Soil Conservation Measures

24 Grade 8 Agriculture questions on Soil Conservation Measures, with worked marking schemes. 24 questions are available on this topic in full.

1. Question 1

   1 mark

   A Grade 8 learner observes that the school garden, located on a gentle slope, is developing small channels of eroded soil after the rains. The agriculture teacher advises planting strips of grass between the crop rows. What is the MAIN reason for planting these grass strips?

   A. To provide grazing for the school's cattle

   B. To make the garden look attractive

   C. To bind the soil and slow down surface runoff

   D. To increase the temperature of the soil

   (1 mark)

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2. Question 2

   1 mark

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

   A. Formation of rills and gullies on the land

   B. Deepening of the topsoil layer

   C. Increased crop yields every season

   D. Reduced runoff during heavy rains

   (1 mark)

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3. Question 3

   1 mark

   Which farming practice is MOST likely to accelerate soil erosion on a slope?

   A. Planting grass along the contours

   B. Applying mulch to the soil surface

   C. Cultivating up and down the slope

   D. Practising crop rotation with legumes

   (1 mark)

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4. Question 4

   1 mark

   Strip cropping controls erosion by alternating strips of:

   A. Bare soil with more bare soil

   B. Water channels with dry channels

   C. Only tall trees with shorter trees

   D. Cover crops with erosion-prone crops across the slope

   (1 mark)

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5. Question 5

   1 mark

   Which of the following BEST explains why cover crops such as beans reduce soil erosion?

   A. They make the soil surface bare and smooth

   B. They increase the steepness of the slope

   C. They dry up all the water in the soil

   D. Their leaves and stems shield the soil and reduce runoff speed

   (1 mark)

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6. Question 6

   3 marks

   State three effects of soil erosion on crop production. (3 marks)

   (3 marks)

   Marking scheme

   Any three (1 mark each): loss of fertile topsoil leading to poor/reduced yields; exposure of the subsoil which is less fertile; loss of soil nutrients and organic matter; reduced water infiltration/moisture; destruction of crops and land through gullies; increased cost of buying fertilisers to restore fertility.

7. Question 7

   6 marks

   A farmer in Machakos County is worried because every rainy season, soil and water rush down the slope of his cultivated land, carrying away topsoil and forming small channels.

   (a) (i) Identify the type of soil erosion described above. (1 mark)

   (a) (ii) State ONE other type of soil erosion that the farmer may experience on the same farm. (1 mark)

   (b) Describe TWO biological (vegetative) soil conservation measures the farmer could adopt to control erosion on the sloping land. (4 marks)

   (6 marks)

   Marking scheme

   (a) (i) Rill erosion (the small channels formed by running water indicate rill erosion). (1 mark) (a) (ii) Any ONE other type, e.g. sheet erosion / gully erosion / splash (raindrop) erosion. (1 mark) (b) Biological/vegetative conservation measures (any TWO, 2 marks each): - Cover cropping/mulching: planting crops such as sweet potatoes or beans that spread over the ground, or covering soil with dry grass, reduces the impact of raindrops and slows surface run-off so soil is held in place. - Grass strips/strip cropping: planting strips of grass such as Napier grass along the contour traps soil being washed down and slows water movement. - Afforestation/agroforestry: planting trees and shrubs whose roots bind the soil together and whose canopy reduces rain splash. - Contour grass/cover establishment along terraces to stabilise the bunds. (Award any two well-described measures.)

8. Question 8

   1 mark

   A farmer in Kitui notices that after heavy rains, fertile topsoil is washed downhill from her sloping maize field. Which soil conservation measure would BEST reduce this loss?

   A. Constructing terraces across the slope

   B. Burning crop residues on the field

   C. Leaving the land bare after harvest

   D. Ploughing up and down the slope

   (1 mark)

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9. Question 9

   1 mark

   A Grade 8 learner is helping on a farm where the soil on a gentle slope is loose and easily blown away. The teacher suggests planting grass strips along the contour. What is the MAIN role of these grass strips?

   A. To provide shade for the crops

   B. To slow runoff and trap soil being moved downhill

   C. To increase the acidity of the soil

   D. To attract pests away from the crops

   (1 mark)

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10. Question 10

    4 marks

    Explain how each of the following measures conserves soil on a sloping farm:

    (a) Mulching (2 marks)

    (b) Terracing (2 marks)

    (4 marks)

    Marking scheme

    (a) Mulching: covers the soil surface so raindrops do not hit the soil directly, reduces splash/runoff and keeps soil moist so particles are not carried away (2 marks). (b) Terracing: breaks the long slope into shorter level sections/steps that slow down runoff and allow water to soak in, reducing the volume and speed of water that carries soil (2 marks).

11. Question 11

    1 mark

    A steep hillside near a river is losing soil rapidly. The most suitable long-term measure to stabilise the slope is to:

    A. Establish grass strips and trees along the contours

    B. Remove all vegetation to plant crops

    C. Graze many animals to compact the soil

    D. Plant only annual maize every season

    (1 mark)

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12. Question 12

    1 mark

    A farmer in Murang'a notices that after every heavy downpour, fertile topsoil is washed down the slope of his maize farm, leaving the upper part of the field bare and rocky. Which soil conservation measure would BEST reduce this loss of topsoil on the sloping land?

    A. Constructing terraces across the slope

    B. Ploughing up and down the slope

    C. Removing all grass from the field edges

    D. Burning crop residues after harvest

    (1 mark)

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13. Question 13

    3 marks

    Describe how planting trees (agroforestry) helps to conserve soil and water on a farm. Give three points. (3 marks)

    (3 marks)

    Marking scheme

    Any three (1 mark each): tree roots bind/hold soil particles together preventing erosion; the canopy/leaves reduce the force of raindrops hitting the soil; fallen leaves form mulch/cover that reduces runoff and adds organic matter; trees increase water infiltration into the soil; act as windbreaks reducing wind erosion.

14. Question 14

    4 marks

    A learner observes that a maize field on a gentle slope has developed several small channels after the rainy season.

    (a) Name the type of soil erosion shown by these small channels. (1 mark)

    (b) State three soil conservation measures the farmer can use to prevent this erosion. (3 marks)

    (4 marks)

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15. Question 15

    4 marks

    Distinguish between a cut-off drain and a gabion as used in soil conservation. (4 marks)

    (4 marks)

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16. Question 16

    6 marks

    A farmer in Machakos County notices that after every heavy rain, fertile topsoil is washed away from his sloping maize field, leaving gullies and exposed roots. He decides to take action to protect his soil.

    (a) (i) Identify the type of soil erosion described by the formation of gullies on the slope. (1 mark)

    (a) (ii) State ONE other type of soil erosion that could occur on the same farm. (1 mark)

    (b) Describe TWO mechanical (structural) soil conservation measures the farmer could use to control erosion on the slope. (4 marks)

    (6 marks)

    Marking scheme

    (a)(i) Gully erosion. (1 mark) (a)(ii) Any one of: sheet erosion; rill erosion; splash (raindrop) erosion. (1 mark) (b) Any TWO, well described (2 marks each): - Constructing terraces (e.g. fanya juu/fanya chini terraces) across the slope: soil is dug along the contour to form a trench with a ridge (thrown upslope for fanya juu, downslope for fanya chini), which slows down running water and traps soil so it settles instead of being carried downhill. - Building cut-off drains / contour bunds: channels or raised banks are made along the contour to intercept and divert run-off water safely away from the field, reducing its speed and erosive power. - Constructing gabions / check dams in the gullies: stone-filled wire cages or barriers are placed across the gully to slow water flow, trap silt and prevent the gully from deepening. (Award 4 marks for any two correctly described measures.)

17. Question 17

    1 mark

    Agroforestry contributes to soil conservation mainly by:

    A. Preventing any crops from growing

    B. Tree roots binding the soil and the canopy reducing raindrop impact

    C. Increasing the slope steepness

    D. Removing all ground cover from the farm

    (1 mark)

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18. Question 18

    1 mark

    Mulching helps to conserve soil by:

    A. Increasing the speed of water flowing over the soil

    B. Encouraging gully formation

    C. Protecting the surface from raindrop impact and reducing runoff

    D. Making the soil surface hard and bare

    (1 mark)

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19. Question 19

    1 mark

    Which of the following is a biological method of controlling soil erosion?

    A. Constructing gabions across a gully

    B. Planting cover crops such as sweet potatoes

    C. Building stone-faced terraces

    D. Digging cut-off drains

    (1 mark)

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20. Question 20

    1 mark

    A farmer in Murang'a notices that after every heavy rain, the topsoil on his sloping maize field is washed downhill, leaving deep channels. Which soil conservation measure would BEST control this on his steep land?

    A. Ploughing up and down the slope

    B. Leaving the land bare during the dry season

    C. Constructing terraces across the slope

    D. Burning crop residues after harvest

    (1 mark)

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21. Question 21

    1 mark

    Contour ploughing conserves soil mainly because it:

    A. Increases the depth of the topsoil instantly

    B. Adds nutrients directly to the soil

    C. Kills weeds along the furrows

    D. Slows the downhill flow of runoff water

    (1 mark)

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22. Question 22

    4 marks

    A farmer in a high-rainfall area of Kericho has a steep coffee farm losing soil during storms.

    (a) State two biological methods of soil conservation the farmer can adopt. (2 marks)

    (b) Give two reasons why soil conservation is important on this farm. (2 marks)

    (4 marks)

    Marking scheme

    (a) Any two (1 mark each): planting cover crops; agroforestry/planting trees; establishing grass strips; strip cropping; mulching with vegetation. (b) Any two (1 mark each): maintains soil fertility for good crop yields; prevents loss of topsoil; reduces gully/land degradation; conserves soil moisture; protects water sources from siltation.

23. Question 23

    1 mark

    Which structure is specifically constructed to intercept and divert runoff water away from a cultivated field to a safe outlet?

    A. Cut-off drain

    B. Cover crop

    C. Mulch layer

    D. Grass strip

    (1 mark)

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24. Question 24

    1 mark

    A gabion is used in soil conservation to:

    A. Trap silt and check erosion in a gully

    B. Add nitrogen to the soil

    C. Store harvested rainwater for irrigation

    D. Provide shade for young seedlings

    (1 mark)

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