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    Erosion is an important natural process, resulting in the distribution of the product of geologic weathering, and is part of both soil formation and soil loss. The world's landscapes have been sculpted by erosion. When the result is particular enough, we enshrine them in National Park as we did in Grand Canyon. Where erosion has worn down mountain and spread soil over the plains, or deposited rich alluvial silt in river bottoms, we gladly farm it. Erosion is a disaster only when it occurs in the wrong place at the wrong time.

    In some places, erosion occurs so rapidly, that anyone can see it happen. Deep gullies are created where water scours away the soil, leaving fencepost and trees sitting on tall pedestals as the land erode away around them. In most places, however erosion is more subtle. It is a creeping disaster that occurs in small increments. A thin layer of top soil is washed off fields year after year until nothing eventually nothing is left but poor-quality of subsoil that requires more and more fertilizer and water to produce any crop at all.

    The net effect, worldwide, at this general, widespread topsoil erosion is a reduction in crop production equivalent in removing about 1 percent of world cropland each year. Many farmers are able to compensate for this loss by applying more fertilizer and by bringing new land into cultivation. Continuation of current erosion rate, however, could reduce agricultural production by 25 percent in Central America and Africa and 25 percent in South America by the year 2000. The total annual soil loss from croplands is though to be 25 billion metric tons. About twice that much soil is loss from rangelands, forest, and urban construction site each year.

    In addition to reduce land fertility, this erosion result in sediment-loading of river and lake, siltation of reservoirs, smothering of the wetlands and coral reefs, and clogging of water in takes and waterpower turbines. It makes river unnavigable, increases the destructiveness and frequency of floods, and cause gullying that turns good lands into useless wastelands.


 

I. Answer the following questions based on the text.

1. What is erosion?

2. When is erosion called a disaster?

3. What has happened in the Grand Canyon?

4. How does erosion happen rapidly?

5. How does subtle erosion happen?

6. What are the effects of topsoil erosion?

7. How do farmers compensate the effect of topsoil erosion?

8. How much is the total annual soil loss from croplands?

9. How could continuation of current erosion rates in 2000 reduce agricultural production?

10. What is the effect of erosion in river?


 

II. Choose the correct words in brackets.

  1. We have to ( advertise / relate ) this new product to the public.
  2. Good service will ( retain / generate ) the customers to call the firm again.
  3. The advertisement must be ( objective / communicative ).
  4. The good advertisements make the customers ( effective / receptive ) to them.
  5. The ( reason / purpose ) of promotion is to increase the sale.
  6. The product are ( available / existed ) in supermarket now.
  7. I'll keep shopping in my favorite mall. I don't need to have ( comparative / effective ) shopping in another place.
  8. Will the advertisement raise good ( behavior / attitude ) of the new customers?
  9. The shop gives ( regular / temporary ) discount every month.
  10. The trend is ( impossible / predictable ) by observing the market.

silahkan download kunci jawaban pada link berikut:

http://www.ziddu.com/download/4479897/THEKEYofagro.pdf.html

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