A、It is not meant to be harvested. B、It needs little fertilizer. C、It can keep the main crop warm. D、It can be harvested in off-

Agriculture experts have a message for farmers worldwide: Take care of your soil, and your soil will take care of you. By using the techniques of "conservation agriculture," they say farmers can save their land and save money at the same time. This is becoming more important as the world’s population grows. More people means more food needs to be grown to feed them. Most modem agriculture looks like long rows of green crops covering large areas of land. They have neat rows of single kinds of plants with uncovered soil in between. Trey Hill’s farm in the US state of Maryland does not look anything like that. Instead, there are green plants mixed in with what is left from other plants. Farmer Hill is going against farming practices that are thousands of years old—till the fields before planting and leave the soil bare in the off-season. And many farmers plant the same crop year after year. All three of these methods can wear out the soil, however. Some experts are backing the so-called conservation agriculture used by farmers like Hill. He plants his crops into what is left of the crop before—without tilling the soil. In the off-season he covers his fields with different crops. They hold onto the soil, and help prevent erosion, when water and wind remove soil. The cover crop is not meant to be harvested. Instead, it feeds the soil. Hill says, this kind of farming is more profitable. Less tilling means using less fuel for his farm equipment. He buys less fertilizer because his cover crops feed the soil.
Questions 9 to 11 are based on the passage you have just heard.
9. What do agriculture experts say about conservation agriculture?
10. What can we learn about traditional farming practices?
11. What can we learn about the cover crop?