VOA慢速英语2014 建造保护作物的防风林（在线收听）

Building a Windbreak to Protect Crops  建造保护作物的防风林

This is the VOA Special English Agriculture Report.

这里是美国之音慢速英语农业报道。

Soil conservation methods help farmers protect their land from the damage caused by farming and the forces of nature. One method of soil conservation is the use of windbreaks. Windbreaks are barriers formed by trees and other plants. Farmers plant these barriers around their fields.

土壤养护方法可帮助农民保护土地不受农作和自然力量的破坏，土壤保护的一个办法就是使用防风林，防风林是由树木和其他作物做成的障碍，农民在农田周围种上这些障碍物。

They stop the wind from blowing soil away. They also keep the wind from damaging or destroying crops.

防风林可防止土壤流失，不让风吹走土壤，还能使作物免受风的损坏或破坏。

Windbreaks can be highly valuable for protecting grain crops. For example, studies have been done on windbreaks in parts of West Africa. These studies found that grain harvests were as much as twenty percent higher in fields protected by windbreaks compared to fields without them.

防风林对保护谷物作物来说很有作用，比如，西非部分地区已经对防风林做了研究。研究发现，与那些没有防风林保护的农田相比，那么有保护的农田谷物产量能提高20%。

But here is something interesting about windbreaks. They seem to work best when they allow some wind to pass through the barrier of trees or plants around a field. If not, then the movement of air close to the ground will lift the soil. Then the soil will be blown away.

防风林还有其他有趣的地方，当防风林允许部分风穿过树木或作物的障碍时，它们起的作用最好。否则，土壤附近空气的运动会掀起土壤，这样土壤就会被吹走。

For this reason, a windbreak works best if it contains only sixty to eighty percent of the trees and plants that would be 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.

因此，包含60%到80%的树木或作物组成的防风林能形成坚固的防线，一条容易记住的法则是，防风林能保护的面积相当于防风林树木高度的10倍。

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 or other plants with leaves. Locally grown trees and plants are considered the best choices for windbreaks.

每个防风林至少应该包含两条防线，一个是大树，第二个紧挨着的是低矮些的有叶子的树。当地长的树木和作物最适合做防风林。

Studies have shown that some kinds of trees can grow well even if the quality of the land is not very good. One kind of tree is the white pine. Another is the loblolly pine.

研究表明，即使土壤质量不是很好，有些种类的树木仍能长得很好。一种是白松，一种是厚皮刺果松。

Windbreaks not only protect land and crops from the wind. Surplus trees can be cut down and used or sold for wood.

防风林不仅能保护土地和作物免受风的破坏，额外的树木应该砍下来使用或出售。

Trees reduce the damaging effects of wind and rain. Their roots help protect soil from being washed away. And trees can provide another valuable service for agriculture. They can provide grazing animals with shade from the sun.

树木能减少风和雨带来的破坏，树木的根能保护土壤免于流失。树木还能为农业提供其他更有价值的作用，能给放牧牲畜提供遮阴处。

And that's the VOA Special English Agriculture Report. 

这里是美国之音慢速英语农业报道。