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Chapter 15-Food and Agriculture
Feeding the World
Humans and Nutrition
FamineFamine- Widespread starvation (Ex: Ethiopia)Food for energy (calories) and as building material for body tissue MalnutritionMalnutrition- When the body does not have enough Calories (1 kilocalorie) or variety of foods to fulfill needs– Ex: Amino acid deficiencyAmino acid deficiency
Famine
Major Nutrients in Human Foods
Sources of NutritionDiet- the type and amount of foods eatenBalanced diet = HEALTHY
Diets Around the World
Vary by regionDeveloped nations= more foods (high in proteins and fatsU.S. - almost 1/2 Calories from meat, fish, and oils
The Ecology of Food
Farmland replaces natural ecosystemsFood efficiency- quantity produced on a given area of land w/ limited inputs of energy and resources– More energy and resources required for animals– Meat - more nutrients per gram
The Ecology of Food
Yield- amount of food produced in a given areaResearchers interested in organisms that can survive in various climates w/out chemicals and large amounts of water
World Food Problems
Food production not increasing fast enough with human pop. growthMalnutrition result of poverty, war and political strife (transportation problems)Drought- prolonged period during which rainfall is below average – No irrigation– Seeds not available – Soil degradation
The Green Revolution
Worldwide crop yield increases ;new variety and techniquesB/w 1950 and 1970, Mexican wheat up eight-fold; India doubled riceNeg. effects: large amts of water, chemicals, and machinery; crop decline- degradation and overuse– Subsistence farmers- grow only enough food for
local use; can’t afford machinery/chemicals
Chapter 15- Food and Agriculture
Section 2- Crops and Soil
Agriculture
Arable land- land that can be used to grow crops– Plowing- mixes nutrients loosens soil particles, and
uproot weeds– Fertilizers- enrich soil with nutrients for better health
and growth of plants Irrigation- bringing in water for crops
– Chemicals used to kill pests
Agriculture
Traditional– Farmer or animal pulled
plow– Manure used as fertilizer– Weeds removed by hand – Water flowed through
ditches
Modern– Machine plows – Synthetic chemical
fertilizers– Weeds removed by
machines– Overhead sprinkler and
drip systems
Traditional Vs. Modern
Fertile Soil: The Living Earth
Fertile soil can support the growth of healthy plants.– Topsoil- Organically rich surface layer
• Living organisms, rock particles, water, air, and organic material (decomposing)
– Soil forms from rocks broken into smaller fragments by water, wind, and chemical weathering (rock minerals react to form new chemicals)
• Temperature changes allow for rocks to crack and break• 1000s of years for centimeters of soil
Soil Composition Surface Litter
Topsoil
Zone of Leaching
Subsoil
Rock Particles
Bedrock
Soil Erosion
Wearing away of rocks or soil by wind and water– Half of original US topsoil
lost in last 200 years– Farming increases
Land Degradation
Human activity or natural processes damage the land to the point of being inable to support the ecosystem.Desertification- Land in which arid or semiarid areas become more desert-like because of human activity or climatic changes.– Ex: Sahel, N. Africa used to plant crops and allow land to lie
fallow for a few years to replenish; Increase in pop. caused fallow periods to be shorter or none at all. Large areas can not support crops anymore and have desertified
Sahel, N. Africa
Soil ConservationSoil erodes downhill- soil-retaining terracesContour plowing on gentler slopesNo-till farming- Harvest a crop without turning soil so remains hold soil in place– Leaves soil packed causing lower crop yields
Enriching the Soil
Organic matter such as manure and leaves was traditionally added Inorganic fertilizers have doubled food production in 50 years– Nitrogen, Phosphorous, Potassium– Erosion pollutes waterways with these
Modern way is combining inorganic fertilizers and compost (partly decomposed organic material)– Some garbage can form compost
Compost
Salinization
The accumulation of salts in the soil– CA and AZ– Irrigation from river or groundwater; saltier than rain
• Raises groundwater levels• Evaporation leaves salts behind• Prevent by lining irrigation canals or water heavily
Pest Control
Insects eat 13% of crops in N. America– Tropical areas worse– 33% worldwide
Pest- any organism that occurs where it is not wanted or occurs in large enough numbers that it causes ecological damageWild plants naturally protected
Agricultural Pests
PesticidesChemicals used to kill insects, weeds, and other crop pestsCan harm beneficial wildlife, plants, insects, and peoplePests can evolve a resistance after prolonged use– 500 species worldwide
Cancer rates and nervous disorders are higher in agricultural areas that use pesticides as well as factories that produce themPersistent- Does not break down quickly or easily– Accumulates in water and soil– Biomagnification
• Ex: DDT and Bald Eagle
Biological Pest Control
The use of living organisms to control pests – India tried 1st; prickly pear
cactus and American beetle
Pathogens- organisms that cause disease– Bacillus thuringiensis (Bt)
kills caterpillars
Plant defenses- plants bred for chemical compounds and physical barriers– “VNT” resistant to certain
pestsDefensive chemicals from plants used– In-home sprays– Less harmful– Biodegradable
Pest ManagementDisrupting insect breeding – Growth regulators
• Chemicals interfere with some stage of life cycle
• Ex: Monthly flea meds– Pheromones
• Chemicals produced by one organisms to affect the behavior of another
• Used to confuse insects– Can also make insects sterile
with x-rays or chemicals
Integrated Pest Management– Modern method of
controlling crop pests– Reduce pests without
elimination– Different program for
each pest– Biological method first– Cultivation second– Insecticides last
Engineering a Better Crop Traditional: Save seeds from best plants with fewest pestsModern: Genetic Engineering- genetic material in living cell is modified for medical or industrial use– Can isolate genes from one organism and implant in
another– Genetically modified plants (GM)– Ex: inserting a bacterium insecticide gene – Problems:
• Products not fully tested• Genes transferred to wild plants
Sustainable Agriculture
Low-input farming– Minimizes use of energy,
water, pesticides, and fertilizers
– Planting productive, pest-resistant crops
Chapter 15- Food and Agriculture
Section 3- Animals and Agriculture
Domesticated Animals
Less energy required to raise animalsBasis for protein in dietDomesticated- Bred and managed for human use– About 50 animal species– Chicken, sheep, cattle, honey bees, silkworms, fish,
and shellfish– Goats, pigs, and buffalo
Food from Water
Fish are important food sourceOverharvesting- catching or removing more organisms than a population can replace– No-fishing zones improve
after a few years• Necessary for fish markets
to prosper
AquacultureThe raising of aquatic organisms for human use or consumption– Began in China 4,000 yrs ago– Catfish, oysters, salmon,
crayfish and rainbow trout– 23% of seafood– 20% of protein from fish and
other aquatic organisms
Ranch- raise fish to release– Fish return to birthplace to
breed– Captured, bred and re-
released
Fish farms have many small ponds with circulating waterCan create waste/pollution, deplete local water supplyFew cases damaged sensitive wetlands
Aquaculture
Livestock
Domesticated animals that are raised to be used on a farm or to be sold for profit– Used for leather, wool,
eggs, meat, draft animals to pull equipment and manure
RuminantsCattle, sheep, and goatsCud-chewing with 3 to 4 chambered stomachsCud- Regurgitated food that is rechewed to increase digestionSpecial microorganisms allow digestion of plant materialsCommon in N. America, India, and Africa for meat, milk, blood, dung and work power
Poultry
Domesticated birds raised for meat and eggs; good source of amino acidsChicken production increased more than any other livestock since 1961Farms are cramped, artificial environment
Poultry
Poultry
Ducks and geese – Integrated system in China
• Meat• Droppings fertilize rice paddies• Irrigation of mulberry trees, home of silkworms, occurs
from ponds• Plant materials and filtered sewage dumped as food for
carp and other fish