Food and Agriculture

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.

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.

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

Other Plant Food Sources1. Potatoes2. Barley3. Sweet Potato4. Cassava

(source of tapioca)

5. Grape6. Soybean7. Oats8. Sorghum9. Sugarcane

10. Millet11. Banana12. Tomato13. Sugar Beet14. Rye15. Orange16. Coconut17. Cottonseed18. Apple19. Yam

20. Peanut21. Watermelon22. Cabbage23. Onion24. Bean25. Pea26. Sunflower

Seed27. Mango

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)

Agroecosystems

• Ecosystem created by agricultural practices–characterized by low

• Genetic diversity• Species diversity• Habitat diversity

AgroecosystemsAgroecosystems differ from natural ecosystems

in five major ways:1.Farming attempts to stop ecological succession2.Species diversity is low

a.farmers usually practice monocultureb.monoculture tends to ß soil fertility

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

4.Food chains are far more simple in agroecosystems

5.Plowing is like no other natural disturbancea.plowing can Ý erosion b.cause more nutrient loss (which is replaced

by fertilizer)

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

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:1. China2. United States3. India4. Canada5. Ukraine

Livestock

· 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

Wilkes, A

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Publishing, N

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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

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

Malnutrition/Famines• 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

Limits on Food Production

· arable land· precipitation· temperature· global warming (ice age temp was

only 5o C less than now!)

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

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.

New vs. OldAgriculture

Soil Resources

• What is Soil?• Ways We Use and Abuse Soil• Erosion

How much Land is Arable?

Pests and Pesticides

The problem with chemicals

• Groundwater contamination• Effects of low concentrations?• Bioaccumulation and Biomagnification

Pesticides Pro and Con• 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

Types of Pesticides• 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

Types of Pesticides• 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

Integrated Pest Management

• 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

Parts of IPM• 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