By Inc. Encyclopaedia Britannica
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The surface of the Earth is constantly changing; mountains are lifted up, and streams begin to erode them away; valleys are cut deeper by rivers, and coastlines change with the action of the oceans. While certain aspects of erosion are actually helpful—it is through erosion processes that soils are formed—some types of erosion can be very damaging to the land. Soil erosion caused by human activity is The history of american farming one of the most destructive erosional forces. Because artificially created erosion can happen much more quickly than natural geologic erosion, it is sometimes referred to as accelerated erosion.
The endless movement and recycling of water between the atmosphere, the land’s surface, and underground is called the water cycle, or the hydrologic cycle. Two separate forces make the water cycle work. The energy of the sun and the force of the Earth’s gravity drive it. Water vapor is carried through the atmosphere by air currents. When the air cools, it condenses, forming clouds. Some of the moisture falls back to Earth as rain, snow, hail, or sleet. 41 42 agriculture Once the water reaches the ground, it can go in several directions before it returns again to the atmosphere.
Weeds know no boundaries. They are invading government- managed public land, farms, forests, parks, and private lands. Millions of Facts About American Agriculture • • • • • • • The food and fiber industry accounts for 20% of America’s production and employs 20% of our population. Agriculture is the United States’ biggest employer. More than 21 million people have a job that is related to agriculture and the food industry. One farmer can feed 129 people. Americans spend roughly $2,328 each year on food for each person.