effect of global warming on soil organic carbon

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Effect of global warming on soil organic carbon Dina Khadija and Dr. P. K. Mani Department of Agril. Chemsitry and Soil Science Bidhan Chandra Krishi Viswavidyalaya West Bengal, India

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Page 1: Effect of global warming on soil organic Carbon

Effect of global warming on soil organic carbon

Dina Khadijaand

Dr. P. K. ManiDepartment of Agril. Chemsitry and Soil Science

Bidhan Chandra Krishi Viswavidyalaya West Bengal, India

Page 2: Effect of global warming on soil organic Carbon

GLOBAL WARMING• According to IPCC (2001) the average temperature of Earth is

projected to increase by 1.5-5.8°C during the 21st century

• Climate change is related to Green House Gas(GHG) causing Global Warming

Different sectors contributing to GHGs emission (percent)Water

vapourCarbon dioxide Methane Nitrous oxide Ozone HFCs PFCs SF6

36-76% 9-26% 4-9% 5% 3-7% 2.2% 2.2% 2.2%

[HFC= hydro fluro carbon; PFC= poly fluro carbon; SF6= sulfur hexa fluride]

(Source : Kyoto Protocol)

Page 3: Effect of global warming on soil organic Carbon

Change in global average temperature 1850-2005 shown as a change(°C)relative to the 1961-1990 long- term

average (from IPCC WGI,2007)

Page 4: Effect of global warming on soil organic Carbon

Temperature is projected to increase by 1.5 to 5.8 oC by 2100

FUTURE TEMPERATURE PROJECTION

Page 5: Effect of global warming on soil organic Carbon

CARBON DIOXIDE METHANE

NITROUS OXIDE

Green House Gases on the rise

Page 6: Effect of global warming on soil organic Carbon

Soil Organic CarbonAll availed amenities by industrialized societies are based on fossil fuel derived energy. Thus, the modern civilization can be appropriately termed “the Carbon Civilization” or the C-Era (Rattan Lal,2007),

The modern civilization is dependent on C-based energy sources. It is literally hooked on carbon, and in need of a big-time rehabilitation.

Page 7: Effect of global warming on soil organic Carbon

World soil constitute 3rd largest global C poolPool Amount(Pg )

Ocean 38,100Soil (1 m depth)SOC(soil organic carbon)SIC(soil inorganic carbon)

1550950

Vegetation 610Atmosphere 760Fossil fuels 4130

% of global C pool (Source: Hillel, 2011)

Major C sink. (Source: Lal, 2008)

Page 8: Effect of global warming on soil organic Carbon

Soil organic carbon forms part of the natural carbon cycle

Additional human inputs

Page 9: Effect of global warming on soil organic Carbon

Active – easily oxidizable and fuels soil food web

Passive – longer residence time and contributes to SOC build up

Carbon pool

Page 10: Effect of global warming on soil organic Carbon

Why is carbon important ?

Major building block for life of all organisms in Earth.

Basic input for crop production, important from agricultural point of view.

Some beneficial role of SOC in soil: Physical effect

Chemical effect

Biological effect

Page 11: Effect of global warming on soil organic Carbon

C

Carbon is a “keystone”

N PK Ca

Mg S

Zn Mn

Cl Bo

Building of agriculture

Page 12: Effect of global warming on soil organic Carbon

H2O N

Carbon is the “Lord of the Rings”

KP Ca Mg

Bo

Cu

S Cl Zn

Mn

Mo Fe Na

C

Nutrient cycling requires carbon!

Page 13: Effect of global warming on soil organic Carbon

Soil Organic C Dynamics

Time

Rel

ativ

e C

con

tent

(g C

m-2)

P > D P > DP < D

P = net primary production D = decomposition

(Janzen et al., 1998)

loss

sequestration

Originalaccumulation

Conversion tocultivated agriculture

Adoption ofconservation

practices

prairie agroecosystem

Page 14: Effect of global warming on soil organic Carbon

Managing soil organic matter as the key to soil, air, and water quality.

(Source:Lal,2007)

Page 15: Effect of global warming on soil organic Carbon

Losses of Carbon from the Soil

A. Oxidation of C (as Carbon-di-oxide)

B. Agricultural practices causing reduction of SOC in

soils

Page 16: Effect of global warming on soil organic Carbon

Removal of C from fields

Page 17: Effect of global warming on soil organic Carbon
Page 18: Effect of global warming on soil organic Carbon

Why is the response of soil carbon to global warming important ?

The size of the pool of SOC is large compared to gross and net

annual fluxes of carbon to and from the terrestrial biosphere.

Small changes in the SOC pool could have dramatic impacts on

the concentration of CO2 in the atmosphere.

Increased release of terrestrial C under warming would lead to a

positive feedback,resulting in increased global warming.

Page 19: Effect of global warming on soil organic Carbon

Factors affecting the response of SOC to global warming

1. The balance of carbon inputs to , and outputs from , the soil

2. Increasing decomposition rate under global warming

3. Global and regional trends in changes in NPP and SOC loss

4. Overall impact – transient versus equilibrium effects

Page 20: Effect of global warming on soil organic Carbon

1.The balance of inputs to & outputs from the soil

The level of SOC in a particular soil is determined by many

factors including climatic factors (e.g., temperature and moisture

regimes) and edaphic factors (e.g., soil parent material, clay

content, cation exchange capacity; Dawson and Smith, 2007).

The rate of carbon input to the soil is also related to the

productivity of the vegetation growing on that soil , measured by

NPP. NPP varies with climate, land cover, species composition,

and soil type (Falge et al.,2002).

Page 21: Effect of global warming on soil organic Carbon

2. Increasing decomposition rate under global warming

Increased temperatures accelerate rates of microbial

decomposition

Increase CO2 emission by soil respiration

Results a positive feedback to global warming.

Page 22: Effect of global warming on soil organic Carbon

Assumed temperature dependencies of SOC decomposition

(Parton et al. 1987)

Page 23: Effect of global warming on soil organic Carbon

Temperature sensitivity of SOC pools

Some studies suggest that recalcitrant C is not sensitive to

temperature variation (Giardina and Ryan, 2000).

Recalcitrant and labile pools have a similar temperature

sensitivity (Fang et al., 2005).

The temperature dependence of SOC decomposition is the

result of a number of processes that effectively contributes to

the rate of mineralization (Agren and Wetterstedt, 2007).

Page 24: Effect of global warming on soil organic Carbon

Schematic diagram of temperature sensitivities derived from various methods and their affecting factors.

(Source : Smith et al.,2007)

Page 25: Effect of global warming on soil organic Carbon

Sensitive/vulnerable regions and soils

High latitude regions are thought to be particularly vulnerable

High latitudes are projected to experience some of the greatest

warming (Mitchell et al ., 2004).

This is particularly true of permafrost soils in the taiga and

tundra that hold around 500 Pg C, and could lose this carbon

rapidly under warming ( Zimov et al ., 2006).

Page 26: Effect of global warming on soil organic Carbon

MEASURING SOIL RESPONSES TO GLOBAL WARMING

A.Soil respiration measurement in the laboratory

B.Soil respiration measurement in the field

1.Static absorption 2.Dynamic (or steady-state)chambers

3.Enrichment(or non-steady-state)methods

Page 27: Effect of global warming on soil organic Carbon

Dynamic (or steady-state) chambers

Sr =∆c (f/A)

Where Sr is the efflux of CO2 from the soil, ∆c is the

difference in CO2 mass fraction in the incoming and

outgoing air streams, f is the gas flow rate through

the chamber, and A is the surface area covered by the

chamber (Nakayama, 1990).

Page 28: Effect of global warming on soil organic Carbon

Enrichment (or non-steady-state) methods

The soil efflux(Sr) can be measured by:

Sr=(∆c/∆t)(V/A)

where ∆c is the CO2 concentration increment in the chamber in the time interval ∆t, V is the volume of air within the chamber, and A is the soil surface area covered by the chamber.

Page 29: Effect of global warming on soil organic Carbon

Holding carbon in the soil!

Page 30: Effect of global warming on soil organic Carbon

Sequestering carbon

Creating negative carbon

emission

Mulching Cover cropping

Soil amendment

s*Biochar*Manure

Creating positive nutrient budget

Biofertilizer

Chemical fertilizer

Strategies of soil carbon sequestration(Lal,2004)

Page 31: Effect of global warming on soil organic Carbon

ConclusionCarbon content in soil is about twice as large as that of in the

atmosphere and about three times that in the vegetation.

Global warming causes large amounts of carbon in terrestrial

soils to be lost to atmosphere , making them a greater carbon

source than sink.

Strategies of soil carbon sequestration will help to mitigate

climate change itself.

Page 32: Effect of global warming on soil organic Carbon

Soil is meant to be covered.

Manage soil carbon - make the world a better place.

Page 33: Effect of global warming on soil organic Carbon

Soil is meant to be covered.

Manage soil carbon - make the world a better place. Thank you for your attention

We need stronger footprints on / for soils!