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 3000 tried as crops 300 grown for food 100 species used on large scale for food 15 to 20 species15 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
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
Agroecosystems Agroecosystems differ from natural ecosystems in five major ways: 1.Farming attempts to stop ecological succession 2.Species diversity is low a.farmers usually practice monoculture b.monoculture tends to 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 disturbance a.plowing can 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.China 2.United States 3.India 4.Canada 5.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 hence, plant material originally unusable for man is converted into food sources that can be ingested by man
Wilkes, Angela. My first word board book. (1999) DK Publishing, NY.
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 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 5 o 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.
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