在线词典,在线翻译

有机农业养活世界的局限性

所属:听力板块 阅读:2511 次 评论:1 条 [我要评论]  [+我要收藏]

小编摘要:有机农业避免了使用化学杀虫剂和人工化肥。支持者表示,有机农业比传统方式更环保。但研究表明,有机农业每公顷产量通常更低。

 The Limits to Organic Farming in Feeding the World

Organic farming avoids the use of chemical pesticides and manmade fertilizers. Supporters say organic farming is better for the environment than conventional methods. But studies have shown that organic farming generally produces less food per hectare.

That lower yield means feeding the world organically would require more land. But good farmland is limited. And scientists say deforestation from the clearing of land for agriculture is already a problem for climate change.
In a new study, researchers wanted to measure the difference between conventional and organic yields. So they combined the results of sixty-six earlier studies. They found that some organic farms can yield almost as much as conventional farms. But most cannot.

Verena Seufert at McGill University in Montreal, Canada, was the lead author of the study in the journal Nature.

VERENA SEUFERT: "Conventional yields are typically higher than organic yields. But with certain management practices, certain environmental conditions, and certain crop species, this yield difference can be quite small."

On average, organic farms produced twenty-five percent less compared to conventional farms. But yields of organic fruits and other perennial crops nearly equaled the yields from conventional ones. So did the yields of legumes such as soybeans. Legumes produce some of their own nitrogen fertilizer.

However, organic vegetables and cereal crops like maize and wheat had a lot lower yields compared to conventionally grown crops.

Ms. Seufert says the soil on organic farms holds water better, and that can reduce the yield difference. Also, organic farmers can improve their yields by making sure their crops get enough fertilizer. But increasing the nitrogen is harder to do organically, using just animal waste and crop rotations.

Organic farmers rotate food crops with plants that fertilize the soil. But while these "cover," or fertilizer, crops are growing, food crops have to be grown on other land. And if farmers use manure, they have to feed the animals that produce it, and that requires grazing land or crop land.

The United Nations predicts that world demand for food will grow seventy percent by the middle of the century. John Reganold is a soil scientist at Washington State University. He says no one should dismiss organic agriculture as part of the solution.

JOHN REGANOLD: "I think when people see these studies, their first reaction is, 'Well, my goodness, organic farming can't feed the world.' Guess what? Conventional farming cannot sustainably feed the world."

Mr. Reganold -- who was not part of the study -- says farming is increasingly a combination of organic and conventional methods.

JOHN REGANOLD: "And it's really going to be a blend of these, I think, more diverse systems that are going to save us."

标签:voa special
0
2012-05-02 21:15 编辑:pliny
分享到:
关注海词微博:
发表评论:
表达一些您的想法吧!已有1条评论>>
登录,再发表评论
文明上网,理性发言!
最新评论:
您可能还感兴趣的文章:
  • [听力板块]美国最流行的小孩名字

    2010年美国出生的小孩有一个优先的机会被取名为“贝拉”或“爱德华”。这两个名字分别是10大最受欢迎的女孩和男孩名字中的一个。无独有偶,这恰恰是广受欢迎的描述吸血鬼的暮光系列的小说和电影
  • [听力板块]自然博物馆的一场生动科学展览

    户外、露天似乎是学习自然科学的天然场所。在南加州这种人们更喜欢户外的地方,它也极具意义。目前,洛杉矶县自然历史博物馆正为游客把展览从室内搬到户外。