Lecture 1 - soil

Question 1

soil is a major reservoir of what?

Answer 1

microbial biodiversity with which humans have evolved

Question 2

what is the global importance of soil?

Answer 2

the essential foundations of sustainable agriculture and ecosystems and the global economy

Question 3

how does the microbial world influence human wellbeing?

Answer 3

directly, and indirectly via effects on food quality, climate and the environment

Question 4

what percentage of land is cultivated?

Answer 4

9% of the 30% land surface - little scope for future expansion

Question 5

why is there little scope for future expansion of land for cultivation?

Answer 5

• A small amount of the earth’s surface is actually suitable for cultivations

Question 6

the population is increasing but why are yields not?

Answer 6

related to the quality of the soils – not optimal conditions to produce maximum output

Question 7

what do ecological footprints tell us about the current situation of the worlds resources?

Answer 7

were stamping out the worlds resources -The average ‘ecological footprint’ of a human in high income countries like ours is 5-10 ha but there are only 1.9 ha of productive land per person in the world

Question 8

what is the growing issue with soil and water management?

Answer 8

• Water management is a big issue and soil management for water is a big issue e.g. filtration and run off
• 97% of available fresh water passes through the soil and into the ground water
• More than 70% of available freshwater is used in agriculture

Question 9

9 soil ecosystem services

Answer 9

1. Food production: crops and livestock
2. Fresh water: filtration and storage
3. Fibre: cotton, linen, wool
4. Wood: construction, paper
5. Fuel: wood, peat, straw, biomass
6. Carbon and nutrient storage
7. Climate regulation
8. Waste detoxification and pollution control
9. Host biodiversity and support the biodiversity of above-ground ecosystems

Question 10

what is our biggest household footprint?

Answer 10

• Our consumption of goods and services (individual greenhouse gas emissions)

Question 11

what is the issue with soil loss?

Answer 11

we are losing a resource that is, for practical purposes and human timespans, essentially non-renewable

Question 12

how long does it take for 1cm of topsoil to regenerate?

Answer 12

about 200yrs

Question 13

nearly 33% of the worlds arable topsoil is lost to what?

Answer 13

erosion and pollution (especially with salt) in the last 40 yrs

Question 14

what does erosion lead too?

Answer 14

preferential removal of organic matter and clay - removing nutrients and releasing CO2

Question 15

what two things have been added to the revised universal soil loss equation?

Answer 15

c= cropping and management 
p = soil conservation practices to reduce erosion

Question 16

what do the terms of the soil loss equation explain?

Answer 16

explain why soil is lost

Question 17

what is the difference between the factors c and p in the soil loss equation?

Answer 17

factors we can control

Question 18

4 main anthropogenic causes of soil erosion?

Answer 18

1) cultivation
2) over -grazing
3) deforestation
4) salinization

Question 19

5 examples of cultivation causing soil erosion

Answer 19

1) tillage
2) bare soil
3) crops with small roots,
4) reduced soil organic matter,
5) compaction

Question 20

what is salinization?

Answer 20

salt pollution from poor irrigation- leading to very poor vegetation

Question 21

what 2 things define soil degradation?

Answer 21

1. Loss of soil quality - loss of organic matter, salinization, loss of nutrients, infertility.
2. Loss of soil quantity - soil erosion and loss of soil volume by oxidation of peat

Question 22

what does loss of topsoil cause?

Answer 22

soil quality decline- Soil erosion preferentially loses clay, and organic matter that store nutrients. This reduces the capacity of the soil to store nutrients and water.

• More nutrient inputs (fertilizer) are needed to support crop growth.
• A higher proportion of fertilizer is washed out causing pollution.

Question 23

how can soil effect flood risks?

Answer 23

Eroded soil silts up rivers, and degraded soil stores less water

Question 24

how is deforestation effecting soil?

Answer 24

Soil is being washed away due to deforestation into rivers -Soil erosion rates may slow down over time once the topsoil has been depleted

Question 25

how self sufficient is the UK for food?

Answer 25

52% - enough to feed us from 1st January to 10 days into July each year. - rest comes from international sources

Question 26

It’s easy to blame the farmers but it’s important to know why the farmers are having to manage the soil in unsustainable ways - why?

Answer 26

they arent paid enough to prioritise soils