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CHAPTER 15-1: FEEDING THE WORLD
Famine = widespread starvation from shortage of food Malnutrition = condition when people do not get enough calories or nutrients (from eating a variety of foods) that meet the body’s nutritional needs (ex: AA deficiency or vitamin deficiency) Diet = the amount and kinds of foods eatenA good one has enough calories and a balance of the right nutrients, vitamins, and mineralsIn most parts of the world, people eat a diet high in carbohydrates (biggest crops – grains)In more developed countries, people eat more proteins and fatsPoverty plays a big role in malnutrition Food efficiency = how much food can be produced on a given amount of land with limited inputs of energy and resources- Ideal food crops efficiently produce large amounts of food with little impact on the environment- Plant foods require less land, energy, and water to produce the same number of calories from meat (which is why most diets in the world are plant-based)- Currently, people are trying to improve food production by studying plants and organisms that have a high yield (yield = the amount of food that can be produced in a given area) World food problems (malnourishment because of):- Unequal distribution – poverty, war, and political strife can disrupt food distribution so people don’t get enough to eat (the production is OK but the people don’t get any of it)- Drought – can decrease crop yields and leave no seeds for the next year. This can cause famine where food is grown locally. The Green Revolution- Using new crop varieties and applying modern agriculture to increase yieldo upside – feed more peopleo downside – the crop varieties and methods required the use of a lot of fertilizers, pesticides, and irrigation which causes soil degradation. Also, it put out farmers who couldn’t afford the machinery.CHAPTER 15-2: CROPS AND SOILS
Arable land = land that can be used for crops Traditional agriculture – done by small groups of people on small tracts of land. uses low-tech tools (like manual plowing) and organic/natural fertilizers and methods of pest control Subsistence farming – growing only enough food for local use Modern agriculture – relies on heavy fossil-fueled machinery and chemical pesticides and fertilizers to farm large amounts of land for high yield Fertile soil = can support the growth of plants- It exists in layers – topsoil, subsoil, bedrock- Topsoil – nutrient-rich surface layer that contains living things, rock particles, water, air, and organic mater erosion = wearing away of rock/soil by water and wind (modern agriculture increases it)- Erosion happens when the soil is exposed- Land degradation happens when the soil is damaged so bad it can’t support the ecosystem anymore- Desertification – when land in drier places becomes more desert-like because of human activities or climate changeso It decreases the amount of arable lando It happens because of overgrazing, too many crops, erosion, driving farm machinery over it- Too much farming and not enough fallow (rest) is bad. Natural plants prevent erosion by shielding the ground from wind/rain and holding the soil in place Soil conservation protects topsoil and reduces erosion – it helps sustainable farming- Terracing (cutting steps into a hillside)- Contour plowing (plowing w/ the direction of the land) – stops downhill erosion- No-till farming (farming without ripping up the soil) Enriching the soil – compost (partially decomposed stuff) + chemical fertilizers salinization = accumulation of salts in the soil- it becomes a problem in dry areas with little rainfall or poor irrigation methods- long-term irrigation can make it worse- using organic instead of chemical fertilizer can decrease salinization -------- pest = any organism that occurs where it is not wanted or that occurs in large enough numbers that it causes ecosystem damage- includes plants, fungi, insects, and microorganisms modern farmers rely on pesticides = chemicals used to kill pests- upside – effective- downsides – pest resistance, negative health effects, pollutiono pesticide resistance – pests evolve resistance à pest problem gets worseo pesticides are designed to kill things à they may be dangerous to humanso persistent pesticides do not break down and stay in the environment (DDT)§ they concentrate in the bodies of animals§ DDT causes the formation of thin shells in birds of prey§ DDT has since been banned in the US Alternatives – biological pest control = using living things to control pests- BT (a bacteria) kills caterpillars- Plant defenses (tougher skin or chemical repellants the plants make)- Chemicals extracted from plants that are sprayed- Growth regulators – substances that mess with the pest life cycle Integrated pest management – the goal is not eliminate, but control pest problems using a mix of methods that causes minimal environmental and economic damage Engineering better crops- Using genetic engineering to modify (change for the better) crop plants- Putting favorable traits into plants (ex: resistance to things) à the plants are then called GM (genetically modified)- GM foods is a hot topic of debate All this is in hopes of sustainable agriculture = low-input farming that minimizes the use of energy, water, pesticides, and fertilizers- Move toward more dependence on plant versus animal sources of food- Example: wheat uses less energy to produce than cattleCHAPTER 15-3: ANIMALS AND AGRICULTURE
Most animal protein comes from domesticated animals – animals that are bred and managed for human use- Examples include: chicken, sheep, cattle, bees, fish, shellfish, goats, pigs From the water – harvesting fish and shellfish has become big industry- Problem – over-harvesting = removing more organisms from a pop than the pop can replace à affects fish supplies and disrupts ecosystems- Solution – aquaculture = raising seafood for human useo fish farms and rancheso can cause environmental damage if not managed properly – especially water and wetlands From the land – livestock = domesticated animals for farms or profit- Uses include meat, draft animals to pull carts and plows, milk, wool, poop- ruminants = cud-chewing mammals with 3- to 4- chambered stomachso cud – the stuff they regurgitate and chew from the 1st stomach-ruminants include cattle, sheep, and goats- poultry = domesticated birds raised for meat and eggs (good sources of essential AA)-poultry includes chickens, turkeys, ducks, and geeseGoogle Sites
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