久久亚洲国产成人影院-久久亚洲国产的中文-久久亚洲国产高清-久久亚洲国产精品-亚洲图片偷拍自拍-亚洲图色视频

您現在的位置: > Language Tips > Audio & Video > Special Speed News  
 





  Building a windbreak to protect crops
[ 2006-05-10 08:56 ]

This is Shep O'Neal with the VOA Special English Agriculture Report.

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 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 60 to 80 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 Volunteers in Technical Assistance. VITA, now part of EnterpriseWorks/VITA, is on the Web at vita.org.

Internet users can read and listen to our Agriculture Reports at voaspecialenglish dot com. And if you have a question, send it to special@voanews.com. Make sure to include your name and tell us where you are from. We might be able to answer your question on the air, but please know that we cannot answer questions personally.

This VOA Special Agriculture Report was written by Gary Garriott. I'm Shep O'Neal.


windbreak : 防風林

 
 
 




主站蜘蛛池模板: 亚洲欧美另类自拍第一页 | 午夜综合网| 欧美在线一区二区三区不卡 | 欧美精品亚洲精品日韩一区 | 欧美在线综合 | 超级碰碰碰在线观看 | 中国精品自拍 | 九九视频在线 | 日韩在线观看一区二区三区 | 成 人 黄 色 大 片 | 色九九 | 美女的被男人桶爽网站 | 久草视频在线资源站 | 久草视频精品在线 | 香蕉久久夜色精品国产2020 | 一级做a爰片性色毛片视频图片 | 久草福利在线观看 | 一级成人a免费视频 | 99久久精品国产免费 | 午夜成人免费影院 | 另类欧美视频 | 国产综合视频在线观看一区 | 日韩高清在线二区 | 亚洲欧美日韩久久精品第一区 | 视频在线一区二区三区 | 国产99久久精品 | 亚洲欧美另类日本久久影院 | 成在线人视频免费视频 | 亚洲国产精品日韩高清秒播 | 国产男女爽爽爽爽爽免费视频 | 欧美aaaaaabbbbb | 武松大战潘金莲三级在线 | 国产一久久香蕉国产线看观看 | 国产99高清一区二区 | 亚洲欧美日韩精品久久亚洲区色播 | 成人网18免费网 | 免费观看日本视频 | 性午夜| 精品久久成人 | 全部aⅴ极品视觉盛宴精品 全部免费a级毛片 | 波多野一区二区三区在线 |