Food and Agriculture
D.Knauss
RRHS
2006
Nutrition
• Famine- widespread starvation
• Malnutrition- condition that occurs when
people do not consume enough Calories or
do not eat enough variety of foods.
• Calorie = 1000 calories
• 1 calorie = amount of energy needed to
raise 1 gram of water 1 degree Celsius.
Nutrition (continued)
– Since 1 gram of water = 1 mL of water. 1
Calorie = amount of energy needed to raise the
temperature of 1 liter of water 1 degree Celsius
• Carbohydrates= sugars= energy
– Examples- potatoes, pasta, sugar, starches,etc
• Lipids= fats= energy and materials for
making membranes and hormones
– Examples- fatty foods, nuts, oils, etc
Nutrition (continued)
• Proteins= amino acids =used for making
enzymes and help maintain metabolism
– Meat, fruits, and vegetables
• Amino Acid deficiency- occurs from not
getting all of the amino acids necessary to
maintain basic metabolism
• Diet- type and amount of food a person eats
Nutrition (continued)
• Developed countries- tend to eat more food
and a larger proportion of proteins and fats
than those in developing countries
Food Ecology
• Efficiency- measure of the quantity of food
produced on a given area of land with
limited inputs of energy and resources
• Average efficiency of raising livestock is
very poor (only 10% of plant energy gets
stored in the animals)
• Meat generally provides more nutrients per
gram than most food from plants
Food Ecology
• Yield- the amount of food that can be
produced in a given area
– Researchers looking for organisms that can
thrive in various climates with little fertilizer,
pesticides, or fresh water.
World Food Problems
• Unequal distribution- food is not spread
equally in all areas of the world or even
within the same country
• Droughts and Famines– Drought- prolonged period where the rainfall is
below average
– One year of drought is salvageable but after
several years the soil will be unusable due to
loss of microbes
Green Revolution
• Production of food crops rose dramatically
in Mexico and India due to new crop
varieties and new agricultural technologies
– Negative effects- crops required high amounts
of fertilizers, water, and pesticides
– Subsistence farmers- (farmers who grow food
only for local use) unable to afford the new
seed and technologies
Farming
• Arable land- land that can be used to grow
crops
• Farming
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Plowing
Fertilization
Irrigation
Pest control
Harvesting
Farming
• Plowing is also referred to as “Tilling”
(Roto-tiller)
• Plows- pulled by tractor, livestock, or the
farmer themselves
– Mixes soil nutrients, loosens soil for planting,
uproots weeds
• Irrigation- water flowing through ditches,
sprayers, also involves tiling fields for
drainage
Farming
• Fertilizing- manure for most organic farms
mixed with crop rotation. Nitrogen
fertilizers are often used on all farms
regardless
• Pest control- both animal and plant pests are
addressed through spraying or by biological
methods(insect predators).
• Harvesting- done by hand or by machine
Soil Profiles
• Plants depend on soil for nutrients,
stability, and moisture. Knowing about
the soil profile can help the farmer
determine what they can do to ensure a
good crop from one year to the next.
Soil Erosion
• Almost all farming methods increase soil
erosion
• Land degradation- human activity or
natural processes damage the land so
that it can no longer support the natural
ecosystem
• Desertification- process by which land in
arid or semiarid areas becomes more
desert-like because of human activities
Soil Erosion
• Desertification- (continued)
– Areas affected by desertification include the
Great Plains, the Sahel region in Africa, etc.
Soil Conservation Practices
• Fallow- leaving the land unplanted for several
years to regain its fertility
• Contour plowing- farmer plows rows across the
hill to hinder soil erosion downslope
Soil Conservation Practices
• Terracing- farmer builds step-like areas where
crops can grow (best with valuable crops like
grapes and coffee)
Soil Conservation Practices
• No-till farming- crops are harvested and
planted without tilling of the soil.
– Advantage- less soil erosion and less time is
needed to prepare for next crop
– Disadvantage- soil compaction reduces plant
productivity over time
Soil Enrichment Practices
• Fertilizers– Organic- leaves and manure
– Inorganic- chemical fertilizers applied by
using sprays, pellets, or direct injection into
the soil (Nitrogen)
– Most farmers use a blend of both
• Compost- partly decomposed organic
material
Compost Bin
Salinization
• Accumulation of salts in the soil.
– Major problem in California and Arizona
where the soil is naturally salty to begin
with.
– Salts accumulate until no plants can grow
Pest Control
• Insects in North America eat about 13%
of all crops
• Insects across the world destroy about
33% of the world’s potential food harvest
• Crop plants have no built-in defenses
against pests like wild plants do. Wild
plants also have predators that live in or
on the plant
Pesticides
• Chemicals used to kill insects, and other
crop pests. These chemicals can also
harm beneficial plants, insects, wildlife,
and people
• Pesticide resistance- ability of an insect to
survive a particular pesticide.
Pesticides
– Pest organisms typically have high
reproduction rates which allows for more
genetic variation. This means that some
members of the population may evolve a
resistance to the pesticide
• Human health concerns– Children who live in these areas sometimes
have cancer rates higher than the national
average
Pesticides
• Persistent Pesticides- does not break
down quickly or easily in the
environment
– Results in these compounds accumulating in
the soil and water systems for days to
decades to forever
– DDT used in the 1970’s is still detectable in
women’s breast milk
Pest Management
• Biological Pest Control- use of living
organisms to control pests
• Pathogens- organisms that cause disease
• Plant Defenses- farmers select varieties of
plants that contain specific defenses
against pests (tougher skin, chemical
compounds, etc)
Pest Management
• Chemicals from Plants- use a plant’s
natural defense mechanism as a pesticide
for other plants
– Advantage is that they are more
biodegradable
• Disrupting Insect Breeding– Growth regulators- interfere with some stage
of a pest’s life cycle
– Pheromones- sex hormones that attract
males to areas where females are not
Pest Management
• Disrupting Insect Breeding- (continued)
– Irradiate males so that they cannot produce
viable sperm. Females then lay unfertilized
eggs
• Integrated pest management- idea is to
reduce pest damage to a level that is
economically acceptable
Pest Management
• Genetic Engineering- technology in which
genetic material is modified for medical
or industrial use (GM = genetically
modified)
– Problems- may cause problems if GM plants
are allowed to breed with wild species
Sustainable Agriculture
• Farming that conserves natural resources
and helps keep the land productive
indefinitely
• Also referred to as low-input farming
Animals and Agriculture
• Approximately 50 animal species have been
bred and managed for human usedomesticated
• Overharvesting- catching or removing from
a population more organisms than the
population can replace
– Fishing
– Important for the continuation of the species
and for businesses to survive
Animals and Agriculture
• Aquaculture- raising of aquatic organisms
for human use or consumption
– China is the world leader in this area
– Fish Farms- raised in individual ponds until
mature enough to harvest
– Ranch- young are raised and then are released
into the wild. Adults are harvested when they
come back to spawn
Environmental Damage from
Aquaculture
• Large amounts of waste
• Local water supplies can be depleted
• Damage nearby wetland areas
Livestock
• Domesticated animals raised to be used on a
farm or ranch or to be sold for profit
• Provide the following:
– Meat
– Eggs
- Leather
- Draft Animals
- Wool
- Manure
• Ruminants- cud-chewing mammals that
have 3- to 4-chambered stomachs
• Cud- food that the animals regurgitate from
their first stomach to chew again
Livestock
• Cattle can be used for:
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Milk
Blood
Meat
Dung
• Chickens- numbers have increased by a
greater percentage than any other livestock
Livestock
• Poultry- domesticated birds raised for meat
and eggs
• Ducks and Geese- not used as often as a
food source but in certain areas fulfill other
important roles
– Fertilizer
– Watch “dog”
Livestock
• Environmental Problems- HUGE
environmental problems occur due to the
waste products from livestock farms.
– High nitrogen fertilizer kills fish in streams and
also can be toxic waste depending on what the
birds are fed
– Avian flu is also a huge health problem across
the world at this time