Soil Processes Wk 1

Question 1

Which 4 spheres is the pedosphere related to?

Answer 1

atmosphere, hydrosphere, lithosphere, biosphere

Question 2

how do you get parent material?

Answer 2

It can be newly deposited or fresh rock that has reached the surface.

Question 3

what is the effect of physicsal weathering?

Answer 3

the surface area to volume ratio increases.

Question 4

why do weathering processes take place?

Answer 4

minerals in the earth are formed under different conditions including:
high pressure, high temperature, no water, no oxygen, high pH

Question 5

List 6 physical weathering processes

Answer 5

pressure release
decrease in temperature
daily temperature changes
frost wedging
root expansion
salt weathering

Question 6

what is pressure release? also called exfoliation

Answer 6

rocks rise and decrease in pressure causes expansion and thus cracks to form.

Question 7

decrease in temperature physical weathering?

Answer 7

volume change so cracks form.

Question 8

what is salt weathering?

Answer 8

salt crystals grow and these retain water so freeze-thaw occurs.

Question 9

Which processes result in the formation of soil structure?

Answer 9

erosion, transportation as sediment, plant cycles and earthworms.

Question 10

equation for pore space %

Answer 10

water% + air%

Question 11

what are the components of soil?

Answer 11

mineral matter, organic matter, water, air

Question 12

Where is the list of many equations you need to learn?

Answer 12

BACK OF YOUR BOOK!

Question 13

particle density of mineral matter

Answer 13

2.65 g cm -3

Question 14

particle density organic matter

Answer 14

0.9-1.3 g cm -3

Question 15

particle density water

Answer 15

1 g cm -3

Question 16

what is dry bulk density?

Answer 16

the weight of soil without water per volume of hte total soil.

Question 17

why do we use dry bulk density?

Answer 17

if we have g of C per kg of soil, we can convert to g of C per cubic meter of soil.

Question 18

how do we measure dry bulk density?

Answer 18

take a fixed volume of soil and place it in an oven for 24 hours.

Question 19

what is the mass fraction water?

Answer 19

the amount of water divided by the mass of the DRY soil

Question 20

what is equivalent depth of soil water

Answer 20

if you have 250mm of water in 1 m3, you pretend you stack all the soil on top of all the water. The equivalent depth of soil water is then 0.25m.

Question 21

how do we classify soil texture?

Answer 21

by particle size distribution. you have the fine earth fraction <2mm and above this is gravels and stones.

Question 22

what is the fine earth fraction split into?

Answer 22

clay, silt, sand ( in increasing order of size.)

Question 23

properties of clay

Answer 23

sticky, formable, soft, shiny surface, high plasticity.

Question 24

properties of silt

Answer 24

non-sticky, rough, and floury surface after squeezing

Question 25

properties of sand.

Answer 25

cannot be deformed, feels grainy.

Question 26

what is leem?

Answer 26

a combination of clay and silt. It is not the same as loam.