Lecture 1

Question 1

age of universe

Answer 1

13.7 +/- -.13 billion years

Question 2

age of our solar system

Answer 2

4.5 billion

Question 3

virtually all elements heavier than C have originated from

Answer 3

a supernovae - exploding super-stars from before our sun existed

Question 4

soils a major source of

Answer 4

microbial diversity

Question 5

effects of disconnecting form soil

Answer 5

increase in inflammatory diseases and metabolic disorders

Question 6

average ‘ecological footprint’ of a human in high income countries like ours is ____ ha but there are only ___ha of productive land per person in the world

Answer 6

require 5-10 ha

only 1.9 ha per person

Question 7

only __% of the earths surface is land & only _% of this area is cultivated with little scope for future expansion

Answer 7

30% is land and only 9% is cultivated

Question 8

whole of our food production is coming off of a cube =

Answer 8

20 x 20 x 20 km = 8000 km^3

Question 9

UK wheat yield trends

Answer 9

increased in previous years but now plateaued

Question 10

fresh water and soil

Answer 10

soil is the big filter

-97% of available freshwater passes through the soil into groundwater

Question 11

it is estimated that it takes _ million litres of water to grow a hectare of maize

Answer 11

5 million litres

Pimental et al 2004

Question 12

soil has a significant role in _____ ecosystem services

Answer 12

almost in all
it has crucial foundational role in at least 9 of these
-without soil well lose almost all ecosystem services

Question 13

soil ecosystem services

Answer 13

1) Food production
2) fresh water
3) fibre
4) wood
5) fuel
6) carbon & nutrient storage
7) climate regulation
8) waste detoxification & pollution control
9) host biodiversity & support biodiversity of above-ground ecosystems

Question 14

soil loss curve

Answer 14

Church 2010

– same pattern as global warming, exponential growth in soil loss

Question 15

a cm of top soil typically takes ____ to form

Answer 15

> 200 years to form

–yet it can be swept away in a few seasons.

Question 16

most of the organic matter and fertility of soil is concentrated in ____ of soil

Answer 16

in the top 20cm (the topsoil)

Question 17

each year we lose __ billion trees and __ billion tonnes of fertile soil

Answer 17

15 billion trees and 24 billion tonnes of fertile soil

Question 18

for every person on the planet _ trees are lost and more than __ tonnes of soil is eroded each year

Answer 18

2 trees & more than 3 tonnes of soil

Question 19

nearly __% of the worlds arable topsoil lost to erosion or pollution in the last 40 years

Answer 19

33%

Question 20

global soil erosion is increased by __% by human activity

Answer 20

60%

Question 21

revised universal soil loss equation =

Answer 21

A = R x LS x K x C x P

A= potential annual soil erosion 
R = Rainfall erosivity 
LS = slope length & steepness factors 
K = soil erodibilty
C = cropping and management 
P = soil conservation practices to reduce erosion losses

Question 22

main anthropogenic causes of soil erosion

Answer 22

• Cultivation (tillage, bare soil, crops with small roots, compaction)
• overgrazing
• deforestation
• salinization - salt pollution from poor irrigation

Question 23

europe soil formation rates inc dust depositions range from

Answer 23

0.3-1.4Mg (tonnes) ha-1 yr-1

Question 24

nearly __ the UK for comes from international sources

Answer 24

half

Question 25

china annual loss of soil

Answer 25

7 km^3 per year

croplands are losing soil at an average rate of nearly 28 tonnes per ha per year

Question 26

nearly a billion tonnes of soil lost each year in the EU __% of this is from ___ land with a mean rate of __ tonnes per ha

Answer 26

68%
agricultural
3.24 tonnes per ha

Question 27

soil degradation issue:

Answer 27

• loss of soil quality (loss of organic matter, salinisation, loss of nutrients, infertility)
• loss of soil quantity

loss of quality often increases risks of loss of quantity too

Question 28

eroded soil __ up rivers and degraded soil stores less ___ increasing flood risks

Answer 28

silts

water

Question 29

globally soil degradation costs

Answer 29

about 10 trillion US dollars a year (2015)

Question 30

___ is the most profitable arable crop in the UK

Answer 30

Wheat

• farmers only get 3.9% of supermarket price
• 25-fold increase

Question 31

is there national data looking at soil health +depth and erosion

Answer 31

lacking in the UK, Sweden better samples