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Food and Agriculture. History and Types of Agriculture. Demand-based agriculture - production determined by economic demand and limited by classical economic supply and demand theory. This approach became common during the industrial revolution.

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History and Types of Agriculture

Demand-based agriculture - production determined by economic demand and limited by classical economic supply and demand theory. This approach became common during the industrial revolution.

Resource-based agriculture - production determined by resource availability; economic demand usually exceeds production. This approach was the original type of farming 10,000 years ago. Modern approaches are very high tech and somewhat more expensive.

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Plant Food Sources

  • 250,000 plant species Þ

  • 3000 tried as crops Þ

  • 300 grown for food Þ

  • 100 species used on large scale for food Þ

  • 15 to 20 species provide vast majority (90%) of man’s food needs

  • It takes about 16 pounds of grain to produce one pound of edible meat

  • Largest crop volumes provided by: wheat, rice, corn, potatoes, barley

    • Wheat and rice supply ~60% of human caloric intake

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Sweet Potato

Cassava (source of tapioca)






Other Plant Food Sources

  • Peanut

  • Watermelon

  • Cabbage

  • Onion

  • Bean

  • Pea

  • Sunflower Seed

  • Mango

  • Millet

  • Banana

  • Tomato

  • Sugar Beet

  • Rye

  • Orange

  • Coconut

  • Cottonseed

  • Apple

  • Yam

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Types of Crops

  • Cash crops vs. subsistence crops

    • cash crops may provide non-food products (latex)

    • provide products which do not make up our primary nutrition (tea, coffee)

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  • Ecosystem created by agricultural practices

    • characterized by low

      • Genetic diversity

      • Species diversity

      • Habitat diversity

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Agroecosystems differ from natural ecosystems in five major ways:

  • Farming attempts to stop ecological succession

  • Species diversity is low

    • farmers usually practice monoculture

    • monoculture tends to ß soil fertility

  • Farmers plant species (crops) in an orderly fashion - this can make pest control more difficult

  • Food chains are far more simple in agroecosystems

  • Plowing is like no other natural disturbance

    • plowing can Ý erosion

    • cause more nutrient loss (which is replaced by fertilizer)

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World Food Supply and the Environment

  • Our current food problem is the result of our human population

  • Food production depends upon favorable environmental conditions

  • Agriculture changes the environment - such changes can be detrimental

  • Food supply can be adversely affected by social unrest that influence agriculture

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Grain Production

  • Grain production increased from 631 to 1780 million metric tons from 1950 to 1990.

  • Has leveled off since then

  • Top five countries in order of producing the most amount of grain are:

    • China

    • United States

    • India

    • Canada

    • Ukraine

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· domesticated livestock (sheep, pigs, chickens, cattle) are an important food source for humans

· ruminants (four-chambered stomachs) contain bacteria that can convert plant tissue to animal protein/fat Þ hence, plant material originally unusable for man is converted into food sources that can be ingested by man

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Wilkes, Angela. My first word board book. (1999) DK Publishing, NY.

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Meat Sources

  • About 90% of all meat and milk are consumed by United States, Europe and Japan which constitute only 20% of world population

  • About 90% of the grain grown in the United States is used for animal feed

  • 16 kg of grain Þ 1 kg of meat

    • By eating grain instead would get 20 times the calories and 8 times the protein

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Malnutrition and Famines

  • One quarter of the human population is malnourished

    • Sub-Saharan Africa (~225 million)

    • East and Southeast Asia (~275 million)

    • South Asia (~250 million)

    • Parts of Latin America

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  • Stem from not enough calories per day in addition to not getting the necessary amounts of carbohydrates, proteins, lipids (fats), minerals, and vitamins

  • Generally diets are high in starches

  • Famine conditions

    • Major droughts -- Political instability

    • Population sizes -- Land Seizures

    • Massive immigration -- Pestilence

    • Floods -- Distribution breakdown

    • Wars --Panic buying

    • Chaos in economy -- Hoarding

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Limits on Food Production

· arable land

· precipitation

· temperature

· global warming (ice age temp was only 5o C less than now!)

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Methods to Increase Food Supply

  • Improved irrigation and utilization of water

    • Drip irrigation

  • Increasing arable land

    • Difficult because of precipitation and temperature

  • Eating lower on the food chain

    • Most rangeland is not arable and humans cannot utilize grass/hay as food; therefore, this argument is not considered valid

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Methods to Increase Food Supply

  • Food distribution modification

    • Today distribution of food is a major problem in Africa/Asia

    • Best solution: teach locals how to best utilize their land with appropriate technology so they can attempt to support themselves and not rely on others.

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New vs. Old


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Soil Resources

  • What is Soil?

  • Ways We Use and Abuse Soil

  • Erosion

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The problem with chemicals

  • Groundwater contamination

  • Effects of low concentrations?

  • Bioaccumulation and Biomagnification

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Kill unwanted pests that carry disease (rats, mosquitoes, Tse-Tse flies)

Increase food supplies

More food means food is less expensive

Effective and fast-acting

Newer pesticides are safer, more specific

Reduces labor costs on farms

Food looks better

Agriculture is more profitable

Accumulate in food chain

Pests develop resistance – 500 species so far

Resistance creates pesticide treadmill

Estimates are $5-10 in damage done for $1 spent on pesticide

Pesticide runoff

Destroy bees - $200 million

Threaten endangered species

Affect egg shell of birds

5% actually reach pest

~20,000 human deaths/year

Pesticides Pro and Con

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Types of Pesticides Tse-Tse flies)

  • Biological – Ladybugs, parasitic wasps, etc.

  • Carbamates effect nervous system of pests more water soluble than chlorinated hydrocarbons

    • Aldicarb, aminocarb, carbaryl (Sevin), carbofuran, Mirex

  • Chlorinated Hydrocarbons affect nervous system –

    • Aldrin, Chlordane, DDT, dieldrin, lindane and paradichlorobenzene

  • Fumigants are used to sterilize soil and prevent grain infestation

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Types of Pesticides Tse-Tse flies)

  • Inorganic – arsenic, copper, lead, mercury

    • Highly toxic and bioaccumulation

  • Organic or natural – derived from plants such as tobacco and chrysanthemum

  • Organophosphates – extremely toxic, low persistence

    • Malathion, parthion, chlophyrifos, acepate, propetamphos and trichlofon

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Integrated Pest Management Tse-Tse flies)

  • Some practices for preventing pest damage may include

    • inspecting crops and monitoring crops for damage

    • using mechanical trapping devices

    • natural predators (e.g., insects that eat other insects)

    • insect growth regulators

    • mating disruption substances (pheromones)

    • if necessary, chemical pesticides

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Parts of IPM Tse-Tse flies)

  • Polyculture instead of monoculture

  • Intercropping – alternate rows of crops that have different pests

  • Planting pest-repellent crops

  • Mulch to control weeds

  • Natural insect predators – ladybugs, preying mantis, birds

  • Rotating crops to disrupt insect cycles

  • Using Pheromones to attract insects to traps

  • Releasing sterilized insects