VOALearningEnglish2012.5.28---The Limits to Organic Farming in Feeding the World

VOALearningEnglish2012.5.28---The Limits to Organic Farming in Feeding the World

The Limits to Organic Farming in Feeding the World
This is the VOA Special English Agriculture Reportt, from http://voaspecialenglish.com | http://facebook.com/voalearningenglish
Organic farming avoids the use of chemical pesticides and manmade fertilizers. Supporters say organic farming is better for the environment than other methods. But studies have shown that organic farming often 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. The findings were reported in the journal Nature. The study's lead author was Verena Seufert of McGill University in Canada. She says convention farms usually have higher yields than organic ones. But some activities, environmental conditions and even crops can narrow the differences. 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 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 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 says world demand for food will grow seventy percent by the middle of the century. John Reganold is a scientist at Washington State University. He says no one should dismiss organic agriculture as part of the solution. He says farming is increasingly a mix of organic and conventional methods. For VOA Special English, I'm Alex Villarreal.(Adapted from a radio program broadcast 01May2012)

有機農業養活世界的界限
這是美國之音特別英語農業Reportt，從http://voaspecialenglish.com | http://facebook.com/voalearningenglish

有機耕作避免使用化學殺蟲劑和人工化肥。支持者說，有機農業對環境是優於其他方法。但有研究顯示，有機耕作往往產生較少，每公頃的糧食。產量低，意味著餵養有機世界將需要更多的土地。但良好的耕地是有限的。科學家們說，從結算砍伐森林用於農業的土地已經是一個氣候變化的問題。在一項新的研究中，研究人員希望測量的常規和有機期國債收益率之間的差異。因此，他們結合了六十六個早期的研究結果。他們發現，一些有機農場可以產生傳統的農場幾乎一樣多。但最不能。這項研究結果發表在“自然”雜誌上。該研究報告的主要作者是Verena的Seufert在加拿大麥吉爾大學。她說，公約農場通常有更高的收益率比有機的。但一些活動，環境條件，甚至作物可以縮小分歧。平均而言，有機農場生產的二十五個傳統的農場相比，減少百分之。但有機水果和其他多​​年生作物的產量幾乎相當於從傳統的產量。這樣做的豆類，如黃豆產量。豆類生產一些自己氮肥。然而，有機蔬菜和穀類作物的產量比常規種植的作物低很多。 Seufert女士說，有機農場的土壤持水更好，也可以減少產量差異。此外，有機農民可以提高產量，以確保作物獲得足夠的肥料。但增加氮是很難做到有機，只使用動物廢棄物和作物輪作。有機農民與培肥土壤的植物，旋轉的糧食作物。不過，雖然這些“蓋”，或肥料，作物生長，其他土地上種植糧食作物。如果農民使用農家肥，他們餵動物產生，而這需要放牧的土地或耕地。聯合國說，世界對糧食的需求將增長到本世紀中葉的70％。約翰Reganold是在美國華盛頓州立大學的科學家。他說，任何人都不應駁回有機農業作為解決方案的一部分。他說，農業是越來越多的有機和常規方法的混合。美國之音特別英語，我亞歷克斯比利亞雷亞爾。（改編01May2012從一個電台節目中播出）