CHAPTER 13

Food, Soil Conservation, and Pest Management

Soil- A renewable resource if maintained properly.

Eroded rock Mineral nutrients Decaying organic

matter Water Air Microorganisms

Weathering Physical

Wind, water, moving plates

Chemical acids

Biological Lichens, roots

Soil make-up How soil is formed…

Why is soil so important?

Nutrients needed by plants are in soil Nutrients by humans are then taken up

by plants or animals that get them from the soil

Water purifier Removes carbon from the atmosphere

and stores it as carbon compounds

Soil Layers

Soil horizons are viewed through a soil profile

O horizon= surface litter A horizon= topsoil and humus (partially

decomposed plants and animals and clay, silt, and sand)

B horizon= subsoil C horizon= parent rock Bedrock

Soil profiles in different biomes

Which biome(s) is most often converted to cropland?

Why do you think this is the case?

Water movement through soil Infiltration- Waters natural movement

down through soil dissolving minerals and organic matter and carrying them lower as it moves- leaching

Soil properties:

Soil is composed of Clay- smallest particle size Silt- medium Sand- larger

Loam is the best for plants. An even mixture of all three.

Textural Triangle

Soil properties continued…

Porosity or void fraction is a measure of the void (i.e., "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%.

How much “space” is available to “hold” water.

Which picture is more likely made up of a soil like gravel? Sand?

What is permeability?

http://techalive.mtu.edu/meec/module06/Permeability.htm

How do porosity and permeability of soil relate? LAB!

The relationship between Porosity and Permeability In some soils porosity and permeability have

a direct relationship, as you have more pores water can flow through easier.

In some soils porosity and permeability have an indirect relationship, as you have more pores there are more places for water to get trapped thus decreasing the permeability.

It depends on medium type and compaction of the medium.

Core Case Study: What is Golden Rice? http://www.youtube.com/watch?v=sbxA4

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FOOD SECURITY AND NUTRITION

Global food production has stayed ahead of population growth. However:

One of six people in developing countries cannot grow or buy the food they need.

Others cannot meet their basic energy needs (undernutrition / hunger) or protein and key nutrients (malnutrition).

Food Challenges for the FUTURE:

1)poverty 2)making and moving enough food to sustain a

growing population 3)doing so sustainably (not degrading soil and

water) Use of fossil fuels in farming Wastes from plants and animals Erosion of the soil Degradation of the minerals and vitamins from the

soil Polluting water by increasing fertilizer run-off, animal

waste run-off

FOOD SECURITY AND NUTRITION

Food security means that every person in a given area has daily access to enough nutritious food to have an active and healthy life. Need large amounts of macronutrients (protein,

carbohydrates, and fats).

Need smaller amounts of micronutrients (vitamins such as A,C, and E).

Food Security Act of 1985- subsidy for taking highly eroded land and planting it with grasses to restore soil.

FOOD SECURITY AND NUTRITION

One in three people has a deficiency of one or more vitamins and minerals, especially vitamin A, iodine (causes goiter - enlargement of thyroid gland), and iron (causes anemia).

Measles and diarrhea kill many children in developing countries.

Figure 13-2Figure 13-2

War and Corruption leading to Hunger

Starving children collecting ants to eat in famine-stricken Sudan, Africa which has been involved in civil war since 1983.

Money spent on weapons, manpower used for fighting, no stability, land maintained by rich only.

Figure 13-3Figure 13-3

Hunger from war…

http://www.youtube.com/user/WorldConcernVideos?v=q6gYK7474sE&feature=pyv

Solutions: Reducing Childhood Deaths from Hunger and Malnutrition There are several ways to reduce childhood

deaths from nutrition-related causes: Immunize children. Encourage breast-feeding. Prevent dehydration from diarrhea. Prevent blindness from vitamin A deficiency. Provide family planning. Increase education for women.

Overnutrition: Eating Too Much Over nutrition and lack of exercise can lead to

reduced life quality, poor health, and premature death. The same problems undernourished people face.

A 2005 Boston University study found that about 60% of American adults are overweight and 33% are obese (totaling 93%).

Americans spend $42 billion per year trying to lose weight. $24 billion per year is needed to eliminate world

hunger.

FOOD PRODUCTION

Croplands- grains, 77% of food on 11% of land 50% of most people’s diet is based on grains

Rangelands- meat and cattle, 16% of food on 29% of land

Oceanic Fisheries and aquaculture- fish, 7% of food

Industrial Food Production: High Input Monocultures

About 80% of the world’s food supply is produced by industrialized agriculture. Uses large amounts of fossil fuel energy, water,

commercial fertilizers, and pesticides to produce monocultures.

Greenhouses are increasingly being used taking up natural flow of land. (can cause erosion issues)

Plantations are being used in tropics for cash crops such as coffee, sugarcane, bananas.

Fig. 13-4, p. 275

Plantation agriculture

Shifting cultivation

Industrialized agriculture

No agriculture

Intensive traditional ag.

Nomadic herding

Industrial Food Production:

Livestock production in developed countries is industrialized: Feedlots are used to fatten up cattle before

slaughter. Most pigs and chickens live in densely

populated pens or cages. Most livestock are fed grain grown on cropland. Systems use a lot of energy and water

and produce huge amounts of animal waste. Lots of methane released (GHG).

What is the Japan-syndrome? Industrialization Less people farming

more $/person more meat wanted by people that now have more money more grain needed to feed animals less land to grow grain because more land needed for urbanization and livestock

Problems with sustainably growing enough food to sustain growing population: Soil erosion and depletion of minerals Water depletion and pollution from runoff Overgrazing Overfishing Increased fuel costs Increased atmospheric temperatures ALL LEAD TO BIODIVERSITY LOSS DUE TO

HABITAT LOSS AND RESOURCE DEGRADATION

Fig. 13-6, p. 276

Natural Capital

Croplands

• Help maintain water flow and soil infiltration • Food crops

• Provide partial erosion protection• Fiber crops

• Can build soil organic matter

• Crop genetic resources• Store atmospheric carbon

• Provide wildlife habitat for some species • Jobs

Ecological Services

Economic Services

Is food production in the US efficient?

Food production doubled with no increase in land use since 1950. Mostly due to

genetic engineering

Net Energy Loss- 10 units of nonrenewable fossil fuels used to get 1 unit of food.

Yes No

Traditional Agriculture: Low Input Polyculture

Many farmers in developing countries use low-input agriculture to grow a variety of crops on each plot of land, interplanting, through: Polyvarietal cultivation: planting several

genetic varieties of the same crop.

Intercropping: two or more different crops grown at the same time in a plot. Ex. Grain that uses Nitrogen and legume that puts it back into the soil.

Agroforestry: crops and trees are grown together. Trees provide shade and lower transpiration rate.

Polyculture: different plants are planted together and they mature at different times. Keeps ground covered with plants and reduces erosion.

Traditional Agriculture: Low Input Polyculture

Research has shown that, on average, low input polyculture produces higher yields than high-input monoculture. Keeps soil fertile,

helps with water purification.

Figure 13-8Figure 13-8

SOIL EROSION AND DEGRADATION

Soil erosion lowers soil fertility and can overload nearby bodies of water with eroded sediment. Sheet erosion: surface water or wind peel

off thin layers of soil. Rill erosion: fast-flowing little rivulets of

surface water make small channels. Gully erosion: fast-flowing water join

together to cut wider and deeper ditches or gullies.

Soil erosion problems and solutions: http://www.youtube.com/watch?v=QT7h

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Desertification: Degrading Drylands

About one-third of the world’s land has lost some of its productivity because of drought and human activities that reduce or degrade topsoil.

China’s dustbowlFigure 13-12Figure 13-12

Salinization and Waterlogging Repeated

irrigation can reduce crop yields by causing salt buildup in the soil and waterlogging of crop plants.

Figure 13-13Figure 13-13

Fig. 13-15, p. 281

CleanupPrevention

Soil Salinization

Solutions

Reduce irrigation

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

Flush soil (expensive and wastes water)

Stop growing crops for 2–5 years

Install underground drainage systems (expensive)

Salinization and Waterlogging of Soils: A Downside of Irrigation

Example of high evaporation, poor drainage, and severe salinization.

White alkaline salts have displaced crops.

Figure 13-14Figure 13-14

SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION Modern farm machinery can plant crops

without disturbing soil (no-till and minimum tillage). Conservation-tillage farming:

Increases crop yield. Raises soil carbon content. Lowers water use. Lowers pesticides. Uses less tractor fuel.

Downside-expensive machinery

SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION

Terracing, contour planting, strip cropping, alley cropping, and windbreaks can reduce soil erosion.

Figure 13-16Figure 13-16

SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION Fertilizers can help restore soil nutrients,

but runoff of inorganic fertilizers can cause water pollution. Organic fertilizers: from plant and animal

(fresh, manure, or compost) materials. Commercial inorganic fertilizers: Active

ingredients contain nitrogen, phosphorous, and potassium and other trace nutrients.

What is the green revolution? High input agriculture and produces

more food per unit of land. Use of pesticides Use of irrigation Use of fertilizers Growing monocultures of genetically

engineered plants Keep ground covered all year long with

different plants

THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT Lack of water, high costs for small farmers,

and physical limits to increasing crop yields hinder expansion of the green revolution.

Since 1978 the amount of irrigated land per person has declined due to: Depletion of underground water supplies. Inefficient irrigation methods. Salt build-up. Cost of irrigating crops.

THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT Modern agriculture has a greater harmful

environmental impact than any human activity.

Loss of a variety of genetically different crop and livestock strains might limit raw material needed for future green and gene revolutions. In the U.S., 97% of the food plant varieties

available in the 1940 no longer exist in large quantities.

Fig. 13-18, p. 285

Biodiversity Loss Soil Water Air Pollution Human Health Loss and degradation of grasslands, forests, and wetlands

Erosion Water waste Greenhouse gas emissions from fossil fuel use

Nitrates in drinking water

Loss of fertility Aquifer depletion

Pesticide residues in drinking water, food, and air

Salinization Increased runoff and flooding from cleared land

Other air pollutants from fossil fuel use

Fish kills from pesticide runoff

Waterlogging

Sediment pollution from erosion Greenhouse gas

emissions of nitrous oxide from use of inorganic fertilizers

Contamination of drinking and swimming water with disease organisms from livestock wastes

Desertification

Killing wild predators to protect livestock

Fish kills from pesticide runoff

Surface and groundwater pollution from pesticides and fertilizers Belching of the

greenhouse gas methane by cattle

Loss of genetic diversity of wild crop strains replaced by monoculture strains

Bacterial contamination of meat

Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes

Pollution from pesticide sprays

THE GENE REVOLUTION

Selective Breeding: (Take along time, only mix similar species, not long before pests wipe out) Artificial selection has been used for

centuries to develop genetically improved varieties of crops.

Cross breeding has also been used. Genetic engineering develops improved

strains at an exponential pace compared to selective breeding.

What is gene splicing and how does it lead to recombinant DNA? http://www.youtube.com/watch?v=uQ9M

-r1dXcE

Mixing Genes

Genetic engineering involves splicing a gene from one species and transplanting the DNA into another species.

Figure 13-19Figure 13-19

THE GENE REVOLUTION

The winged bean, a GMF, could be grown to help reduce malnutrition and the use of large amounts of inorganic fertilizers.

Figure 13-20Figure 13-20

Problems with the gene revolution: Controversy has arisen over the use of

genetically modified food (GMF). Critics fear that we know too little about the long-

term potential harm to human and ecosystem health.

There is controversy over legal ownership of genetically modified crop varieties and whether GMFs should be labeled.

Could create herbicide resistant plants Could create new allergies Should a seed company have the legal right to sue

a farmer for using a second year seed?

PRODUCING MORE MEAT

About half of the world’s meat is produced by livestock grazing on grass.

The other half is produced under factory-like conditions (feedlots). Densely packed livestock are fed grain or

fish meal. Antibiotic injections, hormone injections

Meat Production

Eating more chicken and farm-raised fish and less beef and pork reduces harmful environmental impacts of meat production.

Why do you think this is?

Fig. 13-21, p. 289

Trade-Offs

Animal Feedlots

Advantages Disadvantages

Increased meat production

Need large inputs of grain, fish meal, water, and fossil fuelsHigher profits

Concentrate animal wastes that can pollute water

Less land use

Reduced overgrazing

Reduced soil erosion

Antibiotics can increase genetic resistance to microbes in humans

Help protect biodiversity

CATCHING AND RAISING MORE FISH AND SHELLFISH Government subsidies given to the fishing

industry are a major cause of overfishing. Subsidies are not taken away because fishing

industry would suffer and many would lose jobs. Redirect money toward new jobs in fishing industry. Marine Stewardship Council (MSC)- sustainable

fishing seal 3 ways to sustain fisheries

Quotas Reserves Regulating gear and methods Limiting the number of fishing boats

Aquaculture: Aquatic Feedlots Raising large numbers of fish and shellfish in

ponds and cages is world’s fastest growing type of food production.

Fish farming involves cultivating fish in a controlled environment and harvesting them in captivity.

Fish ranching involves growing specific species that live part of their lives in freshwater and part in saltwater. Fish are held for the first few years, released,

and then harvested when they return to spawn.

Fig. 13-24, p. 292

Trade-Offs

Aquaculture

Advantages Disadvantages

High efficiency Needs large inputs of land, feed, and water

High yield in small volume of water

Large waste output

Destroys mangrove forests and estuaries

Can reduce overharvesting of conventional fisheries Uses grain to feed

some species

Low fuel use Dense populations vulnerable to disease

Tanks too contaminated to use after about 5 years

High profits

Profits not tied to price of oil

Fig. 13-25, p. 293

Solutions

More Sustainable Aquaculture

• Use less fishmeal feed to reduce depletion of other fish

• Improve management of aquaculture wastes

• Reduce escape of aquaculture species into the wild

• Restrict location of fish farms to reduce loss of mangrove forests and estuaries

• Farm some aquaculture species in deeply submerged cages to protect them from wave action and predators and allow dilution of wastes into the ocean

• Certify sustainable forms of aquaculture

SOLUTIONS: MOVING TOWARD GLOBAL FOOD SECURITY

People in urban areas could save money by growing more of their food. Urban gardens provide

about 15% of the world’s food supply.

Up to 90% of the world’s food is wasted.

Figure 13-26Figure 13-26

Government Policies and Food Production Governments use three main approaches to

influence food production: Control prices to keep prices artificially low. Provide subsidies to keep farmers in business. Let the marketplace decide rather that

implementing price controls.

Solutions: Steps Toward More Sustainable Food Production We can increase food security by slowing

populations growth, sharply reducing poverty, and slowing environmental degradation of the world’s soils and croplands.

PROTECTING FOOD RESOURCES: PEST MANAGEMENT

Organisms found in nature (such as spiders) control populations of most pest species as part of the earth’s free ecological services.

Figure 13-27Figure 13-27

PROTECTING FOOD RESOURCES: PEST MANAGEMENT

Advantages and disadvantages of conventional chemical pesticides.

Figure 13-28Figure 13-28

The ideal Pesticide and the Nightmare Insect Pest The ideal pest-killing chemical has these

qualities: Kill only target pest. Not cause genetic resistance in the target

organism. Disappear or break down into harmless

chemicals after doing its job. Be more cost-effective than doing nothing.

Superpests Superpests are

resistant to pesticides.

Superpests like the silver whitefly (left) challenge farmers as they cause > $200 million per year in U.S. crop losses.

Figure 13-29Figure 13-29

Pesticide Protection Laws in the U.S. Government regulation has banned a number

of harmful pesticides but some scientists call for strengthening pesticide laws. The Environmental Protection Agency (EPA), the

Department of Agriculture (USDA), and the Food and Drug Administration (FDA) regulate the sales of pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).

The EPA has only evaluated the health effects of 10% of the active ingredients of all pesticides.

Fig. 13-30, p. 299

What Can You Do?

Reducing Exposure to Pesticides

• Grow some of your food using organic methods.

• Buy organic food.

• Wash and scrub all fresh fruits, vegetables, and wild foods you pick.

• Eat less or no meat.

• Trim the fat from meat.

Other Ways to Control Pests

There are cultivation, biological, and ecological alternatives to conventional chemical pesticides. Fool the pest through cultivation practices. Provide homes for the pest enemies. Implant genetic resistance. Bring in natural enemies. Use pheromones to lure pests into traps. Use hormones to disrupt life cycles.

Other Ways to Control Pests Genetic

engineering can be used to develop pest and disease resistant crop strains.

Both tomato plants were exposed to Both tomato plants were exposed to destructive caterpillars. The genetically destructive caterpillars. The genetically altered plant (right) shows little damage.altered plant (right) shows little damage.

Figure 13-32Figure 13-32

SOLUTIONS: SUSTAINABLE AGRICULTURE Three main ways to reduce hunger and

malnutrition and the harmful effects of agriculture: Slow population growth. Sharply reduce poverty. Develop and phase in systems of more

sustainable, low input agriculture over the next few decades.

Fig. 13-33, p. 302

Solutions

Sustainable Organic Agriculture

More Less

High-yield polyculture

Soil erosion

Soil salinizationOrganic fertilizers

Aquifer depletionBiological pest control Overgrazing

Integrated pest management

Overfishing

Loss of biodiversity

Efficient irrigation Loss of prime

croplandPerennial crops

Crop rotationFood waste

Water-efficient crops

Subsidies for unsustainable farming and fishing

Soil conservation

Subsidies for sustainable farming and fishing

Population growth

Poverty

Sustainable Agriculture

Results of 22 year study comparing organic and conventional farming.

Figure 13-34Figure 13-34

Solutions: Making the Transition to More Sustainable Agriculture

More research, demonstration projects, government subsidies, and training can promote more sustainable organic agriculture.

Figure 13-35Figure 13-35