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Chapter 15-Food and Agriculture

Chapter 15-Food and Agriculture. Feeding the World. Humans and Nutrition. Famine - Widespread starvation (Ex: Ethiopia) Food for energy (calories) and as building material for body tissue

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Chapter 15-Food and Agriculture

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  1. Chapter 15-Food and Agriculture Feeding the World

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

  3. Famine

  4. Major Nutrients in Human Foods

  5. Sources of Nutrition • Diet- the type and amount of foods eaten • Balanced diet = HEALTHY

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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; can’t afford machinery/chemicals

  11. Chapter 15- Food and Agriculture Section 2- Crops and Soil

  12. 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

  13. 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 Agriculture

  14. Traditional Vs. Modern

  15. 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

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

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

  18. 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

  19. Sahel, N. Africa

  20. 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

  21. 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

  22. Compost

  23. 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

  24. 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

  25. Agricultural Pests

  26. 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 Pesticides

  27. The use of living organisms to control pests India tried 1st; 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 Biological Pest Control

  28. 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 Pest Management

  29. 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

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

  31. Chapter 15- Food and Agriculture Section 3- Animals and Agriculture

  32. 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

  33. 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

  34. 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 Aquaculture

  35. Aquaculture

  36. 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

  37. 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

  38. 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

  39. Poultry

  40. Poultry • 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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