VOA慢速英语 在不均匀的世界寻求肥料使用平衡
Seeking Balance in Fertilizer Use in an Uneven World
在不均匀的世界寻求肥料使用平衡
This is the VOA Special English Agriculture Report.
Fertilizer use differs from country to country, and from too little to too much. Nitrogen and phosphorus can produce big crops. But they can also pollute water and air.
A recent policy discussion in the journal Science compared the nutrient balances of different agriculture systems. Researchers compared the use of fertilizer in three areas that grow maize as a major grain: China, Kenya and the United States. By two thousand five, they say, farms in northern China produced about the same amount of corn per hectare as farms in the American Midwest. But the Chinese farmers used six times more nitrogen, and produced almost twenty-three times more surplus nitrogen.
Government policies can have an influence. For example, as China sought food security, its policies increased fertilizer use.
The researchers note that farmers in the Midwest used too much fertilizer on their crops through the nineteen seventies. But improved farming methods later increased their yields and, at the same time, made better use of chemical nitrogen fertilizer.
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