unit 05 food & agriculture. chapter 11 producing enough food for the world
TRANSCRIPT
Unit 05Food & Agriculture
1.6
1.8
1.4
1.1
1.1
0.5
1.1
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0.6
0.6
0.4
1.2
5.6
8.1
Today:• 2 billion people lack reliable access to food• 800 million people today are chronically malnourished• 300 million of these are children
Today:• 2 billion people lack reliable access to food• 800 million people today are chronically malnourished• 300 million of these are children
UN regional forecastBillions of people Developed
countries
Latin AmericaWest Asia and North Africa
Sub-Saharan Africa
South Asia
East Asia
20201990
Who cares about food and agriculture?
Percents indicate the percent of people in each location that are undernourished.
Quality of Food Malnourishment
One in three people has a deficiency of one or more vitamins and minerals, especially vitamin A, iodine (causes goiter - enlargement of thyroid gland), and iron.
• A micronutrient disorder
Figure 13-2Figure 13-2
War and the EnvironmentUndernourishment
Starving children collecting ants to eat in famine-stricken Sudan, Africa which has been involved in civil war since 1983.
Figure 13-3Figure 13-3
Kwashiorkor
Kwashiorkor is an ailment that results from severe protein deficiency. It is mainly seen in the tropical and subtropical regions of west and central Africa. It commonly occurs when a child is weaned onto a diet deficient in protein after the birth of another child.
• A macronutrient disorder
In the Ga language of Ghana, kwashiorkor means "the sickness of the child who is displaced from the breast”or “the disease of the displaced child"
The photograph above shows Sudanese children
with severely swollen abdomens, a characteristic symptom of kwashiorkor
Daily Intake of Calories Worldwide
Eating Too MuchOvernutrition
• Overnutrition and lack of exercise can lead to reduced life quality, poor health, and premature death.
• A 2005 Boston University study found that about 60% of American adults are overweight and 33% are obese (totaling 93%).
• Americans spend $42 billion per year trying to lose weight.
• $24 billion per year is needed to • eliminate world hunger.
Increased food demand matrix
Caloric Caloric shift shift to meat to meat
productproductss
HighHigh
MediumMedium
LowLow
Population X income growthPopulation X income growth
Year 2020Year 2020Demand Demand
+75%+75%•Population Population growth +45% growth +45%
•Increased meat Increased meat consumption consumption +30%+30%
• Shift to Shift to “healthy” and “healthy” and specialized foodsspecialized foods
LowLow MediumMedium HighHigh
61%61% 88%88% 147%147%
51%51% 76%76%
Base CaseBase Case100%100%
39%39% 61%61% 88%88%
ProjectionProjection(75%)(75%)
Source: IFPRI, FAO
•In India, the gains from the “Green Revolution” are getting saturated
Population and Income Growth will Fuel Increased Food Demand
Food Production
• Food production from croplands, rangelands, ocean fisheries, and aquaculture has increased dramatically.
• Wheat, rice, and corn provide more than half of the world’s consumed calories.– Fish and shellfish are an important source of food
for about 1 billion people mostly in Asia and in coastal areas of developing countries.
Industrial Food Production: High Input Monocultures
• About 80% of the world’s food supply is produced by industrialized agriculture.– Uses large amounts of fossil fuel energy, water,
commercial fertilizers, and pesticides to produce monocultures.
– Greenhouses are increasingly being used.– Plantations are being used in tropics for cash
crops such as coffee, sugarcane, bananas.
Plantation agriculture
Shifting cultivation
Industrialized agriculture
No agriculture
Intensive traditional ag.
Nomadic herding
Locations of the world’s
principal types of food
production.
World Land Use
Crops
Rangeland:
Provides food for grazing and browsing animals without plowing and planting
Pasture:
Plowed, planted and harvested to provide forage for animals
Geographic Distribution of World Production of a Few MAJOR
Small-grain Crops
World Small Grain Production
Aquaculture
• Aquaculture– The farming of food in aquatic habitats
• Mariculture– The farming of ocean fish
Site of mollusk cultivation in eastern Canada Vietnamese fishery.
Six Ways Agroecosystems Differ from Natural Ecosystems
1. Try to stop ecological succession and keep the agroecosystem in an early successional state
2. Monoculture: Large areas planted with a single species
3. Crops are planted in neat rows4. Farming greatly simplifies biological diversity5. Plowing is unlike any natural soil disturbance6. Genetic modification of crops.
Limiting Factors• Limiting Factor: • The single requirement for growth
available in the least supply in comparison to the need of an organism
2 Types of Life-Important Chemicals1. Macronutirents2. Micronutirents
Synergistic Effects: a change in availability of one resource affects the response of an organism to some other resource
Increasing the Yield per Acre
1. The Green Revolution- Programs that have led to the development of
new strains of crops with higher yields, better resistance to disease or better ability to grow under poor conditions
2. Improved Irrigation
Organic Farming
3 Qualities1. It is more like natural ecosystems than
monocultures2. It minimizes negative environmental impacts3. The food that results from it does not contain
artificial compounds
Genetically Modified Food Genetically Modified Crops are modified by
genetic engineers to produce higher crop yields and increase resistance to drought, cold, heat, toxins, plant pests and disease.
Chapter 12
Effects of Agriculture on the Environment
Many environmental problems result from agriculture:
• Soil erosion • Sediment transport and
deposition downstream• On-site pollution from
fertilizers and pesticides• Deforestation
• Desertification• Degradation of water
aquifers• Salinization• Accumulation of toxic
metals and organic compounds
• Loss of biodiversity
PROTECTING FOOD RESOURCES: PEST MANAGEMENT
Organisms found in nature (such as spiders) control populations of most pest species as part of the earth’s free ecological services.
Figure 13-27Figure 13-27
PROTECTING FOOD RESOURCES: PEST MANAGEMENT
• We use chemicals to repel or kill pest organisms as plants have done for millions of years.
• Chemists have developed hundreds of chemicals (pesticides) that can kill or repel pests.– Pesticides vary in their persistence.– Each year > 250,000 people in the U.S. become ill
from household pesticides.
PROTECTING FOOD RESOURCES: PEST MANAGEMENT
• Advantages and disadvantages of conventional chemical pesticides.
Figure 13-28Figure 13-28
Individuals Matter: Rachel Carson
• Wrote Silent Spring which introduced the U.S. to the dangers of the pesticide DDT and related compounds to the environment.
Figure 13-AFigure 13-A
The ideal Pesticide and the Nightmare Insect Pest
• The ideal pest-killing chemical has these qualities:– Kill only target pest.– Not cause genetic resistance in the target
organism.– Disappear or break down into harmless chemicals
after doing its job.– Be more cost-effective than doing nothing.
Superpests
• Superpests are resistant to pesticides.
• Superpests like the silver whitefly (left) challenge farmers as they cause > $200 million per year in U.S. crop losses.
Figure 13-29Figure 13-29
Pesticide Protection Laws in the U.S.
• Government regulation has banned a number of harmful pesticides but some scientists call for strengthening pesticide laws.– The Environmental Protection Agency (EPA), the
Department of Agriculture (USDA), and the Food and Drug Administration (FDA) regulate the sales of pesticides under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA).
– The EPA has only evaluated the health effects of 10% of the active ingredients of all pesticides.
Other Ways to Control Pests
• Genetic engineering can be used to develop pest and disease resistant crop strains.
Both tomato plants were exposed to destructive caterpillars. The genetically altered plant (right) shows little damage. Figure 13-32Figure 13-32
Case Study Integrated Pest Management: A Component of Sustainable Agriculture
• An ecological approach to pest control uses a mix of cultivation and biological methods, and small amounts of selected chemical pesticides as a last resort.– Integrated Pest Management (IPM)
Case Study Integrated Pest Management: A Component of Sustainable Agriculture• Many scientists urge the USDA to use three
strategies to promote IPM in the U.S.:– Add a 2% sales tax on pesticides.– Establish federally supported IPM demonstration
project for farmers.– Train USDA personnel and county farm agents in
IPM.• The pesticide industry opposes such measures.
Biological Pest Control
Integrated Pest Management
– Control of agricultural pests using several methods together, including biological and chemical agents
– Goals:• To minimize the use of artificial chemicals• To prevent or slow the buildup of resistance by pests to
chemical pesticides
Fig. 13-30, p. 299
What Can You Do?
Reducing Exposure to Pesticides
• Grow some of your food using organic methods.
• Buy organic food.
• Wash and scrub all fresh fruits, vegetables, and wild foods you pick.
• Eat less or no meat.
• Trim the fat from meat.
SoilSoil Formation: Soil is formed slowly as rock
(the parent material) erodes into tiny pieces near the Earth's surface. Organic matter decays and mixes with inorganic material (rock particles, minerals and water) to form soil.
Soil Horizons (layers): Soil is made up of distinct horizontal layers; these layers are called horizons. They range from rich, organic upper layers (humus and topsoil) to underlying rocky layers ( subsoil, regolith and bedrock).
Humus• The main contributor to the fertility of the soil.
It originates from decomposing material. • Found on the SURFACE of the soil• So for examples one reason why grasslands are
considered the “bread baskets of the world is because of their great fertility due in large part to the natural humus which accumulates because grasses form a large amount of organic matter that decomposes.
• Tropical rainforests, however, DO NOT have a large amount of humus because the decomposition rate there is so fast the nutrients are almost immediately reabsorbed by plants. This is why the tropical rainforest does not yield fertile soil when it is cut down.
• Some forests do have humus, however, deciduous forests accumulate humus because of the decomposition of plants and animals. Temperate rainforests also contain humus because needles and leaves will decompose.
• Importance: nutrients (fertility), holds water, improves soil aeration, prevents erosion, improves habitats for soil living organisms, improves soil structure, allows roots to grow more easily.
O Horizon - The top, organic layer of soil, made up mostly of leaf litter and humus (decomposed organic matter).A Horizon - The layer called topsoil; it is found below the O horizon and above the E horizon. Seeds germinate and plant roots grow in this dark-colored layer. It is made up of humus (decomposed organic matter) mixed with mineral particles.E Horizon - This eluviation (leaching) layer is light in color; this layer is beneath the A Horizon and above the B Horizon. It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil (in the process of eluviation).B Horizon - Also called the subsoil - this layer is beneath the E Horizon and above the C Horizon. It contains clay and mineral deposits (like iron, aluminum oxides, and calcium carbonate) that it receives from layers above it when mineralized water drips from the soil above.C Horizon - Also called regolith: the layer beneath the B Horizon and above the R Horizon. It consists of slightly broken-up bedrock. Plant roots do not penetrate into this layer; very little organic material is found in this layer.R Horizon - The unweathered rock (bedrock) layer that is beneath all the other layers.
Testing Soil
• Chemical– pH– salinity– organic content (measuring humus)– Testing for major elements such as N, P, K, S or trace
elements such as Co, B, Ca, Mg etc.• Physical
– Soil Texture– Porosity – how much water the soul can old due to the
amount of air/space available– Moisture content
Global Outlook: Soil Erosion
• Soil is eroding faster than it is forming on more than one-third of the world’s cropland.
Figure 13-10Figure 13-10
Where Eroded Soil Goes: Sediments Also Cause Environmental Problems
Ways to slow erosion:• Making Soil Sustainable• Contour Plowing• No-Till Agriculture
– Combination of farming practices that include not plowing the land and using herbicides to keep down weeds.
Very severeSevereModerate
Desertification of arid and semi-arid lands
Case Study: Soil Erosion in the U.S. Some Hopeful Signs
• Soil erodes faster than it forms on most U.S. cropland, but since 1985, has been cut by about 40%.– 1985 Food Security Act (Farm Act): farmers
receive a subsidy for taking highly erodible land out of production and replanting it with soil saving plants for 10-15 years.
Desertification
• Desertification is the deterioration of land in arid, semi- arid and dry sub humid areas due to changes in climate and human activities
• Can be caused by– Poor farming practices– Conversion of marginal grazing lands to croplands
Desertification: Degrading Drylands
About one-third of the world’s land has lost some of its productivity because of drought and human activities that reduce or degrade topsoil.
Figure 13-12Figure 13-12
Carrying Capacity of US Pasture & Rangelands
Average number of cows per square kilometer
•Bad farming practices have lead to an increase in desertification in the US. •Climate suggests that 1/3 of the earth should be deserts, however now deserts cover nearly 50% of the planet because of human action!
Salinization and Waterlogging
Repeated irrigation can reduce crop yields by causing salt buildup in the soil and waterlogging of crop plants.
Figure 13-13Figure 13-13
Fig. 13-15, p. 281
CleanupPrevention
Soil Salinization
Solutions
Reduce irrigation
Switch to salt-tolerant crops (such as barley, cotton, sugarbeet)
Flush soil (expensive and wastes water)
Stop growing crops for 2–5 years
Install underground drainage systems (expensive)
Salinization and Waterlogging of Soils: A Downside of Irrigation
• Example of high evaporation, poor drainage, and severe salinization.
• White alkaline salts have displaced cops.
Figure 13-14Figure 13-14
SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
Modern farm machinery can plant crops without disturbing soil (no-till and minimum tillage.– Conservation-tillage farming:
• Increases crop yield.• Raises soil carbon content.• Lowers water use.• Lowers pesticides.• Uses less tractor fuel.
SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
Terracing, contour planting, strip cropping, alley cropping, and windbreaks can reduce soil erosion.
Figure 13-16Figure 13-16
SUSTAINABLE AGRICULTURE THROUGH SOIL CONSERVATION
• Fertilizers can help restore soil nutrients, but runoff of inorganic fertilizers can cause water pollution.– Organic fertilizers: from plant and animal (fresh,
manure, or compost) materials.– Commercial inorganic fertilizers: Active
ingredients contain nitrogen, phosphorous, and potassium and other trace nutrients.
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
• Since 1950, high-input agriculture has produced more crops per unit of land.
• In 1967, fast growing dwarf varieties of rice and wheat were developed for tropics and subtropics.
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
• Lack of water, high costs for small farmers, and physical limits to increasing crop yields hinder expansion of the green revolution.
• Since 1978 the amount of irrigated land per person has declined due to:– Depletion of underground water supplies.– Inefficient irrigation methods.– Salt build-up.– Cost of irrigating crops.
THE GREEN REVOLUTION AND ITS ENVIRONMENTAL IMPACT
• Modern agriculture has a greater harmful environmental impact than any human activity.
• Loss of a variety of genetically different crop and livestock strains might limit raw material needed for future green and gene revolutions.– In the U.S., 97% of the food plant varieties available in
the 1940 no longer exist in large quantities.
Fig. 13-18, p. 285
Biodiversity Loss Soil Water Air Pollution Human Health Loss and degradation of grasslands, forests, and wetlands
Erosion Water waste Greenhouse gas emissions from fossil fuel use
Nitrates in drinking water
Loss of fertility Aquifer depletion
Pesticide residues in drinking water, food, and air
Salinization Increased runoff and flooding from cleared land
Other air pollutants from fossil fuel use
Fish kills from pesticide runoff
Waterlogging
Sediment pollution from erosion Greenhouse gas
emissions of nitrous oxide from use of inorganic fertilizers
Contamination of drinking and swimming water with disease organisms from livestock wastes
Desertification
Killing wild predators to protect livestock
Fish kills from pesticide runoff
Surface and groundwater pollution from pesticides and fertilizers Belching of the
greenhouse gas methane by cattle
Loss of genetic diversity of wild crop strains replaced by monoculture strains
Bacterial contamination of meat
Overfertilization of lakes and rivers from runoff of fertilizers, livestock wastes, and food processing wastes
Pollution from pesticide sprays
THE GENE REVOLUTION• To increase crop yields, we can
mix the genes of similar types of organisms and mix the genes of different organisms.– Artificial selection has been used for centuries to
develop genetically improved varieties of crops.– Genetic engineering develops improved strains at an
exponential pace compared to artificial selection.
• Controversy has arisen over the use of genetically modified food (GMF).
The Terminator Gene
• A genetically modified crop which has a gene to cause the plant to become sterile after the first year
Grazing on Rangelands
• Overgrazing occurs when the carrying capacity is exceeded. It can cause severe damage to lands
• It is important to properly manage livestock, including using appropriate lands for gazing and keeping livestock at a sustainable density
SOLUTIONS: SUSTAINABLE AGRICULTURE
• Three main ways to reduce hunger and malnutrition and the harmful effects of agriculture:– Slow population growth.– Sharply reduce poverty.– Develop and phase in systems of more
sustainable, low input agriculture over the next few decades.
Fig. 13-33, p. 302
Solutions
Sustainable Organic Agriculture
More Less
High-yield polyculture
Soil erosion
Soil salinizationOrganic fertilizers
Aquifer depletionBiological pest control Overgrazing
Integrated pest management
Overfishing
Loss of biodiversity
Efficient irrigation Loss of prime
croplandPerennial crops
Crop rotationFood waste
Water-efficient crops
Subsidies for unsustainable farming and fishing
Soil conservation
Subsidies for sustainable farming and fishing
Population growth
Poverty
Sustainable Agriculture
Results of 22 year study comparing organic and conventional farming.
Figure 13-34Figure 13-34
What Can You Do?
Sustainable Organic Agriculture
• Waste less food
• Eat less or no meat
• Feed pets balanced grain foods instead of meat
• Use organic farming to grow some of your food
• Buy organic food
• Eat locally grown food
• Compost food wastes