VOA慢速英语2012--Agriculture Report - The Limits to Organic Farming in Feeding the World

Agriculture Report - The Limits to Organic Farming in Feeding the World

This is the VOA Special English Agriculture Report.

Organic farming avoids the use of chemical pesticides¹ 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 perennial³ 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 maize⁴ 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 rotations⁵.

Organic farmers rotate food crops with plants that fertilize² the soil. But while these "cover," or fertilizer, crops are growing, food crops have to be grown on other land. And if farmers use manure⁶, 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."

And that's the VOA Special English Agriculture Report. To read and listen to more stories for people learning English, go to www.voanews.cn. You can also find our captioned⁷ videos at the VOA Learning English channel on YouTube. I'm Jim Tedder⁸.

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Contributing: Steve Baragona

1 pesticides   

n.杀虫剂( pesticide的名词复数 )；除害药物

参考例句：

• vegetables grown without the use of pesticides 未用杀虫剂种植的蔬菜
• There is a lot of concern over the amount of herbicides and pesticides used in farming. 人们对农业上灭草剂和杀虫剂的用量非常担忧。 来自《简明英汉词典》

2 fertilize   

v.使受精，施肥于，使肥沃

参考例句：

• Fertilizer is a substance put on land to fertilize it.肥料是施在地里使之肥沃的物质。
• Reading will fertilize his vocabulary.阅读会丰富他的词汇。

3 perennial   

adj.终年的；长久的

参考例句：

• I wonder at her perennial youthfulness.我对她青春常驻感到惊讶。
• There's a perennial shortage of teachers with science qualifications.有理科教学资格的老师一直都很短缺。

4 maize   

n.玉米

参考例句：

• There's a field planted with maize behind the house.房子后面有一块玉米地。
• We can grow sorghum or maize on this plot.这块地可以种高粱或玉米。

5 rotations   

旋转( rotation的名词复数 )； 转动； 轮流； 轮换

参考例句：

• Farmers traditionally used long-term rotations of hay, pasture, and corn. 农民以往长期实行干草、牧草和玉米轮作。
• The crankshaft makes three rotations for each rotation of the rotor. 转子每转一周，曲轴转3周。

6 manure   

n.粪，肥，肥粒；vt.施肥

参考例句：

• The farmers were distributing manure over the field.农民们正在田间施肥。
• The farmers used manure to keep up the fertility of their land.农夫们用粪保持其土质的肥沃。

7 captioned   

a.标题项下的； 标题所说的

参考例句：

• This paper reviews the production, development and nationalization of the captioned materials. 本文就铜系合金引线框架材料的生产、发展和国产化进程作一论述。
• Please advise other considerable hotels for this captioned group. 请推荐其它一些高级的旅馆给这一群打标语的人。

8 tedder   

n.（干草）翻晒者，翻晒机

参考例句：

• Jim Tedder has more. 吉姆？特德将给我们做更多的介绍。 来自互联网
• Jim Tedder tells us more. 吉姆？泰德给我们带来更详细的报道。 来自互联网