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12-3 What Environmental Problems Arise from Food Production?
• Concept 12-3 Food production in the future may be limited by its serious environmental impacts, including soil erosion and degradation, desertification, water and air pollution, greenhouse gas emissions, and degradation and destruction of biodiversity.
Producing Food Has Major Environmental Impacts
• Higher yield crops have __________________ the amount of land used to grow food
• Good News! – This has helped to protect biodiversity by reducing the destruction of ________________ and _______________________
• Despite this encouraging news, many analysts point out that industrialized agriculture has ____________ environmental effects than any other human activity
reduced
forestsgrasslands
greater
Fig. 12-10, p. 289
Natural Capital Degradation
Food Production
Biodiversity Loss Soil Water Air Pollution Human Health
Loss and degradation of grasslands, forests, and wetlands in cultivated areas
Erosion Water waste Emissions of greenhouse gas CO2 from fossil fuel use
Nitrates in drinking water (blue baby)
Loss of fertility Aquifer depletion
Pesticide residues in drinking water, food, and air
Salinization Increased runoff, sediment pollution, and flooding from cleared land
Emissions of greenhouse gas N2O from use of inorganic fertilizers
Fish kills from pesticide runoff
Waterlogging
Contamination of drinking and swimming water from livestock wastes
Killing wild predators to protect livestock
Desertification Pollution from pesticides and fertilizers Emissions of
greenhouse gas methane (CH4) by cattle (mostly belching)
Increased acidity
Loss of genetic diversity of wild crop strains replaced by monoculture strains
Algal blooms and fish kills in lakes and rivers caused by runoff of fertilizers and agricultural wastes
Bacterial contamination of meat
Other air pollutants from fossil fuel use and pesticide sprays
Topsoil Erosion Is a Serious Problem in Parts of the World
• Soil erosion is the movement of soil components, especially surface litter and topsoil, by ___________ and __________________
• Some erosion of topsoil is ________________, but much is caused by human activities
• In undisturbed, vegetated ecosystems, the roots of plants help to ________________ the topsoil.
• Undisturbed topsoil can also _____________ the water and nutrients needed for plants
waterwind
natural
anchor
store
Topsoil Erosion on a Farm in Tennessee
Fig. 12-11, p. 289
Flowing water is the ___________ cause of erosion largest
Natural Capital Degradation: Gully Erosion in Bolivia
Fig. 12-12, p. 290
Severe erosion by water can lead to _______________ gullies
Wind Removes Topsoil in Dry Areas
Fig. 12-13, p. 290
Wind loosens and blows topsoil away, especially in areas witha __________ climate and relatively ___________, exposed land dry flat
Topsoil Erosion Is a Serious Problem in Parts of the World
• Two major harmful effects of soil erosion are…• Loss of soil ___________________ through the
depletion of plant nutrients
• Water __________________ in nearby surface water where eroded topsoil ends up as _________________
fertility
pollutionsediment
Drought and Human Activities Are Degrading Drylands
• In arid and _________________ parts of the world, food production is being threatened by desertification…
• This occurs when the productive potential of topsoil falls by ___________ or more due to…• Prolonged _______________________• Human activities such _____________________ and
___________________________
• Results in the ________________________ of existing desert areas or the ___________________ of new ones
semi-arid
10%drought
deforestationovergrazing
expansioncreation
Severe Desertification
Fig. 12-15, p. 291
Sand dunes threatening to take over an oasis in the Sahel regionof West Africa
Fig. 12-16, p. 292
Moderate Severe Very severe
Moderate (10-25% drop) Severe (25 – 50% drop) Very severe (more than 50% drop)
Excessive Irrigation Has Serious Consequences
• Irrigation accounts for ______ of the water that humans use and helps to produce ______ of our food
• Irrigation water is a dilute solution of various ______ that are picked up as the water flows over soil and rocks
• Salinization is the gradual ___________________ of salts in the soil from irrigation water• Lowers crop yields and can even kill plants• Affects 10% of world croplands
70%45%
salts
accumulation
Depletion of ground and surface water supplies!
• Another problem with irrigation is ________________________• Occurs when water accumulates underground and
gradually ______________ the water table.• This can deprive plants from getting the _________
they need…(they need oxygen as well)
If you don’t respire, you expire
waterlogging
raisesgases
Agriculture Contributes to Air Pollution and Projected Climate Change
• Industrialized agriculture contributes to climate change any time forests or grasslands are ___________ or _______________• Less ________ absorption• Burning results in the __________________ of many
greenhouse gases into the atmosphere
• A related problem is the increasing loss of ______________________ - the genetic variety of animal and plant species used to provide food• Scientists estimate that we have lost ________ of the
genetic diversity of agricultural crops
cleared burned
CO2
release
agrobiodiversity
3/4
Fig. 12-18, p. 294
Trade-Offs
Genetically Modified Crops and Foods
Advantages Disadvantages
Need less fertilizer Unpredictable genetic and ecological effectsNeed less water
Harmful toxins and new allergens in foodMore resistant to
insects, disease, frost, and drought No increase in yields
Grow faster More pesticide-resistant insects and herbicide-resistant weedsMay need less
pesticides or tolerate higher levels of herbicides
Could disrupt seed market
May reduce energy needs
Lower genetic diversity
There Are Limits to Expanding the Green Revolutions
• Green revolutions (increased yield) are _________________...• Usually require large ________________ of fertilizer,
pesticides, and water• Often too __________________ for many farmers
• Can we expand the green revolution by• Irrigating more cropland?• Improving the efficiency of irrigation?• Cultivating more land? Marginal land?• Using GMOs?• Multicropping?
limitedinputs
expensive
Fig. 12-19, p. 295
Trade-Offs
Animal Feedlots
Advantages Disadvantages
Large inputs of grain, fish meal, water, and fossil fuels
Increased meat production
Greenhouse gas (CO2 and CH4) emissions
Higher profits
Less land use
Reduced overgrazing
Concentration of animal wastes that can pollute water
Reduced soil erosion Use of antibiotics can
increase genetic resistance to microbes in humans
Protection of biodiversity
ConnectionsMeat Production and Ocean Dead Zones
• Our Midwest, for example, uses much manufactured, inorganic ___________________ just to grow crops for use as animal ______________
• Much of this fertilizer runs off cropland and ends up in the _____________________ river which eventually flows to the ______________
• Each year, this creates an oxygen ________________ dead zone slightly larger than the state of Massachusetts
fertilizersfeed
Mississippiocean
depleted
Fig. 12-20, p. 296
Trade-Offs
Aquaculture
Advantages Disadvantages
Large inputs of land, feed, and water
High efficiency
High yield Large waste output
Reduced over- harvesting of fisheries
Loss of mangrove forests and estuaries
Some species fed with grain, fish meal, or fish oilLow fuel use
Dense populations vulnerable to diseaseHigh profits
Review Questions
• What are two main detrimental effects of soil erosion?
• Distinguish between…• Desertification• Salinization• Waterlogging
Decrease in soil fertilityWater pollution
Soil potential decreases by 10%Accumulation of salts in soil
Accumulation of water in soil…Raises the water table
Review Questions
• What are some detrimental environmental effects of industrialized meat production?
• What are some detrimental environmental effects of aquaculture?
High inputs of food, water, energy
Concentrated animal waste & gas production
Antibiotic use..passes through food chain
Use of land/water space (estuaries)High inputs of food
Dense populations…vulnerable to disease