A.
Agricultural methods of Native Americans
B.
Irrigation techniques used by the Hopi
C.
Soil quality in the American Southwest
D.
Native American methods of storing emergency food supplies
正确答案:A
译文
In past centuries, Native Americans living in the arid areas of what is now the southwestern United States relied on a variety of strategies to ensure the success of their agriculture. First and foremost, water was the critical factor. The soil was rich because there was little rain to leach out the minerals, but the low precipitation caused its own problems. Long periods of drought could have made agriculture impossible; on the other hand, a sudden flood could just as easily have destroyed a crop.
Several techniques were developed to [#highlight2]solve[/highlight2]the water problem. The simplest was to plant crops in the :floodplains and wait for the annual floods to water the young crops. A less dangerous technique was to build dikes or dams to control the flooding. These dikes both protected the plants against excessive flooding and prevented the water from escaping too quickly once it had arrived. The Hopi people designed their fields in a checkerboard pattern, with many small dikes, each enclosing only one or two stalks of maize (com), while other groups built a series of dams to control the floods.
Another strategy Native Americans used to ensure a continuous food supply was to plant their crops in more than one place, hoping that if one crop failed, another would survive. However, since the soil was rich and not easily exhausted, the same patch of ground could be cultivated year after year, whereas in the woodlands of the eastern United States it was necessary to abandon a plot of ground after a few years of farming. In the Southwest, often two successive crops were planted each year.