AP Environmental Science: Unit 5 Review - Land and water Use

Tragedy of the Commons

• suggests that individuals will use shared resources in their own self interest rather than keeping with the common good, resulting in resource depletion
• "area used by everyone but regulated by no one"

 Agricultural Practices

• agricultural practices that can cause environmental damage include tilling, slash-and-burn farming, irrigation, and the use of fertilizers
• clearcutting - economically advantageous but leads to soil erosion, increased soil and water temperatures, flooding

The Green Revolution

• The Green Revolution started a shift to new agricultural strategies and practices in order to produce food production
• mechanization - pros: efficient $, easy cons: fossil fuel uses, combustion, extraction
• monoculture - pros: easy, fertilizer, same pests cons: 1 plant type, loss of biodiversity, habitat, genetics
• artificial fertilizer - pros: high yield, easy cons: runoff, eutrophication
• artificial pesticide - pros: high yield, easy cons: health, evolution of pests
• irrigation - pros: maximum yield, customize cons: deplete freshwater

Irrigation Methods

• the largest human use of freshwater is for irrigation
• flood irrigation - involves flooding an agricultural field with water, about 20% of the water lost to evaporation and runoff
• furrow irrigation - involves cutting furrows between crop rows and filling them with water, inexpensive about ⅓ of the water is lost 
• spray irrigation - involves pumping groundwater into spray nozzles across an agricultural field, only ¼ or less of the water lost to evaporation or runoff, more expensive and requires more energy to run
• drip irrigation - uses perforated hoses to release small amounts of water to plant roots, only about 5% of the water lost, this system is expensive and so is not often used

Pest Control Methods

• a consequence of using common pest-control methods such as pesticides is that organisms can become resistant to them 
• crops can be genetically engineered to increase their resistance to pests and disease, using genetically modified crops, this can lead to loss of genetic diversity

Integrated Pest Management

• integrated pest management - combination of methods used to effectively control pest species while minimizing the disruption to the environment
• biological - introduction of natural pest predators
• physical - barriers that protect crops
• chemical - poison that kills pests
• crop rotation and intercropping

Meat Production

• it takes approximately 20 times more land to produce the same amount of calories from meat as from plants
• CAFOs - concentrated animal feeding operations
• pros: less expensive than other methods, which can keep costs to consumers down
• cons: tend to be crowded, animals are fed grains, feedlots generate a large amount of organic waste can contaminate ground and surface water
• free range grazing - animals have access to pasture  all the time
• rotational grazing - where grassland is sequentially grazed and then rested to allow vegetation recovery
• pros: allows animals to graze on grass during their entire lifecycle, tends to be free from antibiotics,.organic waste from animals acts as fertilizer
• cons: requires large areas of land, meat produced is more expensive for consumers
• overgrazing - occurs when too many animals over graze a particular area of land, can lead to soil erosion
• consuming less meat can reduce CO2, CH4, and N2O emissions

Aquaculture 

• pros: highly efficient, requires only small areas of water, and requires little fuel
• cons:  fish that escape can compete or breed with wild fish, disease incidences, wastewater

Sustainable Agriculture

• contour plowing - follows the natural contours of the land when plowing to reduce environmental impact
• windbreaks - style using trees to be placed around the crops. This prevents winds from eroding the soil
• perennial crops - plants that live for multiple years
• terracing - technique for farming that builds platforms on hills to reduce erosion
• no-till agriculture - agricultural method in which farmers do not turn the soil between seasons 
• strip cropping - cultivation in which different crops are sown in alternate strips to prevent soil erosion
• adding limestone balances acidic soils

Sustainable Forestry

• methods for mitigating deforestation include reforestation, buying wood harvested using sustainable forestry techniques, and reusing wood
• prescribed burns - forests are set on fire under controlled conditions in order to reduce the occurrence of natural fires