Chapter 11:Chapter 11:Agriculture, Aquaculture and Agriculture, Aquaculture and the Environmentthe Environment

OverviewOverview An Ecological Perspective on An Ecological Perspective on AgricultureAgriculture

Can We Feed The World?Can We Feed The World? What We Grow on the LandWhat We Grow on the Land SoilsSoils Controlling PestsControlling Pests The Future of AgricultureThe Future of Agriculture Genetically Modified Food: Genetically Modified Food: Biotechnology, Farming, and EnvironmentBiotechnology, Farming, and Environment

AquacultureAquaculture

AgroecosystemAgroecosystem

1.1. Ecological succession stopped Ecological succession stopped to keep the agroecosystem in an to keep the agroecosystem in an early-successional stateearly-successional state

2.2. Focus on MonocultureFocus on Monoculture Monoculture - large areas planted Monoculture - large areas planted

with a single specieswith a single species Counteracted by crop rotationCounteracted by crop rotation

3.3. Crops planted in neat rows and Crops planted in neat rows and fieldsfields

Makes crops vulnerable to pestsMakes crops vulnerable to pests

4.4. Farming greatly simplifies Farming greatly simplifies biological diversity and food biological diversity and food chainschains

5.5. Plowing is unlike any natural Plowing is unlike any natural soil disturbancesoil disturbance

Nothing in nature repeatedly and Nothing in nature repeatedly and regularly turns over the soil to a regularly turns over the soil to a specific depthspecific depth

6.6. Genetic modification of cropsGenetic modification of crops

AgroecosystemAgroecosystem

Can We Feed the World?Can We Feed the World?

To answer this we must To answer this we must understand how crops grow and understand how crops grow and how productive they can behow productive they can be

Most viable of human activities Most viable of human activities but is it sustainable?but is it sustainable? Regions farmed for thousands of Regions farmed for thousands of yearsyears

Farming changed local ecosystemsFarming changed local ecosystems

Can We Feed the World?Can We Feed the World?

History of agriculture is a History of agriculture is a series of human attempts to series of human attempts to overcome environmental overcome environmental limitations and problems.limitations and problems. Each solution creates new problemsEach solution creates new problems Should expect some side effectsShould expect some side effects Multiple pressures on agricultural Multiple pressures on agricultural landland

Can We Feed the World?Can We Feed the World?

As population grows, the production As population grows, the production of agriculture must growof agriculture must grow

Food supply is already inadequate Food supply is already inadequate for some peoplesfor some peoples Increasingly marginal land will need to Increasingly marginal land will need to be put into productionbe put into production

Food supply also greatly influenced Food supply also greatly influenced by social disruptions and social by social disruptions and social attitudesattitudes

How We StarveHow We Starve

People “starve” in two waysPeople “starve” in two ways

1.1. UndernourishmentUndernourishment Lack of sufficient calories in Lack of sufficient calories in

available foodavailable food Manifests as famineManifests as famine

2.2. MalnourishmentMalnourishment Lack of specific chemical Lack of specific chemical

components of food, such as components of food, such as protein, vitamins, or other protein, vitamins, or other essential chemical elementsessential chemical elements

How We StarveHow We Starve UndernourishmentUndernourishment

Marasmus – Marasmus – progressive progressive emaciation caused by emaciation caused by lack of protein and lack of protein and caloriescalories

Kwashiorkor – a lack Kwashiorkor – a lack of sufficient of sufficient protein in the dietprotein in the diet

Chronic hunger – Chronic hunger – enough food to stay enough food to stay alive but can not alive but can not live satisfactory or live satisfactory or productive livesproductive lives

How We StarveHow We Starve

World food production must provide World food production must provide adequate nutritional quality and adequate nutritional quality and quantity.quantity.

Food emergencies affected 34 countries Food emergencies affected 34 countries worldwide at the end of 20worldwide at the end of 20thth century century Africa has the most acute food shortagesAfrica has the most acute food shortages Food distribution major problemFood distribution major problem World food aid does not meet all the World food aid does not meet all the caloric need of peoplecaloric need of people

Best solution is to increase local Best solution is to increase local productionproduction

What We Grow What We Grow on the Landon the Land CropsCrops

Of Earth’s ½ Of Earth’s ½ million plant million plant species, only about species, only about 3,000 are 3,000 are agricultural cropsagricultural crops

150 species 150 species cultivated on large cultivated on large scalescale

Most of world’s Most of world’s food provided by 14 food provided by 14 crop speciescrop species

6 provide 80% of 6 provide 80% of the total caloriesthe total calories

LivestockLivestock

Forage- crops grown for domestic Forage- crops grown for domestic animalsanimals In US 14 million areas of alfalfaIn US 14 million areas of alfalfa

Domestic animals includeDomestic animals include 14 billion chickens14 billion chickens 1.3 million cattle1.3 million cattle ~1 billion each sheep, ducks and pigs~1 billion each sheep, ducks and pigs 700 million goats700 million goats 160 million water buffalo160 million water buffalo 18 million camels18 million camels

LivestockLivestock

RangelandRangeland Provides food for grazing and Provides food for grazing and browsing animals w/o plowing and browsing animals w/o plowing and plantingplanting

PasturePasture Plowed, planted and harvested to Plowed, planted and harvested to provide forageprovide forage

Large world market in small grain Large world market in small grain cropscrops See next slideSee next slide

Livestock- effect on Livestock- effect on environmentenvironment About half the About half the earth’s land area is earth’s land area is used as rangelandused as rangeland Most is easily Most is easily damaged by grazing damaged by grazing (drought)(drought)

Much of the Much of the rangeland is rangeland is overgrazedovergrazed

Grazing cattle Grazing cattle trample stream banks trample stream banks and release waste and release waste into streamsinto streams

SoilsSoils Soils are not just “dirt”Soils are not just “dirt”

Key to life on landKey to life on land Earth modified over time by physical, Earth modified over time by physical, chemical and biological processes chemical and biological processes into a series of layers called into a series of layers called horizonshorizons O horizon - organic layer on top of soilO horizon - organic layer on top of soil A (& E in some soils) horizon- upper A (& E in some soils) horizon- upper horizonhorizon

B horizon - zone of accumulationB horizon - zone of accumulation C horizon - most similar to parent C horizon - most similar to parent materialmaterial

SoilsSoils

Soil fertilitySoil fertility Capacity of a soil to supply nutrients Capacity of a soil to supply nutrients necessary for plant growthnecessary for plant growth

Geologically younger soils are typically Geologically younger soils are typically more fertilemore fertile

Soil DrainageSoil Drainage Soils with high clay content hold water Soils with high clay content hold water wellwell

Soil with high sand content drain very Soil with high sand content drain very wellwell

Restoring Our SoilsRestoring Our Soils Soil erosion has Soil erosion has decreased 40% in USdecreased 40% in US Due to better farming Due to better farming practicespractices

Use of chemical Use of chemical (artificial) (artificial) fertilizers increased fertilizers increased soil fertility in 20soil fertility in 20thth centurycentury

Use of phosphorus Use of phosphorus (mined and in guano) (mined and in guano) in fertilizers in fertilizers increased soil increased soil fertilityfertility

Limiting FactorsLimiting Factors Crops require 20 chemical elements Crops require 20 chemical elements at the right amount at the right at the right amount at the right time of yeartime of year MacronutrientsMacronutrients micronutrientsmicronutrients

High-quality agricultural soil hasHigh-quality agricultural soil has All the chemical elements required for All the chemical elements required for plantsplants

A physical structure that lets air and A physical structure that lets air and water move freelywater move freely

Retains water wellRetains water well Mixture of soil particle sizeMixture of soil particle size

Limiting FactorsLimiting Factors

Liebig’s LawLiebig’s Law Single factor determines the Single factor determines the growth and therefore the presence growth and therefore the presence of a species of a species

Growth of a plant is affected by Growth of a plant is affected by one limiting factor at a timeone limiting factor at a time

Limiting FactorsLimiting Factors

Two elements may have a Two elements may have a synergistic effectsynergistic effect A change in the availability of A change in the availability of one resource affects the response one resource affects the response of an organism to some other of an organism to some other resource.resource.

Chemical elements may become Chemical elements may become toxic when levels are to hightoxic when levels are to high

Controlling PestsControlling Pests Pests are undesirable Pests are undesirable

Competitors, parasites, and predatorsCompetitors, parasites, and predators Agricultural pests include:Agricultural pests include:

InsectsInsects NematodesNematodes Bacterial and viral diseasesBacterial and viral diseases WeedsWeeds VertebratesVertebrates

Loss can be largeLoss can be large Estimated at 1/3 of potential harvest Estimated at 1/3 of potential harvest and 1/10 of the harvested cropand 1/10 of the harvested crop

Controlling PestsControlling Pests

Farms are maintained in early stage Farms are maintained in early stage of ecological succession and of ecological succession and enriched by fertilizers and waterenriched by fertilizers and water Great area for cropsGreat area for crops Great area for early-successional Great area for early-successional plants (weeds)plants (weeds)

Weeds compete for all resourcesWeeds compete for all resources Light, water,nutrients, and space to Light, water,nutrients, and space to growgrow

Pesticides- HistoryPesticides- History

Stage 1 Broad Spectrum Stage 1 Broad Spectrum Inorganic ToxinsInorganic Toxins Search for chemicals that would Search for chemicals that would reduce abundance of pestsreduce abundance of pests

Goal was narrow-spectrum (species-Goal was narrow-spectrum (species-specific), but most were broad-specific), but most were broad-spectrumspectrum

Ex: Arsenic, toxic to all lifeEx: Arsenic, toxic to all life Killed pest and beneficial organismsKilled pest and beneficial organisms

Stage 2: Petroleum based sprays Stage 2: Petroleum based sprays and natural plant chemicals and natural plant chemicals 1930’s1930’s Ex: nicotineEx: nicotine

Pesticides- HistoryPesticides- History

Pesticides- HistoryPesticides- History

Stage 3: Artificial Organic Stage 3: Artificial Organic Compounds Compounds DDT, broad-spectrum DDT, broad-spectrum Aldrin and dieldrin used to control Aldrin and dieldrin used to control termites termites

ProblemsProblems Toxic to humans, has been found in breast Toxic to humans, has been found in breast milkmilk

Secondary OutbreaksSecondary Outbreaks Pests develop resistancePests develop resistance

Stage 4: Return to biological and Stage 4: Return to biological and ecological knowledgeecological knowledge IPM - Integrated Pest ManagementIPM - Integrated Pest Management

Goal is to reduce use of artificial Goal is to reduce use of artificial pesticidespesticides

Biological control- the use of Biological control- the use of biological predators and parasites to biological predators and parasites to control pestscontrol pests

BacillusBacillus thuringiensis thuringiensis (BT) - Proved safe and (BT) - Proved safe and effectiveeffective

Pesticides- HistoryPesticides- History

Integrated Pest Integrated Pest ManagementManagementIPM uses a combination of methodsIPM uses a combination of methods

Biological controlBiological control Chemical pesticidesChemical pesticides Methods of planting crops (mixed Methods of planting crops (mixed fields)fields)

Goal can be control not Goal can be control not elimination of pestelimination of pest Economically makes senseEconomically makes sense Does less damage to ecosystem, Does less damage to ecosystem, soil, water and airsoil, water and air

Other biological control agentsOther biological control agents Small wasps that parasitize Small wasps that parasitize caterpillarscaterpillars

Both effective and narrow spectrumBoth effective and narrow spectrum LadybugsLadybugs Sex pheromones (chemicals released Sex pheromones (chemicals released to attract opposite sex) used as to attract opposite sex) used as bait in trapsbait in traps

Biological ControlBiological Control

The Future of The Future of AgricultureAgriculture Three major technological Three major technological

approaches to agricultureapproaches to agriculture1.1. Modern mechanized agricultureModern mechanized agriculture

2.2. Resource-based agricultureResource-based agriculture Organic food productionOrganic food production

3.3. BioengineeringBioengineering

How can crop production How can crop production keep up with population keep up with population growth?growth? Increased Increased production per production per acreacre Technology drivenTechnology driven

New Crops and New Crops and HybridsHybrids New or yet unused New or yet unused plants could do plants could do well in poorer well in poorer agricultural soilagricultural soil

Green RevolutionGreen Revolution

The Green RevolutionThe Green Revolution

Name attached to the post WWII Name attached to the post WWII programs that have led to the programs that have led to the development of development of new strain of crops w/ higher new strain of crops w/ higher yieldyield

better resistance to disease better resistance to disease or better ability to grow under or better ability to grow under poor conditionspoor conditions

How can crop production How can crop production keep up with population keep up with population growth?growth? Better irrigation techniques Better irrigation techniques

Could improve crop yield and reduce Could improve crop yield and reduce overall water useoverall water use

Drip irrigationDrip irrigation HydroponicsHydroponics

Eating Lower on Food ChainEating Lower on Food Chain Same area of land could produce 10–Same area of land could produce 10–100 times more vegetation than meat 100 times more vegetation than meat per yearper year

How can crop production How can crop production keep up with population keep up with population growth?growth? Organic faming Organic faming

Three qualitiesThree qualities More like nature ecosystem than More like nature ecosystem than monoculturemonoculture

Minimizes negative environmental impactsMinimizes negative environmental impacts The food that results does not contain The food that results does not contain artificial compoundsartificial compounds

One of the fastest growing sectors One of the fastest growing sectors in US agriculturein US agriculture

Genetically Modified Genetically Modified FoodFood Scientist have been able to transfer Scientist have been able to transfer specific genetic characteristics from one specific genetic characteristics from one individual to another, from one population individual to another, from one population to another, and from one species to to another, and from one species to another. another.

Genetic engineering in agriculture involves Genetic engineering in agriculture involves several practicesseveral practices Faster and more efficient ways to develop hybridsFaster and more efficient ways to develop hybrids Introduction of the terminator geneIntroduction of the terminator gene Transfer of genetic properties from widely Transfer of genetic properties from widely divergent kinds of lifedivergent kinds of life

Genetically Modified Genetically Modified FoodFood Considerable interest in Considerable interest in developing crops developing crops With entirely new characteristicsWith entirely new characteristics

E.g. nitrogen fixationE.g. nitrogen fixation With tolerance of drought, cold, With tolerance of drought, cold, heat and toxic chemical elements. heat and toxic chemical elements.

Genetically Modified Genetically Modified CropsCrops Three methodsThree methods

1. Faster and more efficient 1. Faster and more efficient development of new hybridsdevelopment of new hybrids

2. Introduction of the “terminator 2. Introduction of the “terminator gene”gene”

3. Transfer of genetic properties 3. Transfer of genetic properties from widely divergent kinds of from widely divergent kinds of lifelife

New HybridsNew Hybrids

From an environmental perspective, From an environmental perspective, genetic engineering to develop hybrids genetic engineering to develop hybrids w/in a species is likely to be a benign w/in a species is likely to be a benign as the development of agricultural as the development of agricultural hybrids has been w/ conventional methods.hybrids has been w/ conventional methods.

Concern that genetic modification may Concern that genetic modification may produceproduce ““superhybrids”superhybrids” Could become pest or transfer genes to closely Could become pest or transfer genes to closely related weedsrelated weeds

The Terminator GeneThe Terminator Gene

Makes seeds from a crop sterileMakes seeds from a crop sterile Done for environmental and economic Done for environmental and economic reasonsreasons

Prevents a gmo from spreadingPrevents a gmo from spreading Protects the market for the corporation Protects the market for the corporation that developed itthat developed it

Critics note Critics note Farmer’s in poor nations must be able to Farmer’s in poor nations must be able to grow next years crops from their own grow next years crops from their own seedsseeds

Transfer of GenesTransfer of Genes

Genes transfer from one major life Genes transfer from one major life form to anotherform to another Most likely to have negative and Most likely to have negative and undesirable impactsundesirable impacts

E.g., E.g., BacillusBacillus thuringiensisthuringiensis Produce toxin that kills caterpillarsProduce toxin that kills caterpillars Gene identified and transferred to Gene identified and transferred to corncorn

Engineered corn now produces its own Engineered corn now produces its own pesticidepesticide

Bacillus thuringiensis bacteria(a natural pecticide). The genethat caused the pecticide (BT)was placed in corn throughgenetic engineering.

BT corn contains its ownpesticide in every cell ofthe plant.

Pollen from the BT corn is also toxic and when it lands on milkweed, monarch butterflies that eat the milkweed may die.

Transfer of GenesTransfer of Genes

Bt plants thought to be a Bt plants thought to be a constructive step in pest controlconstructive step in pest control No longer need to spray pesticideNo longer need to spray pesticide

Bt plants produce toxin in all Bt plants produce toxin in all cellscells Even in pollen that can spreadEven in pollen that can spread Monarch butterflies that eat pollen Monarch butterflies that eat pollen may diemay die

Transfer of GenesTransfer of Genes

Much concern worldwide about Much concern worldwide about the political, social and the political, social and environmental effects of environmental effects of genetic modification of crops.genetic modification of crops.

AquacultureAquaculture Most marine and Most marine and freshwater food freshwater food obtained by obtained by huntinghunting Not sustainableNot sustainable

Aquaculture- Aquaculture- the farming of the farming of food in aquatic food in aquatic habitatshabitats Important Important protein sourceprotein source

AquacultureAquaculture

Extremely productive on a per-area Extremely productive on a per-area basisbasis Flowing water brings food into the pond Flowing water brings food into the pond from outsidefrom outside

Can exploit multiple niches in the pondCan exploit multiple niches in the pond May be able to utilize waste products May be able to utilize waste products (treated sewage)(treated sewage)

Mariculture - the farming of ocean Mariculture - the farming of ocean fish.fish. Also increasing production of oysters Also increasing production of oysters and musselsand mussels