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CHAPTER 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 supply. • The GM industry defends its safety and proclaims that GM crops are necessary to meet growing food demand. 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 Erosion • The process by which material, such as topsoil, is moved from one place to another • Caused by natural processes and human activities • Often occurs faster than soil is formed, depleting fertile topsoil Did You Know? More than 19 billion hectares (47 billion acres) of the world’s croplands suffer from erosion and other forms of soil degradation resulting from human activities. • Crops, trees, and other plant communities protect soil from erosion.
Lesson 12. 2 Soil Degradation and Conservation Farming Practices That Reduce Erosion • Intercropping: Different crops mixed together • Crop rotation: Crops are alternated. • Shelterbelts: Tall plants block wind. • 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 Desertification • 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 • The Dust Bowl was a major desertification event in the 1930 s. Area affected by the Dust Bowl
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 horizons. • 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 Mc. Cormick patents the reaper (increased harvest with less labor) • Vid Clip • John Deere manufactures steel plows (cultivate larger acreages
1840’s • 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)
1850’s • Factory-made agricultural machinery readily available (large scale farming) • Farmers begin to organize (improved influence and marketing opportunities)
1860’s • 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 agriculture)
1870’s • 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)
1880’s • 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)
1890’s • First gasoline tractor built (agriculture’s greatest achievement) • Boll weevil invades U. S. cotton (forced farmers to diversify & improve land management) • Rural Free Delivery (mail service to farmers improved communication)
1900’s • 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)
1910’s • Disease resistant plants developed (improved crop yield and quality) • Mechanical combine developed (threshed crops on the move to harvest more acres faster) • American Farm Bureau organized (national farmer organization) • Smith-Lever Act (formally established cooperative extension service) • Smith-Hughes Act (established agricultural education in public schools)
1920’s • 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
1930’s • 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 farmers) • In 1935, the number of farms in the United States peaked at 6. 8 million.
1940’s • 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
1950’s • Anhydrous ammonia becomes available (greatly increased crop yields) • Screw worm eradicated by release of sterile male flies (first application of biotechnology in agriculture)
1960’s • 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
1970’s • High-yielding wheat varieties developed (increased ag exports & wheat acreage expansion) • Hog cholera eradicated (first successful elimination of disease in livestock)
1980’s • 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)
1990’s • 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)
2000’s • 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 corporations. • 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 U. S. ag product sales.
2000+ • In 2002, the average 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 percent increase from 1997. • In 2002, there were 7, 913 multiple race farmers in the United States.
2000+ More of the same (improvements in current technology) Digital animal identification Biofuel use in farming Intense water management E-Commerce 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 civilization.
Lesson 12. 3 Agriculture Traditional Agriculture • Agriculture “powered” by people and animals • Does not require fossil fuels • Practiced widely until the Industrial Revolution
Lesson 12. 3 Agriculture Industrial Agriculture • Agriculture that requires the use of fossil fuels • Involves mechanized farming technology, manufactured chemicals, and largescale irrigation • To be efficient, large areas are planted with a single crop in a monoculture. Did You Know? Today, more than 25% of the world’s croplands support 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 1900 s Benefits: • 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 Costs: • Led to a 7000% increase in energy used by agriculture • 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 Pollinators • Pollination is the process by which plants reproduce sexually. • 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. • Malnutrition and undernourishment are most common in the developing world. Kwashiorkor, a disease caused by protein deficiency. • Agriculture scientists and policymakers are working toward food security—the guarantee of an adequate food supply for all people 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 tolerance. • 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 insecticides. • Herbicide-resistant crops encourage tillage conservation.
Lesson 12. 4 Food Production Industrial Food Production: Feedlots • 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 stress
Lesson 12. 4 Food Production Industrial Food Production: Aquaculture • 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 (NH 3) Fish Wastes, Uneaten Feed Nitrosomonas Bacteria Nitrite (NO 2) Fish Feed Nitrobacter Bacteria Algae, Plants Nitrate (NO 3)
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 … • Nitrobacteria 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 strong. • Fish swim along and eat the plants, releasing ammonia as waste and • THE WHOLE CYCLE STARTS AGAIN!
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 1/10 th the fertilizer and 1/100 th the water of traditional systems • Outperforms traditional agriculture up to 30: 1
More about aquaponics: • It is a closed-loop ecosystem. • 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 plants • 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 2
Pretty great system, right? • An aquaponic system is nearly a total recycling program. • Plants feed fish. • Fish waste feeds bacteria. • 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 (NH 3) Fish Wastes, Uneaten Feed Nitrosomonas Bacteria Nitrite (NO 2) Fish Feed Nitrobacter Bacteria Algae, Plants Nitrate (NO 3)
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). Trunk Head Tail
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.
Surfaces: • Dorsal – upper surface • Ventral – lower or abdominal surface • Anterior – front or head • Posterior or caudal – tail or rear Dorsal Posterior or caudal Anterior Ventral
9 Body Systems: 1. Skeletal – rigid framework giving shape and protection 2. Muscular – provides internal and external movement 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. 7. 8. 9. Circulatory – distributes blood throughout the body Nervous – provides information and conveys impulses throughout the body Sensory – sight, touch, taste, small, sound 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 pharynx • 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 forms • 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 the use of fossil fuels and chemicals used for transportation and storage. Did You Know? Organic food purchases increased 200% from 1999 to 2008.