VOA慢速英语 2008 0121a

This VOA Special English Development Report.

 
A windbreak of trees
Farmers use different kinds of soil conservation methods to protect their land against damage from 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. Studies in parts of West Africa, for example, found that grain harvests can be twenty percent higher in fields protected by windbreaks. This was compared to fields without such protection. 

Windbreaks can help protect a farmer's land. However, windbreaks seem to work best when they allow a little wind to pass through. If the wall of trees and plants blocks the wind completely, then violent air motions¹ will take place close to the ground. These motions cause the soil to lift up into the air where it will be blown away.

For this reason, a windbreak is best if it has only sixty to eighty percent of the trees and plants needed to make a solid line.

An easy rule to remember is that windbreaks can protect areas up to ten times the height of the tallest trees in the windbreak.

There should be at least two lines in each windbreak. One line should be large trees. The second line, right next to it, can be shorter trees and other plants with leaves. Locally grown trees and plants are best for windbreaks.

Windbreaks not only protect land and crops from the wind. They can also provide wood products. These include wood for fuel and longer pieces for making fences.

You can get more information about windbreaks and other forms of soil conservation from the group EnterpriseWorks/VITA. Its address on the Web is enterpriseworks.org. 

And that's the VOA Special English Development Report. Internet users² can find transcripts³ and MP3s of our reports at voaspecialenglish.com. If you have a question, send it to [email protected], and please include your name and country. We cannot answer questions personally but we might be able to answer your question on the air.

 

1 motions   

n.（物体的）运动( motion的名词复数 )；提议；通便

参考例句：

• She just went through the motions of being a poetess. 她只不过装成一个女诗人。 来自《简明英汉词典》
• He always accompanied his speech with motions. 他讲演时总是伴以手势。 来自《简明英汉词典》

2 users   

用户，使用者( user的名词复数 )

参考例句：

• The new software will prove a boon to Internet users. 这种新软件将会对互联网用户大有益处。
• Ramps should be provided for wheelchair users. 应该给轮椅使用者提供坡道。

3 transcripts   

n.抄本（ transcript的名词复数 ）；转写本；文字本；副本

参考例句：

• Like mRNA, both tRNA and rRNA are transcripts of chromosomal DNA. tRNA及rRNA同mRNA一样，都是染色体DNA的转录产物。 来自辞典例句
• You can't take the transfer students'exam without your transcripts. 没有成绩证明书，你就不能参加转学考试。 来自辞典例句