unit 05 food & agriculture. chapter 11 producing enough food for the world

Unit 05Food & Agriculture

Chapter 11

Producing Enough Food for the World

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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.


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.



• 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.


• Advantages and disadvantages of conventional chemical pesticides.


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.


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.

http://www.enchantedlearning.com/geology/label/soillayers/

http://www.enchantedlearning.com/geology/label/soillayers/

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.


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.


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.


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.


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.


Terracing, contour planting, strip cropping, alley cropping, and windbreaks can reduce soil erosion.



• 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.


• 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.


• 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.


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

unit 05 food & agriculture. chapter 11 producing enough food for the world

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