The damage to crops caused by rodents, weeds, and insects can be reduced by using poisons, but their use may harm other plants or animals as well, and pests tend to develop resistance to poisons.
Heating, salting, smoking, drying, cooling, and airtight packaging are ways to slow down the spoiling of food by microscopic organisms. These methods make it possible for food to be stored for long intervals before being used.
Modern technology has increased the efficiency of agriculture so that fewer people are needed to work on farms than ever before.
Places too cold or dry to grow certain crops can obtain food from places with more suitable climates. Much of the food eaten by Americans comes from other parts of the country and other places in the world.
By the end of the 8th grade, students should know that:
Early in human history, there was an agricultural revolution in which people changed from hunting and gathering to farming. This allowed changes in the division of labor between men and women and between children and adults, and the development of new patterns of government.
People control the characteristics of plants and animals they raise by selective breeding and by preserving varieties of seeds (old and new) to use if growing conditions change.
In agriculture, as in all technologies, there are always trade-offs to be made. Getting food from many different places makes people less dependent on weather in any one place, yet more dependent on transportation and communication among far-flung markets. Specializing in one crop may risk disaster if changes in weather or increases in pest populations wipe out the crop. Also, the soil may be exhausted of some nutrients, which can be replenished by rotating the right crops.
Many people work to bring food, fiber, and fuel to U.S. markets. With improved technology, only a small fraction of workers in the U.S. actually plant and harvest the products that people use. Most workers are engaged in processing, packaging, transporting, and selling what is produced.