VOA慢速英语 2007 0306a（在线收听）

This is the VOA Special English Agriculture Report.

To call something marginal means it is not very good. Farmers have their own way to define marginal land: It is the last to be planted under good conditions, and the first to be avoided under poor conditions.

Low quality soil is not the only reason land could be considered marginal. It might be in an area where rainfall is limited. Or a hillside might rise too steeply.

There are uses for marginal land, however. Most often it is used as grassland. Grasses provide excellent feed for grazing animals like cattle, sheep and goats.

Grass seed can be bought from a supplier. Or native grasses can be used. But it is important to establish good ground cover to avoid soil loss through erosion.

Forage crops like clover and alfalfa can 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. But legumes put nitrogen back into the soil. Forage crops also help limit erosion.

However, using marginal land for grazing is not a simple issue. There is a risk of overgrazing. Cattle can damage forage crops by eating down to the roots. Also, the weight of the animals crushes the soil and can make it too hard for growing.

A way to reduce the harm is to move animals from one field to another. This method is known as rotational grazing. Experts say rotational grazing is extremely important for marginal land.

Another use for marginal land is for tree crops. Studies have shown that the white pine and loblolly pine are two kinds of trees that grow well on such land. They grow fast and provide good quality wood. Another tree is the poplar, found in many parts of the world. Slower-growing trees like the black walnut also provide a nut crop.

Trees support the soil. They reduce the effects of wind and rain. And they help block the sun.

Failure to take the care needed to protect marginal lands can make a bad situation worse. But good planning can turn a marginal resource into a highly productive one.

This VOA Special English Agriculture Report was written by Mario Ritter. Our reports are online at www.unsv.com. If you have a question about agriculture, send it to [email protected]. We might answer it on our program. I'm Barbara Klein.
  原文地址：http://www.tingroom.com/voa/2007/3/40073.html