Soils

Question 1

What is soil fertility?

Answer 1

the ability of soil to sustain plant growth

Question 2

How does water content affect soil fertility?

Answer 2

Essential for organisms and plants that live in soil
Good drainage so not water logged
Plant nutrients are absorbed in ionic form

Question 3

How does soluble materials affect soil fertility?

Answer 3

Macronutrients present such as nitrogen in the ionic form of nitrites
Micronutrients present such as magnesium and iron
Toxic ions are absorbed onto mineral particles so cannot dissolve in water

Question 4

How does air content affect soil fertility?

Answer 4

Living organisms in soil and processes that increase fertility are aerobic

Question 5

How does DOM affect soil fertility?

Answer 5

Releases plant nutrients as it decomposes
Increases water retention
Provides food for soil biota

Question 6

How does pH affect soil fertility?

Answer 6

Usually 5.5-7 which is the range of tolerance for most plants
Acidic soils increase the leaching of plants nutrients and damage root cell membranes
In alkaline conditions phosphates become insoluble

Question 7

How do detritivores affect soil fertility?

Answer 7

They break up DOM and release nutrients into the soil
Worms also increase soil drainage and airation

Question 8

How do decomposers affect soil fertility?

Answer 8

Break down DOM
Secrete digestive enzymes
They rely on detritivores to physically break up DOM to increase the surface are

Question 9

What does nitrogen fixing bacteria do?

Answer 9

Converts gaseous nitrogen to ammonium ions

Question 10

What does nitrifying bacteria do?

Answer 10

Oxidises ammonium ions to nitrite ions then to nitrate ions

Question 11

What does Mycorrhizal fungi do?

Answer 11

Forms symbiotic relationships with plant roots and aids phosphate uptake by the plant

Question 12

What is soil texture?

Answer 12

The property controlled by the portions of different size categories of mineral particles present in the soil

Question 13

What is capillary action?

Answer 13

Tiny pore spaces between clay particles allow water underground to rise to the surface

Question 14

What is nutrient retention?

Answer 14

Nutrient ions absorb easily onto clay particles but not sand

Question 15

What is ease of cultivation?

Answer 15

The lack of cohesion between particles in sandy soil makes it easier to cultivate than clay soils

Question 16

How does soil depth affect soil fertility?

Answer 16

Deeper soils are less likely to become waterlogged or dry out rapidly
Aid good root anchorage

Question 17

How do human activities such as aeration by ploughing and drainage?

Answer 17

Makes soils more aerobic, this increases rates of nitrogen fixation, nitrification and the decomposition of DOM

Question 18

How does human activities affect soil nutrient levels?

Answer 18

Farmers add inorganic fertilisers, organic matter
Help support natural processes that increase nutrient levels such as bacterial nitrogen
Deplete nutrient levels: soil erosion, biomass removal

Question 19

How does irrigation affect soil nutrient levels?

Answer 19

Increases the fertility of soil where water is a limiting factor of growth
Dissolves nutrients that can be absorbed with plants in ionic form

Question 20

How does soil compaction affect soil fertility?

Answer 20

Excessive use of heavy machinery reduces aeration
Waterlogging more likely

Question 21

How does pH control affect soil fertility?

Answer 21

Helps to ensure nutrients are soluble but not too easily leached

Question 22

What is wind erosion?

Answer 22

When soil is dry (especially soil with low clay content), particles loose with little cohesion, soil blows away
Causes problems where the soil is deposited

Question 23

What is rain splash erosion?

Answer 23

When soil partials are dislodged in all directions by the splash of a raindrop

Question 24

What is surface run off erosion?

Answer 24

When the infiltration capacity of the soil has been exceeded and water flows over the soil surface

Question 25

What is slumping and landslide erosion?

Answer 25

The increased mass and lubrication of water makes the downward movement of soil more likely Often in deforestation

Question 26

How does vegetation reduce soil erosion?

Answer 26

natural windbreaker- reducing kinetic energy reduces the impact of raindrops organic matter helps to bind soil together plant roots hold soil together plants help increase infiltration of water reducing run off

Question 27

What is the effect of vegetation removal?

Answer 27

removes the protection from erosion

Question 28

What is the effect of ploughing vulnerable soils?

Answer 28

breaks up the soil structure, exposing particles to erosion

Question 29

What is the effect of overgrazing?

Answer 29

Less DOM Increased exposure of soil and risk of erosion Disturbance and root damage from hooves

Question 30

What is the effect of reduced soil biota?

Answer 30

Use of agrochemicals reduces the living organisms in the soil Less detritivores and decomposers

Question 31

What is the effect of soil compaction?

Answer 31

Smaller interstitial spaces so infiltration rate is reduced leading to move surface run off

Question 32

What is the effect of cultivating steep slopes?

Answer 32

Surface run off has more kinetic energy, ploughing would add to the loose particles that are more likely to erode

Question 33

What are the effects of soil erosion?

Answer 33

Reduced productivity Sedimentation in rivers and reservoirs Increased atmospheric particles Desertification

Question 34

How does long term crops reduce soil erosion?

Answer 34

the growth of plants the don't require frequent planting and soil disturbance roots hold together soil particles

Question 35

How does zero-tillage cultivation reduce soil erosion?

Answer 35

minimizes soil disturbance as seeds are drilled directly into the ground

Question 36

How does contour ploughing reduce soil erosion?

Answer 36

reduces erosion as water flow is stopped by the ploughed furrows and looses kinetic energy

Question 37

How does tied ridging reduce soil erosion?

Answer 37

Retains water from rain and therefore increases infiltration and reduces run off

Question 38

How does terracing reduce surface run off?

Answer 38

narrow fields held in place by retaining walls built along the contours

Question 39

How does rows of stones reduce surface run off?

Answer 39

reduce run off and reduce the erosion rate