Unit 2- Organics

Question 1

Percentage of organic matter in soils

Answer 1

0.5-5%

Question 2

Organics are heterogeneous or homogeneous?

Answer 2

Heterogeneous

Question 3

Organic matter is composed of?

Answer 3

Decomposed plant and animal matter

Question 4

Significant source of which elements? (5)

Answer 4

Carbon
Nitrogen 
Phosphorus 
Potassium 
Surfer

Question 5

Organic matter has more pores. How does this benefit soil and ecosystems?

Answer 5

Can hold and store more water

Question 6

Soil Organics provide?

Answer 6

Entertain to microbes
Macronutrients to plants
Aggregate stability
Water holding capacity

Question 7

Soil Organics influence?

Answer 7

Thermal properties 
PH of soil solutions
CEC
Weathering of minerals
Toxicity

Question 8

The second largest carbon sink on earth

Answer 8

Soil organic carbon pool

Question 9

Soil organic matter is highly variable in surface soils (t/f)

Answer 9

True.

Also organic matter decreases with depth

Question 10

Soil organic matter varies because of what influences?

Answer 10

Topography 
Hydrology 
Vegetation
Soil organisms 
Climate
Parent material

Question 11

What are the 4 pools of organic matter?

Answer 11

1. Organic Residues
2. Biomass
3. Water soluble Organics
4. Humus

Question 12

Which pool is composed of various stages of decomposition of organic matter but are still RECOGNIZABLE

Leaf matter
Caracases
Dead roots
Logs

Answer 12

Pool 1 organic residues

Question 13

Which pool is composed of:

Microbial biomass fraction
Enzymes

Answer 13

Pool 2 biomass

Question 14

Which pool is composed of a soil solution? (Organic + inorganic + water)

Answer 14

Pool 3 - water soluble Organics

Question 15

Activity of soil enzymes change with their _________.

Answer 15

Environment.

Question 16

Which pool consists 50% carbon by mass?

Answer 16

Pool 4: humus

Question 17

Two groups of humus are:

Answer 17

Non-humic (20-30%)

Humic (60-80%)

Question 18

Humus can transport or concentrate mineral t/f

Answer 18

True