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Building a Windbreak to Protect Crops

andyg 于2007-08-19发布 l 已有人浏览
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&raquo Download Audio(mp3) By Gary Garriott 2007-8-19 This is the VOA Special English Development Repor

» download audio(mp3)
by gary garriott
2007-8-19

this is the voa special english development report.

a windbreak of trees

farmers use different kinds of soil conservation methods to protect their land from damage by farming and the forces of nature. one important form of soil conservation is the use of windbreaks.

windbreaks are barriers formed by trees and other plants with many leaves. farmers plant them in lines around their fields.

windbreaks stop the wind from blowing soil away. they also keep the wind from destroying or damaging crops. they are very important for growing grains, such as wheat.

there have been studies done on windbreaks in parts of west africa, for example. these found that grain harvests can be twenty percent higher in fields protected by windbreaks compared to fields without such protection.

however, windbreaks seem to work best when they allow a little wind to pass through. if the wall of trees and plants stops wind completely, then violent air motions will take place close to the ground. these motions will lift soil into the air where it will be blown away.

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