Chapter 7 - Land and Water Use

Feeding a Growing Population

  • Certain factors are needed to feed a population adequately.
  • Human Nutritional Requirements   * A healthy diet requires 2500 calories for the average male and 2000 calories for the average female.   * Healthy diet requires a balanced intake of protein, carbohydrates, and fat.   * Only 100 known plant species meet the requirements for human nutritional needs.   * Just 8 species of animal protein supplies over 90% of the world’s needs.

Types of Agriculture

  • Cultivated land covers 9% of earth’s landmass and 14% of earth’s biomass.
  • Alley Cropping (Agroforestry)   * Method of planting crops in strips with rows of trees or shrubs on either side.
  • Conservation Tillage   * Leaves at least 30% of crop residue on the soil surface during the critical soil erosion period.
  • Contour Farming   * Farming with row patterns that run nearly level around the hill.
  • Crop Rotation   * Planting a field with different crops throughout the year to reduce soil nutrient depletion.
  • High-Input Agriculture   * Includes the use of mechanized equipment, chemical fertilizers, and pesticides.
  • Industrial Agriculture or Corporate Farming   * A system characterized by high-input agriculture that is focused on maximizing productivity and profitability.
  • Intercropping   * To grow more than 1 crop in the same field.
  • Interplanting   * Growing two different crops in the same area at the same time.
  • Locally grown-Farmers’ Markets   * Farmers’ markets feature foods sold by farmers directly to consumers.
  • Low-Input   * Depends on hand tools and natural fertilizers
  • Monoculture   * The cultivation of a single crop
  • No Till   * Inject seeds into slits or holes in the soil by a machine to minimize soil disturbance.
  • Organic Farming   * A form of agriculture that relies on crop rotation, green manure, compost, biological pest control, and mechanical cultivation to maintain soil productivity and control pests.
  • Polyculture   * Uses different crops in the same space, in imitation of diversity of natural ecosystems.
  • Subsistence   * Agriculture carried out for survival. Usually organic.
  • Terracing   * Graduated terrace steps used to farm on hilly or mountainous terrain.
  • Tillage   * Conventional method in which the surface is plowed which breaks up and exposes the soil.

Agricultural Productivity

  • Implies greater output with less input.
  • Increases in productivity are linked with pollution, issues of sustainability, safety, and demand for resources.
  • Fertilizer   * Provide plants with nutrients needed to grow healthy and strong.   * Inorganic Fertilizer     * Fertilizer mined from mineral deposits and manufactured from synthetic compounds.     * Chemical fertilizers contain salts that plant roots absorb quickly, but don't provide a food source for microorganisms or earthworms.   * Organic Fertilizer     * Fertilizer that originates from an organic source.     * Improves the quality of the soil.
  • Genetically Modified Crops   * A recent study concluded that GM Crops have reduced chemical pesticides usage by 37%, increased crop yields by 22%, and increased farmer profit by 68%.

Sustainable Agriculture

  • Emphasize production and food systems that are profitable, environmentally sound, and energy efficient.
  • The Agricultural and Green Revolutions
  • First Agricultural Revolution   * First wide-scale transition of many human cultures from hunting and gathering to agriculture and settlement.
  • Second Agricultural Revolution   * Coincided with the Industrial Revolution that occurred in England.   * It moved agriculture to generate the surpluses needed to feed thousands of people working in factories.
  • First Green Revolution   * Involved planting monocultures, using high applications of inorganic fertilizers and pesticides and the widespread use of artificial irrigation systems.
  • Second Green Revolution   * Involved genetically engineered crops that produce the most yields per acre.

Controlling Pests

  • Types of Pesticides   * Biological     * Living organisms to deal with pests. Examples include bacteria, ladybugs, milky spore disease, parasitic wasps, and certain viruses.   * Carbamates     * Affect the nervous system of pests.     * Carbamates have a higher risk of being dissolved in surface water.   * Chlorinated Hydrocarbons and other persistent organic compounds     * Chlorinated hydrocarbons are synthetic organic compounds that belong to a group of chemicals known as persistent organic pollutants (POPS).   * Fumigants     * Used to sterilize soil and prevent pest infestation of stored grain.   * Inorganic     * Broad-based pesticides that include arsenic, copper, lead and mercury.   * Organic or Natural     * Natural poisons derived from plants.   * Organophosphates     * Extremely toxic but remain in the environment for only a brief time.
  • Costs and Benefits of Pesticide Use   * Pros     * Kill Unwanted pests     * Increase the food supply     * Food is less expensive     * Reduce labor costs     * Agriculture is more profitable   * Cons     * Can accumulate in food chains     * Pests develop resistance     * Pesticides are expensive to purchase and apply     * Pesticide runoff and it affects aquatic environments.     * Inefficient