● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Soil Characteristics Soil Composed of: - Inorganic: Weathered rock from minerals (main component of soil) - Organic: decaying organisms Soil Formed in 3 Ways: - Mechanical Weathering: flowing, freezing, thawing water - Chemical Weathering: rock decomposition → water dissolves minerals out of rock; oxygen → reacts with iron-containing minerals to form → iron oxide (rust); acids formed by → anthropogenic and natural sources (volcanoes) - Biological Weathering: organisms disintegrate and/or decompose rock and organic matter mechanically and/or chemically Chemical Factors: pH, ion content, ion holding capacity Physical Factors: soil particles and bedrock Soil must be able to provide air and water for plant roots Particle Size & Arrangement. Nature of Layers, Texture & Slope - How soil holds water, allows permeation, root growth permission, oxygen permeation Subsidence: land can shift/sink Soil Layers: humus/organic, topsoil, eluviated layer/exit layer, subsoil, parent material , bedrock - Horizon → each layer of soil O Horizon: fresh decaying leaf litter, organic waste A Horizon: nutrient rich, dark, organic matter (humus) with inorganic particles (sand, silt, clay), porous E Horizon: lighter, little/no organic matter, leaching zone B Horizon: subsoil, particles from A horizon (clay, organic matter, iron/aluminum oxides), inorganic (silt, clay, gravel) C Horizon: parent material, broken down rock R Horizon: bedrock Darker the soil, richer in organic matter and moisture Sand (biggest particles), Silt, Clay (smallest), Humus (varies/ not analyzed in soil composition) TEXTURE – determined by the ratio of sand, silt and clay; excludes organic matter. - Ribbon Test/Feel Test, Soil Texture Triangle, Jar Method STRUCTURE- when soil clumps and forms shape → effects how water, roots and air move through - Granular: high permeability - Blocky: moderate - Platey: low - Aggreated: high - Columnar: moderate - Massive: low CONSISTENCE – adhesion and cohesion of the soil particles; how soil resists pressure from wind, water, machinery, etc. - Varies w/ moisture content Porosity and permeability: determined by particle size and organic matter content - water holding capacity & capillary action (cohesion + adhesion) Infiltration = permeation of water through soil with the force of gravity Leachate = liquid containing salts, minerals, fertilizers, etc. that permeates through the soil that eventually pollutes groundwater and surface waters. CH 12.1: What is Food Security and Why is it Difficult to Attain? The greatest obstacles to providing enough food for everyone are poverty, corruption, political upheaval, war, bad weather, and the harmful environmental effects of industrialized food production. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. Food Security: People's ability to access sufficient, safe, nutritious food to maintain a healthy and active life Food Insecurity: chronic hunger and poor nutrition Dave Battisti: climate scientist projects food shortage Rosamond Naylor: food scientist projects food shortage Macronutrients: carbohydrates, proteins, and fats Micronutrients: vitamins and minerals Chronic Undernutrition (hunger): people who can’t grow or buy enough food Sources of Protein: animals and plants Function of Proteins: build and repair tissue Sources of Carbs: wheat, corn, rice Function of Carbs: energy Sources of Lipids: fats, nuts, oils Function of Lipids: build membrane tissue and create hormones Chronic Malnutrition: deficiencies of protein and other key nutrients Effects of Malnutrition: weakness, disease, hinders development FAO: UN Food and Agriculture Organization Famine: worst form of hunger, extreme shortage of food Iron Function: component of hemoglobin → oxygen transport through blood (lack → anemia → fatigue, risk of infection, increases risk of death during childbirth) Iodine Function: thyroid hormones → control metabolism rate (lack → retardation, stunted growth, goiter) Vitamin A Function: eyesight (lack → blindness → death) Overnutrition: too much food/ exceeds energy use → obesity Ch 12.2: How is Food Produced? 1. Agriculture: growing edible plants in nutrient rich topsoil & raising livestock for food and labor 2. Croplands: grains and provide about 77% of the world’s food using 11% of its land area 3. Rangelands, Pastures & Feedlots: meat → 16% of the world’s food; 29% of the world’s land area 4. Fisheries & Aquaculture: 7% of food 5. These systems use 40% of world’s land 6. 14/50,000 plants supply 90% of world’s calories (wheat, rice, corn = 40%) - ⅔ of world survive on wheat, rice and corn 7. Disease, degradation, climate change makes us vulnerable to food shortage if sources become endangered - Violates principle of sustainability 8. Violations: nonrenewable fossil fuels, does not rely on a diversity of crops as a form of ecological insurance, and neglects the conservation and recycling of nutrients in topsoil, don’ t include harmful effects on labels 9. Tech → increase in food prod. - Fertilizer, pesticide, grain variety, industrial prod. of livestock and fish 10. Irrigation: artificial water supply to crops I. Industrialized Crop Production Relies on High-Input Monocultures 1. Two types of crop agric. → industrialized agriculture and subsistence agriculture 2. Industrialized Agriculture (high input): heavy equipment, high financial capital , fossil fuels, water, inorg. fertil., pesticides → monocultures (single crops) - Increase yield of monoculture - 80% of world food Plantation agriculture: industrialized agriculture used primarily in tropical LDC’s - Cash crops: bananas, soybeans, sugarcane, palm oil, veggies 4. Greenhouses used to grow crops year-round → heated w/ geothermal E & saves water (water can be purified & recycled) II. Hydroponics 1. Hydroponics: growing plants by exposing their roots to a nutrient-rich water solution instead of soi • Crops can be grown indoors under controlled conditions almost anywhere. • Yields and availability are increased because crops are grown year round • In dense urban areas, crops can be grown on rooftops, underground with artificial lighting (as is now done in Tokyo, Japan), and on floating barges, thus requiring much less land • Fertilizer and water use are reduced through the recycling of nutrient and water solutions. • no pesticides, runoff, erosion, buildup of minerals 2. Hydroponics disadvantages → expensive, ppl think its technologically complex, threatens existing companies 3. Countries → New Zealand, Netherlands, US, Germany III. Science Focus: Soil is the Base of Life on Land 1. Soil: mixture of eroded rock, mineral nutrients, decaying organic matter, water, air and living organisms - Formation begins from bedrock weathering - Nutrients for plants, holds and purifies water, organisms living in soil control climate by removing CO2 - Bacteria, decomposers break down organic matter in top 2 horizons IV. Traditional Agriculture Often Relies on Low-Input Polycultures 1. 2.7B ppl practice traditional agriculture 2. Traditional subsistence agriculture: supplements energy from the sun with the labor of humans and draft animals to produce enough crops for a farm family’s survival, with little left over to sell or store as a reserve for hard times 3. traditional intensive agriculture: farmers increase their inputs of human and draft-animal labor, animal manure for fertilizer, and water to obtain higher crop yields → can feed families and sell 4. Polyculture: several different crops on same plot (principle of sustainability) 5. slash-andburn agriculture: involves burning and clearing small plots in tropical forests, growing a variety of crops for a few years until the soil is depleted of nutrients, and then shifting to other plots to begin the process again - crops rely on sunshine and natural fertilizers such as animal manure - Provide food year- round - Cover soil, reducing erosion - S&B Polyculture lessens water use and fertilizer - Produces higher yield 6. All crop production depends on having fertile topsoil 7. Green Revolution: first develop and plant selectively bred, high yield monocultures, second produce high yields by high inputs of water and inorganic fertilizers/pesticides, third increase # of crops through multiple cropping 8. 1950-1970: first green revolution 9. 1967- now: second green revolution → increased world’s food production V. Industrialized Food Production in the US- The 1st Green Revolution 1. Agribusiness: small # of corps controlling food processing, growing, distribution and sale 2. Since 1950 yields of wheat, corn & soybeans doubled w/o taking more land from industrialization - Kept grasslands, forests and wetlands safe 3. Ppl in LDC’s spend 40% of income on food → 1.4B poorest ppl spend 70% → US spend 10% of income 3. 4. Hidden costs: taxes, pollution, degradation, health VI. Crossbreeding and Genetic Engineering Can Produce New Varieties of Crops and Livestock 1. Gene Revolution → crossbreeding through artificial selection 2. Genetic Engineering: alter genetic material through adding, deleting or altering DNA strains → gene splicing - Scientists can transfer genes across species 3. GMOs (Genetically Modified Organisms) 4. Age of Genetic Engineering → GM’s planted on 12% of land across 23 countries (half in US) - GMs: cotton, soybean, canola - EUR Union restricts GM 5. 80% of corn, soybean and cotton in US are GMO (GM labels not required by law) VI. Meat Production Has Grown Steadily 1. Meat, eggs, milk → second major food producing system - 56B animals killed for food/year - Meat prod. Likely to double 2050 as affluence rises 2. ½ of meat comes from grazing livestock / other ½ from enclosed factory farms - Raising animals to gain weight fast in feedlots and concentrated animal feeding operations (CAFOs) - Not environmentally friendly (animal waste) - Causes increased grain demand (Japan, Taiwan, South Korea import 70%) VI. Fish and Shellfish Have Increased Dramatically 1. Fishery: concentration of a particular aquatic species suitable for commerical harvesting in a given ocean area or inland body of water. 2. Aquaculture: practice of raising marine and freshwater fish in ponds or underwater cages in coastal or open ocean waters. - Fastest growing 3. 63% of fisheries depleted or overexploited → reduce pollution + overfishing 4. China leader of seafood consumption 5. Aquaculture devoted to raising species that feed on plants (carp, catfish, tilapia, shellfish) 6. Farming of meat eating fish growing → Salmon and shrimp 7. 37% of wild fish catch converted to fish meal/oil VII. Industrial Food Production Requires Energy 1. Ind. Food Prod made possible by energy → oil and natural gas used for machines, irrigation, pesticides, and inorg. fertilizers - Fossil fuels used for processing and transportation - Food prod uses most fossil fuels 2. 10 units of nonrenewable fossil fuel energy to put 1 unit of food energy on the table 3. Reasons for fossil fuel dependency → transportation, factories, processing, producing → results in net energy loss CH 12-3 What Environmental Problems Come from Industrialized Food Production? Concept: Future food production may be limited by soil erosion and degradation, desertification, water and air pollution, climate change from greenhouse gas emissions, and loss of biodiversity. I. Producing Food Has Major Env. Impacts 1. Agricultural advances → increase in food produced per unit of cropland → less land used → protects biodiversity 2. Biodiversity Loss → Loss and degradation of grasslands, forests, and wetlands in cultivated areas Fish kills from pesticide runoff Killing wild predators to protect livestock - Loss of genetic diversity of wild crop strains by monoculture strains 3. Soil Degradation → erosion - Erosion - Loss of fertility - Salinization - Waterlogging - Desertification - Increased acidity 4. Water → waste - Aquifer depletion - Runoff, sediment pollution, flooding - Algal blooms 5. Air → greenhouse gases from fossil fuels - Pesticide pollution 6. Human Health → nitrates in drinking water (blue baby) - Pesticide residues - Livestock waste contamination 7. Agric = most harmful environmental impacts II. Topsoil Erosion is a Serious Problem 1. Soil Erosion: movement of topsoil components by actions of wind and water 2. Roots help anchor soil and prevent unnatural erosion 3. Largest cause of erosion = moving water 4. Dry areas more prone to erosion 5. Lose natural capital in form of fertile topsoil when removing soil holding crop - Through farming, deforestation, overgrazing, and off road vehicle use 6. Topsoil erosion major effects → loss of soil fertility & water pollution - Violates chem cycling (principle of sustainability) 7. Some analysts say topsoil erosion estimates overstate bc don’t account for abilities of farmers to restore degraded land III. Drought and Human Activities Are Degrading Drylands 1. Desertification: when productive potential of topsoil falls by 10% or more b/c of drought and human activities (overgrazing, deforestation) - Moderate (10-25%) - Severe (20-25%) - Very Severe ( 50% +) - Can lead to desert or expansion of desert 2. 70% of world’s drylands used for agric. threatened by desertification 3. Most lands threatened in Africa and Asia 4. Climate change → extended drought → expand desertification → threaten food supplies IV. Excessive Use of Irrigation Water Has Serious Consequences 1. Irrigation accounts for 70% of water 2. Most irrigation water is dilute solution of salts picked up 3. Salinization: A process in which mineral salts accumulate in the soil, killing plants; occurs when soils in dry climates are irrigated profusely 4. severe salinization: China, India, Egypt, Pakistan, Mexico, Australia, and Iraq 5. Waterlogging: water accumulates underground and gradually raises water table when farmers put large amounts of irrig. Water to leach salt deeper into soil - Deprives plants of oxygen - Lowers productivity of crops and kills them after awhile - Contributed to depletion of groundwater and surface water V. Agric. Contributes to Air Pollution and Projected Climate Change 1. clearing/burning forests for farming pollutes air - ¼ of human emissions → g-house gases → climate change → areas unsuitable for plant growth 2. Livestock emissions of methane can be reduced by grass grazing 3. Nitrous oxide (330x the warming capacity of CO2) released in huge amounts by inorganic fertilizers, forest burning, livestock manure VI. Food and Biofuel Production Systems Have Caused Major Losses of Biodiversity 1. The Amazon → cutting and burning of cerrado 2. Clearing for biodiesel fuel (cars), releases g-house gases 3. Losing agrobiodiversity → reducing genetic library → can lead to famine 4. failure to preserve agrobiodiversity as ecological insurance policy = violation of the biodiversity principle of sustainability 5. Seed banks hold vital varieties but vulnerable to power outages → irreversible loss VII. Genetic Engineering Could Solve Some Problems but Create Others 1. Genetically Modified (GM) food Pros & Cons: - Pros: Need less water, fertilizer, energy & pesticides, grow faster, more resistant - ConsUnknown genetic & eco effects, harmful allergens, no increase in yields, disrupt seed market, lower genetic diversity 2. Don’t know enough abt long term effects 3. Call for further controlled field study & regulation VIII. There Are Limits to Expansion of the Green Revolutions 1. Slowdown in global grain strains ← keep putting inorg.fert., pest., & water, no increase in yield 2. Irrigated land per person declining → poverty, population growth, wasteful use of water 3. Water supply declining, aquifer and surface water depletion - Climate change → melt glaciers & cause drought (himalayan area affected) - Could use technology to help 4. Clearing land for more food is unsustainable 5. Commercial fertilizer → increasing soil acidity, air pollutants from burning coal → decreases yield VX. Industrialized Meat Production Has Harmful Environmental Consequences 1. Brazil top beec exporter 2. Top cause of amazon degradation = clearing for cattle ranches 3. Industrialized livestock=55% of topsoil depletion and ⅓ of water pollution from fertilizer 4. Antibiotics can build resistance to human duseases and create evolved diseases 5. Excessive animal waste, not enough returned to nutrient cycling = violation of principle of sustainability & pollutes/contaminates X. Aquaculture Can Harm Aquatic Ecosystems 1. Fish meal and fih oil come from wild fish catch - Used to feed farmed fish but inefficient Takes more fish to make fish oil and meal, depletes fish population - Farmed fish can escape and breed with wild fish disturbing gene pool 12-4 Managing Crops from Pests I. Nature Controls the Population of Most Pests 1. pest is any species that interferes with human welfare by competing with us for food, invading lawns and gardens, destroying building materials, spreading disease, invading ecosystems, or simply being a nuisance 2. clear forests and grasslands, plant monoculture crops, and douse fields w/ chemicals to kill pests, we upset natural balance 3. Natural enemies (predators, parasites, & disease) naturally control pests 4. Spiders = important pest predators II. Using Pesticides 1. Pesticides: chemicals to kill or control pests - Types of pesticides: insecticides (insect killers), herbicides (weed killers), fungicides (fungus killers), and rodenticides (rat and mouse killers) 2. 1600’s Nicotine Sulfates from tobacco leaves → insecticides 3. first-generation pesticides—mainly natural chemicals borrowed from plants 4. DDT= first of the second generation pesticides 5. Biopesticides: natural repellants, use has increased - Some contain essential oils from spices 6. Use of pesticides increased since 1950 7. Broad Spectrum Agents toxic to many species (DDT, malathion & parathion) 8. Selective/narrow spectrum agents are only toxic to a narrow range of pests 9. Pesticides vary in persistence (length of time in env) 10. Organophophosphates toxic to humans, short persistence 11. More pesticides used on private areas (lawns, pools, gardens) than cropland III. Case Study: Rachel Carson 1. Biologist at USFWS → witnessed birds dying from DDT → published Silent Spring → caused controversy but contributed to ban of harmful pesticides and gave insight on their effects IV. Modern Synthetic Pesticides Have Several Advantages 1. Pros: - save lives by preventing premature deaths from disease - increase food supply and farmer’s profits work fast & last long - health risks are low when used properly advancements make them safer V. Modern Synthetic Pesticides Have Several Disadvantages 1. Cons: - Genetic resistance - Farmers have to pay more to combat resistance - Can harm necessary predators and parasites - Pollution - Harm wildlife (bees, birds and fish) - Bad for human health 2. Pesticide companies argue that exposure is too low to do harm VI. Pesticide Use Has Not Reduced U.S. Crop Losses to Pests 1. 1942-1997 crop loss went from 13%-17% 2. Every dollar spent on pesticides = $5-$10 in damage costs (env, social, human health) 3. Alt. pesticide use could cut use of chemical pesticides w/o lowering crop yield VII. Case Study: The Law of Unintended Consequences 1. 1955 Shabah (Malaysia), malaria → sprayed dieldrin, DDT relative → successful, but killed other species - Killed insect eating lizarda → cats killed → rat pop. soared → Operation Cat Drop - Killed wasps that ate caterpillars → caterpillar pop. soared → ate roofs - Situation was controlled VIII. Laws and Treaties Can Help to Protect Us from the Harmful Effects of Pesticides 1. EPA, USDA, FDA: regulate sale and use of 25000 commercial pesticide products - Federa Insescticide, Fungicide, and Rodenticide Act (FIFRA) - EPA supposed to assess health risks but 10% tested after years - 1996 Food Quality Protection Act: EPA must reduce allowed levels of pesticide residue in food by factor of 10 when info is inadequate (passed bc of growing suspicion) 2. Acts not strict enough (EPA lazy) 3. Boomerang effect or circle of poison 4. Export of pesticides can cause harmful cycle, US argues to keep exporting for money IX. There Are Alternatives to Conventional Pesticides 1. Fool pests → cultivation (rotating crops and adjusting planting times) 2. Homes for pest predators w polyculture 3. Genetic resistance for plants to pests 4. Bring natural enemies 5. Use insect perfumes (pheromones) to lure pests into traps 6. Use hormones to disrupt pest life cycle 7. Reduce synthetic herbicides to control weeds X. Integrated Pest Management Is a Component of More Sustainable Agriculture 1. Integrated Pest Management: pests evaluated, then bio, cultivation, and chemical strategies used to control them (best way to control pests) - IPM goal: reduce crop damage - Monitor carefully - Broad spectrum not used 2. 1986- indonesia banned 57/66 rice pesticides → use dropped 65% and production rose 3. IPM reduced pesticide use in Brazil by 90% 4. IPM Pros: reduce water use, slow genetic resistance, reduce input of fertilizers, pollution prevention 5. IPM Cons: takes expert knowledge, takes longer, use varies, expensive 6. 3 Point IPM Strategy: 2% sales tax, federal IPM demonstration project, & training 12-5 How Can We Improve Food Security? Government Subsidies Can Help or Hinder Food Security? Agric. = risky business & depends on - Weather - Crop prices - Pests and diseases - Loan interest rates - Global market 2. Influence food prod. → 1) control prices w/ max price mandates, 2) subsidies 3. Subsidies make up ⅓ of farm income - Can promote overproduction and unsustainable practices 4. Trawling: net dragged through water to catch fish II. Other Government and Private Programs are Increasing Food Security 1. 2008 UN World Food Program → system of buying food from small farmers - Increase econ security 2. Aid programs to reduce pop. growth - Family planning, education, jobs, small loans to poor 3. Programs to help children in poverty ($5-10) - Immunizing, vitamin A capsules, salt and sugar in water 4. Diverse gene pool w. Gene banks for diversity 12-6 How Can We Produce Food More Sustainably? 1. I. 1.
