Passage One

It's early August and the countryside appears peaceful. Planting has long been finished and the fields are alive with strong, healthy crops. Soybeans and wheat are flourishing under the hot summer sun, and the corn, which was "knee-high by the fourth of July", is now well over six feet tall. Herds of dairy and beef cattle are grazing peacefully in rolling pastures which surround big, ted barns and neat, white farmhouses. [Everything as far as the eye can see radiates a sense of prosperity.]Welcome to the Midwest-one of the most fertile agricultural regions of the world.

The tranquility of the above scene is misleading. Farmers in the Midwest put in some of the longest workdays of any profession in the United States. In addition caring for their crops and livestock, they have to keep up with new farming techniques, such as those for combining soil erosion and increasing livestock production. It is essential that farmers adopt these advances in technology if they, want to continue to meet the growing demands of a hungry world.

Agriculture is the number one industry in the United States and agricultural products are the country's leading export. American farmers manage to feed not only the total population of the United States, but also millions of other people throughout the rest of the world. Corn and soybean exports alone account forapproximately 75 percent of the amount sold in world markets.

This productivity, however, has its price. Intensive cultivation exposes the earth to the damaging forces of nature. Every year wind and water remove tons of rich soil from the nation's croplands, with the result that soil erosion has become a national problem concerning everyone from the farmer to the consumer.

Each field is covered by a limited amount of topsoil, the upper layer of earth which is richest in the nutrient and minerals necessary for growing crops. Eversince the first farmers arrived in the Midwest almost 200 years ago, cultivation and,consequently, erosion have been depleting the supply of topsoil. In the 1830s,nearly two feet of rich, black top soil covered the Midwest. Today the average depth is only eight inches, and every decade another inch is blown or washed away.This erosion is steadily decreasing the productivity of valuable cropland. A United States Agricultural Department survey states that if erosion continues at its present rate, corn and soybean yields in the Midwest may drop as much as 30 percent overthe next 50 years.

Questions 1-5 are based on Passage One.

The underlined sentence in Para. 1 implies that ____.