Chapter 14: Food & Soil Resources. three systems T he three systems humans depend on for their food supply Croplands (77%) – land used for planting crops;

Chapter 14: Food & Soil Resources

Chapter 14: Food & Soil Resources

The three systemsthree 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)

HumanFood Supply

Rangelands FisheriesCroplands

Major increase in food production post-1950

TractorsFarm Equip.

Irrigation

FertilizersPesticides

FeedlotsFeed Pens

GrowthHormones

CarefulBreeding

High-TechGear &

Electronics

Aquaculture

input

Human Population Growth and Food Production

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)

Lack of Diversity in FoodLack of Diversity in Food

30,000 edible plant species

But 90% of all food only comes from 15 plants [esp. wheat, rice, corn] and 8 animals- [esp. beef, pork, chicken]

Fish-1% energy6 % protein

3 grain crops that provide

“more than ½ of the calories

people consume”.

Major Types of AgricultureMajor 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

Industrialized agricultureIndustrialized agriculture

Shifting cultivationShifting cultivation

Plantation agriculturePlantation agriculture

Nomadic herdingNomadic herding

Intensive traditional agricultureIntensive traditional agriculture

No agricultureNo agricultureFig. 12.2, p. 263

The Green RevolutionThe Green Revolutionincreased 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!

Green-Revolution- increasing global food production…

Green-Revolution- increasing global food production…

Farm more land = Increase crop yield / land area

High-yieldmonocultures = selective breeding

genetic engineering (GMO’s)

High Input = high energy input (8% world oil)

fertilizers, pesticides, water

High intensity frequency of

cropping= dwarf varieties- 3-5x yield

multicropping (2-3/year)

MonoculturesMonocultures• 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”).

Figure 9.4aWheat monoculture in Washington

Green revolution: Environmental impactsGreen 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.

First green revolution(developed countries)First green revolution(developed countries)

Second green revolution(developing countries)

Second green revolution(developing countries)

Major International agricultural research centers and seed banksMajor International agricultural research centers and seed banks

Energy Use in Food Production:Industrial Agriculture

(United States)

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.

Energy Use in Food Production: Traditional and Traditional Intensive

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-

1. Polyvarietals - varieties of 1 crop

2. Intercropping - 2+ different on same plot (legumes/grain)

3. Agroforestry/alley cropping - crops/trees together

4. Polyculture - many plants maturing at different times on same plot

Advantages include: < energy input, erosion/weather protection, pest/herbicides not needed

Polyculture

Agroforestry

Intercropping

Polyvarietals

Soil Erosion and DegradationSoil Erosion and DegradationCauses: 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.

Causes of soil degradationCauses of soil degradation

Most soil degradation is caused by:

• livestock overgrazing

• deforestation

• cropland agriculture

Figure 8.2

Types of soil erosionTypes of soil erosion

Figure 8.11

Splash erosion

Rill erosion

Gully erosion

Sheet erosion

DesertificationDesertification

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”.

The Dust BowlThe 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

DesertificationDesertification

ConsequencesCauses

Worsening drought

Famine

Economic losses

Lower living standards

Environmentalrefugees

Overgrazing

Deforestation

Erosion

Salinization

Soil compaction

Natural climate change

Preventing soil degradationPreventing soil degradation

Several farming strategies to prevent soil degradation:• Crop rotation

• Contour farming

• Intercropping

• Terracing

• Shelterbelts

• Conservation tillage

Soil conservationSoil 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 districts worked with farmers to disseminate scientific knowledge and help them conserve their soil.

Crop rotationCrop rotation• Alternating the crop planted (e.g., between corn and

soybeans) can restore nutrients to soil and fight pests and disease.

Figure 8.16a

Contour farmingContour farming

• Planting along contour lines of slopes helps reduce erosion on hillsides.

Figure 8.16b

IntercroppingIntercropping• Mixing crops such as in strip cropping can provide

nutrients and reduce erosion.

Figure 8.16c

(c) Alley cropping

TerracingTerracing• 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.

ShelterbeltsShelterbelts

• Rows of fast-growing trees around crop plantings provide windbreaks, reducing erosion by wind.

Figure 8.16e

Conservation tillageConservation 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

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

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

DisadvantagesAdvantages

Trade-Offs

Conservation Tillage

Central Case: No-Till Agriculture in BrazilCentral 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.

IrrigationIrrigation• 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.

Waterlogging and salinizationWaterlogging 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.

Reduce irrigation

Switch to salt-tolerant crops(such as barley, cotton, sugar beet)

Prevention

Flushing soil(expensive andwastes water)

Not growing crops for 2-5 years

Installing under- ground drainagesystems (expensive)

Cleanup

Solutions

Soil Salinization

Global fertilizer usagesGlobal fertilizer usages• Fertilizer use has risen dramatically in the past 50 years.

Figure 8.19b

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%

OvergrazingOvergrazing

• 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

OvergrazingOvergrazing

• Overgrazing can set in motion a series of positive feedback loops.

Figure 8.21

Global food productionGlobal food productionWorld agricultural production has risen faster than

human population.

Figure 9.1

Global food securityGlobal 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.

NutritionNutrition• 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

Food Production, Nutrition and Environmental EffectsFood 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

Fig. 12.9, p. 269

Poverty MalnutritionDecreasedresistanceto disease

High deathrate forchildren

Decreasedenergy

Decreasedability

to learn

Decreasedability

to work

Shortenedlife

expectancy

Feedback loop

Biodiversity Loss

Loss and degradation of habitat fromclearing grasslands and forests anddraining wetland

Fish kills from pesticide runoff

Killing of wild predators to protectlivestock

Loss of genetic diversity fromreplacing thousands of wild cropstrains with a few monoculture strains

Soil

Erosion

Loss of fertility

Salinization

Waterlogging

Desertification

Environmental effects of food production

Air Pollution

Greenhouse gas emissions from fossilFuel issue

Other air pollutants from fossil fuel use

Pollution from pesticide sprays

WaterWater waste

Aquifer depletion

Increased runoff andflooding from land clearedto grow crops

Sediment pollution fromerosion

Fish kills from pesticiderunoff

Surface and groundwaterpollution from pesticidesand fertilizers

Overfertilization of lakesand slow-moving riversfrom runoff of nitrates and phosphates fromfertilizers, livestockwastes, and foodprocessing wastes

Human Health

Nitrates in drinking water

Pesticide residues in drinking water,food, and air

Contamination of drinking andswimming water with disease organisms from livestock wastes

Bacterial contamination of meat

Pesticide usePesticide 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

Biological controlBiological 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.”)

Biological controlBiological control

• Biocontrol has had success stories.

• Bacillus thuringiensis (Bt) = soil bacterium that kills many insects. In many cases, seemingly safe and effective.

Figure 9.7

Cactus moth, Cactoblastis cactorum (above), was used to wipe out invasive prickly pear cactus in Australia.

But biocontrol is riskyBut 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.

Integrated pest management (IPM)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

Genetic modification of foodGenetic 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.

Some GM foodsSome GM foods

Figure 9.12

Golden rice: Enriched with vitamin A.But too much hype?

Bt crops: Widely used on U.S. crops.But ecological concerns?

Ice-minus strawberries: Frost-resistant bacteria sprayed on.Images alarmed public.

FlavrSavr tomato: Better taste?But pulled from market.

Prevalence of GM foodsPrevalence of GM foods

Figure 9.13

Scientific concerns about GM organismsScientific 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?

Socioeconomic and political concerns about GM productsSocioeconomic 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?

Europe vs. AmericaEurope vs. America• Europe: 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.

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

Preserving crop diversityPreserving 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.

Seed banks preserve seeds, crop varietiesSeed 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

Animal agriculture: Livestock and poultryAnimal agriculture: Livestock and poultry

• Consumption of meat has risen faster than population over the past several decades.

Figure 9.15

Feedlot agricultureFeedlot agriculture• Increased 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

Feed lotsFeed lots• More production of livestock in smaller,

condensed spaces; Produce more using less space and energy

• Increases need for antibiotics due to enclosed spaces; leads to issues of cruelty to animals

• Hormones given to produce larger animals for more meat= more $!

Feedlot agriculture: Environmental impactsFeedlot agriculture: Environmental impacts

• Immense amount of waste produced, polluting air and water nearby

• Intense usage of chemicals (antibiotics, steroids, hormones), some of which persist in environment

• However, if all these animals were grazing on rangeland, how much more natural land would be converted for agriculture?

Food choices = energy choicesFood 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

Grain feed input for animal outputGrain feed input for animal output

• Some animal food products can be produced with less input of grain feed than others.

Figure 9.17

Land and water input for animal outputLand 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

AquacultureAquaculture

• The raising of aquatic organisms for food in controlled environments

• Provides 1/3 of world’s fish for consumption

• 220 species being farmed

• The fastest growing type of food production

Benefits of aquacultureBenefits of aquaculture

• Provides reliable protein source for people, increases food security

• Can be small-scale, local, and sustainable

• Reduces fishing pressure on wild stocks, and eliminates bycatch

• Uses fewer fossil fuels than fishing

• Can be very energy efficient

Environmental impacts of aquacultureEnvironmental 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.

Catching and Raising More FishCatching and Raising More Fish

Fisheries Fisheries

Fishing methods (See Fig. 14-24 p. 299) Fishing methods (See Fig. 14-24 p. 299)

Sustainable yield Sustainable yield

Overfishing- decreased biodiversity; affects aquatic food chains; bycatch; loss of food

Overfishing- decreased biodiversity; affects aquatic food chains; bycatch; loss of food

Commercial extinction Commercial extinction

Aquaculture- collectively involves fish farming and ranching; salmon and shrimp

Aquaculture- collectively involves fish farming and ranching; salmon and shrimp

Environmental impacts of aquacultureEnvironmental 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

purse-seine

drift net

aquaculture

trawl bag

3 methods used to catch fish:

Highly efficient

High yield in smallvolume of water

Increased yieldsthrough cross-breeding and genetic engineering

Can reduce over-harvesting of conventional fisheries

Little use of fuel

Profit not tied to price of oil

High profits

Advantages

Large inputs of land, feed, And water needed

Produces large and concentrated outputs of waste

Destroys mangrove forests

Increased grain productionneeded to feed some species

Fish can be killed by pesticide runoff from nearby cropland

Dense populations vulnerable to disease

Tanks too contaminated touse after about 5 years

Disadvantages

Trade-Offs

Aquaculture

• Reduce use of fishmeal as a feed to reduce depletion of other fish

• Improve pollution management of aquaculture wastes

• Reduce escape of aquaculture species into the wild

• Restrict location of fish farms to reduce loss of mangrove forests and other threatened areas

• Farm 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 ocean

• Set up a system for certifying sustainable forms of aquaculture

Solutions

More Sustainable Aquaculture

Sustainable agricultureSustainable agriculture• Agriculture that can practiced the same way far into the

future• Does not deplete soils faster than they form• Does not reduce healthy soil, clean water, and

genetic diversity essential for long-term crop andlivestock production

• Low-input agriculture = small amounts of pesticides, fertilizers, water, growth hormones, fossil fuel energy, etc.

• Organic agriculture = no synthetic chemicals used. Instead, biocontrol, composting, etc.

Organic farmingOrganic farming• Small percent of market, but is growing fast

– 1% of U.S. market, but growing 20%/yr

– 3–5% of European market, but growing 30%/yr

Organic produce:• Advantages for consumers: healthier; environmentally

better

• Disadvantages for consumers: less uniform and appealing-looking; more expensive

Conclusions: ChallengesConclusions: 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.

Conclusions: ChallengesConclusions: 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.

Conclusions: SolutionsConclusions: 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.

Conclusions: SolutionsConclusions: 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.

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 les food

•Reduce or eliminate meat consumption

•Feed pets balanced grain foods instead of meat

•Use organic farming to grow some of your food

•Buy organic food

•Compost your food wastes

What Can You Do?

Sustainable Agriculture

REVIEW QUESTIONS!

QUESTION: ReviewQUESTION: ReviewIntegrated pest management may involve all of the

following EXCEPT… ?

a. Close population monitoring

b. Biocontrol

c. Exclusive reliance on pesticides

d. Habitat modification

e. Transgenic crops

QUESTION: ReviewQUESTION: Review

What do seed banks do?

a. Lend money to farmers to buy seeds

b. Pay farmers to store seeds

c. Buy seeds from farmers

d. Store seeds to maintain genetic diversity

e. None of the above

QUESTION: ReviewQUESTION: Review

Which is NOT a benefit of aquaculture?

a. Provides a reliable protein source

b. Reduces pressure on natural fisheries

c. Produces no waste

d. Uses fewer fossil fuels than commercial fishing

e. All of the above are benefits

QUESTION: Weighing the IssuesQUESTION: 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.

QUESTION: Interpreting Graphs and DataQUESTION: Interpreting Graphs and Data

With 500 kg of water, you could produce … ?

a. 2 kg of protein from milk

b. Protein from 50 chickens

c. 750 kg of protein from beef

d. 15 eggsFigure 9.18b

QUESTION: ViewpointsQUESTION: 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.

QUESTION: ReviewQUESTION: ReviewWhich 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.

QUESTION: ReviewQUESTION: 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.

QUESTION: ReviewQUESTION: Review

Erosion occurs through… ?

a. Deforestation.

b. Excessive plowing.

c. Overgrazing rangelands.

d. Two of the above.

e. All of the above.

QUESTION: ReviewQUESTION: Review

Drip 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.

QUESTION: Weighing the IssuesQUESTION: Weighing the IssuesYou are farming an extremely steep slope that is sunny and

very windy. What strategies would you consider using?

a. Crop rotation

b. Contour farming

c. Intercropping

d. Terracing

e. Shelterbelts

f. No-till farming

QUESTION: Interpreting Graphs and DataQUESTION: Interpreting Graphs and Data

Grain produced per person has… ?

a. Risen steadily

b. Fallen sharply

c. Increased since 1983

d. Decreased since 1983

Figure 8.3