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 Malnutrition- When the body does not have enough Calories (1 kilocalorie) or variety of foods to fulfill needs Ex: Amino acid deficiency

Famine

Major Nutrients in Human Foods

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

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

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

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

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

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

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

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

Agriculture Traditional Modern 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

Traditional Vs. Modern

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

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

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

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

Sahel, N. Africa

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

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

Compost

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

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

Agricultural Pests

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

Biological Pest Control 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

Pest Management Integrated 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

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

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

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

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

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

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

Aquaculture

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

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

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

Poultry

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