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Issues and Impacts of Agriculture
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Our ability to produce enough food to feed to world depends on 3 things:
land water and energy About 10% of Earth’s land surface can be used for agriculture (arable land) About 70% of Earth’s water is used for agriculture About 24% of GHG emissions come from agriculture
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Main Topics - FYI Methods of producing food Increasing food production
Environmental effects of food production Issues of sustainability
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A World of 9 Billion Famine – widespread starvation due to a shortage of food By 2050, 9 billion people will need to be fed Feed a nutritious diet is difficult Food production can be increased without permanently harming the environment
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MALNUTRITION – lack of sufficient calories or lack of essential nutrients
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What do we eat? DIET – type and amount of food eaten
Worldwide – most people eat grains
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Diet Around the World How do the diets of people in developed countries compare with the diets of people in developing countries? Their diets are higher in calories, especially from fats and proteins.
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Sources of food worldwide
Of 30,000 edible plants, only 15 species supply 90% of our food Primary plants: wheat, corn, and rice Provide > ½ calories people consume Primary animals: cattle, pigs, and chicken Secondary: eggs, milk & cheese
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A food crop that produces a large amount of food with little negative environmental consequences is ideal 1 Calorie of animal food uses more energy, water and land than plant food 90% energy loss up the food chain Land can produce more food when used to grow plants than animals Meat provides more nutrients per gram than plants
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More Efficient Foods Less Waste
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World Food Problems There is enough food to feed up to 10 billion people However, most of us consume ~1/3 of our calories from animals We need more food every year Today’s malnutrition results from poverty Lack of enough water for irrigation Income less than $1/day Africa, Asia & mountainous South America
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World Food Problems FYI
Fewer people living in poverty since 1980 However :
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World Food Problems To feed the people of 2050 HOW?
We will need to produce more food We will need to abolish poverty HOW? Increasing subsistence farmer productivity Irrigation
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Agriculture History - FYI
In early agriculture, people began planting seeds from plants they liked most Agriculture and livestock provided a stable food supply, which allowed the development of modern civilization
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Types of Agriculture Traditional Modern Plowing – bio-powered
Fertilizer – organic manure Irrigation – ditch Pest control – manual removal Modern Plowing – fossil fuel powered Fertilizer – synthetic chemicals Irrigation – sprinklers & drip Pest control – synthetic chemicals
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Ecology of Food Different kinds of agriculture have different environmental impacts
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Major Types of Agriculture
Traditional subsistence Shifting cultivation Nomadic herding Traditional intensive Plantation Industrialized
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Shifting cultivation in tropical
forests in developing countries Land Labor Capital Nomadic herding in developing countries Land Labor Capital
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Industrialized agriculture Traditional intensive agriculture
Land Industrialized agriculture in developed countries Labor Capital Fossil fuel energy Land Traditional intensive agriculture in developing countries Labor Capital Fossil fuel energy
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World Food Production Plantation agriculture
Industrialized agriculture Shifting cultivation Plantation agriculture Nomadic herding Intensive traditional agriculture No agriculture
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THE GREEN REVOLUTION – a large increase in crop production using modern agricultural techniques, new crop varieties, and farming practices in developing countries in the mid- to late 1900s
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Green Revolutions First green revolution (developed countries)
Second green revolution (developing countries) Major International agricultural research centers and seed banks
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Producing Food by Green-Revolution Techniques
High-input monoculture Selectively bred or genetically-engineered crops High inputs of fertilizer Extensive use of pesticides High inputs of water
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THE GREEN REVOLUTION – a large increase in crop production using modern agricultural techniques, new crop varieties, and farming practices in developing countries in the mid- to late 1900s PROS – Large yields produced New varieties of grain (if enough water, fertilizer and pesticides) Saved millions of people from starvation in India and Pakistan Reduced the price of food Improved lives of millions Prevented some deforestation and habitat loss by increasing yields on cultivated land
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THE GREEN REVOLUTION CONS – Increases mostly on large farms
Led to a 7000% increase in energy used by agriculture Worsened erosion, salinization, desertification, eutrophication, and pollution Subsistence farmers do not have the money for water and chemicals required by new crops varieties Does not meet the needs of subsistence farmers who need: Small-scale irrigation Cash crops (fruits and vegetables)
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Results of Green Revolution: Mixed
Higher yields per acre when fertilizers and pesticides available Lower yields when fertilizers and pesticides unavailable Increased dependence on cash economy Increased dependence on fossil fuel Increased imports of fertilizers and pesticides
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Food Production since the Green Revolution
Rapid increases in total production Prices decreasing Shortages in developing countries Approaching limits on meat production
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Unintended consequences: Killer Bees
Mild-mannered, low honey producing Italian bee X Aggressive, high honey producing African bee? Hope for a mild-mannered, high producing bee Instead, got an aggressive, low producing bee Worse yet – it escaped, and is interbreeding with other bees making them aggressive & low producing too!
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Environmental Effects of Food Production
Biodiversity loss Soil degradation Air pollution and climate effects Water pollution Human health
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Biodiversity Loss Soil Loss and degradation of habitat from clearing grasslands and forests and draining wetland Invasive species out competing natives Killing of wild predators to protect livestock Loss of genetic diversity from replacing thousands of wild crop strains with a few monoculture strains Erosion Loss of fertility Salinization from irrigation Desertification
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LAND DEGREDATION Soil Erosion Desertification Soil Salinization
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Causes of Soil Erosion Wind Water (#1) People
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Erosion Facts ~ ½ the original topsoil has been lost in the US over the past 200 years Most farming methods increase the rate of soil erosion Plowing loosens soil an removes plants that hold soil in place Runoff from irrigation carries soil with it
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Soil Erosion: A Global Problem
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Soil Erosion Often occurs faster than soil is formed, depleting fertile topsoil Crops, trees, and other plant communities protect soil from erosion
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Did You Know? More than 19 billion hectares (47 billion acres) of the world’s croplands suffer from erosion and other forms of soil degradation resulting from human activities.
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Impacts of Soil Erosion
Loss of soil fertility Sediment runoff causes problems in surface water (pollution, clog ditches, boat channels, reservoirs) #1 source of U.S. water pollution Renewable only on LONG timeframes (200-1,000yrs. for 1 inch)
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What time of year do you think most farm fields in U. S
What time of year do you think most farm fields in U.S. are vulnerable to erosion? That’s right - SPRING
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On Agricultural land in U. S
On Agricultural land in U.S. today, soil is eroding 16 times faster than it is created
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Desertification When land in arid or semi-arid regions becomes more desert-like due to agricultural practices
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Some estimates predict that 50 million people could be displaced in the next 10 years due to desertification. Africa's Ambitious "Great Green Wall"
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SOIL SALINIZATION Major problem in areas of low rainfall and naturally salty soil (CA, AZ, Africa, Near & Middle East) Irrigation water saltier than rainwater Evaporation leave behind salts REMEDIATION Line irrigation canals Water soil heavily to wash out salts
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Soil Salinization
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Soil Conservation (Farming Practices That Reduce Erosion)
Terracing: Steep slopes turned into “steps” Contour Plowing: plowing across the slope Intercropping: Different crops mixed together Drip Irrigation: minimize use of water
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Contour and Strip Cropping
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Soil Conservation (Farming Practices That Reduce Erosion)
Crop rotation: Crops are alternated Shelterbelts: Tall plants block wind Conservation tillage: Soil turnover is reduced No-Till Farming: crop harvested without turning over soil
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Greenhouse gas emissions from fossil fuel use
Air & Climate Water Greenhouse gas emissions from fossil fuel use Other air pollutants from fossil fuel use Pesticide drift from spraying Dust / airborne particulates Weather alteration from large scale clearing Aquifer depletion Water diversions Increased runoff and flooding from land cleared to grow crops Sediment pollution from erosion Fish kills from pesticide runoff Surface and groundwater pollution from pesticides, fertilizers & livestock Overfertilization (eutrophication) of lakes and slow-moving rivers from runoff of nitrates and phosphates from fertilizers, livestock wastes, and food processing wastes
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Human Health Nitrates in drinking water Pesticides residues in drinking water, food, and air Contamination of drinking and swimming water with disease organisms from livestock wastes Bacterial contamination of meat Farm worker exposure & working conditions
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Controlling Pests Pests affect crop production
Worldwide 33% of potential food harvest PEST – any organism that occurs where it is not wanted or occurs in large enough numbers to cause economic damage Weeds, insects, fungi
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PESTICIDES Chemicals to kill insects, weeds & other crop pests
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Pests and Weed Control Chemical pesticides: Effective and cheap, but can lead to resistance
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PESTICIDE – HUMAN HEALTH CONCERNS
Pesticides are designed to kill organisms – what is the effect on humans? Cancer rates in children higher than national average Workers in pesticide factories become ill Accidental chemical leaks (Bhopal, India-1000’s die) Users must follow safety guidelines
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PESTICIDES - PERSISTENT
Do not break down rapidly into harmless forms 1950's DDT video DDT banned in the US in the 1970’s Still detected in environment Effects -
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Soil Pollution Too much, or carelessly timed irrigation can waterlog crops and lead to salinization—a buildup of salts in upper soil horizons. Toxic persistent pesticides can remain in soil for a long time, eventually filtering to groundwater. Evaporation Transpiration Waterlogging Less permeable clay layer
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Pests and Weed Control Biological Pest Control: using living organisms to control pests
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Pests and Weed Control Pathogens: organisms that cause disease
Most common – Bacillus thuringiensis (Bt) Kill pest caterpillars (but can kill unintended targets
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Pests and Weed Control Plant Defenses: varieties of plants bred to have defenses against pests Chemical compounds that repel pests Physical barriers to impede pests
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Pests and Weed Control Plant Chemicals: uses plant’s defensive chemicals Chrysanthemum plants Less harmful to humans and pets Biodegradable
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Pests and Weed Control Growth Regulators: interference with pest life cycle Pheromones: chemicals that affect the behavior of pests Sterilization: eggs produced that do not develop
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Pests and Weed Control Biological pest control: Permanent solution, but can harm non-target organisms Integrated pest management: combines chemical and biological pest-control methods goal – minimize economic loss from pest damage Cactus moth larvae are used to control prickly pear cactus, but also threaten many rare, native cacti around the world.
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Integrated Pest Management
Combination of farming methods, biological pest control and chemical pest control
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Increasing World Crop Production
Crossbreeding and artificial selection Genetically modified organisms (GMOs) Continued Green Revolution techniques Introducing new foods Working more land
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Sustainability Sustainable agriculture conserves natural resources
Minimizes the use of energy, water, pesticides & fertilizers Involves planning productive, pest-resistant crops that require little energy, pesticides, fertilizers & water
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Alternative Solutions: Sustainable Agriculture
Low-input agriculture Organic farming Non-meat alternatives Research in sustainable techniques
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In Summary: Supplying food for the world’s growing population was and still is an issue. Policy and research play a big role. Efforts to increase production have focused on: Improved varieties thru breeding and genetic engineering Inputs, esp. chemicals (fertilizers & Pesticides), energy and water Agriculture has multiple impacts on the environment and human health Sustainable agricultural techniques are growing but far behind conventional
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