soil carbon sequestraon and climate change · 2019-03-04 · parameter soil scientists...

SoilCarbonSequestra0onandClimateChange

Rattan Lal Ohio State University

Columbus, OH 43210 USA

PARAMETER SOIL SCIENTISTS GEOMORPHOLOGISTS/SEDIMENTOLOGISTS

1. Can soils make a difference?

Yes No, small if any

2. Is soil erosion a source or sink?

Source Sink

3. Can agriculture be a solution?

Of course, it must be No, may not make much difference

SOME ANOMALIES AND CONTRADICTIONS

3

Carbon Management and Sequestration Center

ANTHROPOGENIC EMISSIONS (Pg) BY CARBON CIVILIZATION

I.  Land use (i)  Prehistoric : 320 (ii)  1750-2010 : 136 (iii)  2010-2030 : 30

II. Fossil Fuel combustion (i)  1750-2010 : 200 (ii)  2010-2030 : 190

These emissions have and will affect the ecosystems from which we derive food, feed, fiber, fuel and shelter.

Short-Term : Exchange of C between atmosphere, biosphere, soil and the ocean, 100-103

years (decadel scale)

Long-Term : Geochemical cycles which affect C exchange between rocks and the surficial reservoirs, 100-107 years (multimillion years scale)

SHORT VS. LONG-TERM CYCLE

Reservoir C Pool (1018 g) Carbonate in Rocks 60,000

Organic C in Rocks 15,000

Ocean (HCO3-, CO3

-2) 42

Soils 4

Atmosphere 0.8

Biosphere 0.6

There is extremely little CO2 in the atmosphere compared to that in the rocks. Thus, if inputs and outputs are not closely balanced, the atmosphere would become overwhelmed with CO2.

CARBON POOLS IN DIFFERENT RESERVOIRS FOR THE LONG-TERM CYCLE

1.  Uptake of atmospheric CO2 by weathering of Ca and Mg silicates. 2.  Weathering of ancient organic matter on the continent and burial

of new OM in marine sediments. 3.  The thermal breakdown at depth of carbonate minerals and OM

via metamorphism, magmatism and diagenesis.

Fossil fuel combustion by humans is a special case of greatly accelerated OM weathering.

PROCESSES OF LONG-TERM C CYCLE

OCEAN (42) SOILS (4)

ATMOSPHERE (0.8) BIOTA (0.6)

CARBONATES (60,000)

ROCK ORGANICS (15,000)

Volc

anis

m, M

etam

orph

ism

, D

iage

nesi

s

Bur

ial

Wea

ther

ing W

eathering

Diagenesis

Volcanism, M

etamorphism

Burial

THE LONG-TERM CARBON CYCLE (1018G) BERNER (2009)

CO2 + CaSiO3 CaCO3 + SiO2 CO2 + MgSiO3 MgCO3 + SiO2 -Urey Reactions

WEATHERING OF SILICATES

Reservoir Pool (1015 g) Ocean 42,000 Fossil Fuel 5,000 Soils (2-m) 4,000 Atmosphere 780 Biota 620

CARBON POOLS IN DIFFERENT RESERVOIRS FOR THE SHORT-TERM CYCLE

10


Land Fossil Fuel Ocean

THE TERRESTRIAL AND OCEANIC PROCESSES IMPACTING ATMOSPHERIC CHEMISTRY

Atmosphere 800 Pg

(400 ppmv) + 4.3 Pg/yr (2.2 ppm/yr)

11


GLOBAL CARBON BUDGET SOURCES

FF combustion and cement production (10 PgC/yr) +

Land Use Conversion (1.6 PgC/yr) +

Erosion (1.1 PgC/yr) +

Ocean Precipitation (0.77 PgC/yr)

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GLOBAL CARBON BUDGET SINK

Ocean Uptake (2.3 PgC/yr) +

Atmosphere Uptake (4.3 PgC/yr) +

Weathering (0.22 PgC/yr) +

NBP (0.75 PgC/yr) +

Unknown Land Sink (3.8 PgC/yr)

13


KNOWN UNKNOWNS IN GLOBAL C BUDGET

Source: Erosion-Induced C Emission Sinks: Soil uptake, forest uptake

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Burial of Biomass

Burying trees in a landfill

Biochar burial Oceanic burial •  Crop residues •  Trees •  Legislation

restriction Karlen, Lal et al., 2009. Crop residues: The rest of the story. Env. Sci. & Tech. 43: 8011-8015.

15


TROPICAL DEFORESTATION

Decade

Deforestation (106 ha/yr)

C Emission (TgC/yr)

C removal by Regrowth (TgC/yr)

Average Range Average Range Average Range 1990s 887 646-1238 115 61-168 115 61-168

2000s 880 602-1237 97 53-141 97 53-141

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The efficiency of natural sinks has decreased by 5% over the last 50 years, and will continue to do so in the future.

DECLINING EFFICIENCY OF NATURAL SINKS

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GRAIN YIELD AND GLOBAL WARMING

Each (°C) degree of global warming could potentially cut grain yield by 10%, with devastating

effects on food security.

Nabhan (2013)

18


URBAN AGRICULTURE

It is more than just about growing food in urban lands, but also the nurturing of friendship and community spirit of solidarity among neighbors by sharing the produce, and fostering the culture of restoring drastically disturbed soils around the homesteads of

urbanites.

19


CLIMATE-RESILIENT AGRICULTURE

•  If thought of global warming creeps into your mind while restoring degraded soils by establishing a cover crop, applying mulch, using compost or planting trees; don’t stop nurturing the soil but instead do so with even a greater enthusiasm and urgency.

•  To reduce to size of the over-grown footprint of the C-civilization, we need more than just the science. We also need the political willpower to restore eroded, salinized, compacted, and depleted soils and strengthen their ecosystem functions and services.

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Mitigating Climate Change

Geo-Engineering

Sequestering Emission Carbonation

Improve Efficiency

Low C-Fuel

No C-Fuel

Biotic

Terrestrial

Oceanic

Oceanic Geologic

Abiotic

C-Neutral Fuel

Reducing Emission

1.  Geologic sequestration EOR, CBM, Saline Aquifers

2.  Oceanic sequestration

3. Carbonation

Will reactions which occur over hundreds of millions of years over the geologic time scale be effective over human time scales of decades?

MIMICKING THE LONG-TERM C CYCLE (SHORT-CUT)

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Atmosphere Fossil Fuel Ocean

Terrestrial Biosphere

•  Soil •  Biota

POTENTIAL MITIGATION STRATEGIES INVOLVING THE TERRESTRIAL BIOSPHERE

23


•  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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VULNERABLE CARBON POOLS

TROPIC REGION

HIMALAYAS

25


1500 x 1 0 15 C

1.1 x 10 15 g/ y r

5.7 x 10 15 g/ y r C

3.99 x 10 15 g/ y r

0.57 x 10 15 g/ y r

decomposition and emission to the atmosphere

Stored within the terrestrial ecosystem

Displaced due to erosion

Transported to the ocean

In world soil

GLOBAL SOIL EROSION & DYNAMICS OF SOIL ORGANIC CARBON

26


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 So

il C

Poo

l

0

Maximum Potential

Rate ΔY

ΔX

Attainable Potential

C Sink C

apacity

Δt

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

MRT = Pool Flux

SOIL C SEQUESTRATION

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Sustainable Intensification

NO PANACEA NOR A SILVER BULLET

Precision Farming

Farming System Analysis

INM Disease/

Suppressive Soils

Nutrition- Sensitive

Agriculture

The Nexus

Approach

GMOs Micro-Irrigation

Agroforestry

CA

T R

A D

E O F

F

S Nutrition- Sensitive

Agriculture

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Surface drainage (Ridge/furrow system)

No-tillage (Periodic fallowing)

No-tillage (Periodic fallowing and

Chiseling)

Minimum tillage (Disc plowing)

Plowing at the end of rain (Rough seedbed)

Dry farming Water harvesting

Water erosion

Water erosion- crusting

Water logging- water erosion

Water and wind erosion

Wind erosion – drought stress

Perhumid Humid Subhumid Semi-arid Arid Sand

Sandy loam

Clay loam

Silty clay loam

Silt loam

Loamy sand

Soi

l Tex

ture

Clay

Moisture Regime

SOIL TILLAGE GUIDE TEXTURE VS. MOISTURE REGIME

Lal 1985

29


Microaggregates

Soil Aggregates

Sand or Silt particles

Domain of clay crystals forming part of microaggregates

CARBON SEQUESTRATION IN STABLE MICROAGGREGATES (WILLIAMS et al., 1967)

A hypothetical model of a soil aggregate, illustrating the clustering of clay crystals to form domains, of domains to form microaggregates, and of microaggregates to form aggregates. Molecules of soil organic matter acts as bonding agents between domains and microaggregates, and sand and silt particles (after Williams et al., 1967)

Crop Residues Humus Biochemical Transformations

+ (N, P, S etc.)

Elemental Ratio Cereal Residues Humus

Elemental Ratio Cereal Residues Humus C:N 100 12 C:P 200 50 C:S 500 70

C:N 100 12 C:P 200 50 C:S 500 70

Straw photo: http://shannahatfield.com/2013/09/24/hay-vs-straw/ Humus photo: http://www.davecullen.com/forum/index.php?topic=26820.3285

NUTRIENTS REQUIRED TO CONVERT BIOMASS INTO HUMUS

TRADING NUTRIENTS FOR CARBON

Sequestration of 10,000 kg of biomass C as humus requires additional nutrients:

•  833 kg N

•  200 kg P

•  143 kg S

These ingredients will produce + 17,241 kgof humus

28,000 kg of C in residues 62,000 kg of residues (oven dry)

Recalculated from Himes, 1998.

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1.  Measurements are lacking 2.  Soils have been used exploitatively/extractively 3.  Soil management has been such as to make them

source •  Drainage •  Plowing •  Residue removal

WORLD SOILS HAVE NOT BEEN A MAJOR SINK IN THE PAST

33


1.  Understand the biogeochemical mechanisms determining the carbon exchanges between the land, oceans and atmosphere,

2.  How these exchanges respond to climate change through climate-ecosystem feedbacks, which may accentuate or dampen both regional and global climate change, and

3.  What are possible interventions to manage these feedbacks.

SCIENTIFIC CHALLENGES IN-SHORT-TERM CARBON CYCLE

34


1.  By being a source or sink of atmospheric gases via (i)  Natural and anthropogenic disturbances (ii)  N enrichment by converting N2 into reactive N (iii)  S deposition

2.  Climate change and soil carbon (i)  Release of CO2 by warming induced decomposition, (ii)  Increase in erosion

ROLE OF TERRESTRIAL ECOSYSTEMS IN THE SHORT-TERM CARBON CYCLE

35


•  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

36


WHERE MANAGEMENT IS POSSIBLE

2. Mined lands 3. Drained peatlands

Managed Ecosystems 1. Croplands 2. Plantations 3. Grasslands

1. Degraded Soils (i) Eroded (ii) Salinized (iii) Chemically degraded (iv) Physically degraded

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N, P, K, Zn, H2O

TOWARDS C-NEUTRAL AGRICULTURE

Chatting with plants

through molecular-

based signals No-till Farming

INM

Soil biota and ecosystems services

•  Animal Power •  Rotations

•  Sustainable intensification (SI)

•  Rhizospheric processes

•  Disease- suppressive soils

•  Soil-less agriculture

•  Sky farming

•  Urban agriculture

•  Sky farming

•  Recarbon-

ization of the biosphere

•  Nutrition-sensitive agriculture

•  SI

•  Soil-less agriculture

•  Sky farming

•  Urban agriculture

•  Restorative agriculture

TECHNOLOGICAL INNOVATIONS

•  Hand Tools GR

EEN

REV

OLU

TIO

N

� M

achi

ne p

ower

�

Ferti

lizer

s �

Ger

mpl

asm

YEAR

REL

ATIV

E FO

OD

PR

OD

UC

TIO

N (M

g/ha

)

WORLD POPULATION (BILLIONS)

12

8

6

4

1

0.8

15 20

1750 1850 1950 1975 2000 2025 2050 2015

0.8 1 3 4 6 8 9.6 7.6

� C

onse

rvat

ion

agric

ultu

re �

Mic

ro-ir

rigat

ion

�

Pre

cisi

on fa

rmin

g �

Per

enni

al c

ultu

re

� C

ompl

ex ro

tatio

ns �

GM

Os

�  Improved cultivars

�  Biotech- nology

�  No-till farming

�  INM

�  IPM

� Carbon sequestration

Will Climate Change: 1.  Amplify SOM depletion 2.  Exacerbate soil erosion 3.  Alter global C cycle

more drastically 4.  Affect NPP through CO2

fertilization effect

Will Soil Processes: 1.  Have mitigative impact 2.  Adversely impact

agronomic yield 3.  Increase the land-based

C sink 4.  Decrease SOC pool

through C-input in soil at high temperatures

SOIL ORGANIC MATTER AND CLIMATE CHANGE

•  No, C sink capacity of soils of agro-ecosystems is finite (~1 PgC/yr for 50-100 years).

•  But, it has numerous co-benefits and is the more cost-effective option.

•  Restoring soil quality , of which SOC pool is the important determinant, is essential to human wellbeing and nature conservancy.

CAN SOIL C SEQUESTRATION MITIGATE CLIMATE CHANGE?

41


SOIL STEWARDSHIP

Soil stewardship and care must be embedded in every fruit and vegetable eaten, in each grain

ground into the bread consumed, in every cup of water used, in every breath of air inhaled, and in

every scenic landscape cherished.

42


en.wikipedia.org www.worldwildlife.org

www.seeturtles.org HANDOUT / Reuters

Water Carbon

Nitrogen Phosphorous

Sulfur

SOIL: THE GLOBAL ICON LAL, 2014

soil carbon sequestraon and climate change · 2019-03-04 · parameter soil scientists...

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