Soil Degradation and Conservation

Question 1

Human activities that lead to soil degradation:

Answer 1

Overgrazing Deforestation Unsustainable agriculture

Question 2

What does overgrazing cause to happen?

Answer 2

Bare patches of grass where roots can no longer hold the soil together. Rain and wind cause the patches to grow larger.

Question 3

What does overcropping cause to happen?

Answer 3

Soil nutrient depletion making the soil susceptible to wind erosion.

Question 4

What does deforestation cause to happen?

Answer 4

If it happens to a big enough extent the soil will be prone to erosion. Leaves of trees slow down raindrops, which stops them explosively removing soil particles. Also root systems bind soil together and absorb water.

Question 5

Examples of unsustainable agricultural techniques?

Answer 5

• Removal of crops after harvest • Growing crops in rows with uncovered soil in between. • Excessive use of pesticides. • Irrigation • Monocultures

Question 6

Why is excessive use of pesticides unsustainable?

Answer 6

In the long run the soil will be too toxic for further agricultural use. This is called toxification.

Question 7

How is irrigation an example of unsustainable agricultural techniques?

Answer 7

In spray irrigation systems a large part of the water evaporates before reaching the crops. The minerals dissolved in the irrigation water remain in the top layer of the soil and form a hard salty crust that will make the land unsuitable for growing crops.

Question 8

What does irrigation cause? (process name)

Answer 8

Salinisation

Question 9

What are monocultures?

Answer 9

When the same crop is grown year after year.

Question 10

How are monocultures an example of unsustainable agriculture?

Answer 10

Nutrients are depleted from the soil and the soil loses its fertility.

Question 11

What are the three main processes of soil erosion?

Answer 11

1. Sheet wash 2. Gullying 3. Wind Erosion

Question 12

What is sheet wash?

Answer 12

Large areas of the surface soil are washed away during heavy storm periods in mountainous areas such as landslides.

Question 13

What is gullying?

Answer 13

Channels develop on hillsides following rainfall. Over time these channels become much deeper.

Question 14

What is wind erosion?

Answer 14

On drier soils high winds continually remove the surface layer.

Question 15

Methods to stop soil erosion:

Answer 15

1. Addition of soil conditioners 2. Wind reduction 3. Soil conserving cultivation techniques 4. Improved irrigation techniques 5. Stop plowing marginal lands 6. Crop rotation

Question 16

Why do soils become acidic?

Answer 16

• Acid rain • The breakdown of organic matter • Nitrification of ammonium ions to nitrates • Leaching removes basic ions

Question 17

What is a good method of wind reduction?

Answer 17

Planting hedges or trees between fields. These are called shelter belts. Or build fences. Or alternating high and low crops in adjacent fields.

Question 18

What is growing cover crops?

Answer 18

Growing fast growing crops between the rows of main crops or between harvests to add protection for the soil.

Question 19

What is plowing?

Answer 19

Breaks up soil structure and temporarily increases drainage.

Question 20

What is contour farming?

Answer 20

Plowing and cultivating along the contour lines.

Question 21

How can irrigation techniques be improved?

Answer 21

Covering irrigation canals will reduce evaporation, thereby reducing salinization. Drip irrigation involves pipes in the field with holes where each plant is.

Question 22

What is a crop rotation?

Answer 22

When you change the crop planted every several years to decrease the chance of disease or pest build up.