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The Habitable Planet: A Systems Approach to Environmental Science 


Demographers project that Earth's population will peak during the 21st century at approximately ten billion people. But the amount of new cultivable land that can be brought under production is limited. In many nations, the need to feed a growing population is spurring an intensification of agriculture—finding ways to grow higher yields of food, fuel, and fiber from a given amount of land, water, and labor. This unit describes the physical and environmental factors that limit crop growth and discusses ways of minimizing agriculture's extensive environmental impacts.

Interactive Labs

Ecology Lab (Units 4, 7, 9, 13)

As you learned in Unit 4, ecosystems are a complex and delicate balancing game. The addition or removal of any species affects many other species that might compete for or provide food. In this lab you will get a chance to “build your own” ecosystem, and explore the effects of these interrelationships.launch lab


Unit 7: Agriculture // Glossary

A diesel-equivalent, processed fuel derived from biological sources (such as vegetable oils), that can be used in unmodified diesel-engine vehicles.

Derived from biomass — recently living organisms or their metabolic byproducts, such as manure from cows.

A flammable, colorless, slightly toxic chemical compound with a distinctive perfume-like odor. Also known as ethyl alcohol, drinking alcohol, or grain alcohol, in common usage it is often referred to simply as alcohol.

harvest index
The ratio of grain weight to total plant weight.

integrated pest management (IPM)
The use of a combination of the following to limit pest damage to agricultural crops: (1) agricultural practices (2) biological control agents (3) introduction of large numbers of sterile male insects (4) timed application of synthetic chemical pesticides and (5) application of pheromones and juvenile hormones.

The growing of a single plant species over a large area.

organic agriculture/farming
A form of agriculture which avoids or largely excludes the use of synthetic fertilizers and pesticides, plant growth regulators, and livestock feed additives.

An organic compound containing at least one covalently bonded chlorine atom.

A process in green plants and some bacteria during which light energy is absorbed by chorophyll-containing molecules and converted to chemical energy (the light reaction). During the process, carbon dioxide is reduced and combined with other chemical elements to provide the organic intermediates that form plant biomass (the dark reaction). Green plants release molecular oxygen (02), which they derive from water during the light reaction.

selective breeding
The process of developing a cultivated breed over time.

Tiny openings or pores, found mostly on the under-surface (epidermis) of a plant leaf, and used for gas exchange.

The evaporation of water from aerial parts of plants, especially leaves but also stems, flowers, and fruits.

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Series Directory

The Habitable Planet: A Systems Approach to Environmental Science 


Harvard Smithsonian Center for Astrophysics in association with the Harvard University Center for the Environment. 2007.
  • Closed Captioning
  • ISBN: 1-57680-883-1