Controlling Soil Erosion

21 Grade 6 Agriculture questions on Controlling Soil Erosion, with worked marking schemes. 21 questions are available on this topic in full.

1. Question 1

   1 mark

   Which farming practice BEST reduces soil erosion on a steep slope?

   A. Leaving the land bare

   B. Digging terraces across the slope

   C. Ploughing up and down the slope

   D. Burning all the grass

   (1 mark)

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2. Question 2

   3 marks

   Explain why ploughing up and down a slope is discouraged, and state what should be done instead.

   (3 marks)

   Marking scheme

   Ploughing up and down creates furrows that run downhill; these channel running water straight down the slope, increasing its speed and washing away topsoil (2 mks). Instead the farmer should plough across the slope along the contour (contour ploughing) so the ridges hold water and soil in place (1 mk).

3. Question 3

   1 mark

   Planting trees along the edges of a farm to reduce wind erosion creates a

   A. Gully

   B. Terrace

   C. Windbreak

   D. Compost pit

   (1 mark)

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4. Question 4

   1 mark

   A cut-off drain is dug across a slope in order to

   A. Store drinking water for the family

   B. Grow vegetables inside the drain

   C. Increase erosion on the lower side

   D. Direct running water safely away from the field

   (1 mark)

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5. Question 5

   4 marks

   Explain how each of the following controls soil erosion: (a) mulching (b) terracing.

   (4 marks)

   Marking scheme

   (a) Mulching (2 mks): the mulch covers the soil and cushions it from raindrop impact, slows run-off and reduces water flow so soil is not washed away. (b) Terracing (2 mks): terraces are level steps cut across the slope that break the length of the slope, slowing running water and trapping soil so it settles instead of being carried downhill.

6. Question 6

   1 mark

   Mulching helps to control soil erosion because the mulch

   A. Makes the soil heavier and wetter

   B. Speeds up water run-off

   C. Cushions the soil from the force of raindrops

   D. Removes all plant nutrients

   (1 mark)

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7. Question 7

   1 mark

   Rainwater running down a bare, sloping field carries away the top layer of soil. This type of soil erosion is called

   A. Wind erosion

   B. Water erosion

   C. Splash erosion by animals

   D. Land subsidence

   (1 mark)

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8. Question 8

   1 mark

   Contour ploughing means ploughing

   A. Only during heavy rain

   B. Straight down the slope

   C. In a spiral toward the river

   D. Across the slope, following the same level

   (1 mark)

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9. Question 9

   1 mark

   Cover cropping controls soil erosion mainly by

   A. Drying out the soil completely

   B. Removing the topsoil quickly

   C. Making the land steeper

   D. Covering the soil so raindrops do not hit it directly

   (1 mark)

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10. Question 10

    3 marks

    A grassed strip is planted along the contour of a farm.

    (a) Name this soil conservation structure.

    (b) Explain how it reduces soil erosion.

    (3 marks)

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11. Question 11

    3 marks

    State three reasons why controlling soil erosion is important for a farmer.

    (3 marks)

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12. Question 12

    1 mark

    Which of these human activities MOST increases soil erosion?

    A. Building terraces on a slope

    B. Planting grass on bare ground

    C. Applying mulch to crop beds

    D. Clearing all vegetation from a hillside

    (1 mark)

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13. Question 13

    2 marks

    Trees are important in controlling soil erosion. State two ways trees help to reduce soil erosion.

    (2 marks)

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14. Question 14

    4 marks

    A school in a hilly area loses topsoil from its garden every rainy season.

    (a) State two signs the pupils could observe that show soil erosion is happening.

    (b) Suggest two methods they could use to control the erosion.

    (4 marks)

    Marking scheme

    (a) Any 2 signs (1 mk each): exposed plant roots; gullies/channels cut into the ground; muddy/brown run-off water; shallow soil / rocks showing; silt deposited downhill. (b) Any 2 methods (1 mk each): digging terraces along contours; planting cover crops/grass strips; mulching the beds; planting trees/windbreaks; making cut-off drains; contour ploughing.

15. Question 15

    1 mark

    Achieng notices deep channels cut into the school playground after heavy rain. These channels are best described as

    A. Contours

    B. Terraces

    C. Furrows

    D. Gullies

    (1 mark)

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16. Question 16

    6 marks

    A farmer wants to grow maize on a gently sloping piece of land. Describe three practices the farmer can use to prevent soil erosion while growing the crop.

    (6 marks)

    Marking scheme

    Any 3 practices well explained (2 mks each): Contour ploughing/planting across the slope so ridges hold water and soil; making terraces or cut-off drains to break the slope and divert run-off; planting grass strips/cover crops or mulching between rows to protect the soil surface; planting trees along boundaries as windbreaks. Award 1 mk for naming, 1 mk for correct explanation.

17. Question 17

    1 mark

    A farmer plants napier grass in strips along the contours of a hillside mainly to

    A. Provide shade for the house

    B. Increase the speed of water flow

    C. Attract more birds to the farm

    D. Trap soil and slow down running water

    (1 mark)

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18. Question 18

    1 mark

    Grass planted in a waterway (grassed waterway) helps control erosion by

    A. Drying up the stream completely

    B. Making water flow faster downhill

    C. Blocking the water so it floods the crops

    D. Slowing water and holding soil in place

    (1 mark)

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19. Question 19

    4 marks

    Distinguish between water erosion and wind erosion, giving one example of where each is likely to occur in Kenya.

    (4 marks)

    Marking scheme

    Water erosion (2 mks): soil is carried away by running water, e.g. on steep/hilly slopes such as the central highlands during heavy rain. Wind erosion (2 mks): soil is blown away by wind, e.g. in dry, bare areas such as the arid parts of northern Kenya. Award 1 mk for correct definition and 1 mk for a suitable Kenyan example in each.

20. Question 20

    1 mark

    Which of the following is a sign that soil erosion is taking place on a farm?

    A. Exposed plant roots on the surface

    B. Even, flat ground everywhere

    C. Thick, dark topsoil forming

    D. More earthworms in the soil

    (1 mark)

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21. Question 21

    1 mark

    When wind blows loose, dry soil away from a bare field, the erosion is caused by

    A. Running water

    B. Grazing goats

    C. Ocean waves

    D. Wind

    (1 mark)

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