chapter 13

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

WlkUP8

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/WorldConc

ernVideos?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 agricultureShifting cultivationIndustrialized agriculture

No agricultureIntensive 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—increasing crop yields

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

klD2l2M

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

INCREASE SOIL QUALITY AND CROP YIELDS BY… 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

INCREASE SOIL QUALITY AND CROP YIELDS BY… 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.

PLANT COVER CROPS WINDBREAKS, ROTATE CROPS

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.

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 depletionPesticide 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

WaterloggingSediment 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 Ideal Pesticide 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.

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

number of harmful pesticides (DDT). 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).

PROTECTING FOOD RESOURCES: PEST MANAGEMENT

Advantages and disadvantages of conventional chemical pesticides.

Figure 13-28Figure 13-28

Integrated Pest Management Using a combination of BIOLOGICAL,

CHEMICAL, AND PHYSICAL pest management. Lower the use of pesticides Reduce pest populations

BIOLOGICAL METHODS Introduce predators Create habitats for predators Introduce parasites Introduce disease-carrying bacteria Introduce sterile males to lower

reproductive success Genetically modified plants that resist

pests

CHEMICAL METHODS Use pheromones to attract pests to traps Spray crops with hot water to scald pests Use less persistent pesticides Spray crops with soap solution

PHYSICAL METHODS Noise to repel pests Physical barriers Statues, scarecrows, etc.

Sustainable Agriculture

Results of 22 year study comparing organic and conventional farming.

Figure 13-34Figure 13-34

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.

THE GENE REVOLUTION Selective Breeding: (Take along time,

only mix similar species, not long before pests wipe out) Artificial selection is breeding two similar

organisms such as two types of corn or tomatoes to improve the quality of the food.

Cross breeding is breeding two different species.

Genetic engineering FASTER!!

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 GMOs could be

grown to help reduce malnutrition, reduce use of large amounts of inorganic fertilizers, use less water, grow faster and larger, etc.

Figure 13-20Figure 13-20

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

genetically modified food (GMF). We know too little about the long-term potential

harm to human and ecosystem health. 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?

Can GM foods save the world?

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 Why would eating more farm raised fish

and chicken reduce environmental affects? Which animals convert grain to biomass

faster? Food Chain!!

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.

Aquaculture Aquaculture species: Seaweeds, mussels,

oysters, mollusks, shrimp, salmon, trout, catfish

For aquaculture to be profitable it must: be marketable, inexpensive to raise, efficient at converting feed to biomass, grow quickly, and disease resistant

Downsides: it takes away natural habitats, water wastes, accidental release of non-native species, transmission of diseases into the wild

Fig. 13-24, p. 292

Trade-Offs

Aquaculture Advantages Disadvantages

High efficiency Needs large inputs of land, feed, and waterHigh 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 speciesLow 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

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.