Soils (p1)

Question 1

What is the cultivation of long-term crops?

Answer 1

Growth of crops that don’t need replanting often and therefore soil disturbance and erosion. E.g. grassland, bush & tree crops like fruit, tea & coffee.

Question 2

What is zero-tillage cultivation?

Answer 2

Direct drilling of seeds into the ground causes less soil disturbance.

Question 3

What is the purpose of contour ploughing?

Answer 3

Plough at 90° to the slope to produce horizontal furrows across sloping ground.

Question 4

How does ploughing and drainage affect soil?

Answer 4

Makes the soil more aerobic, increasing rates of nitrogen fixation, nitrification, and decomposition of DOM.

Question 5

How do farmers increase nutrient levels in soil?

Answer 5

By adding inorganic fertilisers and organic matter.

Question 6

What can deplete soil nutrient levels?

Answer 6

Soil erosion, biomass removal, and inhibiting natural processes that increase nutrient levels.

Question 7

What is the role of irrigation in agriculture?

Answer 7

Increases fertility where water is a limiting factor to growth.

Question 8

What are the effects of soil compaction?

Answer 8

Reduces aeration and makes waterlogging more likely especially when soil is wet.

Question 9

What is the significance of pH control in soil?

Answer 9

Helps to ensure nutrients are soluble but not easily leached.

Question 10

How does temperature affect soil fertility?

Answer 10

Less organic matter added, increased decomposition, less growth, more leaching, and increased nutrient recycling.

Question 11

What are the characteristics of deeper soils?

Answer 11

Less likely to become waterlogged or dry out rapidly, aiding good root anchorage.

Question 12

What are the differences between sandy and clay soils in terms of drainage?

Answer 12

Sandy soils have large pore spaces for fast drainage; clay soils have small pore spaces for slow drainage.

Question 13

What is capillary action in clay soils?

Answer 13

Very small pore spaces allow water underground to rise to the surface.

Question 14

What is the optimal soil type for water retention?

Answer 14

Loam.

Question 15

What is tied ridging?

Answer 15

Used on almost flat land to retain water and increase infiltration.

Question 16

What is the purpose of terracing in agriculture?

Answer 16

To produce fields across sloping ground, increasing water infiltration and reducing surface runoff.

Question 17

What is soil erosion?

Answer 17

A natural process where soil particles are removed by wind or water.

Question 18

What are the effects of accelerated soil erosion?

Answer 18

Reduced productivity, sedimentation, increased particles in the atmosphere, and desertification.

Question 19

What methods can be used to reduce soil erosion?

Answer 19

Windbreaks, multi-cropping, and strip cropping.

Question 20

What are the impacts of deforestation on soil?

Answer 20

Less vegetation to intercept rain, fewer roots to bind soil, and increased wind speed.

Question 21

What is the role of soil biota?

Answer 21

Responsible for decomposition, nutrient recycling, and drainage.

Question 22

What is humus?

Answer 22

A complex mixture of organic materials that helps to hold soil together and retain water.

Question 23

What is the significance of dead organic matter in soil?

Answer 23

Important as a source of nutrients and food for soil organisms.

Question 24

What are the three main soil types?

Answer 24

Sand, silt, and clay.

Question 25

What does soil texture affect?

Answer 25

Nutrient levels, water content, aeration, and drainage.

Question 26

How does moisture content affect soil fertility?

Answer 26

Waterlogged soils can lead to lack of oxygen for roots, while dry soils cause nutrient leaching.

Question 27

What are the main types of peds in soil structure?

Answer 27

* Crumb peds * Blocky peds * Platy peds

Question 28

What is the function of mycorrhizal fungi?

Answer 28

Aids nutrient uptake by plants while gaining carbohydrates from them.

Question 29

What is the relationship between soil aeration and drainage?

Answer 29

Well-drained soils have good aeration, while waterlogged soils have low aeration.

Question 30

Fill in the blank: Soil is composed of _______.

Answer 30

[components of soil]

Question 31

What is the impact of water erosion through rain splash?

Answer 31

Soil particles are dislodged by raindrops and can lead to downhill movement of large amounts of soil.

Question 32

What happens during surface runoff erosion?

Answer 32

Excess water flows over the ground surface when infiltration capacity is exceeded.

Question 33

What occurs during slumping and landslides?

Answer 33

Wet soil on slopes becomes unstable, leading to downward movement of soil.

Question 34

What is humus?

Answer 34

Humus is the complex mixture of organic materials, including organic acids and the breakdown products of lignin. ## Footnote Humus is crucial for soil health as it provides nutrients and food for soil organisms.

Question 35

What are the benefits of humus in soil?

Answer 35

* Helps to hold soil together * Retains water * Aids drainage * Acts as a thermal insulator ## Footnote Fertile soils typically have a high humus content.

Question 36

What is air content in soil?

Answer 36

Air content is found in the spaces between solid particles that are not occupied by water. ## Footnote Air is present within pore spaces that are not completely filled with water.

Question 37

How does high air content affect soil temperature?

Answer 37

High air content means the soil will more easily heat up or cool down, particularly when dry. ## Footnote This is important for soil temperature regulation.

Question 38

What conditions can lead to reduced air content in soil?

Answer 38

* Waterlogging * Compaction * Rainfall * Soil texture * Soil structure ## Footnote Anaerobic conditions can occur when air content is low.

Question 39

What is the ideal pH range for fertile soils?

Answer 39

The ideal pH range for fertile soils is 5.5-7.0. ## Footnote This range is suitable for most plants and soil biota.

Question 40

How does soil pH affect nutrient availability?

Answer 40

Soil pH has a major effect on the availability of nutrients. ## Footnote Alkaline conditions can cause phosphates to become insoluble, reducing fertility.

Question 41

What are the consequences of acidic soils?

Answer 41

* Less growth of plants * Reduced invertebrate activity * Less organic matter * Fewer nutrients added to the soil * Reduced decomposition ## Footnote Acidic conditions hinder soil health and productivity.

Question 42

How can soil pH be raised?

Answer 42

Soil pH can be raised by liming, which involves applying crushed limestone. ## Footnote Liming is a common agricultural practice to improve soil conditions.

Question 43

Why do roots of plants and soil biota need oxygen?

Answer 43

Roots of plants and biota such as earthworms need oxygen to survive and help increase soil fertility. ## Footnote Oxygen is essential for aerobic respiration in soil organisms.

Question 44

What happens in soil with insufficient air (oxygen)?

Answer 44

Insufficient air leads to anaerobic conditions, resulting in incomplete decay of organic matter and releasing methane. ## Footnote This can negatively impact soil health and contribute to greenhouse gas emissions.