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Environmental Science #1 > How human activities affect soil fertility > Flashcards

How human activities affect soil fertility Flashcards

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Biology 101 flashcards
1
Q

what is soil?

A

loose surface material that covers most land

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2
Q

what is a fertile soil

A

a soil that has the nutrients to sustain plant growth and provide plant habitat that results in sustained and consistent yield

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3
Q

what factors can affect soil fertility?

A

Ability to hold water
Nutrients and minerals
Good air content
relatively neutral pH
Dead organic matter
Soil depth
High levels of soil biota
soil structure
soil texture

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4
Q

what is soil texture

A

the characteristics of a soil based on the proportion of the mineral particles that are sand silt and clay

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5
Q

what are the sizes of the soil mineral types (big to small)

A

Sand
Silt
clay

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6
Q

what is the pore size of sand

A

macro

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7
Q

what is the pore size of silt

A

medium- (meso)

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8
Q

what is the pore size of clay

A

micro

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9
Q

what is soil structure

A

how the particles are arranged within the soil

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10
Q

what is the structure of sandy soils

A

rounded grains that don’t lock together so the sandy soils drain more freely

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11
Q

what is the structure of clay soils

A

‘platy’ particles and as they have long flat sides the clay ‘locks’ preventing good drainage

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12
Q

why is soils ability to hold water important

A

water is necessary for all animals and invertebrates
water is needed for the process of photosynthesis
water is also how plants absorb nutrients in ionic form

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13
Q

what is the problem with water logged soil

A

prevents air from reaching the plants and organisms creating an anaerobic environment and a less fertile soil

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14
Q

what are some macro nutrients? (main 3)

A

nitrogen
potassium
phosphorus

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15
Q

what are some micro nutrients

A

copper
iron
magnesium
manganese

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16
Q

why is it important that heavy metals are not absorbed by soils?

A

as they are toxic they would harm plant and animal life reducing soil fertility and the overall biodiversity of the area that is contaminted

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17
Q

why is good air content needed in soil?

A

important for decomposition which breaks down waste into nutrients

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18
Q

why is a neutral pH needed? (soil fertility)

A

acidic conditions cause damage to plant membranes and can leach nutrients out of the soil

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19
Q

what is the best pH range

A

5.5-7

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20
Q

what is the problem with alkaline conditions

A

macronutrients become insoluble making it difficult for plants to absorb them

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21
Q

why is dead organic matter important? (soil fertility)

A

DOM releases nutrients when decomposed
leaf litter and other matter increases the soils ability to hold water

22
Q

why is soil depth important

A

deeper soils hold water for longer and dry out less rapidly don’t get water logged as easily allow plants enough root space needed for growth and stability

23
Q

What are living organisms found in soil called

A

Soil biota

24
Q

What are soil biota important

A

They process DOM and convert it into nutrients and aerate the soil

25
Q

What are mycorrhizal fungi

A

Part of a symbiotic relationship with plant roots important for the absorption of phosphate get glucose in return

26
Q

What are decomposes? (Generally)

A

Broad category that includes fungi and bacteria

27
Q

How do decomposers decompose

A

They release enzymes that digest the DOM
Require detritivores to break up the DOM to make it easily digestible

28
Q

What are detritivores? (species examples)

A

Insects and invertebrates such as worms, millipedes, slugs and wood lice.

29
Q

What do detritivores do?

A

Break up larger DOM into small pieces and release the nutrients into the soil

30
Q

What is the double benefit of worms?

A

They create tunnels and burrows that allow air to circulate and breakdown DOM

31
Q

Why are nitrogen fixing bacteria important

A

Important in converting gaseous forms of nitrogen to ammonium ions

32
Q

Why are nitrifying bacteria important?

A

Important in oxidising ammonium ions (animal waste) to nitrate ions which are important or plant growth

33
Q

How do humans aerate the soil

A

Done by ploughing and putting in drainage
Making conditions favourable for worms

34
Q

Why is aeration important?(bacteria)

A

The soil is more aerobic which allows nitrogen fixing bacteria to exist and convert gaseous nitrogen into ammonium ions helps add nitrogen needed for growth into the soil

35
Q

Why is aerobic soil important for decomposers

A

Decomposers do not usually tolerate anoxic or anaerobic conditions

36
Q

What are the three ways a farmer can add nutrients to the soil?

A

Add organic matter
Add inorganic nutrients
Increase the rate of nitrogen fixing bacteria

37
Q

What is adding organic matter to the soil

A

This means adding manure or animal waste products to the soil

38
Q

What is adding inorganic material to the soil?

A

Adding artificial (man made) pellets of nitrogen, phosphorus etc

39
Q

How can farmers help to increase the rate of nitrogen fixing bacteria?

A

Planting legumes (peas and beans) which naturally add nitrogen rather than taking it away

40
Q

What happens to soil fertility on land which is farmed?

A

Soil becomes infertile overtime and looses structure and ability to hold nutrients because farming degrades soil as soil erosion is increased

41
Q

What is irrigation?

A

This is the addition of water to the soil to help plants grow

42
Q

Why is irrigation important?

A

Plants still need water for photosynthesis even if in nutritious soil
Water carries the dissolved nutrients in ions the plants take the ions up through their roots without water the nutrients couldn’t be picked up

43
Q

What is bulk density

A

The weight of a soil in a given volume

44
Q

What amount of bulk density restricts root growth

A

1.6g/cm*3

45
Q

What soils are more prone to high bulk density

A

Sandy soils as they are more easily compacted

46
Q

What causes high bulk density

A

Heavy machinery or trampling by livestock like cattle

47
Q

What happens to soil pH over time

A

Can become more acidic

48
Q

What can increase soil acidity

A

When plant material is removed alkalinity is removed
When grain pasture and animal products are harvested the soil is left more acidic

49
Q

How can soil acidity be reduced

A

Adding lime or chalk

50
Q

What is the structure of a silty soil?

A

granular material of a size between sand and clay and composed mostly of broken grains of quartz

Environmental Science #1 (90 decks)

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