4History 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.
5Plant Food Sources 250,000 plant species Þ 3000 tried as crops Þ 300 grown for food Þ100 species used on large scale for food Þ15 to 20 species provide vast majority (90%) of man’s food needsIt takes about 16 pounds of grain to produce one pound of edible meatLargest crop volumes provided by: wheat, rice, corn, potatoes, barleyWheat and rice supply ~60% of human caloric intake
7Types 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)
8Agroecosystems Ecosystem created by agricultural practices characterized by lowGenetic diversitySpecies diversityHabitat diversity
9AgroecosystemsAgroecosystems differ from natural ecosystems in five major ways:Farming attempts to stop ecological successionSpecies diversity is lowfarmers usually practice monoculturemonoculture tends to ß soil fertilityFarmers plant species (crops) in an orderly fashion - this can make pest control more difficultFood chains are far more simple in agroecosystemsPlowing is like no other natural disturbanceplowing can Ý erosioncause more nutrient loss (which is replaced by fertilizer)
10World Food Supply and the Environment Our current food problem is the result of our human populationFood production depends upon favorable environmental conditionsAgriculture changes the environment - such changes can be detrimentalFood supply can be adversely affected by social unrest that influence agriculture
11Grain ProductionGrain production increased from 631 to 1780 million metric tons from 1950 to 1990.Has leveled off since thenTop five countries in order of producing the most amount of grain are:ChinaUnited StatesIndiaCanadaUkraine
16Livestock· 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
17Wilkes, Angela. My first word board book. (1999) DK Publishing, NY.
18Meat SourcesAbout 90% of all meat and milk are consumed by United States, Europe and Japan which constitute only 20% of world populationAbout 90% of the grain grown in the United States is used for animal feed16 kg of grain Þ 1 kg of meatBy eating grain instead would get 20 times the calories and 8 times the protein
19Malnutrition and Famines One quarter of the human population is malnourishedSub-Saharan Africa (~225 million)East and Southeast Asia (~275 million)South Asia (~250 million)Parts of Latin America
21Malnutrition/Famines Stem from not enough calories per day in addition to not getting the necessary amounts of carbohydrates, proteins, lipids (fats), minerals, and vitaminsGenerally diets are high in starchesFamine conditionsMajor droughts -- Political instabilityPopulation sizes -- Land SeizuresMassive immigration -- PestilenceFloods Distribution breakdownWars --Panic buyingChaos in economy -- Hoarding
22Limits on Food Production · arable land· precipitation· temperature· global warming (ice age temp was only 5o C less than now!)
23Methods to Increase Food Supply Improved irrigation and utilization of waterDrip irrigationIncreasing arable landDifficult because of precipitation and temperatureEating lower on the food chainMost rangeland is not arable and humans cannot utilize grass/hay as food; therefore, this argument is not considered valid
24Methods to Increase Food Supply Food distribution modificationToday distribution of food is a major problem in Africa/AsiaBest solution: teach locals how to best utilize their land with appropriate technology so they can attempt to support themselves and not rely on others.
50Pesticides Pro and ConKill unwanted pests that carry disease (rats, mosquitoes, Tse-Tse flies)Increase food suppliesMore food means food is less expensiveEffective and fast-actingNewer pesticides are safer, more specificReduces labor costs on farmsFood looks betterAgriculture is more profitableAccumulate in food chainPests develop resistance – 500 species so farResistance creates pesticide treadmillEstimates are $5-10 in damage done for $1 spent on pesticidePesticide runoffDestroy bees - $200 millionThreaten endangered speciesAffect egg shell of birds5% actually reach pest~20,000 human deaths/year
51Types of Pesticides Biological – Ladybugs, parasitic wasps, etc. Carbamates effect nervous system of pests more water soluble than chlorinated hydrocarbonsAldicarb, aminocarb, carbaryl (Sevin), carbofuran, MirexChlorinated Hydrocarbons affect nervous system –Aldrin, Chlordane, DDT, dieldrin, lindane and paradichlorobenzeneFumigants are used to sterilize soil and prevent grain infestation
52Types of Pesticides Inorganic – arsenic, copper, lead, mercury Highly toxic and bioaccumulationOrganic or natural – derived from plants such as tobacco and chrysanthemumOrganophosphates – extremely toxic, low persistenceMalathion, parthion, chlophyrifos, acepate, propetamphos and trichlofon
53Integrated Pest Management Some practices for preventing pest damage may includeinspecting crops and monitoring crops for damageusing mechanical trapping devicesnatural predators (e.g., insects that eat other insects)insect growth regulatorsmating disruption substances (pheromones)if necessary, chemical pesticides
54Parts of IPM Polyculture instead of monoculture Intercropping – alternate rows of crops that have different pestsPlanting pest-repellent cropsMulch to control weedsNatural insect predators – ladybugs, preying mantis, birdsRotating crops to disrupt insect cyclesUsing Pheromones to attract insects to trapsReleasing sterilized insects