Ch 11: Feeding the World

Special Topics

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The

Life-cycle of Food

How we got here • The Green Revolution

1. Plant monocultures of selectively bred or genetically engineered high-

yield varieties of rice, wheat or corn that are disease resistant.

2. Add large inputs of water, fertilizer and pesticides to ensure high yields

3. Get more crops from the same land by multi-cropping

• Pros

– Increased food production allowing us to feed a rapidly growing world,

more food on less land, reduced undernutrition and malnutrition

significantly

• Cons

– Requires huge inputs of oil, water and fertilizer resulting in serious

environmental impacts, may not be sustainable, may permanently

damage soil quality, and many more

Impacts of Industrial Agriculture

Vitamin Deficiencies (malnutrition) Deficiency Symptoms Solutions

Iron Anemia (fatigue, infections, increased risk of death during childbirth)

Iron pills Eat more meat, lentils or enriched grains (fortified)

Vitamin A Childhood blindness, increased risk of infection

Golden rice (GMO with beta carotine), more dairy, more leafy greens, supplements

Iodine (Common in mountainous regions with poor soil)

Goiter (swelling of the thyroid gland), stunted growth, impaired mental capabilities

Eat seafood Iodized salt

Irrigation Methods Process – dig a trench and fill with water Pros - Cheap and easy, gravity driven Cons – water is lost to evaporation and runoff Efficiency – 65%

Process – flood the field and let water soak in Pros – cheap and easy, gravity driven Cons – may disrupt plant growth, water is lost to evaporation and runoff Efficiency – 70-80%

Irrigation Methods Process – water is pumped to nozzles that spray water across the field Pros – more efficient choice Cons – more expensive, requires energy, water is lost to evaporation and runoff Efficiency – 75-95%

Process – hoses with small pores are laid near roots or buried below soil Pros – reduced weed growth (surface soil is dry) Cons – work best in perennial fields since hoses have to moved for plowing and planting (which = time and money) Efficiency – more than 95%

Problems with Irrigation • Soil Salinization

– Repeated irrigation evaporation

– Evaporation leaves small salt deposits

behind.

– Over time the salt deposits build up and can

be toxic to plants – Clean-up: flood field and start over, leach salts

out

– Prevention: install better drainage systems, use

more efficient irrigation systems

• Water Logging – Repeated irrigation rising water table

– Rising water tables flood roots, deprive

bacteria of oxygen – Clean up: wait for fields to drain

– Prevention: install better drainage systems,

use more efficient irrigation systems

Other Soil Problems • Compaction – soil is crushed by

machinery, closing pore spaces – Pore spaces provide oxygen for soil

organisms, space for roots and water infiltration

– Solutions: aerate soil, plant cover crops in the off season, no till agriculture

• Erosion – soil is blown away by wind or washed away by water due to a lack of root structures – Top soil and nutrients are lost,

reducing plant growth, runoff pollutes waterways

– Solutions: plant cover crops in off season, no till agriculture, leave crop residue on fields

Desertification • Repeated insults to soil including compaction, salinization, waterlogging and

erosion can slowly turn once productive areas into deserts

• Most common in the areas directly adjacent to a desert, but increasingly

happening in areas that have been clear-cut for logging purposes

• Generally an irreversible process

• Land can sometimes be used for nomadic grazing

• Consequences: Loss of food production, dust storms, environmental

refugees, famines, droughts

Organic Fertilizer • Animal Manure – waste products from animals

– Pros: free if animals on same farm, provide organic

matter and trace nutrients, improves soil structure,

support soil organisms

– Cons: expensive to transport, possible spread of

diseases, slow to release nitrogen (must be applied

before growing season)

• Green manure – freshly cut green vegetation

plowed into soil

– Pros: increase organic matter and humus, if grown

on site they conserve soil, fix nitrogen, and

encourage beneficial insect growth,

Organic Fertilizer (cont) • Compost – broken down food, paper

and leaves

– Pros: free if produced on site, saves

landfill space, provides organic material

and improves soil structure, support

microorganisms

– Cons: slow to release nutrients (many

are trapped in organic form), potentially

high salt content, weed seeds from

fruits and veggies, excess ammonia

can burn roots

Inorganic Fertilizer • Commercial inorganic fertilizers – fertilizers often

made from fossil fuels that provide N, P, K

– Pros: greatly increase productivity, cheap,

readily available, immediately increase soil

fertility

– Cons: • Lack trace nutrients

• Do not provide organic material

• Do not improve soil structure or support soil

organisms

• May runoff into water bodies causing

eutrophication/dead zones/health impacts

• Usually made from non-renewable resources

• Release nitrous oxide (GHG) and NOx (air

pollutant)

Producing Meat • Rangeland and Pastures – animals roam around

mostly untended land, grazing

– Pros: less environmental impact (usually)

– Cons: uses lots of land = less meat, overgrazing can

occur, threats from predators, expensive, can cause

overgrazing and erosion

Producing meat (cont)

• Concentrated Animal Feedlot

Organizations (CAFO) – animals

are concentrated in an enclosed

area and fed grain or fish meal

– Pros: less land more meat,

higher profits, less habitat loss,

overgrazing and erosion

– Cons: large inputs of grain, water

and fossil fuels, concentrated

animal waste, overuse of antibiotics

and hormones (steroids)

Feedlot Concerns • Efficiency:

– 70% of corn grown in US and 80% of worlds soybeans go to feeding livestock

– One pound of beef requires 2500-6000 gal of water, 16 lbs of grain and 0.75

gal of oil

– It is much more efficient to feed humans directly with the grains than to filter

through animals (10% rule)

• Antibiotic and growth hormone use

– Make cows live longer and grow larger, but may lead to antibiotic resistance.

Hormones may pass into humans (rBST – suspected endocrine disruptor).

• Methane

• cows burp/fart 16% of the methane released (contributes to global warming)

• Waste

• only 50% of animal waste from feedlots is returned to the soil as fertilizer, runoff

leads to eutrophication and drinking water contamination

Fishing Methods • Major problems with

fishing include: • Overfishing due to

overly effective fishing techniques

• Subsidies that make fish too cheap

• Bycatch

Aquaculture • Raising marine and freshwater fish in ponds

and underwater cages – like a feedlot for fish

• Pros:

– Efficient: less water/space more fish, takes pressure off wild species, low fuel usage, high profits

• Cons:

– Need lots of land, feed and water, lots of waste, may destroy estuaries and wetlands, may use grain supply, dense populations increase disease increased use of antibiotics, bioaccumulation of toxins (PCBs, mercury, dioxins, etc) if benthic soil is contaminated

• Possible solution – aquaculture in the open ocean or way inland

Food prices, oil and subsidies • Food prices are strongly correlated with oil prices because

modern agriculture is so mechanized and thus oil dependent. As oil prices increase, so will food prices.

• Agriculture is a risky business because weather, crop prices and pests are unpredictable and can wipe out entire seasons of crops.

– Governments try to control prices or subsidize farmers to keep food prices low

– Governments may also pay farmers not to plant in order to keep prices up

• What should we do:

– Subsidize sustainable farming operations and efficient irrigation systems, fund research into best practices, establish training programs to promote efficient irrigation, alternatives to pesticides and soil management, support locally grown food.

Picture Quizzes!

Which type of agriculture is each picture showing?

Choices: • Industrial agriculture • No Till agriculture • Nomadic grazing • Slash and burn • Traditional agriculture

Which soil conservation technique is shown in each picture?

Choices: • Agroforestry • Contour

Planting • No-till

agriculture • Strip cropping • Terracing

Which growing methods are pictured below?

Choices: • Agroforestry • Crop Rotation • Intercropping • Monoculture • Polyculture