Challenges for 21st Century
Reduce global hunger (food security)
Meet world food demand with
sustainable agricultural practices
Food safety
Feeding the world
• This chapter will discuss food production,
maintenance of soil productivity, and the
challenges of feeding the world.
• Various alternative methods of planting and
harvesting crops, controlling pests, and raising
livestock are examined.
• Imagine you are the owner of this farmland in rural
• What might their daily life involve?
• What concerns and needs would they have in order to
maintain their income and way of life?
• Today less than 10% of agricultural land in the United States is
owned and operated by families. Work with your partner and
brainstorm possible reasons for this situation
• Identify the major causes of malnutrition
• Compare the environmental costs of
producing different types of food.
• Explain how food distribution problems and
drought can lead to famine
• Explain the importance of green revolution
Humans and Nutrition
• Food serves as a source of energy and also serves as a source materials for
building and maintaining body tissues.
Major nutrients in Human Foods
Energy Yield
Wheat, corn,
and rice
4 cal/g
Is the main
source of the
body’s energy
Lipids (oil and
Fatty acids and
fatty alcohol
Olives, nuts,
and animal fats
9 Cal/g
Helps from
and hormones
Amino acids
Animal food
and smaller
amounts from
About 4 Cal/g
Helps build and
maintain all
body structures
Population Growth
Things to ponder
• Hypothesize why everyone does not get enough
• Malnutrition is a condition that occurs when
people do not consume enough Calories or do
not eat a sufficient variety of foods to fulfill all of
the body’s needs.
• In some parts of the world, the only sources of
food may be corn or rice. Each of these food
contains proteins but lacks one of the essential
amino acids.
Food choices
if for the same amount of money, you could buy three loaves of bread
or this one hamburger patty, which would choose and why?
Hamburger patty
Whole grain bread
Refer to the graph in page number 380 in your text book and
answer the following
Discuss with your partner and be prepared to
Why do you think proteins and fats form a larger
percentage of the diets of western, developed
countries, and less in developing countries?
In the United States, almost half of all Calories
people consume come from meat, fish, and oil.
Japanese diet traditionally included rice,
vegetables, and seafood, have started to
consume beef in recent decades.
A healthy diet
• A healthy diet is one that maintains a balance of the right
amounts of nutrients, minerals, and vitamins.
• In most parts of the world, people east large amounts of food
that is high in carbohydrates, such as rice, potatoes and
• The food produced in the greatest amounts all over the world
are grains, whose seeds are rich in carbohydrates. Besides
eating grains, most people east fruits, vegetables, and smaller
amounts of nuts, meats, and other food rich in fat and
Food efficiency
• The efficiency of a given type of agriculture is a
measure of the quantity of food produced on a given
area of land with limited inputs of energy and
• An ideal food crop is one that efficiently produces a
large amount of food with little negative impact on the
• A given area of land can usually produce more food for
humans when it is used to grow plants than when it is
used to raise animals. Can you give reasons?
• Meat from animals generally provides more nutrients
pr gram than most food from plants.
Math Practice
Extra calories
An active man who weighs 70 kg maintains his
weight if he eats 2,700 Cal per day. Unused
calories are converted into stored fat at the
rate of 1 kg of fat per 9,000 Cal that are
unused. If this active man consumes 3,600 cal
per day, how much weight does he gain each
• 3,000 Cal/day – 2,700 Cal/day = 900 Cal/day
• 900 Cal/day x 365 days/year = 328,500
• 328,500 Cal/year÷ 9,000 = 36.5 kg weight
gained /year
• (1 kg of fat per 9,000 Cal)
Old and New Foods
• Researchers hope to improve the efficiency of
food production by studying plants and other
organisms that have high yield – 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
• The Next Diet for a small planet, by Lappe and
her daughter (try to get this book and read.
Thoughts for your mind
• I would like you to consider the potential
global effects if a greater proportion of people
ate plant-and grain based diets as advocated
by Lappe.
Staple food around the world
Asia – rice
Parts of China and India –
Central America –cornmeal
European Countries –potatoes
and bread grains such as
wheat and rye
Ethiopia – millet and
buckwheat – made into a
fermented bread called injera
World Food Problems
• : some people become malnourished
because they do not get enough food.
• Malnourished children in Bangladesh wait for
food assistance.
• It is mainly the
Result of poverty.
World Food Problems
• Unequal Distribution: Food is not equally
divided equally. Even in the United States,
many poor people suffer from malnutrition.
• Wars and political strife can also lead to
malnutrition, because interrupt transportation
• During wars, even if the food is available, it
often cannot be transported to the people
who need it.
Droughts and Famines
• A drought is a prolonged period during which rainfall is below
average. Crops produced without irrigation may produce low
yields or fail entirely.
• If drought occurs, there may be no seed to plant the following
year. People in a given area can usually survive one crop
failure. After a long drought the soil may be less able to
support the production of food crops
World grain production
Worldwide grain
production has
increased steadily,
but not as rapidly as
the population has
The Green Revolution
• Between 1950 and 1970, Mexico increased
the production of wheat eight fold and India
doubled its production of rice.
• Worldwide increase in crop yield resulted
from the use of new crop varieties and the
application of modern agricultural
techniques. These changes were called the
green revolution
Negative effects of Green Revolution
• Most new varieties of grain produce large yields only if they receive
large amounts of water, fertilizer, and pesticides.
• Machinery, irrigation, and chemicals required by new crop varieties
can degrade the soil if they are not used properly.
• Overuse of fertilizers and pesticides can result in lower yield of
• Green revolution had negative impact on subsistence farmers.
Before the green revolution, subsistence farmers worked most of
the world’s farmland. But they could not afford the equipment,
water, and chemicals needed to grow the new crop varieties.
Answer all questions
1. Identify the major causes of malnutrition
2. Explain how drought and the problems of
food distribution can lead to famines.
3. Describe the importance and effects of the
green revolution
4. What do crops of green revolution need in
order to produce high yields?