每周一聽——那些年我們一起練過的聽力（第35期）

在職期間做的最后一期聽力活動啦，希望大家捧場哦�。�！感謝各位蟲子一直以來的支持！�。�

注意：本期活動，答題方式變更。參與活動的蟲子請把自己的答案以站內(nèi)信的方式發(fā)送至本版版主（本期發(fā)給我）并在活動帖里占位回復，方便評分，下周六下期活動發(fā)布之前有效哦。還有其他不懂之處，請在此帖里面直接留言回復，我們將盡快回答。
獎項——聽寫后正確填空者可得BB獎勵
評分規(guī)則：
每篇設空十處，難度逐漸增加，每答對一空獎勵一個BB，答對第十空獎勵2BB。全對的蟲子可得15個BB獎勵。大家加油哦~~~~~~

Studies show farmland in Africa is often lacking in important nutrients. But researchers say a combination of farming   (1)  may help.
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   (2)  more land to grow additional crops.
American researchers say that can happen with greater use of an   (3)  system called perenniation. It mixes food crops with trees and perennial plants – those that return year after year.
Soil scientist John Reganold is with Washington State University.
JOHN REGANOLD: “One of the major problems (is that the) soils are   (4)  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   (5)  .”
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.
JOHN REGANOLD: “They have been actually using  (6)  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   (7)  .”
He estimates that up to two billion dollars worth of nitrogen,   (8)   is lost from African soil each year.
The scientist says the word perenniation 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.
The method is   (9)   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.
John Reganold says he knows of one woman who has had great success with perenniation.
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.             (10)            . Four times what she was getting.”
Mr. Reganold was one of three researchers who wrote a report about perenniation. It was published in the journal Nature.
上期活動答案：
1.        Estimated
2.        Mortality
3.        Informatics
4.        Areas
5.        Developed
6.        causes of death
7.        pleased with
8.        the rate of decline
9.        child survival
10.        there’s a lot of work that remains to be done