Visualizing Environmental Science

Summary 369

3

Challenges of Agriculture 355

1. Prime farmland in the United States is being lost to
   urbanization and urban sprawl. Global declines in plant
   and animal varieties have led many countries to collect
   germplasm, plant and animal material that may be used in
   breeding. Farmers and ranchers strive to increase yields by
   administering hormones and antibiotics to livestock.

Summary

1

World Food Problems 350

1. Undernutrition is a health-threatening underconsumption
   of calories or nutrients that leaves the body weakened and
   susceptible to disease. Overnutrition is a health-threatening
   overconsumption of calories or nutrients.


2. Food insecurity, in which people live with chronic hunger, is
   exacerbated by population growth, environmental problems,
   and poverty.

2

The Principal Types of Agriculture 353

1. Industrialized agriculture uses modern methods requiring
   large capital input and less land and labor than traditional
   methods. Subsistence agriculture requires labor and a large
   amount of land to produce enough food to feed a family.


2. There are three types of subsistence agriculture. In shifting
   cultivation, short periods of cultivation are followed by
   longer periods of fallow. In nomadic herding, carried out
   on arid land, herders move livestock continually to find food
   for them. Intercropping involves simultaneously growing a
   variety of plants on the same field.

✓✓THE PLANNER

2. The green revolution introduced modern cultivation
   methods and high-yield crop varieties to Asia and Latin
   America. These methods require developing nations
   to import energy-intensive technologies and to face
   environmental problems caused by the use of inorganic
   fertilizers and pesticides.


3. Environmental problems caused by industrialized agriculture
   include air pollution from the use of fossil fuels and
   pesticides, water pollution from untreated animal wastes
   and agricultural chemicals, pesticide-contaminated foods
   and soils, and increased resistance of pests to pesticides.
   Land degradation decreases the future ability of the land to
   support crops or livestock. Clearing grasslands and forests
   and draining wetlands to grow crops have resulted in habitat
   fragmentation.

4

Solutions to Agricultural Problems 360

1. Sustainable agriculture uses methods that maintain
   soil productivity and a healthy ecological balance while
   minimizing long-term impacts.


2. Genetic engineering, the manipulation of genes to produce
   a particular trait, can produce more nutritious crops or crop
   plants that are resistant to pests, diseases, or drought.
   Concerns about genetic engineering include unknown
   environmental effects.

5

Controlling Agricultural Pests 364

1. A pesticide is any toxic chemical used to kill pests. Most
   pesticides are broad-spectrum pesticides that kill other
   organisms in addition to the intended pest.

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