Study Fig. 8, which is about soil erosion on cropland in the USA. [Figure 8]

1. (a)(i)Use the data for 2002 to complete Fig. 8. Water erosion = 1.0 billion tonnes per year Wind erosion = 0.7 billion tonnes per year[2]
2. (a)(ii)Between which years was the greatest decrease in soil erosion?[1]
3. (a)(iii)Which type of soil erosion has decreased most between 1982 and 2007?[1]
4. (b)Under what conditions will wind erosion be greatest? Circle two statements. Slow wind speed Fast wind speed Low rainfall High rainfall[2]
5. (c)Fig. 9 describes some of the methods that have been used in the USA to decrease soil erosion. Government policy in the USA has encouraged soil conservation. Farmers have been paid to plant grass or trees on fragile cropland with 14 million hectares being transferred to permanent vegetation cover by 1990. Alternative cultivation methods are also being used. By 1994, 26% of planted cropland was under mulch tillage. This is when crop residue is left on the soil surface. Name two soil conservation methods described in Fig. 9. [Figure 9][2]

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