Franklin Sheridan, age 13, of Butte, Mont., for his question:
HOW CAN WE PREVENT SOIL EROSION?
Erosion is the wearing away of parts of the earth's crust by water or wind. By the time rain water falls on soft ground and runs into a stream, it picks up lots of mud. Wind often drives dust and sand ahead of it, taking away large amounts of precious topsoil. Farmers, especially, have learned ways to protect their fields from the ravages of erosion. Scientists continue to work on ways to prevent it.
A thick growth of plants, such as grass or forest plants, helps to prevent both wind and water erosion by giving the soil a good covering. The roots and leaves of the plants slow up the flow of water. Steep hillsides, pastures and even wooded areas benefit from growing plant covers.
By adding humus to the soil, farmers have discovered that the land becomes much like a sponge. Wind and water erosion can be controlled if the soil sticks together, and it will if there's lots of humus.
Shaping of the ground is another way in which water erosion can be prevented. Often the water can be directed to areas where it will sink in, rather than run off. Digging a ditch around a slope is often one way to accomplish this.
Farmers use this same trick when they plow prior to planting. Instead of plowing up and down a hill, for example, they can plow around the hill. The plowed ditches, called furrows, then catch the water and give it a good chance to sink into the ground. Each row of plants then helps to check the water's runoff. This is called contour farming.
Strip farming is another way farmers help control erosion. Different kinds of crops are planted next to each other. One kind must make a thick covering over the ground. When water carries topsoil from one strip, it will deposit it in the next.
Terrace building is another good way to prevent erosion. Channels in huge steps keep rain and irrigation water from moving and causing damage.
Wind erosion is easy to prevent. But once it has started, it is almost impossible to stop if the weather stays dry.
Rows of thick, tall, strong plants make excellent windbreaks. Windbreaks slow up the force of the wind and are effective ways to fight soil erosion. On flat, large fields, 100 foot tall trees in a line are often put to work as windbreaks.
Wheat stubble and cornstalks are often left on a field all winter by the farmer because they make good windbreaks. They not only keep the wind away from the soil, but the roots also help to hold the soil in place.
The United States government has established soil conservation offices in many areas and experts are available to give the farmer valuable information and assistance on how to prevent erosion or how to establish routines to correct on going problems.