By 2050: 10 billion people we are already having difficulty feeding the population we have today - thus it’s best to use pesticides to be able to keep foods Going Organic - hard when it’s wide-scale can use manure, but not enough shit to sustain the world Fertilizer - Justus von Liebig : What is in manure that allows for crops to grow? o 4 Major Nutrients needed 1) Nitrogen 2) Phosphorus 3) Potassium 4) Various other elements in small amounts o In stores, fertilizers are sold in different ratios of these 4 depending on which plants because they all require different combinations - *Fritz Haber o Combined nitrogen and hydrogen to make ammonia (2NH3) Ammonium Nitrate (NH4NO3) - Ammonia + Nitric Acid - Most widely used fertilizer bc good source of nitrogen - Can also be used as an explosive Disadvantage: o Slowly decomposes to form nitrous oxide / laughing gas GREENHOUSE GAS Hydroponics (SoilLESS gardening) - Ground up coconut shells are used, etc. don’t need soil o But need a good ratio of the nutrients - Largest hydroponic farm in Montreal = on top of a building o In an enclosed environment 1) Can be grown all year round
2) NO pesticides! instead, use predatory insects (ladybugs, etc.) 10,000 insects, 8,000 fungi, 2,000 weeds Apple Scabs - A fungus; a cosmetic problem o Resort to agrochemicals to eliminate scabs Weeds - Grow in between stocks of crop - Suck nutrients from the soil, leaving crops to compete for nutrients Corn Borer: insect infesting corns Nematodes: destroy roots of apple orchids; need chemicals to destroy them NATURAL INSECTICIDES 1) Sulfur - One of the first insecticides used - When burned, produces SO2 (Sulfur Dioxide) o Kills many insects and fungi - When inhaled: has a choking odor 2) Tobacco Plant - Produces nicotine o Evolved as so in order to protect itself against predators o Keeps insects away SYNTHETIC INSECTICIDES 1) Paris Green (Copper Acetoaresenate) - Combine arsenic trioxide and copper acetate - Called Paris Green because used to rid sewers of rats and mice - Used in paints (sold as pigment) o Bad because sometimes arsenic compounds would evaporate from the wallpaper 2) DDT - Paul Muller : introduced DDT; received Nobel Prize in 1948 - Effective against anything that crawled - TODAY: only used in Africa in controlled fashion - Helped shape outcome of WWII bc allied soldiers were sprayed with DDT, preventing lice healthier than Germans - WHO: 25 Million lives saved bc of DDT use PROBLEM: DDT was overused o Eggshells laid by birds broke too frequently fewer hatchings o Population decline of eagles - Rachel Carson: introduced idea that pesticides = double-edged sword o Isn’t bio-degradable there can be build-up - 1969: Banned in Canada - 1972: Banned in USA - 2006: WHO suggests DDT be used to control malaria
o Can kill the mosquitos transmitting DDT o Use it safely by spraying a powdered version inside homes How Dangerous is DDT?
- Spring '11
- Food coloring, Pesticide, E number