| A | B |
|---|
| deforestation | cutting down forests |
| erosion | the carrying away of soil by wind and water, leaving the land less fertile |
| irrigation | collecting and bringing water to crops |
| crop rotation | changing the type of plants in a field to avoid using up the minerals in the soil |
| ecosystem | place where the plants and animals depend on one another and their surroundings for survival |
| pesticide | powerful chemical that kills crop destroying insects |
| conservation | careful use of resources so they are not wasted |
| desalination | removing salt from seawater |
| refugee | person who flees to another country to escape persecution or disaster |
| population density | average number of people living in a square mile or square kilometer |
| natural resource | product of the earth that people use to met their needs |
| renewable resource | resource that cannot be used up or can be replaced |
| nonrenewable resource | resource that cannot be replaced once it is used up |
| export | to sell goods to another country |
| import | to buy goods from another country |
| tariff | tax added to imported goods |
| quota | limit placed on the amount of a product that can be imported from another country |
| free trade | trade that flows freely among countries without trade barriers |
| developed country | country that has a great deal of manufacturing |
| developing country | country that is working toward industrialization |
