5.3 Soil degradation & conservation

Question 1

why can fertile soil be considered a non-renewable resource?

Answer 1

because once depleted, it can take a significant time to restore the fertility, or in some cases it never recovers

Question 2

what are the Stages of Soil Succession

Answer 2

1. Initial colonization: Pioneering organisms, such as lichens and mosses, begin to break down rock surfaces.
2. Early succession: Small plants and microorganisms start to accumulate, contributing to organic matter buildup.
3. Mid-succession: Larger plants establish, further enriching the soil with organic matter and nutrients.
4. Late succession: A complex ecosystem develops with a diverse community of plants, animals, and microorganisms.

Question 3

what kind of human activity has caused processes of soil degradation/ reduce soil fertility?

Answer 3

overgrazing, deforestation, urbanisation, unsustainable agriculture like monoculture, irrigation

Question 4

how does deforestation reduce soil fertility?

Answer 4

Lack of roots means that nutrients can leach from the soil more easily

Question 5

how does urbanisation reduce soil fertility?

Answer 5

often includes big tractors that make the land flat -> makes the soil impermeable and water is unable to infiltrate into the soil -> instead it flows over the soil removing valuable, fertile topsoil

Question 6

case study: the US prairies

Answer 6

The US prairies are so valuable because they have an extremely large amount of organic matter in their soil, with a large layer of topsoil that is extremely fertile, letting roots grow deep and making the soil very productive.

With the onset of drought in 1930, the overfarmed and overgrazed land began to blow away. The wheat shrivelled and died, and became exposed to bare earth leading to soil erosion, because there was no moisture to hold the soil together.

Thousands of residents died from dust pneumonia (clogging of lungs with dirt), there were food shortages, people fled into the city, results in the great depression as there wasn’t much food in the US.

Question 7

soil conservation in commercial farming: reduced tillage (ploughing). what is it?

Answer 7

the soil is not ploughed and ‘turned over’ after every harvest. new seeds are planted into holes, not into lines of ‘upturned’ soil.

Question 8

soil conservation in commercial farming: reduced tillage (ploughing). evaluation

Answer 8

advantage:
- cheap
- not difficult to implement logistically

disadvantage:
- gets rid of traditional habits for many farmers potentially making it difficult to implement as one has to change mindsets
- could increase labour

Question 9

soil conservation in commercial farming: reduced tillage (ploughing). why is it effective?

Answer 9

tilling/ploughing damages soil structure and kills soil fauna (eg: worms), so not tilling maintains the soil health better

Question 10

soil conservation in commercial farming: mulch. what is it?

Answer 10

tiny pieces of organic matter, usually wood chips, are spread over the ground surface

Question 11

soil conservation in commercial farming: mulch why is it effective?

Answer 11

it provides a surface cover, so less topsoil is eroded by the wind. also, the wood slowly decomposes to release nutrients and increase the soil carbon store

Question 12

soil conservation in commercial farming: evaluation.

Answer 12

strengths:
- cheap
- not difficult to implement logistically
- low timescale -> quick effectiveness

weaknesses:
- possibly not able to carry out in a large scale