Chem 181 notes Part 2.docx - Topic 5 Agriculture Lesson 1 Vid 1-photosynthesis plants take up carbon dioxide and water and make oxygen-without

Chem 181 notes Part 2.docx - Topic 5 Agriculture Lesson 1...

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Topic 5: Agriculture Lesson 1 Vid 1 - photosynthesis : plants take up carbon dioxide and water and make oxygen -without photosynthesis no life - 70% of world , 50 years ago was involved in farming in some way -today , 2% of population supply all food for population -hunter-gathers to agriculture developments of agriculture population growth, and need for more and more foodlac -pesticides: designed to kill pests and weeds and fungi -generic engineering also questionable -we will need to use fertilizers, pesticides to feed growing population -manure used for natural fertilizer not enough for all food -Jusus Von Liebig : founder of fertilizer -4 major nutrients needed: nitrogen, phosphorous, potassium and various other elements in small amounts -3 numbers on fertilizer bag= ratio of N,P,K - Fritz Haber : found way to combine nitrogen and hydrogen to make ammonia N2+3H2 2NH3 -NH3+HNO3 NH4NO3 ammonium nitrate (one of most widely used fertilizers in the world) (provides good source of nitrogen) (can also be used as an explosive) -decomposes to nitrous oxide (laughing gas)when heated= greenhouse gas (prevents heat loss, contributes greenhouse effect global warming) -William Gericke , first idea of soiless gardening ( hydroponics) (grow in greenhouses ) -cucumber, tomato, etc -can be grown yearround, without using pesticides -use ladybugs, control pests (aphids and other insects that destroy greenhouse) Video 2 -10,000 insect species, 8000 fungi, 2000 weeds - apple scab (fungus (cosmetic problem, not real problem)) -farmers use chemicals to get rid of scab - botrytis fruit rot (strawberry), stem rust, black spot fungus (destruction) (disease of roses) -weeds suck nutrients in soil - corn borer : invades corn - nematodes destroy roots -cockroaches, bed bugs - sulfur: one of elements that occurs in nature in elemental form -burn surfer, produces SO2 (sulfur dioxide), destroys insects and fungi - tobacco plant produces nicotine (natural) -evolved to protect itself from insects ( nicotine = natural insecticide) -synthetic pesticide ( copper acetoarsenite = arsenic trioxide and copper acetate) -called paris green ( sewers of paris for rats and mice ) -used in paints (wallpaper, and arsenic compound evaporates and toxic for human - DDT (manufactured by chemists) Paul Mueller (medicine won nobel prize) - helpful for fleas, bugs that crawled -helped shape outcome of 2 nd World War (keep free of lice, insects) -25mil lives saved in WWII
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-farmers overused DDT ( eggshells laid by birds broke too frequently (fewer hatching))( eagle population decrease ) - Rachel Carson (Silent Spring; introduced idea of pesticides as double sword) -DDT builds up in food chain ( not biodegradable ; problem with eggs) -DDT banned in Canada 69, US 72 -2006, WHO use DDT to control malaria in Africa (kills mosquito that transmits malaria) -use safe by using powdered form inside walls of homes -how dangerous is DDT?
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