9781422282892

13

Science and Energy

SCIENCE AND Agriculture

1

Words to Understand antimicrobial  describing a substance that kills or limits the growth microorganisms ecosystem  a collection of all living things in a particular environment glucose  sugar in plants that is used as food for energy pathogens  something, such as a virus or a bacterium, that can cause a disease

S ome agricultural scientists spend their days studying farm animals, crops, or diseases. Others want to know how insects and weather conditions affect the growth of plants. Still others work to develop new mechanical tools to make farming easier.

Tim McAllister studies cow dung.

Specifically, McAllister, a research scientist in Canada, is inter- ested in finding the best ways to control bacteria that live in the animal’s poop. A single cow can expel up to 120 pounds (54 kg) of manure a day. Farmers often use the animal waste as an inex-