Soil Organic Matter

Question 1

How much soil volume does SOM take up

Answer 1

0-10%

Question 2

What are the 3 physical properties of SOM

Answer 2

1. Improves physical characteristics
2. Water holding capacity
3. Soil structure & aggregation

Question 3

What are 3 chemical properties of SOM

Answer 3

1. Improves chemical characteristics
2. Adsorptive capacity
3. Buffering capacity

Question 4

Wha are biological properties of SOM

Answer 4

1. Improves biological activity
2. Acts as a “slow release fertilizer”
3. Supports large & varied microbial population

Question 5

What are inorganic forms of carbon

Answer 5

1. CO2 in soil & air
2. Carbonates in lithosphere

Question 6

What is organic carbon

Answer 6

1. SOM
2. SOC

Question 7

What does Low C/N mean

Answer 7

Implies labile plant residue or fertile/easily decomposed SOM

Question 8

What does high C/N mean

Answer 8

Implies resistant plant residue or less fertile/harder to decompose SOM

Question 9

Chernozem C/N ratio

Answer 9

15c : 1n

Easy to decompose = more fertile

Question 10

Luvisol C/N ratio

Answer 10

25c : 1n

Harder to decompose = less fertile

Question 11

Peat C/N ratio

Answer 11

10c : 1n

Lots of N per unit C, plotting soil for house plants

Question 12

What does Labile mean

Answer 12

Soil has low C/N
Easily decomposed

Question 13

What does Recalcitrant mean

Answer 13

Soil has high C/N ratio
Hard to decompose

Question 14

Why is there an annual variation in Atmospheric CO2

Answer 14

Photosynthesis