Chapter 9Food

Do Now

15.1 Feeding the people of the world

“In simplest terms, agriculture is an effort by man to move beyond the limits set by nature.” - Lester R. Brown

Ethiopia 1985Crop failure = 6000 sq mi added to the North African desert = starvation

What people eat

Organic molecules: carbohydrates, protein, lipids (fat)Vitamins and minerals

Underfed people lose resistance to disease

malnutrition: condition caused by lack of necessary nutrients

Kwashiorkor - lack of proteinBloated abdomen, diarrhea, hair loss, liver damage, and ultimately brain damage

Marasmus - low calories and protein

Kwashiorker

•Enough calorie consumption but not enough protein•Common in poor countries•About 50% of elderly living in nursing homes in the US have protein deficiencies.•Decrease in muscle mass, skin pigmentation, enlargement of belly, weakened immune system•Develops in older children and adults

MarasmusAnother protein-energy deficiencyEmaciationSeen in infants younger than 1 yearMajority of time associated with under nutritionFatal in most cases

IODINE DEFICIENCYAccording to WHO Iodine Deficiency is the #1 cause of preventable brain damage and mental retardation.

Results in goiters, stunted growth, mental retardationImpacts thyroid gland which functions in metabolism

CretinismIodine deficiency during pregnancy which stunts fetal developments

Prevention = ionized salt cost about $.05 person/year.

Iron Deficiency Also referred to as anemia

Increased fatigue

Compromise immune system

Harmful to brain development

Easily treated with supplements

Spinach, broccoli, red meat, liver

VAD

Vitamin A DeficiencyFound in meat products, milk, eggsCarrots have cartenoids which convert to vit A in body.Leading cause of preventable blindnessCould lead to maternal death if occurring during pregnancy

Solution is golden ricenew genetically engineered strain of rice containing beta-carotene.Can inexpensively supply vitamin A to malnourished.

Overnutrition

A condition of excess nutrient and energy intake over time.

Overnutrition may be regarded as a form of malnutrition when it leads to morbid obesity

2005 BU study found

60 % of Americans are overweight

An adult who has a BMI between 25 and 29.9 is considered overweight

33 % are obeseBMI >30

Why people go hungry

Increasing population, decreasing foodWealthy people have a lot, poor people have much less

Transportation of food; war, economic troubles, etc droughts: rainfall less than average = crop failure famine: widespread food shortage

Caused by drought, war, inefficient transit, no food storage

Green Revolution

New varieties and techniques introduced (GMO or different strains)

greater yield: amount produced per unit areaNeeded right equipment and fertilizers

subsistence farmers: produce only enough for family

Cannot afford chemicals or machines

fertilizers and pesticides pollute, machines consume energy

Do Now

How do people’s food choices affect the environment?

Earth-friendly Tips to Help Reduce Hunger

Eat more vegetables and grain, less meat

Avoid eating overly processed food

Incorporate more fresh food and less convenience foods into meals

Grow own organic garden

Buy produce from local growers

15.2 Agriculture and Soil

arable: land on which crops can be grown

Amount has decreased 1/5 from 1985-2000

~371 mil acres to houses, mines, roads, factories, & power plants

~ 334 mil acres is unusable because of damaged soil

Farming Methods

Method Then Now

Plowing By animals; Helps plants grow by mixing nutrients & uprooting weeds

Machines

Fertilization Organic fertilizers; manure

Synthetic fertilizers

Irrigation Digging ditches Sprinklers and drip

Pest control Weeds removed by hand; plants covered from insects

Synthetic chemicals

Fertile SoilSoil in which plants are healthy and able to grow rapidly topsoil: loose surface layer of soil where most plants grow

Rock particles, water, air, organic matter (dead matter and excrement)Fungi, bacteria, and microorganisms decompose the matterEarthworms and insects break up soil and let in air

Soil layers

Formed from bedrock

Temperature changes and moisture cause it to break apart

Thousands of years to form a few cm of soil

Topsoil Erosion

erosion: wearing away of topsoil by wind and water

Soil takes a long time to form, but is depleted quicklyUS - 1/2 topsoil lost in past 200 yearsWorldwide - 11% in last 45 years

Problem = can’t support crops to feed the growing population

Plowing loosens soil and blows awayFertility decreases with each crop harvested Clearing of forests

Desertification

Land deteriorates and becomes a desert

Increased population = overuse of land

Shorter times between crop rotations, more grazing animals

Trees and shrubs are cut and none are left to anchor the soil or trap water

Soil Conservation

Contour plowing: plowing across the slope of a hill

Forms tiny ridges that help prevent the soil from washing down the hill

Leave strips of vegetation instead of plowing the entire slop; catches soil and water

Use organic material instead of inorganic fertilizers

Compost or manure

Soil Conservation

No-till farming: seeds of next crop are planted in slits in soil through the remains of previous crop

Roots of first crop hold soil in place while new crop develops; organic matter recycledUses less energy and saves timeCan reduce erosion to 1/10 of other methods

Sustainable Agriculture

Low-input farming: farming without using a lot of energy, pesticides, fertilizer, and water

Organic farming

Aquaculture: “fish farming”“crops” of fish

Preventing Salinization salinization: accumulation of salts in the soil

Irrigation water from rivers and groundwater has more salt than rain water

When water evaporates, a lot of salt is left

Groundwater rises and is drawn up through the soil

Irrigation canals can be lined to prevent water from seeping into soil and raising groundwaterWater soil to wash out salts before seeds are plantedPlant salt-tolerant crops or trees

Trees help shade for less evaporation and keeps groundwater level from rising

Food Varieties

Plants are better adapted to certain environments which can help reduce the amount of chemicals and water used to produce a high yield

Pest Control

Pest Control

pest: any organism that occurs where you don’t want it or in large enough numbers to cause damage; insects, weeds, rodents, etc

North America; insects destroy ~10% of all crops

Kenya; insects destroy ~75%

Worldwide ~ one-third

Problems for cultivated plants

Wild plants grow sporadically They are able to grow because they have developed ways to defend against pests

Cultivated crops are concentrated in one area– Pests will infect one and is easily able to

jump from one to the next and reproduce

Pesticides

• pesticide: substances that kills pests– Insecticide: kills insects specifically

• Health Concerns– DDT causes cancer– Causes people to get really sick, especially in the

factories manufacturing them

• Pollution and Persistence– Many do not break down easily– Accumulates in water which then accumulates in

fish which are eaten by other animals

Resistance

• Pests can develop a resistance, or tolerance, to a specific chemical

• Natural selection– Pest by chance has a trait that helps them

tolerate a chemical pesticide– That organism will live and have the ability

to reproduce and pass on its genes and tolerance

Biological Pest Control

• biological pest control: using living organisms or naturally produced chemicals to control pests– Does not harm the crop– Takes longer for the pest to evolve the resistance

• Pathogens: use bt bacteria to kill caterpillars• Chemicals From Plants: chrysanthemums are

poisonous to certain insects• Disrupting Breeding: crops can be treated with

pheromones to confuse insects– Sterilize insects

Genetically Engineering Foods

• GMO: genetically modified organism

• Insert gene for a specific trait into another organism that you wish to have that trait

• 1994 first GMO for sale: Flavr Savr tomato– Softens slowly, can remain on the vine

longer

Benefits

• Keep produce fresher longer

• Add nutrients

• More successful crops– Higher yield– Virus or pest resistance

• Ability to grow in different conditions

• Feed the world

Risks

• GMO’s contain “foreign” genes• Allergic reactions

– Ex. A shellfish gene in a vegetable; many people are deathly allergic to shellfish

• Religious or ethical reasons• Wild species could become extinct if GM is

introduced and thrives within wild species• Not labeled, but should be

– Ability to trace allergic reaction or illness