This is the VOA Special English Agriculture Report.
这里是美国之音慢速英语农业报道。
Studies show farmland in Africa is often lacking in important nutrients. But researchers say a combination of farming methods may help.
研究显示非洲农田通常缺乏重要养分。但研究人员表示，结合多种耕种方法会有所帮助。
Since the world food crisis several years ago, researchers have directed more of their attention to small farms. Most farms in areas south of the Sahara Desert are only about one or two hectares. One of the goals is to increase production without necessarily clearing more land to grow additional crops.
由于几年前的世界粮食危机，研究人员将更多注意力投向了小农场。在撒哈拉沙漠以南地区的大多数农场的规模只有大约一两公顷。研究人员的目标之一就是在无需清理出更多土地种植其它作物的前提下提高产量。
American researchers say that can happen with greater use of an agricultural system called perennation. It mixes food crops with trees and perennial plants – those that return year after year.
美国研究人员表示充分利用多年生农业体系可以实现这个目标。该体系是将粮食作物和树木以及多年生植物混种。
Soil scientist John Reganold is with Washington State University.
土壤科学家约翰·雷甘纳德（John Reganold）就职于华盛顿州立大学。
JOHN REGANOLD: "One of the major problems (is that the) soils are fairly poor in most of the regions. So how do you grow food on poor soils? There have to be food production systems that can build the soil and improve the yield."
雷甘纳德：“其中一个重要问题就是，很多地区的土壤都比较贫瘠。如果在贫瘠的土地上种植粮食呢？必须具备可以培育土壤并提高产量的粮食生产体系。”
Mr. Reganold says poor soil may have resulted from years of weathering that washed away many nutrients. He says some farmers may have done more harm than good.
雷甘纳德表示，土壤贫瘠可能是因为多年的水土流失造成的。他说，一些农民的做法对土地弊大于利。
JOHN REGANOLD: "They have been actually using farming practices where they’re not putting in organic matter. They’re not putting in fertilizers. They can’t afford those things. And it just runs the soil down. So they’re worsening the situation."
雷甘纳德：“他们实际使用的耕作方式不是投入有机物质和肥料，他们买不起这些。这样一来土壤养分下降，情况持续恶化。”
He estimates that up to two billion dollars worth of nitrogen, phosphorous and potassium is lost from African soil each year.
他估计每年非洲土壤流失的氮、磷、钾的价值超过20亿美元。
The scientist says the word perennation defines three systems that are already used in Africa. The oldest of the three is called evergreen agriculture. This is where farmers plant trees with their crops. John Reganold says farmers in Africa have been doing this for sixty years, but it seems to be growing in popularity.
科学家表示，多年生农业体系定义的三大体系已经在非洲被运用。三大体系中最早被运用的是常绿农业体系，即农民们种植庄稼的同时种树。雷甘纳德表示，非洲农民已经这样干了60年，但这种体系似乎越来越普遍。
The method is gaining widespread use in countries such as Niger, Burkina Faso, Malawi and Zambia. The trees are planted among maize, millet or sorghum crops. They not only add nitrogen to the soil through their roots, but also through their leaves when they fall off and break down. At other times of the year, the trees can protect plants from strong sunlight.
这种做法在尼日尔、布基纳法索、马拉维和赞比亚等国家得到了广泛运用。树木种植在玉米、小米和高粱作物之间。它们不仅可以通过根部增加土壤中的氮，树叶掉落并分解后也能提供氮。而在一年中的其它时间，树木可以防止作物受到强烈日晒。
John Reganold says he knows of one woman who has had great success with perennation.
雷甘纳德表示他认识一位通过多年生农业体系取得巨大成功的女性。
JOHN REGANOLD: "She’s a grandmother in her fifties. Her name is Rhoda Mang’yana and she started using this system about twenty years ago. And her yields initially were about a ton of maize. Now with a good year she gets four tons per hectare. Four times what she was getting."
雷甘纳德：“她是一位50多岁祖母，她的名字是 Rhoda Mang’yana。大约20年前她开始采用这一体系。起初她的玉米产量只有一吨左右。现在如果年头好，每亩她能收获4吨。产量翻了4倍。”
Mr. Reganold was one of three researchers who wrote a report about perennation. It was published in the journal Nature.
雷甘纳德是撰写有关多年生农业体系报告的三位研究人员之一。该报告发表在《自然》杂志上。
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