd generation pesticides2nd generation pesticides Synthetic organic chemicals developed from Synthetic organic chemicals developed from

fossil fuels since 1945fossil fuels since 1945 DDTDDT

Broad–spectrum-Broad–spectrum- toxic to many species toxic to many species Selective-Selective- toxic to a narrowly defined toxic to a narrowly defined

groupgroup Persistent-Persistent- remain in the environment for remain in the environment for

an extended period of timean extended period of time

Use of PesticidesUse of Pesticides

Most pesticide use is in developed Most pesticide use is in developed countriescountries

It’s use started after WWII as a way to get It’s use started after WWII as a way to get rid of extra toxic substances used during rid of extra toxic substances used during the war.the war.

90% of insecticides and 80% of herbicides 90% of insecticides and 80% of herbicides applied to crops in the U.S. are used for applied to crops in the U.S. are used for growing cotton and corngrowing cotton and corn

U.S. lawns are doused with 10x more U.S. lawns are doused with 10x more pesticides/hectare than croplandpesticides/hectare than cropland

The Case for PesticidesThe Case for Pesticides Pesticides kill disease–carrying insectsPesticides kill disease–carrying insects

Until the plasmodium that causes malaria Until the plasmodium that causes malaria became resistant, DDT was commonly used to became resistant, DDT was commonly used to combat it.combat it.

Pesticides increase food supplies and lower Pesticides increase food supplies and lower costscosts Approximately 55% of the world’s food supply is Approximately 55% of the world’s food supply is

lost to pestslost to pests Pesticides increase profits for farmersPesticides increase profits for farmers

Use of pesticides increases crop yieldsUse of pesticides increases crop yields Pesticides work faster and better than Pesticides work faster and better than

alternativesalternatives New pesticides are used at lower ratesNew pesticides are used at lower rates

The Case Against PesticidesThe Case Against Pesticides

The pesticide treadmillThe pesticide treadmill1) Use of pesticides on a crop1) Use of pesticides on a crop2) Pests develop genetic 2) Pests develop genetic

resistance to pesticidesresistance to pesticides3) Dosage of pesticides 3) Dosage of pesticides

increased or new pesticide is increased or new pesticide is usedused

4) Pests develop genetic 4) Pests develop genetic resistance to pesticidesresistance to pesticides

5) repeat5) repeat

600

500

400

300

200

100

1950 1960 1970 1980 1990 2000

Nu

mb

er o

f g

enet

ical

ly r

esis

tan

t in

sect

sp

ecie

s

Year

Neonicotinoids(1995)

Pyrethroids (1978)

Carbamates (1972)

Organophosphates (1965)

DDT/cyclodienes (1946)

The Case Against PesticidesThe Case Against PesticidesBroad-spectrum pesticides affect many Broad-spectrum pesticides affect many

species other than the target.species other than the target.Agricultural workers who are poisoned.Agricultural workers who are poisoned.Waterway and drinking water pollution Waterway and drinking water pollution

due to runoff.due to runoff.Bioaccumulation of persistent pesticidesBioaccumulation of persistent pesticidesBiomagnificationBiomagnification

Other Methods of Pest Other Methods of Pest ControlControl

Genetic engineeringGenetic engineeringDevelopment of disease and pest Development of disease and pest

resistant crop varietiesresistant crop varietiesCould reduce the number and quantity Could reduce the number and quantity

of pesticides needed to protect cropsof pesticides needed to protect cropsPotential limitationsPotential limitations

Eventual pest adaptation to new cropsEventual pest adaptation to new cropsResistance factors may be toxic to Resistance factors may be toxic to

beneficial insects and other animalsbeneficial insects and other animals

Case Study: Bt GeneCase Study: Bt Gene

Bt Gene video 10minBt Gene video 10min


Biopesticides- Biopesticides- plant toxins plant toxins synthesized for mass synthesized for mass productionproduction

Hormones- pheromones to Hormones- pheromones to lure pests into traps or lure pests into traps or other hormones to control other hormones to control maturationmaturation

Birth control- release of Birth control- release of sterile malessterile males

HormonesHormones HormonesHormones

Example: For normal insect Example: For normal insect growth, development, and growth, development, and reproduction to occur, certain reproduction to occur, certain juvenile hormones (JH) and juvenile hormones (JH) and molting hormones (MH) must molting hormones (MH) must be present at appropriate be present at appropriate stages of the life cycle. stages of the life cycle.

If applied at the proper time, If applied at the proper time, synthetic hormones disrupt synthetic hormones disrupt the life cycles of insect pests the life cycles of insect pests and control their population. and control their population.


Integrated pest management-Integrated pest management- each crop each crop and its pests are evaluated as parts of an and its pests are evaluated as parts of an ecological system. ecological system.

A control program is developed that A control program is developed that includes a mix of cultivation, biological includes a mix of cultivation, biological and chemical control methods.and chemical control methods. 1) Crops monitored for damaging levels of 1) Crops monitored for damaging levels of

pestspests 2) Biological control methods used2) Biological control methods used 3) Small amounts of diverse chemicals used to 3) Small amounts of diverse chemicals used to

prevent development of resistance and to prevent development of resistance and to avoid killing beneficial insects and predatorsavoid killing beneficial insects and predators

Integrated Pest ManagementIntegrated Pest Management

The goal: to keep each pest population The goal: to keep each pest population just below the size at which it causes just below the size at which it causes economic loss.economic loss.

Case Study: U.S. CottonCase Study: U.S. Cotton Boll weevils feed on cotton Boll weevils feed on cotton

buds and flowersbuds and flowers Traditionally this plant Traditionally this plant

required 41% of all pesticides required 41% of all pesticides and a tremendous amount of and a tremendous amount of water.water.

USDA Boll Weevil Eradication USDA Boll Weevil Eradication Program has been touted as Program has been touted as one of the most successful one of the most successful integrated pest management integrated pest management systems to date.systems to date. 11stst year numerous malathion year numerous malathion

pesticide treatments and pesticide treatments and stalks are plowed to the stalks are plowed to the ground to prevent winter ground to prevent winter inhabitationinhabitation

Years 2-5 use of pheromone Years 2-5 use of pheromone traps and spraying only in traps and spraying only in fields where weevils are fields where weevils are detected.detected.

Eradication ProgramEradication Program

AP Environmental Science Ch 14 Food Resources © Brooks/Cole Publishing Company / ITP.

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Transcript of AP Environmental Science Ch 14 Food Resources © Brooks/Cole Publishing Company / ITP.