SOIL

Question 1

5 Soil Functions

Answer 1

1. Primary Productivity
2. Water Regulation/Purification
3. Biodiversity Habitat
4. Carbon Regulation/Sequestrian
5. Nutrient Cycling

Question 2

Soil Function: Primary Production Function

Answer 2

The capacity of a soil to produce plant biomass for human use,providing food, feed, fiber and fuel within natural or managed ecosystem boundaries

Question 3

Soil Function: Carbon Sequestration

Answer 3

the capacity of a soil to store carbon in a non-labile form with the aim to reduce the CO2 concentration in the atmosphere

Question 4

Soil Function: Water regulation/purification

Answer 4

Capacity of a soil to receive, store and conduct water for subsequent use, prevent droughts, flooding, erosion and to remove harmful compounds.

Question 5

Soil Function: Nutrient Cycling (incl. calc)

Answer 5

The capacity of a soil to receive, provide and carry over nutrients into harvested crops.
Output/input = fertilizer value x recovery x harvest index

Question 6

Soil Health

Answer 6

Intersection: biology, chemistry + physical.

The capacity of a soil to function within ecosystem and land-use boundaries to sustain biological productivity, maintain environmental quality, and promote plant and animal health

Question 7

Soil Function: Habitat for biological activity

Answer 7

capacity of a soil to support the multitude of soil

organisms and processes, interacting in an ecosystem

Question 8

Causes of High Pathogen Pressure

Answer 8

● Poorly planned crop rotation or diversity
● Poor physical function (e.g. waterlogging)
● Low microbial diversity

Question 9

Good Soil Tilth Outcomes

Answer 9

●Water storage infiltration
● Aeration
● Root growth
● Soil life

Question 10

CASH Biological Indicators (Soil Organic Carbon)

Answer 10

• Soil Organic Matter
• Active Carbon/POXC (labile C)
• Soil Respiration

Question 11

Labile Carbon

Answer 11

Fraction of organic matter readily available as food and energy source to soil microbial community

Question 12

N Volatilization

Answer 12

nitrogen in an organic form (urea), e.g. animal manures or urea fertilizers is converted to ammonia gas (NH3)

Question 13

N Deposition

Answer 13

GAS: input of reactive nitrogen from the atmosphere to the biosphere

Question 14

N Fixation

Answer 14

chemical process that converts atmospheric nitrogen

(N2) into ammonium (NH4), which is taken up by plants or microbes

Question 15

Biological N Fixation

Answer 15

Rhizobia metabolize atmospheric
nitrogen and convert it into N compounds that the plant can uptake in plant root. In exchange, rhizobia use carbon substrates derived from the plant photosynthesis.

Question 16

N Cycling Function of Soil Biology (5)

Answer 16

BIMP-D

• Decomposition
• Bioturbation
• Mineralization
• Immobilization
• Plant Root Aquisition

Question 17

Bioturbation

Answer 17

mixing of plant or animal derived organic material into the mineral matrix of the soil

Question 18

Immobilization

Answer 18

conversion of inorganic compounds to organic compounds by micro-organisms or plants (prevents uptake of the N by plants)

Question 19

Mineralization

Answer 19

oxidation of nutrient compounds in organic matter, releasing the nutrients in soluble inorganic forms that are then available to plants

Question 20

Mineralization sub-processes

Answer 20

AND
Ammonification (organic N to inorganic N)
Nitrification (aerobic)
Dentrification (anaerobic –> heterotrophic denitrifying bacteria & fungi)

Question 21

Mycorrhizae (P Cycling)

Answer 21

Symbiotic relationship: soil fungi & plant roots.

Plant supplies the fungi with sugars, fungal network improves plant’s capacity to absorb water and nutrients.

Question 22

3 Pools SOM (?)

Answer 22

1. Soil
2. SOM
3. Biomass SOM (fungi, bacteria, micro/macro fauna)

Question 23

SOM Additions

Answer 23

Crop residues
Manure
Compost

Question 24

SOM Losses

Answer 24

Soil Respiration

Erosion

Question 25

Processes Contributing to Soil C Gains

Answer 25

``` BAAS: Bioturbation Aggregation Assimilation Stabilization ```

Question 26

Processes Contributing to Soil C Losses

Answer 26

Decomposition

Question 27

Biological Actors of Decomposition

Answer 27

Fragmentation = earthworms, mites, isopods | Microbial Degradation = Bacteria + Fungi

Question 28

Decomposition Sub-processes

Answer 28

FMM: Fragmentation Microbial Degradation Microbial Grazing

Question 29

Decomposition Controls

Answer 29

Climate Soil & Typography Management

Question 30

P cycle losses

Answer 30

* Crop uptake * Runoff and erosion * Leaching

Question 31

P & N Cycle Differences

Answer 31

P is tightly bound, adsorption and desorption are very slow processes

Question 32

N Release Dependent on:

Answer 32

- C:N Ratio (higher= carbon-dominated, requires a lot of decomposition and respiration to get nitrogen) - soil conditions: temperature, moisture, and oxygen (optimal time=late spring and early autumn)