Soil Systems

Question 1

What is soil made up of?

Answer 1

Minerals
Organic material
Water
Air spaces
Biota

Question 2

What is the function of rock particles in soil?

Answer 2

Provides the skeleton of the soil

Question 3

What is humus?

Answer 3

Plant and animal matter in the process of decomposition

Question 4

What is the function of decomposed material in soil?

Answer 4

Food for bacteria
Storage of nutrients
Soil moisture tension
Neutralises pH

Question 5

What is the function of water in soil?

Answer 5

Transporting nutrients
Biota need water for life
Erosion prevention

Question 6

What is the function of minerals in soil?

Answer 6

The texture of the soil, the permeability and ability to retain nutrients
Chemically weathers, releasing nutrients
The clay humic process

Question 7

What is the function of air in the soil?

Answer 7

Plant and biota respiration
Drainage, “empty space”
Nitrogen fixation

Question 8

What do living things do in the soil?

Answer 8

Break down large parts of organic matter
Large burrowing animals help to aerate the soil
They increase the surface area so more material can be decomposed

Question 9

What is salinization?

Answer 9

When evaporation is greater than precipitation water from lower layers of the soil moves upwards along with minerals dissolved in the water. The water evaporates, leaving the minerals on the surface.

Question 10

What is leaching?

Answer 10

When precipitation is greater than evaporation the water moves down into the soil, dissolving minerals and transporting them downwards.

Question 11

What are the different horizons of soil?

Answer 11

O
A
E
B
C
R

Question 12

What are the three main minerals in soil?

Answer 12

Sand, silt and clay

Question 13

What is the is the order of size of sand silt and clay?

Answer 13

Clay smallest
Silt
Sand largest

Question 14

What is a soil called if it has a fairly equal proportion of clay silt and sand?

Answer 14

A loam

Question 15

Properties of sand particles:

Answer 15

They are round so they have more air spaces in between. This means water drains quickly and easily Nutrients also leach easily.

Question 16

Properties of clay particles:

Answer 16

Oblong in shape, less air spaces so get water logged easily. Electrostatic charges between particles.

Question 17

What do the electrostatic charges on clay particles attract?

Answer 17

Humic acids

Question 18

What are macronutrients?

Answer 18

Nutrients needed in larger supply

Question 19

What are micronutrients?

Answer 19

Nutrients needed in a smaller supply, still very necessary

Question 20

Macronutrient examples:

Answer 20

N P K

Question 21

What is porosity?

Answer 21

The amount of space between particles

Question 22

What is permeability?

Answer 22

How easily gases and liquids can pass through the soil

Question 23

Name the processes in the nitrogen cycle:

Answer 23

Nitrogen fixation
Nitrification
Denitrification
Assimilation
Decomposition

Question 24

What is nitrogen fixation?

Answer 24

Atmospheric nitrification is transformed into a soluble form, ammonium.

Question 25

What is nitrification?

Answer 25

A process whereby soluble nitrogen is transformed into a form that is useful to plants. This process happens by bacteria in the soil.

Question 26

What is denitrification?

Answer 26

A process whereby nitrate is transformed into atmospheric nitrogen.

Question 27

What is assimilation in the nitrogen cycle?

Answer 27

A process whereby nitrogen becomes part of the plant tissue.

Question 28

What is decomposition in the nitrogen cycle?

Answer 28

When organic matter is decomposed the nitrogen in it reenters the soil where it is then broken down by bacteria.