VOA慢速英语 2008 1230a
时间：2018-11-27 作者：英语课 分类：VOA慢速英语2008年（十二）月
Alfalfa is sometimes grown on marginal land
We have a question from Jonah Ojowu in Benue State, Nigeria, about a subject we have discussed in the past. Jonah is a postgraduate 1 student in soil and water management at the University of Agriculture in Makurdi. He would like information about the management of marginal lands.
"Marginal" lands might have low quality soil. Or they might be on a hillside that rises sharply. Or they might be in an area that gets limited rainfall. In any case, they are the last to be planted under good conditions and the first to be avoided under bad conditions.
But there are uses for marginal lands. Most often they are used as grasslands 2 for cattle, sheep or goats. A farmer might use native grasses or non-native seed. Either way, it is important to establish good ground cover to avoid the loss of soil through erosion.
Forage 3 crops like clover and alfalfa could be planted. These members of the legume family provide high protein food for grazing animals. They also improve the quality of the soil.
Most plants use up nitrogen. Legumes put nitrogen back into the soil. Forage crops also help reduce erosion of the soil.
But using marginal land for grazing is not as simple as it might sound. Cattle can damage forage crops by eating down to the roots. Also, their weight crushes the soil. That can make the ground too hard for growing.
A way to reduce the damage from overgrazing is to move animals from one field to another. Experts say rotational 4 grazing like this is extremely important for marginal land. We will talk more about rotational grazing next week.
Another use for marginal land is for tree crops. Trees help support the soil. They reduce the damaging effects of wind and rain. And they can provide grazing animals with shade from the sun.
Studies have shown that the white pine and loblolly pine are two kinds of trees that grow well on marginal land. They grow fast and provide good quality wood. Another kind to consider is the poplar. And there are slower-growing trees like the black walnut 5 that provide a nut crop as well as wood.
Marginal lands need care. Failing to take that care might only make a bad situation worse. But good planning can turn a marginal resource into a highly productive one.
And that's the VOA Special English Agriculture Report, written by Mario Ritter. Archives are at voaspecialenglish.com, where you can also contact us with questions that we might be able to answer on our program. I'm Steve Ember.
- I didn't put down that I had postgraduate degree.我没有写上我有硕士学位。
- After college,Mary hopes to do postgraduate work in law school.大学毕业后， 玛丽想在法学院从事研究工作。
- Songs were heard ringing loud and clear over the grasslands. 草原上扬起清亮激越的歌声。 来自《现代汉英综合大词典》
- Grasslands have been broken and planted to wheat. 草原已经开垦出来，种上了小麦。 来自《简明英汉词典》
- They were forced to forage for clothing and fuel.他们不得不去寻找衣服和燃料。
- Now the nutritive value of the forage is reduced.此时牧草的营养价值也下降了。
- A synchronous motor drives the measuring bob at a constant rotational speed.同步马达驱动测锤以恒速旋转。
- With some limitations,this is true also of rotational degrees of freedom.在某些限定条件下，这一说法对转动自由度也成立。