Six feet under. How soil microbial life works to bury atmospheric carbon – and how management can make them sequester more carbon - Rattan Lal

Six Feet Under

Rattan Lal

Carbon Management and Sequestration Center

The Ohio State University

Columbus, OH 43210 USA

2


PopulationEnergy use

DeforestationCO2 EmissionsLand DegradationDesertification

Water use

8000 BC

N1750 1850 1950 2000

Time

Hu

ma

n I

mp

act The answer lies in soils.

Soil Matters

3


Soil is an organic-carbon mediated realm in which

solid, liquid, gas and biology all interact from a

scale of nanometer to landscape.

The Living Soil

The weight of live organisms in arable land is 5 t/ha

4


• A spade of rich garden soil may harbor more species than the entire Amazon nurtures above ground

• A teaspoon of productive soil contains 100 million to

1 billion micro-organisms

(Dunne 2009)

Soil is Life

5


I = P x A x T

P = Population A = Affluence T = Technology

Over the last10,000 years, the number of humans has increased about a thousand-fold from 2- 20 million to7.3 billion.

1.01800

1.31850

1.71900 1.8

1910 1.91920

2.11930

2.31940

2.51950

3.01960

3.71970

4.419805.3

1990

6.12000

7.02011

7.52020

8.12030

8.62040

9.62050

112100

The Anthropogenic Driver

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Causes or Activities Deforestation Land Use Conversion Extractive Farming Inappropriate Irrigation Excessive Plowing Soil, Crop, Animal Management

Processes or Mechanisms Erosion Salinization Nutrient Depletion Acidification Species Extinction

Factors or Agents Climate Physiography Land forms Socio-economic, Ethnic/Cultural Setting

Soil Degradation

Anthropogenic & Natural

Perturbations

Biophysical & Socioeconomic

Interactions

Climate-Soil-Biotic Interactions

Processes, Factors, and Causes of Soil Degradation

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Resilience of Soil-Ecological Systems

It has multiple regimes (stable states) which are separated by thresholds

Thresholds

Critical Threshold

The current state of the system

Possible states in which the system can still have the same function

IrreversibleDegradation

Resilience

8


Threshold/Critical Level

Threshold/Critical Level/Tipping Point: Soil processes and properties have threshold levels (1.1% SOC concentration in soils of the tropics). Beyond threshold level, there is a drastic regime change.

9


Types of Soil Degradation

Anthropogenic Natural

Land Misuse & Soil Mismanagement

Climate Change & Related Factors

Crusting, Sealing

Compaction

Runoff and Erosion

Endangered or Extinct Soil

Un-optimal Soil

Temperature

Inhibited Aeration

Desertification

Physical Degradati

on

Acidification

Salinization

Decline in CEC,

Nutrient DepletionElemental Imbalance

Leaching

Pollution/ Contaminati

on

Chemical Degradation

Loss of Soil Biodiversity

Soil-Borne Pathogens

Decline in Soil Organic

Matter

Emissions of Greenhouse

Gases

Loss of Soil C Sink

Capacity

Biological Degradation

Decline in Soil Quality

Dec

line

in E

cosy

stem

Ser

vice

s

Red

uct

ion

in N

atu

re C

on

serv

ancy

Disruption in Nutrient Cycling

Perturbations of the

Hydrological CycleDecline in Net Biome

Productivity

Loss of Nutrients &

Carbon

Decline in Use Efficiency

of Inputs

Ecological Degradation

Inhibited Denaturing of

Pollutants

Lal (2015)

10


De

clin

e in

Re

silie

nc

e a

nd

Qu

ality

of

So

il an

d E

nv

iron

me

nt

Decline in SOC Pool

Reduction in Soil Biodiversity

Crusting Compaction Increase in Runoff Accelerated Erosion

Loss of Nutrients, C and Water from Ecosystem

Degradation of Soil Structure

Decline in soil and environment quality, and increase in risks of social unrest and political instability

Extractive Farming Indiscriminate plowing Residue removal Negative SOC Budget Negative Nutrient Budget

Decrease in Use Efficiency Loss of Soil Resilience Decrease in ecosystem services

Lal (2015)

11


The Gullied Land In West Africa

Desperateness Desperateness Increase in erosion risks between 1980s and 2090:Increase in erosion risks between 1980s and 2090:

Africa….+36%Africa….+36%World....+14%World....+14%

1500 1500 xx 11001515CC

1.1 1.1 xx 10101515 g/g/yyrr

5.7 5.7 xx 10101515 g/g/yyrr CC

3.99 3.99 xx 10101515 g/g/yyrr

0.57 0.57 xx 10101515 g/g/yyrr

decomposition decomposition and emission to and emission to the atmospherethe atmosphere

Stored within the Stored within the terrestrial ecosystem terrestrial ecosystem

Displaced due to erosionDisplaced due to erosion

Transported Transported to the oceanto the ocean

In world soilIn world soil

12

Carbon Management and Sequestration CenterChief Seattle’s Letter to President

Washington

• We are part of the earth, and it is part of us. The bear, the deer, the great eagle, these are our brothers.

• The rivers are our brother, they quench our thirst.

• The earth does not belong to the man, man belongs to the earth.

• How can you buy or sell the sky? The land?

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Biota620 Pg

Atmosphere840 Pg

+4.0 Pg/yr

Soils (3-m)4,000 Pg

Ocean42,000 Pg + 2.3 Pg/yr

(i) Surface layer: 670 Pg(ii) Deep layer: 36,730 Pg(iii) Total organic: 1,000 Pg

Fossil Fuels4,130 Pg

(i) Coal: 3,510 Pg(ii) Oil: 230 Pg(iii) Gas: 140 Pg(iv) Other: 250 Pg

90 Gt/yr

MRT = 5Yr

MRT = 25Yr

Mean Residence Time (MRT) = 400Yr

MRT = 6Yr

92.3 Pg/yr

The Short-Term Global Carbon Cycle

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• Gross Primary Productivity (GPP) = 123 Gt C/yr

• Net Primary Productivity (NPP) = 63 Gt C/yr

• Net Ecosystem Productivity (NEP) = 10 Gt C/yr

• Net Biome Productivity (NBP) = 3 Gt C/yr

“If we control what plants do with carbon, the fate of CO2 in the atmosphere is in our hands”

-Freman Dyson (2008), BioScience (10/10)

Only 0.05% of the 3800 zettajoules (1021J) of solar energy is absorbed annually as GPP

Biosequestration of Atmospheric CO2

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Strengthening of Elemental and H2O

Cycling

Soil and Water Conservation

Improvements in Rhizospheric Processes Increase in Net Biome Productivity

Increase in Soil Biodiversity Earthworm Activity MBC

Increase in SOC Pool Improvement in Aggregation

Restoration of soil and environment quality, improvement in soil resilience and increase in social

and political stability

Conversion to CA Residue Retention Cover Cropping INM Tillage Elimination

Increase in Use Efficiency of Input Increase in Ecosystem services

Lal (2015)

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Carbon Management and Sequestration CenterSustainable

Agriculture(116-27 BC)

Agricultura “est scientia, quae sint in quoque agro serenda ac facienda,quo terra, (that the land)

maximos (the highest)

perpetetuo (in perpetiuty)

reddat fructus” (yields)

Marcus Terentius Varro

Rerum Rusticarum

Ribri III

(Agricultural topics in

3 books)

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“When we try to pick out anything by itself,we find it hitched to everything else in the universe.”

John Muir(Naturalist)

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Accelerated erosion

Innovative Technology II

Innovative Technology I

Subsistence farming, none or low off-farm input soil degradation

New equilibrium

Adoption of RMPs

Time (Yrs)Lal, 2004

80

100

20

40 60 80 100 120 140 160

40

60

20

Rel

ativ

e S

oil

C P

oo

l

0

Maximum Potential

RateΔY

ΔX

Attainable Potential

C S

ink

Ca

pa

city

Δt

•NT•INM & NUE•Cover Crops•Biochar•Agroforestry•Desert. Control• Afforestation• Pasture Mgmt•H2O harv., DSI

MRT = PoolFlux

Soil C Sequestration

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Sustainable Soil Management

• Replace what is removed,

• Respond wisely to what is changed, and

• Predict what will happen from anthropogenic and natural perturbations

•Enhance soil resilience

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Disease-Suppressive soil

High Soil Biodiversity

Improved Varieties

Complex Rotations

Conservation Agriculture System

Mulch Cover cropNo-till

MycorrhizaeMycorrhizae

RhizobiumRhizobium

Integrated Nutrient Management

21


Corn with no residue. Corn with 100% residue

Drought of 2012

Climate-Resilie

nt Soil

22


““Soil biota is the bioengine of the Earth”Soil biota is the bioengine of the Earth”

There is no such thing as a free biofuel from There is no such thing as a free biofuel from crop residues.crop residues.

There is no such thing as a free biofuel from There is no such thing as a free biofuel from crop residues.crop residues.

Economics of Residue Removal for Biofuel

23

Carbon Management and Sequestration CenterProperties of Agroecosystems

1) Productivity : Total output

2) Stability : Consistency of production

3) Equitability : Fair allocation for all inhabitants of Earth

4) Autonomy : Self-sufficiency

5) Sustainability : Forever

6) Efficiency (Eco) : Producing more with lessAll of th

ese properties depend on soil carbon

pool

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• Total SOC pool to 2-m depth = 2400 Pg

• Increasing SOC pool by 1% = 24 Pg

• 1 Pg = 0.47 ppm

C sink capacity for every 1% increment ≈ 11 ppm

Capacity of Soil Carbon Sink

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Sustainable Soil

Management

1. Causes of Soil

Degradation

• The biophysical process of soil degradation is driven by economic, social and political forces. • Vulnerability to degradation depends on “how” rather than “what” is grown.

2. SoilStewardship

& HumanSuffering 3.

Nutrient,Carbon, &

Water Bank

4.Marginality

Principle

5. Organicvs. Inorganic

Nutrients6. Soil Carbon

& GHG Effect

8. Soil asSink for

Atmospheric CO2 7.

Soilvs.

Germplasm

9. Engine of Economic

Development

10. Traditional Knowledge &

Modern Innovations

• When people are poverty stricken, desperate and starving, they pass on their sufferings to the land.

• It is not possible to take more out of a soil than what is put in it without degrading its quality. • Only by replacing what is taken can a soil be kept fertile, productive, and responsive to inputs.

• Marginal soils cultivated with marginal inputs produce marginal yields and support marginal living. •Recycling is a good strategy especially when there is something to recycle.

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en.wikipedia.orgwww.worldwildlife.org

www.seeturtles.orgHANDOUT / Reuters

Soil: the Global Icon

Environment

Six feet under. How soil microbial life works to bury atmospheric carbon – and how management can make them sequester more carbon - Rattan Lal