Special English 又叫“慢速英语”，是VOA 专为全世界非英语国家初学英语的听众安排的一种简易、规范的英语广播节目。该节目创始于50年代末期，是VOA 的专家们研究如何与世界各地的英语学习者进行交际的产物。它正式开播于1959年10月。当时只面向欧洲和中东，但由于这个节目适合许多国家英语学习者的需要，所以它的广播对象不久就扩大到世界其他地区，并很快在全世界范围内产生了广泛的影响。现在这个节目对欧洲、非洲和拉丁美洲每晚广播一次，对加勒比地区每晚广播一次（星期天除外），对东南亚广播次数最多，每天上午两次，晚上三次。
　　30多年来，VOA 为了办好Special English节目，进行了大量的调查研究工作，对播音速度、内容及用词范围都作了具体规定，基本上达到了既能为英语学习者提供信息，又不损害英语本身风格的目的，使之成为VOA 独具特色，拥有最大量听众的节目。
　

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2008.07.29

Building a Windbreak to Protect Crops

By Jim Tedder / Broadcast date: Tuesday, July 29, 2008

　　This is the VOA Special English Agriculture Report.

A windbreak　　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. Farmers plant these barriers 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 protecting grain crops.

　　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.

　　But windbreaks seem to work best when they allow some winds to pass through them. If the wall of trees and plants blocks the 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.

　　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.

　　If the quality of the land is not very good, studies have shown that one kind of tree that can grow well is the white pine. Another is the loblolly pine.

　　Windbreaks not only protect land and crops from the wind. Surplus trees can be cut down and used to provide wood.

　　Trees reduce the damaging effects of wind and rain. Their roots help protect soil from being washed away. And trees do something else —— they can provide grazing animals with shade from the sun.

　　And that's the VOA Special Agriculture Report. You can get more information about windbreaks and other forms of soil conservation at enterpriseworks.org. And you can also learn more about agriculture at our Web site, www.voaspecialenglish.com. I'm Jim Tedder.