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
Potatoes Barley Sweet Potato Cassava (source of tapioca) Grape Soybean Oats Sorghum Sugarcane Other Plant Food Sources • Peanut • Watermelon • Cabbage • Onion • Bean • Pea • Sunflower Seed • Mango • Millet • Banana • Tomato • Sugar Beet • Rye • Orange • Coconut • Cottonseed • Apple • Yam
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: • 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)
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: • China • United States • India • Canada • 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, 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 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. Old Agriculture
Soil Resources • What is Soil? • Ways We Use and Abuse Soil • Erosion
The problem with chemicals • Groundwater contamination • Effects of low concentrations? • Bioaccumulation and Biomagnification
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