Some key points from WF

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October 31,2007
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5 great things to do this week

• Join Revkins Blog DotEarth
• Rent An Inconvenient Truth
• Read Newt Gingrich A Contract with the Earth
• Sustainability conference at Chico State this
  weekend. See Sac Bee.
• Check out Landvote.org on past and current
  election issues on open space.

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Relative to the recent SoCal fires
1/3 of the housing units in the conterminous US
are on the WUI. This represents 10 of land area.
The Wildland-Urban Interface (WUI) in the US
Radeloff et al 2005 Ecological Applications.
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Landvote.org
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Agriculture a) Food production and distribution,
b) Ag impacts on the environment and c)
Genetically modified organisms (GMOs)
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Sub-Topics

• Nutrition and Food Supplies
• Major Food Sources
• Soil A Renewable Resource
• Ways We Use and Abuse Soil
• New Crops and Genetic Engineering
• Pesticide use and abuse
• Sustainable Agriculture
• Organic Farming

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Nutrition and Food Supplies

• World food supplies 1950 vs. 2000
• Sharply increased
• In richer countries, the most common dietary
  problem is over-nutrition.
• Food prices probably close to historic lows as a
  fraction of income.
• Global food shortage isnt an issue, yet
• Sub-Saharan Africa food production has not kept
  pace with rapid population growth
• With continued population increase and loss of ag
  land food supply may someday soon be limiting
• Asia has experienced the most rapid increase in
  crop production, but also has the largest hunger
  issue

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Countries at risk for inadequate nutrition
The largest fraction of hungry people live in
Africa. The largest number of hungry people live
in Asia.
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Undernourished people


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World Grain, Food Production
?

• Three regions of particular note
• NA and Europe
• Asia
• Africa

The Green Revolution
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The green revolution

• Increase in per acre agricultural production
• How?
• Chemicals fertilizers pesticides
• Agricultural certainty irrigation in dry areas
• Breeding genetics and producing high yielding
  crops

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Total Energy Use in U.S. Agriculture
Energy crisis response
Energy required to process foods and move them to
markets (in the US) may be 5 times that of energy
use on the farm.
Things like fertilizers, pesticides, etc..
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The miracle of crop genetics
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Irrigation

• The artificial provision of water to support
  agriculture
• 70 of all freshwater used by humans is used for
  irrigation.
• Irrigated land globally covers more area than all
  of Mexico and Central America combined.
• Irrigation has boosted productivity in many
  places

PROBLEMS?
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Improved irrigation

• In conventional irrigation, only 40 of the water
  reaches plants.
• Efficient drip irrigation targeted to plants
  conserves water, saves money, and reduces
  problems like salinization.

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Miracle Crop Yield --requires environmental
consistency
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Global fertilizer usages

• Fertilizer use has risen dramatically in the past
  50 years.

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Fertilizing Soils
Nitrogen is often a limiting nutrient. Nitrogen
is the most abundant gas in air, but is an
unusable form. It needs to be fixed. Human
nitrogen fixation, globally, now exceeds natural
nitrogen fixation. Vitousek.
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Fertilizers

• Supply nutrients to crops
• Inorganic fertilizers mined or synthetically
  manufactured mineral supplements
• Organic fertilizers animal manure, crop
  residues, compost, etc.

PROBLEMS?
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Problems caused by fertilization

• Air pollution and ecosystem fertilization
• Water pollution and fertilization
• Groundwater contamination

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In US, Agriculture is a leading contributor to
difficult pollution problems
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Miracle Crop Yield --requires environmental
consistency
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MonoCultures increase risk of pests
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Up to 90 of all pesticides never reach target
organisms.
Ag Chemistry
Problems?
73 of conventionally grown foods have residues
of at least 1 pesticide (USDA), compared to 23
of organic foods.
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Pesticide Resistance

• Pest Outbreak
• Pesticide application
• lt100 mortality
• Survivors reproduce
• Repeated treatment results in lower pest mortality

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Land Resources

• Globally, we are losing per capita cropland
• Cropland per person
• 1970 0.94 acre
• 2000 0.56 acre
• 2050 0.37 acre
• Per capita loss factors
• Population growth
• Less land in cultivation (in some regions)
• Losing ag lands to erosion / degradation
• In developing countries, increasing cropland
  acreage
• Oceania, South America in particular
• Losses in developing world generally because of
  degradation

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If food production increases at a rate slower
than human population growth for the next 50
years

• More people will go hungry even if food
  distribution improves, or
• More natural habitat will be lost to agriculture,
  or
• The 1 billion who eat high on the food chain and
  eat too many calories will have to curtail excess
  consumption of agricultural energy

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Will the green revolution succeed in Asia and
Africa?

• Gaining benefit from high responders (crops)
  requires
• Water for irrigation in relatively dry regions to
  achieve environmental certainty and
• Energy for the chemical applications and
• Money to afford proprietary crop lines

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Will the green revolution succeed in Asia and
Africa?

• Can these region achieve the required chemical
  applications?
• Do these regions have the climatic certainty
  dry, irrigate?
• Both Asia and Africa have problems with this
• Will they be able to afford the crop genetics?

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Food Security

• Poverty is the greatest threat to food security.
• About 815 million people are chronically
  undernourished (200 million are children).
• Chronically undernourished lt 90 of the 2,770
  calories / day needed for an active life.
• Within families that dont get enough to eat,
  women and children have the poorest diets.
• Food security - the ability to obtain sufficient
  food on a day-to-day basis

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Famines Some Causes

• Environmental conditions - drought, insects,
  natural disasters
• National politics - corruption, oppression
• Armed conflict
• Economics - price gouging, poverty, landlessness

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Focus on Aid Focus on local solutions
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Soil.

• Civilization itself rests upon the soil.
• --Thomas Jefferson
• We stand only six inches from desolation, for
  that is the thickness of the topsoil layer upon
  which the entire life of the planet exists
• --R. Neil Sampson

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Soil profile

Thickness varies

• Consists of layers called horizons.
• Simplest
• A topsoil
• B subsoil
• C parent material
• But most have O, A, E, B, C, and R

Figure 8.8
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Soil profile

• O Horizon Organic or litter layer
• A Horizon Topsoil. Mostly inorganic minerals
  with some organic material and humus mixed in.
  Crucial for plant growth
• E Horizon Eluviation horizon loss of minerals
  by leaching, a process whereby solid materials
  are dissolved and transported away
• B Horizon Subsoil. Zone of accumulation or
  deposition of leached minerals and organic acids
  from above
• C Horizon Slightly altered parent material
• R Horizon Bedrock

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Soil as a system

• Parent material, such as bedrock, is weathered to
  begin process of soil formation.

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Soil characterization

• Soil can be characterized by color and several
  other traits
• texture
• structure
• pH

Figure 8.9
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Soil texture
Figure 8.10
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Soil Organisms
Without soil organisms, the earth would be
covered with sterile mineral particles.
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Major Food Sources
APPENDIX
Crops

• Three major crops - wheat, rice, maize
• High latitudes - potatoes, barley, oats, rye
• Warm, wet areas - roots and tubers
• Dry regions of Africa - sorghum and millet
• Fruits and vegetables

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Meat, Milk, and Seafood
APPENDIX

• Milk and meat highly prized, but distribution
  inequitable
• About 90 of the grain grown in North America is
  used to feed cattle, hogs, poultry, and other
  animals!
• Seafood - important protein source in many
  countries - threatened by overharvesting and
  habitat destruction

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Regional soil differences and agriculture

• Soil and soil profiles vary from place to place,
  with implications for agriculture.
• Amazonian rainforest soil Lots of rain leaches
  nutrients from topsoil out of reach of plant
  roots. Other nutrients taken up by lush
  vegetation, leaving little in soil.
• Thus when farmed, soil gives out after a few
  years.
• Kansas prairie soil Low rainfall keeps
  nutrients in topsoil, where plants take them up
  and recycle them back into soil when they die.
  Topsoil rich and productive.

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Essential Nutrients
APPENDIX

• Malnourishment - a nutritional imbalance caused
  by a lack of specific dietary components or an
  inability to utilize essential nutrients
• Protein deficiency diseases kwashiorkor (low
  protein), marasmus (low calories and protein)
• Iron deficiency - anemia - most severe in India
• Iodine deficiency - goiter, hyperthyroidism

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Soil Degradation

• Caused by
• Overcultivating, too much plowing, poor
  planning
• Overgrazing rangeland with livestock
• Deforestation, especially on slopes

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Overgrazing

• When livestock eat too much plant cover on
  rangelands, impeding plant regrowth
• The contrast between ungrazed and overgrazed land
  on either side of a fenceline can be striking.

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Overgrazing

• Overgrazing can set in motion a series of
  positive feedback loops.

Figure 8.21
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Desertification

• A loss of more than 10 productivity due to
• Erosion ---(wind water)
• Soil compaction
• Forest removal
• Overgrazing
• Drought
• Salinization
• Climate change
• Depletion of water resources
• etc.

When severe, there is expansion of desert areas,
or creation of new ones, e.g., the Middle East,
formerly, Fertile Crescent.
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Regions of concern for the health of soils Note
the regions of high human density
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Erosion The Nature of the Problem

• Erosion - natural process, but a disaster when it
  occurs in the wrong place at the wrong time
• Consequence Water table depression results
  leaving crops less able to survive without
  irrigation

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Types of soil erosion
Splash erosion
Rill erosion
Gully erosion
Sheet erosion
Figure 8.11
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Mechanisms of Erosion

• Most soil erosion on agricultural land is rill
  erosion
• Some of the highest erosion rates in the world
  occur in the U.S. and Canada - row crops leave
  soil exposed

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How much land is lost to erosion on ag lands?

• 28 billion tons / year (Enger Smith, Lster
  Brown, Worldwatch)
• 47 billion acres suffer from erosion (Withgott
  Brennan)
• 1/3 of global crop land is losing soil to erosion
  faster than it is being renewed (Chiras)
• 15 million ha / year of agricultural land (8
  million converted to other uses 4 million to
  deserts, 3 million to erosion) Cunningham and
  Cunningham.
• 40 of global ag lands (Miller)
• Lomborg claims much less. Claims that these
  estimates originate from a study of 0.1 ha site
  on a slope in Belgium
• Wikipedia cites land area on earth as 148
  million sq km there are 247 acres / km2 37
  billion acres

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Soil conservation

• As a result of the Dust Bowl,
• the U.S. Soil Conservation Act of 1935 and
• the Soil Conservation Service (SCS)
  were created.
• SCS Local agents in conservation districts
  worked with farmers to disseminate scientific
  knowledge and help them conserve their soil.

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Recent soil conservation laws

• The U.S. has continued to pass soil conservation
  legislation in recent years
• Food Security Act of 1985
• Conservation Reserve Program, 1985
• Freedom to Farm Act, 1996
• Low-Input Sustainable Agriculture Program,
  1998
• Internationally, there is the UNs FAR program
  in Asia.

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Soil conservation

• Many nations followed the U.S. lead
• Today local soil conservation agents help
  farmers in many places in the world.
• Brazils no-till effort is based on local
  associations.
• Farmer and extension agent in Colombia

Figure 8.15
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Preventing soil degradation

• Several farming strategies to prevent soil
  degradation
• Crop rotation
• Contour farming
• Intercropping
• Terracing
• Shelterbelts
• Conservation tillage