Greenhouse gas emission from soil

Question 1

Who is aiming for carbon neutrality?

Answer 1

Political agendas of individual countries and international initiatives

Question 2

What year is the aim for carbon neutrality?

Answer 2

2050

Question 3

How much carbon and nitrogen is stored in the soil? And which part?

Answer 3

1500 Pg of total carbon and 137Pg of total nitrogen in the uppermost meter of the global soil layer

Question 4

What percentage of root respiration contributes towards total soil respiration?

Answer 4

Around 50%

Question 5

How is methane produced in soil?

Answer 5

It is produced by methanogenesis under anaerobic conditions and is consumed by methanotrophic microorganisms that use oxygen and methane for their metabolism under aerobic conditions

Question 6

What drives the release of Nitrous oxide and nitric oxide?

Answer 6

Nitrification and denitrification

Question 7

What is nitrification?

Answer 7

Oxidation of ammonium (NH4+) to Nitrate (NO3-) via Nitrogen Dioxide (NO2-)

Question 8

What is denitrification?

Answer 8

Reduction of Nitrate to Nitrogen Dioxide and dinitrogen

Question 9

What 4 methods release greenhouse gases into the soil?

Answer 9

Microbial Activity.
Root Respiration.
Chemical Decay.
Heterotrophic Respiration.

Question 10

What 6 things do emission flux rates depend on?

Answer 10

Soil water content, soil temperature, nutrient availability, distribution grain size, air pressure and pH-value

Question 11

What does soil humidity control?

Answer 11

Microbial activity

Question 12

What gases does not emit under low water conditions?

Answer 12

NitrIC oxide (NO) 
Methane (CH4)

Question 13

When do Nitric Oxide (NO) emissions decrease in soils?

Answer 13

When soils have below 10% water-filled space due to inhibited nutrient supply

Question 14

What conditions do Methane and nitrous oxide require?

Answer 14

Anaerobic conditions

Question 15

What is anaerobic?

Answer 15

Without oxygen

Question 16

What is Aerobic?

Answer 16

With oxygen

Question 17

What gas produces well in fairly high water-filled space?

Answer 17

Nitrous oxide (N2O-)

Question 18

When is N2O production optimal?

Answer 18

Around 60% Water filled pore space

Question 19

When is N2O production lowest?

Answer 19

When water filled pore space is below 30%

Question 20

What can significantly reduce soil emission?

Answer 20

Long periods of drought

Question 21

What soil property can influence soil moisture?

Answer 21

Grain-size distribution. Soil with larger pools retain less water and therefore reduce emissions

Question 22

What gas do coarse soil textures emit best?

Answer 22

NO (Nitric oxide)

Question 23

What soils have larger NO emissions?

Answer 23

Coarse soil textures

Question 24

What do soils with fine pores support?

Answer 24

The formation of CH4 and N2O produced under anaerobic conditions. CO2 emissions were encountered with fine soil textures

Question 25

How does temperature affect emissions?

Answer 25

Higher temperature leads to higher emissions and higher respiration rates

Question 26

What lack of gas can influence methane and nitrous oxide production?

Answer 26

Decreased O2 concentration

Question 27

What does site exposure influence?

Answer 27

Increased temperature and moisture content

Question 28

How does air pressure affect soil emissions? Why?

Answer 28

Lower air pressure supports higher soil emissions due to reduced counter pressure on the soil

Question 29

What area shows lower CO2 and N2O fluxes?

Answer 29

Burned areas for around 1 month as root respiration is reduced in the absence of plant cover

Question 30

What pH level results in lower soil emissions?

Answer 30

Acidic soils

Question 31

What pH value does CO2 emit highest at?

Answer 31

A neutral pH value

Question 32

What pH value does N2O emission decrease at?

Answer 32

At acidic pH levels

Question 33

What is the optimal pH level for methanogenesis?

Answer 33

Between 4 and 7