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From VOA Learning English, |
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this is the Agriculture Report. |
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Soil conservation methods help farmers |
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protect their land from the damage |
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caused by farming and the forces of nature. |
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One method of soil conservation |
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is the use of windbreaks. |
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Windbreaks are barriers formed by trees and other plants. |
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Farmers plant these barriers around their fields. |
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(SOUND) |
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Windbreaks help prevent the loss of soil. |
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They stop the wind from blowing soil away. |
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They also keep the wind from damaging or destroying crops. |
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Windbreaks can be highly valuable for protecting grain crops. |
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For example, studies have been done on windbreaks |
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in parts of West Africa. |
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These studies found that grain harvests |
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were as much as twenty percent higher in fields protected |
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by windbreaks compared to fields without them. |
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But here is something interesting about windbreaks. |
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They seem to work best when they allow some wind to pass |
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through the barrier of trees or plants around a field. |
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If not, then the movement of air |
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close to the ground will lift the soil. |
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Then the soil will be blown away. |
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For this reason, a windbreak works best |
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if it contains only sixty to eighty percent of the trees |
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and plants that would be needed to make a solid line. |
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An easy rule to remember is that windbreaks |
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can protect areas up to ten times |
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the height of the tallest trees in the windbreak. |
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There should be at least two lines in each windbreak. |
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One line should be large trees. |
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The second line, right next to it, |
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can be shorter trees and other plants with leaves. |
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Locally grown trees and plants |
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are considered the best choices for windbreaks. |
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Studies have shown that some kinds of trees can grow well |
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even if the quality of the land is not very good. |
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One kind of tree is the white pine. |
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Another is the loblolly pine. |
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Windbreaks not only protect land and crops from the wind. |
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Surplus trees can be cut down and used or sold for wood. |
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(SOUND) |
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Trees reduce the damaging effects of wind and rain. |
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Their roots help protect soil from being washed away. |
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And trees can provide another valuable service for agriculture. |
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They can provide grazing animals with shade from the sun. |
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And that's the Agriculture Report from VOA Special English. |
