Soil 309

Question 1

What three particles is soil made from? Put in order of size largest to smallest.

Answer 1

• sand
• silt
• clay

Question 2

Name the five layers of soil (soil horizons) from first to last.

Answer 2

• humus
• topsoil
• subsoil
• Weathered rock fragments
• bedrock

Question 3

Define ‘humus’

Answer 3

The organic component of soil, formed by decomposing leaves and other plant matter that sit on the surface of the ‘topsoil’. It is organic matter after decay.

Question 4

Define the characteristics of ‘topsoil’

Answer 4

Topsoil is the uppermost horizon of soil. It is the most fertile part of the soil containing the most organic matter & soil organisms. It may be dark in colour due to presence of organic matter and humus. Topsoil depth varies but a good root depth would be 30-60cm.

Question 5

Define the characteristics of ‘subsoil’

Answer 5

Subsoil is the layer below the topsoil. It will contain little to no organic matter and be lighter in colour than topsoil. Will contain some roots of larger plants like trees.

Question 6

What are the three MAJOR soil horizons. List first to last.

Answer 6

• topsoil
• subsoil
• parent rock (substratum)

Question 7

When the primary participles of soil are combined, what is it called?

Answer 7

Aggregates or peds

Question 8

Describe aggregates and their structure

Answer 8

Aggregates are clumps of soil made up of primary particles (sand, silt and clay). Their varied shapes allows for soil to have pores for air and water

Question 9

What’s problems can arise if soil gets waterlogged?

Answer 9

It excludes air within the soil affected micro-organisms and earthworms. The soil will warm up slowly in spring and gives poor soil structure.

Question 10

Soils that are dominated by sand are considered…….

Answer 10

Coarse textured

Question 11

Soils that are dominated by clay are considered ……

Answer 11

Fine textured

Question 12

Soils that are strongly influenced by more than one property are considered …..

Answer 12

Medium textured

Question 13

When mixing a soil sample with water, how will the particles seperate? List in order top to bottom

Answer 13

Larger particles have higher density so will fall to the bottom faster

• humus (floats to the top)
• clay
• silt
• sand

Question 14

When using the ‘feel method’ to determine soil texture/structure, what qualities determine either sand, silt or clay soil?

Answer 14

• sand soil will feel gritty between your fingers
• silt soil when wet will feel smooth, not very sticky
• clay soil will feel very sticky and can be moulded into shape easily

Question 15

What causes soil compaction and what are the effects?

Answer 15

Soil compaction is a result of compression of the soils pores that would otherwise transport water and air. It is caused by using heavy machinery, heavy foot fall over an area of use of incorrect tilling methods. It destroys soil structure, soil drains slowly and impedes tooth growth.

Question 16

What are the characteristics of ‘organic matter’

Answer 16

Organic matter is made up of dead and decaying plants, animal waste which releases nutrients during decay. It retains moisture and lots of nutrients.

Question 17

What are the effects of organic matter in soil?

Answer 17

Organic matter contributes to plant growth through its effects on the physical, chemical and biological properties of the soil.

Question 18

How does organic matter decompose?

Answer 18

Decomposition is largely a biological process that occurs naturally. Detritivores such as earth worms feeding and decomposes such as bacteria and fungi.

Question 19

What 5 products are released during the decomposition process?

Answer 19

• Carbon dioxide
• energy
• water
• plant nutrients
• resynthesized organic carbon compounds

Question 20

What are the Benifit of living organisms (worms,bacteria,fungi) in soil?

Answer 20

They decompose organic matter. They improve soil aggregation, which influences soil-water movement and aeration. They enhance nutrient levels. They are essential in developing soil organic matter.

Question 21

How much soil does a tree need?

Answer 21

2 cubic meters of soil for every 1 square metre of crown projection (crown projection is how far the branches come out)

Question 22

What problems occur is soil drys out?

Answer 22

Plants in dried out soil will change colour, soil will harden, soil compaction can occur easily, weeds can germinate on bare soil exposed, moss can develop abs it can stunt growth.

Question 23

When evaluating a site for landscaping what factors should be considered when thinking about the growing media (soil)?

Answer 23

• soils pH
• soils nutrients
• pollution (fumes, dust, lights)
• drainage problems

Question 24

When evaluating the surrounding environment before landscaping a site what factors should be considered?

Answer 24

• shaded areas
• site aspect
• frost pockets

Question 25

What methods are used to measure a site?

Answer 25

• Measuring with a tape
• trundle wheel
• 3.14 x r2 (areas of a circle)
• New technology (drones, GPS mapping)

Question 26

What does the PH scale range from?

Answer 26

1-14

Question 27

On the PH scale define what the lowest to highest numbers represent.

Answer 27

1 = acidic 
7 = neutral 
14 = alkaline

Question 28

What is the main control factor in soil?

Answer 28

Calcium

Question 29

How do you raise PH levels in soil to make it more alkaline

Answer 29

Add lime (granular or powder)

Question 30

How do you lower PH to make it more acidic?

Answer 30

Add fertiliser or ammonium sulphur, sphagnum peat or organic mulch

Question 31

Define ‘loam’

Answer 31

Loam is soil composed mostly of sand, silt, and a smaller amount of clay. its mineral composition is about 40–40–20% concentration of sand–silt–clay

Question 32

What is Soilless Mix?

Answer 32

A soilless mix might look like soil, but it doesn’t contain any inorganic matter (sand, clay, silt, etc.). It’s a mixture of organic materials like peat moss, coconut coir, wood chips, perlite, or vermiculite. There might also be a slow-release fertilizer in there as well.

Question 33

What is John Ennis compost?

Answer 33

Most potting compost or media offered is soil-less and either based entirely on peat, has some peat in its formulation or is peat-free. There are advantages, however, to soil based media and John Innes mixes are widely used.

John Innes Potting Composts
a) Soil mix

7 parts by loose volume medium sterilized loam
3 parts by loose volume peat substitute
2 parts by loose volume coarse sand

Question 34

What are the main organisms in soil?

Answer 34

Bacteria, actinomycetes, fungi, algae, Protozoa, nematodes