AP ENVIRONMENTAL SCIENCE
Unit 4: Feeding the World (Ch. 11)
Can we feed the world?
What do we want to know?
• Can we produce enough food?
• Can we grow crops sustainably?
• Can we produce crops without damaging
ecosystems?
What do we need to understand?
• How crops grow and how productive they can be
Can we feed the world?
• History show that agriculture has been the most
sustainable of all human activities.
• Some regions have been farmed for thousands of
years (Nile Valley)
• Nomadic people would farm an area until it became
degraded before moving on to leave the land fallow
(plowed but left unsown to restore fertility)
• Farming has changed ecosystems
Can we feed the world?
• History of agriculture is a series of human attempts to
overcome environmental limitations and problems.
• Each solution creates new
problems
• Some side effects expected
• Multiple pressures have been
put on agricultural land
Aswan Dam across the Nile
River. First built in 1898,
latest project completed in
1970
Can we feed the world?
• Agricultural Land is defined as any area devoted to
agriculture, the systematic and controlled use of living
organisms (crop or livestock)
• Arable land- land used for producing crops requiring
annual replanting
• Permanent cropland- land used for crops that do not
require annual replanting
• Pastures- natural or artificial grasslands used for livestock
grazing
Can we feed the world?
• 36% of the world’s land
area is considered suitable
agricultural land
• 1/3 (11%) of the land is
arable
• Percentages of arable land
vary by continent
Can we feed the world?
• The role of agriculture in
ecosystems is changing
with the needs of the
human population
• Technology, irrigation,
and genetically modified
foods have changed the
land area available for
agriculture
Can we feed the world?
Can we feed the world?
• Other factors influence the production of
crops even in places that contain arable land
• Social disruptions
• Social attitudes
• Economy
• Weather
Can we feed the world?
• The key to food production in the future:
• Increased production per unit area
• Requires increased use of water, fertilizers, and
pesticides
• OR implementation of ecological principles in the use of
Organic/ BioDynamic farming
• Utilizing marginal lands
Can we feed the world?
• As increased production is demanded there will be
increased in environmental degradation
• Limiting factors to agricultural
production include water needed
for irrigation
Can we feed the world?
How we starve
• People “starve” in two ways
• Undernourishment- lack of sufficient calories in
available food. One has little or no ability to move
or work and eventually dies from lack of energy.
• Malnourishment- lack of specific chemical
components of food, such as protein, vitamins, or
other essential chemical elements.
How we starve
• Food emergencies affected 34 countries worldwide
at the end of 20th century
• Africa has the most acute
food shortages
• Food distribution is a major
problem
• World food aid does not
meet all the caloric needs of
people
*Best solution is to increase local
production
How we starve
• Currently, over 800 million people worldwide lack access to
adequate amounts of food
• 24,000 people starve to death each day (8.8 million/year)
• The primary reason for undernutrition and malnutrition is
poverty
• Food aid focuses on providing food security (adequate
access to safe and nutritious food) to all areas affected by
chronic hunger
How we starve
• Undernourishment manifests as famine
• Obvious, dramatic and fast acting
• Malnourishment is long-term and
insidious
• May not die out right but suffer
impairments
• Can result in brain damage in some
cases and overall less productive,
weaker citizens in most cases
(negative feedback loop)
How we starve
• Major problems of undernourishment
• Marasmus – progressive emaciation caused by
lack of protein and calories
• Kwashiorkor - a lack of sufficient protein in the
diet
• Chronic hunger - enough food to stay alive but
can not live satisfactory or productive lives
How we starve
• 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"
• 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
How we starve
• An equally troubling problem is overeating in some areas of
the world
• Highly processed foods rich in sugars and fats are becoming
large parts of daily diets
• 64% of adult Americans are overweight- up from 40% just
10 years ago
• Overeating also causes trickle down effects in terms of
healthful living and healthcare
How we starve
• Americans spend $42 billion per year trying to lose weight.
• $24 billion per year is needed to eliminate world hunger.
How we starve
How we starve
• World food production must provide adequate nutritional
quality as well as quantity. Is access to quality food a basic
human right? (like clean air and clean water?)
What we eat and what we grow
• Of Earth’s ½ million plant species
• 3,000 agricultural crops
• 150 species cultivated on large scale
• 14 crop species provide most of the food
consumed in the world
• 6 plants provide 80% of the total calories for ALL
humanity
What we eat and what we grow
Wheat
Rice
Maize
Potatoes
Sugar
Beet
Common
Beans
Soybeans Barley
Sweet
Potatoes
Manioc
Sugarcane
Sorghum
Coconuts
Bananas
What we eat and what we grow
• Forage - crops grown for domestic animals
• 14 million acres of alfalfa in the US
• Domestic animals include
• 14 billion chickens
• 1.3 million cattle
• ~1 billion each sheep, ducks and pigs
• 700 million goats
• 160 million water buffalo
• 18 million camels
What we eat and what we grow
• North Carolina crops and livestock products
Crops
Livestock
• Tobacco
• Cotton
• Soybeans
• Corn
• Peanuts
• Wheat
• Hogs & pigs
• Cattle & calves
• Poultry
• Turkeys
• Eggs
What we eat and what we grow
Other Commodities
• Rangeland - provides food for grazing and browsing animals
without plowing and planting.
• Pasture- is plowed, planted and harvested to provide forage.
It is often irrigated for maximum productivity
• Large world market for small grain crops (rice, wheat,
soybeans).
• Production increased from 1966-1996 but has been flat
since 1996
What we eat and what we grow
• Most marine and freshwater food is obtained by hunting.
• Sustainability – this is NOT sustainable
• Aquaculture- the farming of food in aquatic habitats
• Used as an important protein source for many people,
especially in developing countries
• Could be a solution to providing nutritional quality in
diets
• A more sustainable solution to overfishing
What we eat and what we grow
Aquaculture
• Extremely productive on a per-area basis
• Flowing water brings food into the pond from outside
• Can exploit multiple niches in the pond
• May be able to utilize waste products (treated sewage)
• Mariculture- the farming of ocean fish.
• Oysters and mussel production has been on the rise and is
evident locally in Carlsbad on off shore in Ensenada
Agroecosystems
Farming can be considered a disturbance that changes
natural ecosystems in 6 ways:
• 1. Controlled Succession
• Farming attempts to stop natural
succession and keep a system in
the early stages of succession
• Requires planting crops on cleared
land and continuous clearing of land
to keep it clear of unwanted vegetation
Agroecosystems
• 2. Monoculture
• Farming often focuses on the production of just one
species or genetic strain of a species
• The entire crop has similar genomes and therefore can
become susceptible to disease or environmental change
that wipes out the whole crop
• One species using the land for a period of time can reduce
vital nutrients from the system
• Crop rotation, artificial fertilizers, or land left fallow can
return necessary nutrients to the soil
Agroecosystems
• 3. Distribution
• Farming plants crops in even rows and patterns to make
maintenance and harvesting easier
• Even distribution makes it easier for pests to access crops
as an easy food source
Agroecosystems
• 4. Biodiversity
• Farming reduces biological diversity locally and globally
by focuses on just a few key species used in crop
production
• Pest control also reduces biological diversity by reducing
populations of agricultural pests that change the local
food chain
Agroecosystems
• 5. Plowing
• Plowing causes disturbance in the soil that turns over the
soil at a specific depth
• Exposed soil is more susceptible to erosion and loss of
chemical nutrients
• Land that has been plowed
takes longer to recover when
left to natural succession
Agroecosystems
• 6. Genetic Modification
• More recent techniques in increase crop production focus
on the creation of genetically modified species that can
survive in harsher environments with less need for pest
control
Limiting Factors
• The process of agriculture requires large amounts of energy
that have to be sustained by an ecosystem
• The fossil fuel and human energy required per calorie of
food produced is called energy subsidy
• Small scale farm production has low energy subsidy while
large scale mechanized farming has high energy subsidy
• The average U.S. diet has about a 10 calorie energy input
for every calorie you eat
• Food choices are energy choices
Limiting Factors
• High-quality agricultural soil has:
• All the chemical elements required for plants
• A physical structure that lets air and water move freely
• Retains water well
• Mixture of soil particles with various sizes
Limiting Factors
• Liebig’s Law
• Single factor determines the growth and therefore the
presence of a species
• Growth of a plant is affected by one limiting factor (plants
can only grow as much as they have the most limiting
nutrient present)
• 20 chemical elements are required plant nutrients
• Macro- and micro- nutrients
Limiting Factors
• Two elements may have a synergistic effect
• A change in the availability of one resource affects the
response of an organism to some other resource.
• Nutrients may become toxic when levels are to high
(fertilizer burns and salting out from long term irrigation
with high salt content water)
• Older soils more likely to lack trace elements due to leaching
that occurs naturally over time
Future of Agriculture
• Three major technological approaches to agriculture:
• 1. Modern mechanized agriculture
• 2. Resource- based agriculture
• Organic food production
• 3. Bioengineering
Future of Agriculture
• Mechanized Agriculture – demand based
Future of Agriculture
• Resource based agriculture- biological technology applied
and conservation of land, water and energy emphasized
Future of Agriculture
• Organic farming – no artificial chemicals (fertilizers or
pesticides), no genetic engineering, ecological control
History of Agriculture
10,000
years
ago
18th
-19th
century
20th
century
Today
• Resource-based agriculture and what we now call
organic agriculture were introduced
• A shift to mechanized, demand-based agriculture
occurred during the Industrial Revolution
• A return to resource-based agriculture began
using new techniques
• growing interest in organic agriculture as well as
use of genetically engineered crops
Green Revolution
Name attached to the post WWII programs that have led to
the development of:
• new strains of crops w/ higher yields
• better resistance to disease
• or better ability to grow under poor conditions
• Sometimes resulted in the application of large amounts of
chemical fertilizers
• Was made possible by availability of large amounts of
petroleum for making chemical fertilizers
Improved Irrigation
• Better irrigation techniques could improve crop yield and
reduce overall water use by utilizing:
Drip irrigation
Hydroponics
Organic Farming
• Organic faming typically considered to have many qualities:
• More like a natural ecosystem than monoculture
• Minimizes negative environmental impacts
• The food that results does not contain artificial
compounds
• Taste better!!!!
• Sustainable
• Doesn’t expose workers to harmful chemicals
• One of the fastest growing sectors in US agriculture
Monoculture
• Most farming practices employ the use of monoculture to
focus on just one species that they cultivate and harvest
during a growing season
• Advantages:
• Use of climate and pest forecasting to plant hybrids
resistant to obstacles predicted for the year
• Increased crop production if predictions and hybrid growth
is as expected
• Disadvantage:
• If predictions of climate and pests are incorrect crop
production can be very low
Polyculture
• Planting a mixture of crops and/or a broad range of
genotypes in the same area
• Gives lower average yearly production but reduces the
risk of very low production years.
• Labor intense
• Requires better education in
ecology and Integrated Pest
Management (IPM)
Productive Yields
• Effective growth of any crop must take into account the
climate of the region and resources required to grow crops
in areas they are not native to growing in
Eating lower on the food chain
• Some people believe it is ecologically unsound to use
domestic animals for food.
• Eating each step up the food chain leaves much less food
to eat per acre as a result of trophic level inefficiencies
• Eating lower on the food chain conserves resources and
could increase the carrying capacity of an ecosystem
Eating lower on the food chain
• There is value in rangelands that are better suited to
livestock production
• These areas are often hilly or mountainous and therefore
susceptible to rapid erosion of their thin soils
Eating lower on the food chain
• Another problem with the argument not to use domestic
animals in agriculture is that they are a major source of
protein and minerals for many populations.
• Other factors:
• Animals are still used for plowing (the entire Andean
•
•
•
•
Plateau agriculture is an example)
Carrying goods
Wool and leather – source of clothing
Fuel and fertilizer source (excrement)
Eventually these animals can be consumed
Eating lower on the food chain
• The issue of whether or not to consume meat is an issue of
both science and values
• People can choose not to eat meat because of:
• Specific dietary restrictions
• Moral or ethical beliefs
• Religious beliefs (Hinduism, Buddhism, etc.)
Genetically Modified Foods
• Scientist have been able to transfer
specific genetic characteristics from
one species to another
• Genetic engineering in agriculture
involves several practices
• Faster and more efficient ways to develop
hybrids
• Introduction of the terminator gene
• Transfer of genetic properties from widely
divergent kinds of life (antifreeze gene in
fish to strawberries and tomatoes – is this a
good practice?)
Genetically Modified Foods
• Considerable interest in developing crops
• With entirely new characteristics
• E.g. nitrogen fixation
• With tolerance of drought, cold, heat and toxic chemical
elements.
• Most genetic engineering of plants to date has involved
making them either pest resistant, or herbicide resistant –
not making them more productive to provide greater
quantities of food to the people of the world
Climate change and agriculture
• Climate change may increase or decrease yield depending
on the complex interaction between local weather,
evapotranspiration, soil condition, and availability of fresh
water
State of Agriculture Today
• After the Green Revolution (1950-1990) crop production
tripled and per capita output rose to 36% while cost of
production dropped by 1/3
• Since 1990 grain production leveled off and in the past
decade has begun to drop
• Currently, the United States produces 17% of the world’s
grain
State of Agriculture Today
• In North America 24% of labor is involved in food growth
(not including processing and transport)
• Only 0.3% of labor in the United States (9% total in the
food industry)
• 45-65% of labor in developing countries
• Agriculture consumes 17% of all commercial energy in
production and processing
• Solutions to energy use and employment suggest a move to
smaller scale crop production focused on resource based
techniques (concern- yield per acre)
Current Land Use
Potential for
Grazing
Unusable (Ice,
Deserts,
Mountains, etc.)
Arid
14%
Used for
Agriculture
10%
Tropical Forest
51%
11%
8%
Potential for
Cropland
Cultivated
6%
Grazed
Forests, Arid
State of Agriculture Today
• Climate concerns predict a shift in the current land available
for natural cultivation to smaller and smaller bands of land
with enough rain and temperatures that are moderate
enough for most crops
• Where do we look next for land?
• Potential land available in tropical and arid environments
• What will have to be done to the land to make it arable?
• Irrigation, fertilizers, pesticides, equipment
State of Agriculture Today
Untapped resources
• New crops not yet in production
• Microlivestock (insects, etc.)
• 58-78% protein content
• 3-4 times the nutritional value of beef
• Advanced tissue culture
• Transgenomics
State of Agriculture Today
• Think about what you eat…
• Where does it come from?
• What processes are involved in production?
• What has to be added that is not included naturally?
(Vitamin A, Iron, Iodine)