Food

Chapter 10, Environmental

ScienceJ. Stewart-Presenter

• Food is expensive• Modern agriculture hurts the

environment• So...find new crops or...bugs! • Bugs: cheap and easy to get--1500

edible insects, like Mopani • Bugs also provide 58-78% protein by

weight• But, agricultural companies resist

change that could hurt profits• And...would you eat them?

Case Study: Bug cuisine

o Food production: 77% croplands, 16% rangelands, 7% fisheries (3/4 of commercial fisheries fished beyond or at biological limit/sustainable yield)

o Soil and Fertilizers (erosion faster than formation)

o Nutrition and Food (1/6 under- or malnourished, 1/4 overweight)

o Pests and Pesticides o Sustainable agriculture

Key concepts

What is a farm?Is it this?

Or this?

Agriculture began about 10,000 yrs ago. Now:

• 77% food from croplands: BIG 3--corn, rice, wheat=half of all human calories,

• 16% from rangelands, • 7% from fisheries: most

important for about 1 billion humans.

Food production: Successes

Huge advances in technology: production TRIPLED from 1950-85--is it enough?

"Agriculture has a greater harmful environmental impact than any human activity!" (p.219)

- Pollutes air, water, and affects human health

- Leads to soil loss and impacts biogeochemical cycles (CHNOPS)

- Reduces biodiversity- 30% of world's cropland degraded--

17% seriously

Food Production: Issues

• 80% of present ag. • INPUTS: fuel, fertilizer, pesticides• 10 units of energy for 1 energy unit of food (p. 211) • INCLUDES: Plantation ag. (cash crops like coffee),

Feedlots (cows)• Agribusiness in USA:-75% of US ag. production is by large companies-0.3% of world's ag. workforce, yet 17% of world's

production-Food to table = 17% of US commercial energy-More food since 1950, fewer workers

Food production: Industrial/High-input Ag.

o Monocultureso 1st Revolution-High short-term yields

through fertilizer, pesticide inputs (1950s-1970s)

o Multiple cropping each yearo 2nd Revolution- Development of special

varieties--since late 1960's (Next: GMO's since late 1990's)

o Costs: depends on fertile soil, clean water, 8% of world's oil, and other inputs

Food production: Green Revolution

20% is traditional (done by about 40% of world's people).

Includes: -subsistence: human labor, animal power-intensive: small farms with increased inputsMethods focus on increased diversity:-interplanting, polyculture, alley cropping (forestry),

etc.

Food prod: Traditional

...These methods have been shown to be more sustainable and produce higher long-term yields than industrial monocultures.

1 unit of energy input for 10 units of food (p. 211)

• Caused by water and wind and increased with reduced plant cover, overgrazing, vehicle use

• Topsoil is potentially renewable--on 38% of world's cropland it is not renewed

• In USA loss 16x > formation, but slowing

Soil: Erosion

Desertification: drylands lose productivity by 10% or more (only severe cases actually become desert). A problem in 70% of drylands.

Salinization: Irrigation (1/5 of cropland, 40% of food) results in concentration of salts through evaporation. Can kill plants. Problem on 1/5 of irrigated cropland.

Waterlogging: Over-irrigating raises water table with saline water. Problem on 1/10 of irrigated cropland.

Soil: Desertification, Salinization, Waterlogging

Soil conservation is key component of sustainable agriculture. How:

Conservation tillage: keep soil undisturbed, covered with vegetation

Soil: Conservation

Windbreaks: reduce wind erosion

Terracing, contour farming, strip cropping: control water run off

o Fertilizers used to restore lost plant nutrients--esp. N-P-K.

o Organic: From plant and animal sources such as manures, compost. Provide nutrients AND structure (humus).

o Crop rotation: Added diversity minimizes loss of single nutrient.

o Inorganic: Provide nutrients, but NO structure. Runoff is pollutant.

Soil and Fertilizers

o Enough food is produced :) o Distribution inequal: 1/6 of

world underfed :( o Undernutrition=not enough

food. Malnourished=not enough nutrients, esp. protein.

o Problem: poverty. o Undernutrition problem

growing in LDC's. Also lack of micronutrients: vitamin A, iron, and iodine.

Nutrition: Problems

-Immunizations-Education (esp. women), Family

planning-Breast feeding-Vitamins,Nutrients (i.e. A for

blindness, iodine for thyroid/metabolism, iron for blood/anemia)

-Prevent dehydration-Reduce overnutrition in MDCs: Over

68% of Americans overweight or obese (National Health and Nutrition Examination Survey (NHANES), 2012)

Nutrition: Solutions

Human population expected to reach 9 billion by 2050• 3rd Revolution: Genetic Engineering? Over 2/3 of US

supermarket food contains GE crops.• Benefits: Short-term reduction in pesticide, herbicide

use, no loss in nutrition.• Drawbacks: Superbugs, superweeds, persistent

toxins in food, allergies, corporate ownership of seeds, minimal or no long term yield increases, no long-term reduction in inputs, few long-term studies.

Food: Increasing Plant Production

Use more water? Water expensive and aquifers (underground water) are being depleted.

Use more land? Very little new land left that is viable for growing crops.

What can be done? See the green on upcoming slides.

Food: Increasing Plant Production

Meat production is intensive: -Half of world's cropland and water useage, -20x more manure than humans, -22% or more (Sci. Amer., 2009) of

greenhouse gases (CH4, CO2), overgrazing, endanger wild species.

Food: Meat

• 43% of beef from feedlots with as many as 100,000 cattle! Over 50% of pork, about 75% of poultry is non-pasture, “factory” farmed.

• Shift from beef, pork--> to fish, poultry (more grain-efficient) OR grass-fed, free-range cattle.

Food: Meat

Fisheries: Aquatic species suitable for commercial harvest

Food: Fish

About 3/4 of 200 the most valuable fisheries overfished or at limit. Often subsidized by governments.

Careful management would allow 125 of 128 depleted fisheries to recover.

Management: -Quotas-Limit boats-No fish during spawning-Restrict use of long lines, drift nets,

other harmful methods-Create reserves-Consumer

awareness

Food: Fishing Management

Aquaculture

Food: Fish Farming, Ranching

PROSHighly efficientHigh yield in smallvolume of waterIncreased yieldsthrough cross-breeding and geneticengineeringCan reduce over-harvestingLittle use of fuelHigh profits

CONS:Large inputs of land, feed,And water neededProduces large and concentrated outputs of wasteDestroys mangrove forestsIncreased grain production needed to feed some speciesFish can be killed by pesticide runoff fromnearby croplandDense populations vulnerable to disease

Farming=Controlled environmentRanching=Captive with some release (ie salmon)

Pests and FoodPests damage crops and reduce

yield: weeds, herbivorous insects, fungus, microbes.

In balanced ecosystems, pests are not usually a major problem. Ecosystem service: Natural enemies (i.e. ladybugs, spiders eat herbivorous insects).

In agricultural systems (low diversity), up to 55% of crops can be lost to pests.

PesticidesInsecticides (pesticides) kill animal pests, Herbicides

kill plant pests--usually toxic chemicals. But they also...

-Accelerate genetic resistance-Kill natural pest enemies-Do NOT reach target pests 98% of time!-Harm wildlife-Threaten human health: cancer, death In 1942, we lost 7% of crops to insect pests. Now we use 33x more pesticides,

yet we lose 13%!

So why use them?-Can help eradicate disease and save lives-Can increase food supply and profits when used correctly-Work well in short term-New pesticides safer and needed in smaller amountsRachel Carson’s Silent

Spring (1962) raised awareness about DDT and pesticides in general.

Pesticides: SolutionsLaws: 57 pesticides banned by the EPA 1972-2004. Poorly enforced. Different

outside US. 1996 Food Quality Protection Act.

Genetic Engineering?: See previous slidesBiological controls: Introduce natural

enemiesNatural chemicals: Pheromones and

hormones can change pest behavior.Physical controls: Water spray or

vacuuming.

Integrated Pest Management (IPM): 1) Allow for some crop loss, 2) Learn: Biological, physical controls first. 3) Small amount of carefully applied pesticides

How? Educate, change farming subsidies practices, tax pesticides to fund IPM

Mentioned previously: Traditional methods, Soil conservation

Reduce resource input, work with nature (BioSPoRN)

Sustainable Agriculture

MORE:• organic fertilizers• pest control• efficient irrigation• perennial crops• crop rotation• soil conservation• subsidies

LESS:• soil erosion• soil salinization•  overgrazing• overfishing• food waste• population growth

• poverty

ALSO...Reduce poverty

Slow population growth

Miller, Environmental Science, (2006)Fiala, Nathan, How Meat Contributes to

Global Warming, Scientific American, http://www.scientificamerican.com/article.cfm?id=the-greenhouse-hamburger (2009)

National Health and Nutrition Examination Survey (NHANES) (2012)

Carson, Rachel, Silent Spring (1962)

Bibliography

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