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LEC.101 > Lecture 5 - Soils and Civilisations > Flashcards

Lecture 5 - Soils and Civilisations Flashcards

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1
Q

What is soil made of?

A

lots of things: air, living organisms, minerals, water and dead material

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2
Q

Where is soil found?

A

on the terrestrial surface of the Earth

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3
Q

What distinguishes between soil and unconsolidated rock?

A

The presence of life distinguishes soil and unconsolidated rocks

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4
Q

What is soil a medium for?

A

Plant growth

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5
Q

What does soil store and regulate?

A

Water and carbon

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6
Q

A handful of soil has more biodiversity than the Amazon rainforest - true or false?

A

True

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7
Q

Soil stores less carbon than all the forests and atmosphere on the planet - true or false?

A

False

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8
Q

How is soil important for cultural heritage?

A

Stores fossils or preserved human creations preserved in the soil - e.g. Roman shields

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9
Q

How is soil important for our urban areas and buildings?

A

Supports the structures

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10
Q

What questions do we need to answer to determine how fast soil forms?

A

How deep is the soil (tape measure)

How long it has been forming for

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11
Q

How do we determine soil forming rate?

A

depth/time to calculate a yearly growth rate (although we typically use longer time frames, e.g. mm per 1000 years because the rate is so slow

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12
Q

What is the formation speed of soil like?

A

Incredibly slow

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13
Q

What type of resource can we treat soil as because of it’s incredibly slow formation rate?

A

A non-renewable resource

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14
Q

When do we believe agriculture began evolving?

A

around 8000-10,000 years ago

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15
Q

How do we know agriculture was undertaken in the past?

A

Ancient farm tools and Egyptian tomb paintings

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16
Q

What does a plough allow us to do?

A

to till large areas in a short period of time, as opposed to having to plant each crop individually

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17
Q

What was the effect of farming in Greece in the past?

A

The destruction of trees, and planting of crops unconsolidated the land, resulting in a massively increased rate of erosion, in an area that had seen very little erosion before

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18
Q

What are periods of soil instability in the past associated with?

A

the expansion of agriculture

Widespread grazing of cattle

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19
Q

What are periods of soil stability associated with?

A

where people have invested in soil conservation

20
Q

What is the general trend with periods of soil instability overtime?

A

the soil erosion events are episodic, but have been more concentrated in more recent times

21
Q

What is the cycle of soil overuse?

A

Population growth leads to increasing food production and land use - destabilizes soil
Soil erosion increases, soil fertility decreases and crops fail
Land is abandoned and forests replanted
Allows for a period of stabilization and stability

22
Q

How many people has soil sustained over 50 million years?

A

Over 100 billion people

23
Q

How many people currently live with chronic undernourishment?

A

About 1 billion

24
Q

How many extra people is it estimated we will need to feed by 2050?

A

2.3 billion

25
Q

How much do we need to increase cereal production by to lift people out of poverty and support the extra people by 2050?

A

70%

26
Q

To increase cereal production by 70% what needs to change

A

Output in developing countries needs to double

27
Q

What environment do agricultural environments have the same erosion rate as?

A

Alpine regions

28
Q

Are agricultural lands at a soil surplus, or deficit

A

Deficit - more is being washed away than forming

29
Q

How we lose soil nutrients?

A

Harvesting (takes away nutrients)
Gaseous emissions
Soil leaching into the ground

30
Q

How much soil do we estimate is lost every year?

A

35 thousand million tonnes

31
Q

How much nitrogen is displaced yearly?

A

23-42 million tonnes

32
Q

How much phosphorous is displaced yearly?

A

13-26 million tonnes

33
Q

What happens if phosphorous and nitrogen flows into rivers/lakes?

A

Eutrophication

34
Q

Where is the biggest issues with soil nutrition?

A

Africa

35
Q

What is happening to soil nutrition in Africa?

A

soils are losing more nutrients than they’re gaining (by far)

36
Q

Which continent consumes the most fertilizer?

A

Asia

37
Q

How much fertilizer does Africa consume yearly?

A

Essentially 0

38
Q

How have production of rice field in Libya v China differed since the 1960s?

A

The rice yields in Liberia have remained essentially static, while in China they have been steadily rising since the 1960s

39
Q

Soil degradation is a factor in the fall of civilizations - true or false?

A

True

40
Q

Is soil erosion outpacing soil formation?

A

Yes

41
Q

What is happening to soil fertility in sub-Saharan Africa?

A

Falling dramatically

42
Q

What condition are soil resources throughout the world and whats happening to them?

A

only fair, poor or very poor condition and that conditions are getting worse in far more cases than they are improving

43
Q

Who reported on the global status of soils?

A

Intergovernmental Technical Panel on Soils

44
Q

What % of the Planet’s ice-free surface has been cleared for crops or livestock?

A

35%

45
Q

What crop production reduction would there be by 2050 is action is not taken?

A

10%

46
Q

Is soil acidity a problem?

A

Yes, a huge one

47
Q

What 4 steps can we take to solve soil issues?

A

Minimize further degradation and restore in most effected areas
Stabilize global stores of soil organic matter
Reduce/stabilize global use of nitrogen and phosphorus fertilizer - increase use in regions of nutrient deficiency
Improve our knowledge about the state and trend of soil conditions

LEC.101 (5 decks)

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