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