VOA慢速英语 在不均匀的世界寻求肥料使用平衡

　　Farms in western Kenya use just over one-tenth as much fertilizer as American farms. Corn harvests remain small. The researchers say farming methods in Sub-Saharan Africa need to improve or else poor quality soil will increase rural poverty. More than two hundred fifty million people do not get enough nutrients from crops to stay healthy.

　　Nutrient balances in agriculture differ with economic development. Farmers lack enough inputs to maintain soil fertility is parts of many developing countries, especially in Africa south of the Sahara. But countries that are developed or growing quickly often have unnecessary surpluses.

　　Ammonia gas released by fertilized cropland is a cause of air pollution. The land can also release nitrous oxide, a heat-trapping gas. Nitrogen runoffs from farms can create large dead zones, like those in the Gulf of Mexico. Algae microorganisms in the water overpopulate because of the surplus nitrogen. The algae take much of the oxygen from the water. Fish and other organisms die.

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