Soil Science

Revision

 
 

Which of the following is NOT a consequence of soil erosion?

Correct! Soil erosion depletes nutrients through the loss of nutrient-rich topsoil and reduced soil depth means less water is able to be stored in the soil profile for plant growth. Deposition of eroded soil material downstream can be costly to repair. Salinity is another form of land degradation but is not a consequence of soil erosion.

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What size class of particles are usually moved long distances in the air by wind erosion?

Correct! Particles less than 50 um are moved long distances by dispersion in wind at speeds greater than about 4.5 m/s.

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Which soil texture groups are most susceptible to wind erosion?

Correct! Sands and sandy loams are the most susceptible to wind erosion because they tend not to be aggregated.

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On nearly level cropping land, which would be the most appropriate method to reduce soil erosion?

Correct! Strip cropping, which roughly follows the contour and uses a crop rotation that ensures that no two adjacent strips are fallow at the same time, is the most appropriate method to reduce soil erosion on lard with slopes of less then 1%.

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How much soil loss is sustainable in Australia?

Correct! The rate of soil formation in Australia is negligible (<0.4 t/ha/yr) and hence no rate of soil loss can be considered acceptable.

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Which of the following statements is FALSE?

Correct! Most soil loss is due to rill erosion. The other three statements are true.

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The factor K in the Universal Soil Loss Equation is related to the:

Correct! K refers to the erodibility of soil under standard conditions. The kinetic energy and intensity of storms determines the erosivity factor - R.

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Using the USLE, which combination of the length and slope (LS) and crop management (C) factors would predict the MOST soil erosion? Assume all other factors are equal.

Correct! The product of LS and C is greatest for option (d) hence, all other factors equal, this combination will predict the highest rate of soil loss.

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