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Chapter 15-Food and Agriculture Feeding the World.

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Presentation on theme: "Chapter 15-Food and Agriculture Feeding the World."— Presentation transcript:

1 Chapter 15-Food and Agriculture Feeding the World

2 Humans and Nutrition Famine Famine- Widespread starvation (Ex: Ethiopia) Food for energy (calories) and as building material for body tissue Malnutrition Malnutrition- When the body does not have enough Calories (1 kilocalorie) or variety of foods to fulfill needs Amino acid deficiency –Ex: Amino acid deficiency

3 Famine


5 Major Nutrients in Human Foods

6 Sources of Nutrition Diet- the type and amount of foods eaten Balanced diet = HEALTHY

7 Diets Around the World Vary by region Developed nations= more foods (high in proteins and fats U.S. - almost 1/2 Calories from meat, fish, and oils

8 The Ecology of Food Farmland replaces natural ecosystems Food efficiency- quantity produced on a given area of land w/ limited inputs of energy and resources –More energy and resources required for animals –Meat - more nutrients per gram

9 The Ecology of Food Yield- amount of food produced in a given area Researchers interested in organisms that can survive in various climates w/out chemicals and large amounts of water

10 World Food Problems Food production not increasing fast enough with human pop. growth Malnutrition result of poverty, war and political strife (transportation problems) Drought- prolonged period during which rainfall is below average –No irrigation –Seeds not available –Soil degradation

11 The Green Revolution Worldwide crop yield increases ;new variety and techniques B/w 1950 and 1970, Mexican wheat up eight- fold; India doubled rice Neg. effects: large amts of water, chemicals, and machinery; crop decline- degradation and overuse –Subsistence farmers- grow only enough food for local use; cant afford machinery/chemicals


13 Chapter 15- Food and Agriculture Section 2- Crops and Soil

14 Agriculture Arable land- land that can be used to grow crops –Plowing- mixes nutrients loosens soil particles, and uproot weeds –Fertilizers- enrich soil with nutrients for better health and growth of plants Irrigation- bringing in water for crops –Chemicals used to kill pests

15 Agriculture Traditional –Farmer or animal pulled plow –Manure used as fertilizer –Weeds removed by hand –Water flowed through ditches Modern –Machine plows –Synthetic chemical fertilizers –Weeds removed by machines –Overhead sprinkler and drip systems

16 Traditional Vs. Modern

17 Fertile Soil: The Living Earth Fertile soil can support the growth of healthy plants. –Topsoil- Organically rich surface layer Living organisms, rock particles, water, air, and organic material (decomposing) –Soil forms from rocks broken into smaller fragments by water, wind, and chemical weathering (rock minerals react to form new chemicals) Temperature changes allow for rocks to crack and break 1000s of years for centimeters of soil

18 Soil Composition Surface Litter Topsoil Zone of Leaching Subsoil Rock Particles Bedrock

19 Soil Erosion Wearing away of rocks or soil by wind and water –Half of original US topsoil lost in last 200 years –Farming increases

20 Land Degradation Human activity or natural processes damage the land to the point of being inable to support the ecosystem. Desertification- Land in which arid or semiarid areas become more desert-like because of human activity or climatic changes. –Ex: Sahel, N. Africa used to plant crops and allow land to lie fallow for a few years to replenish; Increase in pop. caused fallow periods to be shorter or none at all. Large areas can not support crops anymore and have desertified

21 Sahel, N. Africa

22 Soil Conservation Soil erodes downhill- soil-retaining terraces Contour plowing on gentler slopes No-till farming- Harvest a crop without turning soil so remains hold soil in place –Leaves soil packed causing lower crop yields

23 Enriching the Soil Organic matter such as manure and leaves was traditionally added Inorganic fertilizers have doubled food production in 50 years –Nitrogen, Phosphorous, Potassium –Erosion pollutes waterways with these Modern way is combining inorganic fertilizers and compost (partly decomposed organic material) –Some garbage can form compost

24 Compost

25 Salinization The accumulation of salts in the soil –CA and AZ –Irrigation from river or groundwater; saltier than rain Raises groundwater levels Evaporation leaves salts behind Prevent by lining irrigation canals or water heavily

26 Pest Control Insects eat 13% of crops in N. America –Tropical areas worse –33% worldwide Pest- any organism that occurs where it is not wanted or occurs in large enough numbers that it causes ecological damage Wild plants naturally protected

27 Agricultural Pests

28 Pesticides Chemicals used to kill insects, weeds, and other crop pests Can harm beneficial wildlife, plants, insects, and people Pests can evolve a resistance after prolonged use –500 species worldwide Cancer rates and nervous disorders are higher in agricultural areas that use pesticides as well as factories that produce them Persistent- Does not break down quickly or easily –Accumulates in water and soil –Biomagnification Ex: DDT and Bald Eagle

29 Biological Pest Control The use of living organisms to control pests –India tried 1 st ; prickly pear cactus and American beetle Pathogens- organisms that cause disease – Bacillus thuringiensis (Bt) kills caterpillars Plant defenses- plants bred for chemical compounds and physical barriers –VNT resistant to certain pests Defensive chemicals from plants used –In-home sprays –Less harmful –Biodegradable

30 Pest Management Disrupting insect breeding –Growth regulators Chemicals interfere with some stage of life cycle Ex: Monthly flea meds –Pheromones Chemicals produced by one organisms to affect the behavior of another Used to confuse insects –Can also make insects sterile with x-rays or chemicals Integrated Pest Management –Modern method of controlling crop pests –Reduce pests without elimination –Different program for each pest –Biological method first –Cultivation second –Insecticides last

31 Engineering a Better Crop Traditional: Save seeds from best plants with fewest pests Modern: Genetic Engineering- genetic material in living cell is modified for medical or industrial use –Can isolate genes from one organism and implant in another –Genetically modified plants (GM) –Ex: inserting a bacterium insecticide gene –Problems: Products not fully tested Genes transferred to wild plants


33 Sustainable Agriculture Low-input farming –Minimizes use of energy, water, pesticides, and fertilizers –Planting productive, pest- resistant crops

34 Chapter 15- Food and Agriculture Section 3- Animals and Agriculture

35 Domesticated Animals Less energy required to raise animals Basis for protein in diet Domesticated- Bred and managed for human use –About 50 animal species –Chicken, sheep, cattle, honey bees, silkworms, fish, and shellfish –Goats, pigs, and buffalo

36 Food from Water Fish are important food source Overharvesting- catching or removing more organisms than a population can replace –No-fishing zones improve after a few years Necessary for fish markets to prosper

37 Aquaculture The raising of aquatic organisms for human use or consumption –Began in China 4,000 yrs ago –Catfish, oysters, salmon, crayfish and rainbow trout –23% of seafood –20% of protein from fish and other aquatic organisms Ranch- raise fish to release –Fish return to birthplace to breed –Captured, bred and re- released Fish farms have many small ponds with circulating water Can create waste/pollution, deplete local water supply Few cases damaged sensitive wetlands

38 Aquaculture

39 Livestock Domesticated animals that are raised to be used on a farm or to be sold for profit –Used for leather, wool, eggs, meat, draft animals to pull equipment and manure

40 Ruminants Cattle, sheep, and goats Cud-chewing with 3 to 4 chambered stomachs Cud- Regurgitated food that is rechewed to increase digestion Special microorganisms allow digestion of plant materials Common in N. America, India, and Africa for meat, milk, blood, dung and work power


42 Poultry Domesticated birds raised for meat and eggs; good source of amino acids Chicken production increased more than any other livestock since 1961 Farms are cramped, artificial environment

43 Poultry

44 Ducks and geese –Integrated system in China Meat Droppings fertilize rice paddies Irrigation of mulberry trees, home of silkworms, occurs from ponds Plant materials and filtered sewage dumped as food for carp and other fish

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