Chapter 15 Food and Agriculture

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Section 1: Feeding the World

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Famine: Malnutrition:• Widespread starvation caused by a

shortage of food. • In 1985, drought , erosion, and war

caused a sever famine in Ethiopia. • About 800 million people are

undernourished each day.

• A condition that occurs when people do not consume enough Calories (food energy) or do not eat a sufficient variety of foods to fulfill all of the body’s needs.

• Occurs because of poverty, war, and transportation issues.

• Many forms of malnutrition.• Protein-energy malnutrition results,

affecting the normal physical and mental development of children.

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Sources of Nutrition• Diet: The type and amount of

food that a person eats. • A healthy diet is one that maintains

a balance of the right amount of nutrients, minerals, and vitamins.

• In most parts of the world, people eat large amounts of food that are high in carbohydrates - like rice, potatoes, and bread.

• The food produced in the greatest quantity around the world is grains (rich in carbohydrates).

• Besides grains, people eat fruits, vegetables, and smaller amounts of meats, nuts, and other foods that are rich in fats and proteins.

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Available calorie supply per person/per day

Food Efficiency: Yield:

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•A measure of the quantity of food produced on a given area of land with limited inputs of energy and resources. •An ideal food crop is one that efficiently produces a large amount of food with little negative impact on the environment.

•The amount of food that can be produced in a given area. •Researchers are interested in organisms that can thrive in various climates and that do not require large amounts of fertilizer, pesticides, or fresh water.

Facts About FoodTo raise crops:• Requires less water, less energy,

and less land than raising animals.

• More efficient to raise plants for food – this is why diets around the world are largely based on plants.

• The human body depends on food to build and maintain body tissue.

To raise animals:• Animals used as food are fed

plants.• They only store 10 % of the

energy from the plants – the rest is used to survive.

• Meats provide high levels of nutrients.

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Subsistence farmers: Poverty:• Farmers who grow only

enough food for local use. • They work tiny plots of land

trying provide enough food for their family and a little left over to sell.

8• The state or condition of

having little or no money, goods, or means of support; condition of being poor.

• Malnutrition generally occurs because of poverty.

• Most are usually farm workers or subsistence farmers.

Green Revolution• Introduced new crop varieties with

increased yields through the application of modern agricultural techniques.

• Between 1950 and 1970, Mexico increased its production of wheat eight-fold and India doubled its production of rice without increasing the area of farmland used.

Negative Impacts:• Costly to purchase seeds• Soil degradation • Overuse of water, pesticides, and

fertilizers.

Future of Crops:• Major research today is devoted to

developing plant varieties that produce high yields of nutritious food on poor soil, using as little water and expensive chemicals as possible.

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Section 2: Crops and Soil

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Soil Layers• Surface Litter: fallen leaves and

partially decomposed organic matter

• Topsoil: organic matter, living organisms, and rock particles

• Zone of leaching: dissolved or suspended materials moving downward

• Subsoil: larger rock particles with organic matter, and inorganic compounds

• Rock particles: rock that has undergone weathering

• Bedrock: solid rock layer12

Arable Land: Top Soil: • Soil that can support the growth of

healthy plants is called fertile soil. • Plant roots grow in topsoil. • Topsoil is the surface layer of the

soil. • Usually richer in organic matter

than subsoil. • Fertile topsoil is composed of:

living organisms, rock particles, water, air, organic matter, and decomposing organisms.

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• Land that can be used to grow crops.

• About 10 % of the Earth’s surface is arable land.

• About 3 % of Earth’s surface is urban areas – and growing.

Agriculture: Traditional v’s Modern**Basic processes of farming include: plowing, fertilization, irrigation, and pest control

Traditional Agriculture: • Plows are pushed by farmers or

pulled by livestock.• Plowing helps crops grow by mixing

soil nutrients, loosening soil particles, and uprooting weeds.

• Organic fertilizers are used (manure)

• Irrigated by water flowing through ditches.

• Weeds removed by hand/machine.

Modern: (industrialized countries)• Plowing done by machinery (burns

fossil fuels) • Harvest by machinery.• Synthetic chemical used as

fertilizers.• Overhead sprinklers/drip systems

used to irrigation. • Synthetic chemicals used as pest

control.

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Erosion: Desertification: • The movement of rock and

soil by wind and water. • Washes into nearby rivers or

is blown away in clouds of dust.

• In US – about ½ the original topsoil has been lost to erosion in the past 200 years.

• The process by which land in arid or semiarid areas becomes more desert like.

• Has happened as a result of land degradation.

• Land degradation: when human activity or natural processes damage the land so that it can no longer support the local ecosystem.

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Contour Plowing: No-till Farming:• Form of soil conservation to

save topsoil. • Includes plowing across the

slope of a hill instead of up and down the slope.

• In traditional farming – after harvest – the soil is plowed to turn it over and bury the remains.

• No-till farming: a crop is harvested without turning over the soil.

• Seeds of the next crop are planted among the remains of the previous crop.

• Previous crop holds soil in place.

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Compost: Salinization:• Partly decomposed organic

material. • Used to enrich soil. • Comes from many sources:

cow manure, yard waste, crop waste

• The accumulation of salts in the soil.

• Major problem in places such as California and Arizona (low rainfall and naturally salty soil)

• Irrigation comes from rivers and groundwater – which is naturally saltier than rainwater.

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Pesticides: Pesticide Resistance: • Chemicals used to kill insects,

weeds, and other crop pests. • Can harm beneficial plants

and insects, wildlife, and even people.

• Major crop pest: weeds, insects, and fungi

• The ability to survive exposure to a particular pesticide.

• More than 500 species of insects have developed resistance to pesticides since the 1940s.

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Biological pest Control: the use of living organisms to control pests. • Pathogens: Organisms that cause

disease are used. Most common: Bacillus thuringiensis (Bt). Used to kill the caterpillars of moths and butterflies.

• Plant Defenses: Bred into plants. Can be resistant to fungi, worms, and viruses. Include: chemical compounds that repel pests and physical barriers like tougher skin.

• Chemicals from Plants: Uses the plants’ defensive chemicals. Used mostly in home use insect sprays – because they are less harmful to people/pets.

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Disrupting Insect BreedingGrowth Regulator:• A chemical that interferes

with some stage of a pest’s life cycle.

• Ex. : Once a month dog flea treatments (stops flea eggs from developing)

Pheromones:• Chemicals produced by one

organism that influence the behavior of another organism.

• Can also be used in pest control.

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Integrated pest management: **It is a modern method of controlling pests on crops. **The goal is to reduce pest damage to a level that causes minimal economic damage.

Includes: • Chemical pest control• Biological pest control• Mix of farming methods

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Genetic Engineering: Sustainable Agriculture:• The technology in which

genetic material in a living cell is modified for medical or industrial use.

• Involves isolating genes from one organism and implanting them into another.

• It is a faster way to produce the same results as plant breeding.

• Also known as low-input farming.

• Farming that conserves natural resources and helps keep the land productive indefinitely.

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Section3: Animals and Agriculture

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Overharvesting: Aquaculture:• Catching or removing from a

population more organisms than the population can replace.

• Governments have created no-fishing zones to lessen overharvesting.

• The raising of aquatic organisms for human use or consumption.

• Probably began in China about 4,000 years ago.

• Today – China leads the world in using aquaculture.

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Livestock: Domesticated Animals:• Domestic animals that are

raised to be used on a farm or ranch or to be sold for profit.

• Livestock farms produce most meat that is consumed in developed countries.

• Ex: chickens, sheep, cattle, pigs

• Animals that have been bred and managed for human use.

• About 50 animals species have been domesticated.

• India – has about 1/5 of the world’s population of cattle. Many are never killed or eaten – because they are sacred.

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Ruminants: Poultry: • Cud-chewing mammals that

have three or four chambered stomachs.

• Ex: cattle, sheep, goats• Cud is the food these animals

regurgitate from the 1st chamber of their stomachs and chew again to aid digestion.

• Domesticated birds raised for meat and eggs.

• Are good sources of essential amino acids.

• Ex: chickens, turkeys • Since 1961, the population

of chickens worldwide has increased more than any other livestock.

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