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          12   Soil and Agriculture
            Possible Transgenic Maize in
            Oaxaca, Mexico

• In 2001, genetically modified (GM) transgenes were
  found in native Oaxacan maize.
• Anti-GM activists worry that transgene ―contamination‖
  will threaten the genetic diversity of the planet’s food
• The GM industry defends its safety and proclaims that
  GM crops are necessary to meet growing food

             Talk About It What are the costs and benefits of
             genetically modified food crops?
 Lesson 12.2 Soil Degradation and Conservation

      Some estimates predict that 50 million people
      could be displaced in the next 10 years due to
      desertification, a form of soil degradation.

A dust storm near Stratford, Texas, in 1935
Lesson 12.2 Soil Degradation and Conservation

                                             • The process by which
                                               material, such as topsoil, is
                                               moved from one place to
                                             • Caused by natural processes
                                               and human activities
                                             • Often occurs faster than soil
                                               is formed, depleting fertile
  Did You Know? More than 19 billion
  hectares (47 billion acres) of the         • Crops, trees, and other plant
  world’s croplands suffer from erosion
  and other forms of soil degradation          communities protect soil from
  resulting from human activities.             erosion.
 Lesson 12.2 Soil Degradation and Conservation

              Farming Practices That
                 Reduce Erosion
• Intercropping: Different crops
  mixed together
• Crop rotation: Crops are
• Shelterbelts: Tall plants block
• Conservation tillage: Soil
  turnover is reduced.
• Terracing: Steep slopes turned
  into ―steps‖
• Contour farming: Planting
  perpendicular to hill’s slope
Farming Practices That
   Reduce Erosion
Farming Practices That
   Reduce Erosion
Farming Practices That
   Reduce Erosion
Farming Practices That
   Reduce Erosion
Farming Practices That
   Reduce Erosion
Lesson 12.2 Soil Degradation and Conservation

                 Ranching Practices
                                                • Ranching is the
                                                  raising and grazing
                                                  of livestock.
                                                • Overgrazing causes
                                                  and worsens many
                                                  soil problems.
                                                • Range managers
                                                  encourage grazing
                                                  limits and enforce
                                                  them on publicly
                                                  owned land.
Lesson 12.2 Soil Degradation and Conservation

                  Forestry Practices

• Forestry practices, such
  as clear-cutting, can
  increase erosion.
• Today, practices that
  reduce soil erosion, such
  as selective logging, are
  increasingly common.
 Lesson 12.2 Soil Degradation and Conservation

• Loss of more than
  10% of soil productivity
• Causes: soil compaction,
  erosion, overgrazing,
  drought, or other factors
• Arid and semi-arid lands
  are most prone.
• Affects large amounts of Earth’s
  land areas—up to one third,
  according to one estimate
                                           Area affected by the Dust Bowl
• The Dust Bowl was a major
  desertification event in the 1930s.
Lesson 12.2 Soil Degradation and Conservation

           Soil Conservation Efforts
                                    • U.S. Soil Conservation Act
                                      (1935): Established the Soil
                                      Conservation Service, today
                                      called the Natural Resources
                                      Conservation Service
                                    • Farmer-Centered
                                      Agricultural Resource
                                      Management Program
                                      (FARM): A United Nations
                                      effort that focuses on
                                      resource challenges in
                                      developing nations
Lesson 12.2 Soil Degradation and Conservation

                               Soil Pollution
• Too much, or carelessly timed
  irrigation can waterlog crops
  and lead to salinization—a
  buildup of salts in upper soil
• Toxic pesticides can remain in
  soil for a long time, eventually
  filtering to groundwater.

    Did You Know? Salinization costs
    farmers $11 billion in crop income a
    year worldwide.
Lesson 12.3 Agriculture

                          Humans have been practicing
                          agriculture for about 10,000 years.
Archeologists estimate that, in
ordinary circumstances, the
activity of gathering in
temperate and tropic areas
provides 75 to 80% of the total
calories consumed, with
hunting providing the balance.
In existing hunting and
gathering cultures, women
usually do most of the
gathering, while the men
specialize in hunting.
 Lesson 12.3 Agriculture

        The Beginnings of Agriculture
• People were hunter-gatherers through most of human history,
  until agriculture developed about 10,000 years ago.
Domestication can be defined as a primitive form of
genetic engineering in which certain plants and
animals are brought under human control, their
objectionable characteristics eliminated, their
favorable ones enhanced and in the case of
animals, can be induced to reproduce in captivity. --
Nagle, p. 3.
In the Near East, many
varieties of the wild
cereal grasses, wheat
and barley, shown
below were exploited as
major food sources.
In contrast to hunting and gathering as a mode of
life, agriculture means modifying the environment
in order to exploit it more effectively. Agriculture
alters both the animals and plants it domesticates.
Ultimately, it changes the very landscape itself.
Domestication of Animals
• Cyrus McCormick patents the reaper (increased
  harvest with less labor)
   • Vid Clip
• John Deere manufactures steel plows (cultivate
 larger acreages
• Sir John Lawes invents commercial fertilizer (greatly increased crop yields)
• Grain drill patented (greatly increased wheat acreage & wheat supply)
• Holstein and Jersey dairy cattle imported (improved milk production)
• Factory-made agricultural machinery readily available (large scale farming)
• Farmers begin to organize (improved influence and marketing opportunities)
• Morrill Land Grant Act (established land grant colleges for agricultural research to
  improve food production methods)
• U.S. Department of Agriculture established (government support for & control of
•   Steam powered tractor introduced (beginning of first agricultural revolution – the
    shift to mechanized agriculture)
•   Refrigerated freight cars introduced (ship fruit & vegetables long distances and
    out of season)
•   Barbed wire patented (confined cattle increased beef production & quality)
• First hybrid crop developed – corn (greatly increased yield and quality)
• First pesticide discovered (Bordeaux mixture increased crop yield & quality)
• Federal Hatch Act (established agricultural experiment stations nationwide)
• First gasoline tractor built (agriculture’s greatest achievement)
• Boll weevil invades U.S. cotton (forced farmers to diversify & improve land
• Rural Free Delivery (mail service to farmers improved communication)
• George Washington Carver found new uses for peanuts (agricultural
  expansion and diversification)
• Hog cholera serum developed (first commercial animal health product)
• First agricultural extension agent hired (dispersed agricultural research)
• 4-H Clubs established (first effort to educate rural youth in agriculture)
• Food & Drug Act/Meat Inspection Act (forced improved livestock production
methods to insure food safety)
• Disease resistant plants developed (improved crop yield and quality)
• Mechanical combine developed (threshed crops on the move to harvest more acres
• American Farm Bureau organized (national farmer organization)
• Smith-Lever Act (formally established cooperative extension service)
• Smith-Hughes Act (established agricultural
education in public schools)
• Small tractors developed (mechanized agriculture on small acreages)
• Future Farmers of American founded (agricultural youth leadership organization)
• Agricultural research lays groundwork for second agricultural revolution
• Artificial insemination of dairy cattle became
  commercially feasible due to development of liquid
  nitrogen (improved animal genetics)
• Rural Electrification Association founded (made electricity
  available to rural America and began the move to
  electrical equipment)
• Farm Credit Act passed (provided money for lending to
• In 1935, the number of farms in the United States peaked
  at 6.8 million.

                               U.S.Farmer Feeds

    20     9.8
         1930    1940   1950    1960   1970   1980   1990   2000   2005
• Agricultural pesticide use becomes commercially
  feasible (improves crop production and efficiency)
• Mechanized cotton picker developed (reduced need
  for manual labor)
• End of the “sharecropper” era – agriculture becomes
  a business

                                  U.S.Farmer Feeds

     20     9.8     10.7
          1930    1940     1950    1960   1970   1980   1990   2000   2005
• Anhydrous ammonia becomes available
  (greatly increased crop yields)
• Screw worm eradicated by release of sterile
  male flies (first application of biotechnology
  in agriculture)

                                U.S.Farmer Feeds

   20             10.7     15.5
        1930    1940     1950     1960   1970   1980   1990   2000   2005
• Improved quality of life for Rural America
       • 83% of farms have telephones
       • 98% of farms have electricity
       • 98% of farms have automobiles
• American farmers experience great prosperity

                              U.S.Farmer Feeds

 20             10.7     15.5
      1930    1940     1950     1960     1970   1980   1990   2000   2005
• High-yielding wheat varieties developed (increased ag
  exports & wheat acreage expansion)
• Hog cholera eradicated (first successful elimination of
  disease in livestock)

                               U.S.Farmer Feeds

  60                                        47.7
  20             10.7     15.5
       1930    1940     1950     1960     1970     1980   1990   2000   2005
• Computer use in agriculture (decision-making, equipment control, marketing, communication)
• Boll weevil eradicated (first successful use of scientific research and biotechnology to eliminate a
  crop pest)
• Embryo transfer in cattle perfected (permitted rapid genetic improvement in livestock)

                                     U.S.Farmer Feeds

        80                                                 75.7

        60                                        47.7
        20             10.7     15.5
             1930    1940     1950     1960     1970     1980     1990   2000   2005
• Genetic engineering developed (used in crops in livestock to improve
  production and decrease pesticide use)
• Precision agriculture using GPS technology (more efficient use of fertilizer
  and pesticides to reduce cost and pollution)

                              U.S.Farmer Feeds

 80                                                 75.7

 60                                        47.7
 20             10.7     15.5
      1930    1940     1950     1960     1970     1980     1990    2000   2005
      • Almost 99 percent of all U.S. farms are owned by individuals, family
        partnerships or family corporations. Less than 1 percent of
        America's farms and ranches are owned by non-family
      • About 94 percent of U.S. ag products sold are produced on farms
        that are owned by individuals, family partnerships and family
        corporations. Non-family corporations account for only about 6
        percent of product sales.

                              U.S.Farmer Feeds

 80                                                 75.7

 20             10.7     15.5
      1930    1940     1950     1960     1970     1980     1990    2000    2005
• In 2002, the average age of a farmer was 55.
• There were 236,269 farms operated by women in the United States
  in 2002, a 12.6 percent increase from 1997.
• There were 50,443 farmers of Spanish, Hispanic or Latino origin in
  the United States in 2002, a 51 percent increase from 1997.
• There were 29,145 black farmers in the United States in 2002, a 9
  increase from 1997.
• In 2002, there were 7,913 multiple race farmers in the United States.
More of the same (improvements in current technology)
             Digital animal identification
                Biofuel use in farming
             Intense water management
                    Food security
                 Organic agriculture
                 Who knows?????
 Lesson 12.3 Agriculture

    Selective Breeding and Settlement
• In early agriculture, people
  began planting seeds from
  plants they liked most, a form
  of selective breeding.
• Crop cultivation enabled
  people to settle permanently,
  often near water sources, and
  raise livestock.
• Agriculture and livestock
  provided a stable food supply,
  which allowed the
  development of modern
Lesson 12.3 Agriculture

               Traditional Agriculture
                            • Agriculture ―powered‖ by
                              people and animals
                            • Does not require fossil
                            • Practiced widely until the
                              Industrial Revolution
 Lesson 12.3 Agriculture

                Industrial Agriculture
• Agriculture that
  requires the use of
  fossil fuels
• Involves mechanized
  farming technology,
  chemicals, and large-
  scale irrigation
• To be efficient, large
  areas are planted with
  a single crop in a        Did You Know? Today, more than
                            25% of the world’s croplands support
  monoculture.              industrial agriculture.
 Lesson 12.3 Agriculture

                The Green Revolution
• Introduced new technology, crop
  varieties, and farming practices to the
  developing world in the mid- to late 1900s
   • Increased crop yields and saved millions of
     people from starvation in India and Pakistan
   • Prevented some deforestation and habitat
     loss by increasing yields on cultivated land
   • Led to a 7000% increase in energy used by
   • Worsened erosion, salinization,
     desertification, eutrophication, and pollution
Lesson 12.3 Agriculture

            Pests and Weed Control
• Chemical pesticides:
  Effective and cheap, but can
  lead to resistance
• Biological pest control:
  Permanent solution, but can
  harm nontarget organisms
• Integrated pest
  management: Increasingly
  popular solution, combines
  chemical and biological
  pest-control methods           Cactus moth larvae are used to control
                                 prickly pear cactus, but also threaten
                                 many rare, native cacti around the world.
Brown Plant Hopper
    Nilaparvata lugens
Lesson 12.3 Agriculture

                                              • Pollination is the process by
                                                which plants reproduce
                                              • Agriculture relies on pollinators,
                                                such as insects.
                                              • Native and domesticated
                                                pollinator populations have
                                                declined due to pesticide use,
                                                parasites, and other as-of-yet
                                                unknown causes.

Did You Know? Bees and other insects
pollinate 800 species of cultivated plants.
Lesson 12.4 Food Production

                      Each year, Earth gains 75 million people
                      and loses 5–7 million hectares of
                      productive cropland.
Lesson 12.4 Food Production

                                              Food Security
                                                • Since 1960, our ability to produce
                                                  food has grown faster than the
                                                  human population, but 1 billion
                                                  people are hungry worldwide.
                  QuickTime™ and a
         TIFF (U ncom pressed) decompressor
            are needed to see this picture.
                                                • Malnutrition and undernourishment
                                                  are most common in the developing
                                                • Agriculture scientists and
                                                  policymakers are working toward
                                                  food security—the guarantee of an
                                                  adequate food supply for all people
 Kwashiorkor, a disease caused
 by protein deficiency.
                                                  at all times.
Lesson 12.4 Food Production

     Genetically Modified Organisms
• Organisms that have had
  their DNA modified
• Commonly engineered
  traits include rapid growth,
  pest resistance, and frost
• In the United States,
  85% of corn and 90% of
  soybean, cotton, and
  canola crops come from
  GM strains.
Lesson 12.4 Food Production

     Risks and Benefits of GM Crops

  • Risks:
     • Potential for ―superpests‖ that are resistant to pest-resistant crops
     • Contamination of non-GM plants

                                              • Benefits:
                                                  • Insect-resistant crops
                                                    reduce the need for
                                                  • Herbicide-resistant crops
                                                    encourage tillage
 Lesson 12.4 Food Production

          Industrial Food Production:
• Alternative to open grazing in
  which energy-rich food is
  delivered to a concentrated
  group of livestock or poultry
• Benefits: Reduces soil
  degradation and fertilizer use
• Costs: Requires antibiotic use;
  potential for water
  contamination and animal
Lesson 12.4 Food Production

          Industrial Food Production:
• Fish farming in a controlled environment
• Benefits: Can be sustainable; reduces
  by-catch; reduces fossil fuel use
• Costs: More difficult to control spread
  of diseases; produces a lot of waste;
  potential for farm-raised animals
  to escape into wild

      Did You Know? Aquaculture is the
      fastest-growing type of food production.
        A natural pond setting …

• Fish, bacteria and plants
  all work together to
  provide nutrients and
  dispose of waste.
• The ammonia/
  nitrogen cycle is key.
                              USDA photo/Ken Hammond
  The ammonia/nitrogen cycle:

                         Ammonia (NH3)

            Fish Wastes,                    Nitrosomonas
            Uneaten Feed                       Bacteria

Fish Feed                                                Nitrite (NO2)

                Algae,                     Nitrobacter
                Plants                      Bacteria

                           Nitrate (NO3)
         Here’s how it works …

• Fish live in their own bathroom.
• Fish waste is mostly ammonia.
• Excess feed also produces ammonia.
• Too much ammonia and all the fish are dead.
        Bacteria to the rescue …
• Certain bacteria LOVE ammonia.
• Nitrosomonas bacteria eat up the ammonia and give
  off nitrite.
• But too much nitrite is also dangerous to fish.
  Now it’s more bacteria riding to
           the rescue …
• Nitrobacter bacteria love nitrites.
• These bacteria give off nitrates as a waste product.
• Once again, too many nitrates will kill the fish.
Then it’s plants that step up to the
              plate …
• The plants feed on the nitrates and grow big and
• Fish swim along and eat the plants, releasing
  ammonia as waste and
            What is aquaponics?

• A combination of aquaculture and hydroponics
• Fish, plants and bacteria working together to meet
  each others needs.
   • Fish produce the ammonia
   • Bacteria break down the ammonia to nitrates.
   • Plants feed on the nitrates to produce fish food.
     Aquaponics is experimental:

• True recycling systems that reuse water and nutrients
• No groundwater pollution
• No nutrient runoff
• Less than 1/10th the fertilizer and 1/100th the water of
  traditional systems
• Outperforms traditional agriculture up to 30:1
        More about aquaponics:

• It is a closed-loop
• Combines growing fish
  and plants
• A manmade version of
  Mother Nature’s pond,
  stream and field
  ecosystem               Photo courtesy K. Fitzsimmons.
              A simple system:

• Fish in a fish tank
• Pump moves water from the tank through a series of
  troughs on top of the tank
• Pots have plants in rockwool
• Fish wastes are trapped in the rockwool and feed the
• Clean water flows from plants back to the fish tank.
         More elaborate systems:

• Systems to separate solid vs. dissolved waste
• Automatic monitors, backup pumps
• Automatic fish feeding system
• System to maximize plant growth

• Vid Clip
• Vid Clip 2
         Pretty great system, right?
• An aquaponic system is nearly a total recycling program.
   • Plants feed fish.
   • Fish waste feeds
   • Bacteria
     feed plants.
• But fish grow,
  so you need
  to feed them.

                                    Photo courtesy K. Fitzsimmons.
           System requirements:

• Bacteria like temperatures of 75-80 F
• Bacteria are slow to adapt to changes, so limit
  changes in feed volume.
• Too few fish? Fertilize the plants.
   • In water – not approved for food grade fish
   • Spray on the leaves (foliar)
• Don’t forget light for the plants.
• Avoid too much heat from the lights.
   The ammonia/nitrate cycle

                         Ammonia (NH3)

            Fish Wastes,                    Nitrosomonas
            Uneaten Feed                       Bacteria

Fish Feed                                                Nitrite (NO2)

                Algae,                     Nitrobacter
                Plants                      Bacteria

                           Nitrate (NO3)
What is the value of learning about
          fish anatomy?
• Classify and recognize types of fish
• Distinguish between the sexes
• Spot and diagnose disease
                External anatomy

• Morphology (structure and form) can affect feeding
  and type of culture facility.
   • Fish with small, upturned
     mouths generally are
     herbivores and/or surface
     feeders like tilapia.
   • Fish with downturned
     mouths are generally
     bottom feeders like catfish.
            What tail fins tell us:

• Single-lobed or homocercal tail fins suggest that fish
  are slow swimmers and survive well in water free of
  much movement.
• Fish with forked or heterocercal tail fins are fast
  swimmers and prefer flowing water.
         What body shape tells us:
• Fish like trout, with a body long and tapered towards the
  ends, are the best swimmers and need water space.
• Fish that are wide and flat or tend to stay on the bottom
  require lots of bottom space for growth.
• Fish that are rounded and thin from side to side or
  laterally compressed tend to hover in the water and are
  not particularly fast swimmers.
                   Body regions:
• Head (from the tip of snout to the posterior edge of the
  operculum – the covering over the gills)
• Trunk (from the operculum to the anus)
• Tail (from the anus to the end of the caudal fin).

               More body parts:

• Fins: single dorsal fins, anal fin and caudal (tail) fin;
  and paired pectoral and pelvic (ventral) fins.
• Other structures: teeth in some fish, nostrils or nares,
  eyes, mouth, the operculum, scales, lateral line, anus
  and urogenital opening
• Scales: bony or horny shaped plates in overlapping
  rows. Some fish like catfish do not have scales.
• Dorsal – upper surface
• Ventral – lower or abdominal surface
• Anterior – front or head
• Posterior or caudal – tail or rear


                                         or caudal

              9 Body Systems:

1. Skeletal – rigid framework giving shape and
2. Muscular – provides internal and external
3. Digestive – converts feed for use in the body
4. Excretory – eliminates wastes
5. Respiratory – takes in oxygen and eliminates
   carbon dioxide
               9 Body Systems:

6.   Circulatory – distributes blood throughout the body
7.   Nervous – provides information and conveys
     impulses throughout the body
8.   Sensory – sight, touch, taste, small, sound
9.   Reproductive – creates new organisms
             The swim bladder:

• A long, thin-walled sac, located dorsal in the body
  cavity (near the backbone) and attached to the
• Controls the buoyancy of a fish
• Important for hearing in some species
• Not present in all fish
Lesson 12.4 Food Production

            Sustainable Agriculture
• Does not deplete soil faster than it
• Does not reduce the amount or
  quality of soil, water, and genetic
  diversity essential to long-term crop
  and livestock production
• Organic agriculture is sustainable
  agriculture that does not use
  synthetic chemicals.
• Local, small-scale agriculture reduces   Did You Know? Organic
                                           food purchases increased
  the use of fossil fuels and chemicals    200% from 1999 to 2008.
  used for transportation and storage.

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