Water Use and Industrial Meat Production

5.1 Tragedy of the Commons (TOC)

• Definition: Individuals use shared resources in their self-interest, depleting the resources, rather than keeping with the common good.
• Examples:
  • Overuse of groundwater.
  • Water and air pollution.
  • Overfishing.
  • Overgrazing.
• Conditions:
  • Resource must be public (not privately owned).
  • Resource must be degraded, overused, depleted, or used up in some way.
• Why it happens:
  • No one owns the resource (land, water, air), so no one directly suffers the negative consequences of depletion.
  • People assume others will overuse the resource if they don’t.
  • No penalty for overusing, degrading, or polluting many public resources.
• Problems:
  • Overfishing: fishery collapse (population crash), loss of income, and starvation.
  • Air pollution (from coal-fired power plants): bronchitis, asthma, increased healthcare costs.
  • Pesticide and fertilizer runoff: contaminates drinking water and nearby water bodies, potentially causing cultural eutrophication.
• Solutions:
  • Private land ownership (individual or government).
  • Fees or taxes for use (e.g., permit system for grazing, logging).
  • Taxes, fines, or criminal charges for pollution of shared air, soil, or water resources.
  • Examples:
    • Clean Air Act.
    • Clean Water Act.
    • Safe Drinking Water Act.
    • BLM (Bureau of Land Management): Manages rangelands in western US by collecting grazing fees from ranchers, evaluating land, and repairing effects of overgrazing.

5.3 The Green Revolution

• Definition: A shift to new agricultural strategies and practices to increase food production, with both positive and negative results.
• Strategies and Methods:
  • Mechanization.
  • Genetically Modified Organisms (GMOs).
  • Fertilization.
  • Irrigation.
  • Use of pesticides.
• Mechanization:
  • Increased use of tractors for plowing and tilling fields, and combines for harvesting.
  • Benefits: Increased yield and profits.
  • Drawbacks:
    • Increased reliance on fossil fuels (gasoline/diesel fuel).
    • Emits GHGs to the atmosphere, contributing to climate change.
    • Heavy machinery causes soil compaction, decreasing H2O holding capacity and porosity.
    • Makes topsoil more prone to erosion.
• High-Yield Variety (HYV) Crops:
  • Hybrid or genetically modified crops that produce a higher yield (amount of crop produced per unit of area).
  • Hybrid = cross-pollinating different species, or parent plants with ideal traits.
  • GMOs = crops with new genes “spliced” into their genome.
  • Benefits: Increased yield and food stability in regions previously prone to famine (India, Pakistan, Mexico).
• GMOs:
  • Crops with genes for drought tolerance, pest resistance, faster growth, and larger fruit/grain.
  • Benefits:
    • Increases profitability with fewer plants lost to drought, disease, or pests.
    • Larger plant size + yield/acre.
  • Drawbacks:
    • All genetically identical, so genetic diversity is decreased, and susceptibility to diseases or pests is increased.
  • Example: Bt corn has been modified with a gene from soil bacteria (Bacillus thuringiensis) to produce a protein that kills many different corn pests.
• Synthetic Fertilizer:
  • Shift from organic fertilizers (like manure and compost) to synthetic fertilizers (man made ammonium, nitrate, phosphate).
  • Benefits: Increases yield and profits with more key nutrients needed for plant growth (N, P, K) added to the soil.
  • Drawbacks:
    • Excess nitrate, phosphate are washed off fields and into nearby waters where they cause eutrophication (algae blooms).
    • Requires FFs for production, releasing CO_2 (climate change).
• Irrigation:
  • Drawing water from the ground or nearby surface waters and distributing it on fields to increase plant growth.
  • Benefits: Make agriculture possible in many parts of the world that are naturally too dry (don’t receive enough rain).
  • Drawbacks:
    • Can deplete groundwater sources, especially confined aquifers.
    • Overwatering can drown roots (no O2 access) and cause soil salinization (increase salt level in soil).
• Pesticides:
  • Increase in use of synthetic pesticides - chemicals sprayed on crops that kill weeds, insects, rodents and other pests that eat or damage crops.
  • Benefits: Increases yield and profits with fewer plants lost to pests
  • Drawbacks:
    • Can wash off crops in runoff and kill or harm non-target species in local soil or waters (bees especially).
    • Ex: DDT thinned shells of bird eggs, especially eagles
    • Atrazine causes amphibians and fish intersex

5.4 Impact of Agricultural Practices

• Monocropping:
  • Growing one single species (corn, wheat, soy) of crop.
  • Highly efficient for harvest, pesticide and fertilizer application.
  • Drawbacks:
    • Greatly decreases biodiversity (more prone to pests, fewer nat. predators).
    • Increases soil erosion (crops harvested all at once & soil left bare).
    • Decreases habitat diversity for species living in the area.
• Tilling:
  • Mixing and breaking up soil to make planting easier.
  • Also loosens soil for roots.
  • Drawbacks:
    • Increases erosion by loosening topsoil, breaking up leftover root structure from harvest.
    • Loss of organic matter & topsoil nutrients over time.
    • Increased PM in air (respiratory irritant) and sediments in nearby water (turbidity).
• Slash & Burn:
  • Cutting down vegetation and burning it to clear land for agriculture & return nutrients in plants to soil.
  • Drawbacks:
    • Deforestation.
    • Loss of: habitat, biodiversity, CO2 sequestration (storage), loss of air pollution filtration.
    • Releases CO2, CO, N2O - all GHGs that lead to global warming.
    • Increases PM in air (asthma).
    • Lowers albedo, making area warmer.
• Synthetic (inorganic) Fertilizers:
  • Don’t return organic matter to soil; no increased H_2O holding capacity & no soil decomposers.
  • Leaching: water carries excess nutrients (nitrates & phosphates) into groundwater or into surface waters (as runoff).
  • Contaminates groundwater for drinking.
  • Causes eutrophication of surface waters.

5.5 Irrigation

• The largest human use of freshwater is for irrigation (70%).
• Furrow Irrigation:
  • Trench dug along crops & filled with water.
  • Easy & inexpensive; water seeps into soil slowly.
  • ~66% efficient, 33% lost to runoff & evap.
• Flood Irrigation:
  • Flood entire field; easier but more disruptive to plants.
  • Can waterlog the soil & drown plants.
  • 80% efficient - 20% runoff/evap.
• Spray Irrigation:
  • Ground or surface water pumped into spray nozzles.
  • More efficient (less water loss) than flood or furrow.
  • More expensive (requires energy for pumps & movement of sprinklers
• Drip Irrigation:
  • Most efficient, but also most costly.
  • Over 95% efficient.
  • Holes in hose allow water to slowly drip out.
  • Avoids waterlogging & conserves waters
• Waterlogging:
  • Overwatering can saturate the soil, filling all soil pore space with water.
  • Doesn’t allow air into pores, so roots can’t take in O_2 they need.
  • Can stunt growth or kill crops.
  • Solution: drip irrigation, or soil aeration - poking holes or cores in soil to allow air in & water to drain through soil
• Soil Salinization:
  • Salinization is the process of salt building up in a soil over time.
  • Groundwater used for irrigation naturally has small amounts of salt.
  • Water evaporates, and salt is left behind in soil. Over time, it can reach toxic levels, dehydrating plant roots & preventing growth
  • Solution: drip irrigation, soil aeration, flushing with fresh water, switch to freshwater source
• Global Human Water Use:
  • Industrial: power plants, metal/plastic manufacturing
  • Municipal: households (toilet, shower, drinking water)
  • Agriculture: water for livestock, irrigation water for crops
• Aquifers & Groundwater:
  • Groundwater: H_2O stored in pore space of permeable rock & sediment layers
  • Aquifers useable groundwater deposits for humans
  • Replenished by groundwater recharge (rain water percolating down through soil into aquifer)
  • Unconfined aquifers recharge quickly
  • Confined aquifers recharge are longer-term water deposits that recharge more slowly
• Depletion of Aquifers:
  • Cone of depression: forms when water table is lowered by excessive pumping, depleting water & drying nearby wells
  • Saltwater Intrusion: excessive pumping near coast lowers water table pressure, allowing saltwater to seep into groundwater

5.6 Pest Control Methods

• Pesticides:
  • Chemicals that are toxic to pests
    • Rodenticides kill rodents
    • Fungicides kill fungi
    • Insecticides kill insects
    • Herbicides kill plants
  • Can cause pests to become resistant to pesticide with overuse
    • Genetic biodiversity gives some pests resistant traits to pesticide
    • Pesticide artificially selects for pests with resistance by killing all the non-resistant individuals, leaving only resistant ones
• GMOs (Genetic Modification):
  • Gene for pest resistant trait is added to the plant through genetic modification
    • Bt corn with bacteria gene that produces Bt crystals toxic to pests
    • Roundup Ready crops are GM to be resistant to broad herbicide (Roundup) meaning roundup will kill weeds, but not crops
• GMOs & Pesticide Use
  • Bt corn has decreased insecticide use, since corn makes its own insecticide (Bt crystals)
  • Roundup Ready crops have increased herbicide (glyphosate) use since crops can’t be harmed by it
• GMOs & Genetic Diversity
  • If there is disease or pest that does affect the GM crops, they’re all vulnerable and there’s no chance of a genetic mutation providing an adaptive trait
  • GM crops are all genetically identical (clones) so there is no genetic diversity in the population

5.7 Meat Production Methods

• CAFOs
  • Also called feedlots - densely crowded method where animals are fed grain (corn) to raise them to as quickly as possible
  • Given antibiotics & growth hormones to prevent disease outbreak & speed meat production
  • Benefits:
    • Maximizes land use and profit (most meat production per/unit of area)
    • Minimizes cost of meat for consumers
  • Drawbacks:
    • Animals produce large volume of waste which can contaminate nearby surface or groundwater
    • Produces large amounts of CO2, CH4 (methane), and N_2O (greenhouse gasses → climate change)
• Manure Lagoons
  • Large, open storage pits for animal waste (manure)
  • Waste contains: ammonia (N), hormones, antibiotics, fecal coliform bacteria (e. coli)
  • Heavy rain can flood lagoons & contaminate nearby surface and ground water with runoff
  • e. Coli → toxic to humans
  • Ammonia (N) → eutrophication
  • Antibiotics & growth hormones → alter endocrine (hormonal system) of humans
  • Denitrification of ammonia in manure produces N_2O (extremely powerful GFG)
  • Can be emptied and buried in landfills, or turned into fertilizer pellets
• Free Range Grazing
  • Animals (usually cows) graze on grass & grow at a natural rate without growth hormones
  • Benefits:
    • No need for antibiotics with dispersed population
    • Doesn’t require production of corn to feed animals
    • Waste is dispersed over land naturally, acting as fertilizer instead of building up in lagoons
  • Drawbacks:
    • Requires more total land use/pound of meat produced
    • More expensive to consumer
    • Animals can graze on land too dry for most crop growth
• Overgrazing
  • Too many animals grazing an area of land can remove all the vegetation (grass) which leads to topsoil erosion
  • Animals also compact soil, decreasing H_2O holding capacity → more erosion
  • Desertification can occur if plants are killed by overgrazing & soil is compacted so much that it can’t hold enough water anymore
  • Rotational grazing (moving animals periodically) can prevent overgrazing
  • Can even increase growth of grass by distributing manure (natural fertilizer) & clipping grass back to size where growth is most rapid
• Inefficiency of Meat Production
  • Producing meat for humans to eat is far less efficient than producing plants in terms of energy, land and water use
  • Energy: all of the energy needed to plant, grow, harvest plants to feed to animals (10% rule) PLUS:
    • energy needed to bring water to animals
    • energy needed to house animals
    • energy needed to slaughter & package
  • Water: all of the water for crops that animals eat PLUS the water the animals drink

5.8 Impacts of Overfishing

• Fisheries: populations of fish used for commercial fishing
• Fishery collapse: when overfishing causes 90% population decline in a fishery
  • Population may never recover from fishery collapse due to: decreased biodiversity, inability to find mates, inbreeding depression
  • Decreases genetic biodiversity of fish populations & species biodiversity of ocean ecosystems if species are lost from ecosystem
  • Economic consequences: lost income for fishermen, lost tourism dollars for communities
• Bottom Trawling
  • Especially harmful fishing method that involves dragging a large net along ocean floor
  • Bycatch: unintended species like dolphins, whales, turtles caught in nets
  • Stirs up ocean sediment (turbidity) & destroys coral reef structure
  • Decreases biodiversity by killing non-target species & removing coral reef habitat
• Fishing Down the Food Web & Trophic Cascade
  • As we deplete large, predatory fisheries, we move down to smaller fish species
  • Depletion of smaller fish population limits fishery recovery and decreases food supply of marine mammals & seabirds

5.14 Integrated Pest Management (IPM)

• Using a variety of pest control methods that minimize environmental disruption and pesticide use
  • Crop rotation
  • Intercropping
  • Biocontrol (Bringing in a natural predator or parasite to control the pest)
  • Researching & monitoring pests and targeting methods to specific pest life cycles
• Biocontrol
  • Introducing a natural predator, parasite, or competitor to control the pest population
    • Ladybugs for aphids
    • Spiders for many pest insects
    • Parasitic wasps for caterpillars
  • Can include actually purchasing & spreading the control organisms in fields, or building homes for them/planting habitat they need to attract them naturally
• Crop Rotation
  • Rotating crops (planting a different crop each season) can prevent pests from becoming established since it disrupts their preferred food choice
  • Also disrupts weed growth since diff. crops can be planted at different times, preventing bare soil from being taken over by weeds
• Intercropping
  • “Push-pull” system can be used
    • “Pull” plants emit chemicals that attract moths to lay eggs in them, instead of crop
    • “Push” plants emit volatile chemicals that naturally repel pests away from crop
• Benefits & Drawbacks of IPM
  • Reduces effects on human consumers of produce
  • Reduces death & mutation of non-target species from
    • Ex: many pesticides are carcinogens (cause cancer)
    • Ex: intersex frogs (atrazine)
    • Eagle death (DDT)
    • Bee die offs (glyphosate)
  • Reduces contamination of surface & ground water by agricultural runoff with pesticides
  • Can be more time consuming & costly than just crop dusting pesticides
    • Ex: researching specific pests & planting numerous species of crops

5.16 Aquaculture

• Raising fish, or other aquatic species in cages/enclosures underwater
• Benefits
  • Requires only small amount of water, space, and fuel
  • Reduces risk of Fishery collapse (90% population decline in a fishery)
  • Doesn’t take up any land space (compared to beef, pork, chicken)
• Drawbacks
  • High density produces high concentration of waste (e. coli & eutrophication risks)
  • High density increases disease risk, which can be transmitted to wild populations as well
  • May introduce non-native species or GMOs to local ecosystem if captive fish escape
  • Fish are fed antibiotics which can contaminate water via their waste