Earth Systems & Resources

Chapter 14

Food & Soil Resources

14.1 Types of Agriculture

Where’s the food from?

• Cropland: produce mostly grains. 77% of world’s food

• Rangeland: produce meat (grazing livestock). 16% of world’s food

• Ocean fisheries: seafood products. 7% of world’s food

What feeds the world?• 3 grain crops provide more than half the

calories people consume.• Corn• Rice • Wheat

• Annual crops (need replanted each year)

• 2/3 of the world’s people survive mostly on these grains and little to no meat.

Industrialized Agriculture

• AKA: high-input agriculture• Uses large amounts of fossil fuel energy, water,

commercial fertilizers, pesticides• Produces monocultures (single crop) or livestock

for sale to others• Mostly in developed countries

• Think John Deere

Plantation Agriculture• A form of industrialized agriculture• Involves large monocultures of cash crops such

as:• Bananas• Coffee• Soybeans• Sugarcane• Cocoa• Vegetables

• Mostly in tropical areas of developing countries• Products usually exported to developed

countries.

Traditional Agriculture

• Traditional subsistence agriculture: utilizes human labor, draft animals in order to produce enough food for family to eat

• Think: old work horse

Traditional Agriculture

• Traditional intensive agriculture: still human labor and animals, but also uses fertilizer, primitive irrigation to get higher yields. Enough to feed family and surplus to sell.

• Think: China

Centers of ancient intensive agriculture based civilizations

Industrialized agriculture

Shifting cultivation

Plantation agriculture

Nomadic herding

Intensive traditional agriculture

No agriculture

14.2 Green Revolution

(view time 5:05)

Answer questions on sheet

14.3 Soil Erosion & Degradation

Soil Erosion• Three main causes of soil erosion:

– Water– Wind– People

• Land degradation: natural or human activity that decreases soils ability to support plants or living organisms.

• Soil erosion: movement of soil from one place to another. Typically from wind or water.

• Human activities that increase soil erosion: burning ditches, ATV use, logging, farming, overgrazing of livestock, monoculture, constructuion, etc.

Soil ErosionCauses damages to1. Agriculture2. Waterways (canals)3. Infrastructures (dams)

Interferes with1. Wetland ecosystems2. Reproductive cycles (as in salmon)3. Oxygen capacity4. pH of water.

Common types1. Sheet – soil moves off in horizontal layer2. Rill – fast H20 cuts small channels in soil3. Gully – more extreme version of rill

Learn from the past – Dust Bowl• Dust bowl – occurred in 1930’s (“dirty

thirties”)

• Kansas,

Oklahoma

and Texas

Learn from the past – Dust Bowl• Effect: dust storms killed livestock and wild

animals, families left the area in search of jobs, 1935 Soil Conservation Service was established

Learn from the past – Dust Bowl(View time 1:03)

Law to Know

• 1935 Soil Erosion Act

Established the Soil Conservation Service. Mandates the protection of the nations soil reserves. Deals with soil erosion problems, carries out soil survey, and does research on soil salinity.

Desertification• Desertification: productive land that has lost it’s

productivity due to human activity and natural climate change.

• Human causes: same as soil erosion – overgrazing, over tilling, destruction of natural grasses/plants, and surface mining.

You should be able to give many examples if asked how it is caused.

ConsequencesCauses

Worsening drought

Famine

Economic losses

Lower living standards

Environmentalrefugees

Overgrazing

Deforestation

Erosion

Salinization

Soil compaction

Natural climate change

Solutions to desertification• Low or no-till farming• Rotate grazing animals• Plant trees, native

grasses• Reduce amount of land

cleared of trees• Reduce harmful irrigation• Wait to plow farm fields

until spring

Bad News for Dirt• UN survey: topsoil is eroding faster than it can

be replaced in about 38% of world’s cropland.• Putting a price on it: $375 billion dollars a year

spent on damages.

Good News for Dirt• In the US soil erosion has been cut by 2/3 since

1987.• US has government programs in place to

continue to fight this problem. CRP land = government pays farmers to not farm land for 10-15 years.

Salinization• READ YOUR LAB HANDOUT!!!• Salinization: gradual build up of salts in soil.

Caused by irrigation• How it happens:

– groundwater naturally picks up various salts as it travels through rocks and mineral beds.

– Plants are watered with this ground water through irrigation

– These salts do not evaporate when the water does.

– Salts build up in soil over time.

Figure 14-12Page 283

Reduce irrigation

Switch to salt-tolerant crops(such as barley, cotton, sugar beet)

Prevention

Flushing soil(expensive andwastes water)

Not growing crops for 2-5 years

Installing under- ground drainagesystems (expensive)

Cleanup

SolutionsSoil Salinization

Waterlogging• A problem with irrigation

• Water gets trapped under the surface, but can’t percolate downward – less permeable layers of soil underneath

• Plant roots are then saturated with saline water

EvaporationEvaporation

Transpiration

Evaporation

Waterlogging

Less permeableclay layer

14.4 Soil Conservation

Don’t take notes for this section!

Soil conservation• Conventional-tillage farming: frequently

practiced in midwest. Plowing/disking of fields in fall so it is “ready” in the spring. Leaves topsoil vulnerable for months.

• Conservation-tillage farming: little or no plowing prior to planting. Leave past crop residue on fields, do not plow in fall.

• In 2004, 45% of farm fields utilized a form of conservation-tillage; USDA would like that number to grow to 80% of farm fields.

Terracing: change hillsides into “steps”. Slows water running off.

Contour farming: planting crops across the hill slope instead of up and down. Also

slows water

Strip cropping: Planting alternating rows of cover crop with row crops. The cover crop traps the soil

that erodes from row crop.

Windbreaks: AKA – shelterbelts. Reduces wind speed, roots hold soil, reduce

evaporation

Alley cropping: AKA – agroforestry. Planting crops in alleys between rows of trees or shrubs. Holds soil and reduces

evaporation

Cover crops: planting cover crops (alfalfa, clover, etc) immediately after

harvest to hold soil in place over winter.

14.5 Nutrition

Chronic Undernutrition• Marasmus: diet is low in both calories and

protein. Typically breast feeding babies of malnourished mothers or those just weaned from nursing not getting enough to eat. Starvation.

Malnutrition• A general term for the medical condition caused

by an improper diet or poor food quality.

Kwashiorkor• Kwashiorkor: severe protein deficiency. Can

cause a bloated belly, discolored skin. Can happen when a 1-3 year old child is weaned from breast milk. They can get enough calories, but not enough protein. (not enough meat in diet or protein vegetables)

UNICEF and solutions

• Immunize children• Encourage breast feeding and maternal

nutrition• Vitamin A capsule twice a year (75 cents)• Spacing births more than 2 years apart• Education for women on nutrition, child

care, drinking water sterilization• Most deficient nutrients: vitamin A, iodine,

and iron

Over-nutrition• Over-nutrition leads to overweight and obese adults.• Health problems of over and under nutrition are very

similar – lower life quality, lower life expectancy, susceptibility to disease.

• About 1 in 7 adults in developed countries is overweight. US is one of the worst. Go figure!

• Americans spend $40 billion a year on weight loss, but only $19 billion is spent worldwide on malnutrition.

14.6 Increasing Crop Production

How can we feed the world?

• Genetic engineering of crops –

• Change our eating habits – try new foods, cultivate new crops, use the 1,500 species of edible insects.

• YUM!!

How can we feed the world?

• Polycultures of perennial crops

• Reduce wasted food (70% of food is wasted through spoiling, poor processing, and plate waste)

14.7 Producing More Meat

Where’s the beef?• It is more efficient to use land to produce

grain for human consumption than to use it to produce meat for human consumption.

• WHY??

• When raising livestock you need land for the animals and land for the food for the animals.

• It takes less energy to harvest grain than to process meat products.

Meat and potatoes for dinner?• Moderate grazing is actually good for vegetation.• Problem: most places use pastures where

overgrazing occurs• Production of meat requires more energy and

land than production of grains• Advantages to meat: high in protein, high in iron• Disadvantages to meat: high in fat, too much

can lead to heart disease, high blood pressure, etc.

Home on the range?

• Grazing on ranges can be very hard on the area.

• Grazing animals tend to overgraze and destroy riparian zones (located next to water)

• Animal waste can end up in water supply• Grazing animals may only eat certain

vegetation; other vegetation can then take over.

Developed countries• US consumers spend only about 2% of their

income on domestically produced food. (farm products have dropped in cost, they now cost about 1/3 of what they did in 1910.)

• 10 units of energy (input) to produce 1 unit of food product (output) for industrialized agriculture.

• Traditional subsistence agriculture: 1 unit energy input to 1 unit food output. Video clip (7:08)

• Traditional intensive agriculture: 1 unit energy input to up to 10 units food output.

Increase in Meat Production

• Between 1950-2000, world meat production has increased five times.

• Per capita meat production has more than doubled.

• Remember affluenza!

14.8 FishingWorksheet to come

14.9 Government Agricultural Policy

• Government assistance:– Price controls to keep food prices low– Subsidies and tax breaks to farmers to

encourage food production– If above two are eliminated, market demand

would control costs.–Danger in this: lower income families

might have harder time paying food costs. Would need more financial assistance for these people.

14.10 Sustainable Agriculture

What Can You Do?

High-yield polyculture

Organic fertilizers

Biological pest control

Integrated pestmanagement

Irrigation efficiency

Perennial crops

Crop rotation

Use of more water-efficient crops

Soil conservation

Subsidies for more sustainable farming and fishing

Increase

Soil erosion

Soil salinization

Aquifer depletion

Overgrazing

Overfishing

Loss of biodiversity

Loss of primecropland

Food waste

Subsidies for unsustainable farming and fishing

Population growth

Poverty

Decrease

Solutions

Sustainable Agriculture

Buy organic food

Feed pets balanced grain foods instead of meat

• Compost your food wastes

Please don’t waste food