Carbon sequestration in cropping system

1. Carbon Sequestration
in Cropping Systems
S. S. Pal
Principal Scientist

2. What Is Soil Carbon Sequestration?
Soil carbon sequestration is the process of transferring carbon
dioxide from the atmosphere into the soil through crop residues
and other organic solids, and in a form that is not immediately
reemitted.
“Sequestering” of carbon
helps off-set emissions from fossil fuel combustion and other
carbon-emitting activities while enhancing soil quality and long-
term agronomic productivity.
Soil carbon sequestration can be accomplished
By management systems that add high amounts of biomass to
the soil, cause minimal soil disturbance, conserve soil and water,
improve soil structure, and enhance soil fauna activity.
Continuous no-till crop production is a prime example.
Carbon Sequestration

3. Carbon sequestration

4. Indian agriculture has done remarkably well by increasing
food production from 50 Mt in 1951 to 212 Mt in 2002 and
assuring food security to the nation, in spite of a steady
increase in the population to 1.2 billion presently.
However, perceived impacts of climate change could
adversely affect the food output that needs to increase by
56, 62, 36 and 116 percent for rice, wheat, coarse cereals
and pulses respectively by 2020.
India is anticipated to suffer severely from potential
changes in temperature and precipitation emanating out of
climate change.
While many of the key prevention and mitigation measures
are global in nature, with greater responsibility to contribute
to preventing further imbalance between carbon emission
and attendant climate change impacts and protect the global
heritage of food production.
Indian Context

5. The Global Warming Debate
Human activities have altered the concentration of key
trace gases(CO2, CH4, N2O and CFCs) in the earth’s atmosphere
Atomspheric CO2 concentration increased from 280 ppm V in pre-
industrial era to –380 ppm V at present and potentially to 700 ppm
V towards the end of the twenty-first century (IPCC, 2007).
Similarly, other greenhouse gases like CH4, N2O and tropospheric
ozone (O3) increased 152%, 18% and 36% respectively. The high
global warming potential (GWP) of CH4 [GWP = 23 for the 100-
year horizon (Jain et. al., 2000)] and N2O [GWP = 296 for the
100-year horizon (Jain et. al., 2000)] relative to CO2 [GWP = 1]
amplifies the effect of these gases on climate.
As a consequence of the build-up of atomspheric CO2 and other
greenhouse gases in the atomsphere, Earth’s surface temperature
has increased by 0.74oC since 1850 and is expected to increase by
another 1.1oC-6.4oC by the end of this century (IPCC,2007)

6. Terrestrial and geological sequestration of carbon
dioxide emissions from a coal-fired plant

7. Relationship between carbon
sequestration, land management
and other environmental factors
Intricate relationship exists.
Land management exerts both
positive and negative impact.
Environments factors like temperature
rainfall and relative humidity have
direct bearing on soil carbon
sequestration.

8. The Global Warming Debate
Human activities have altered the concentration of key trace gases
(CO2, CH4, N2O and CFCs) in the earth’s atmosphere
Atomspheric CO2 concentration increased from 280 ppm V in pre-
industrial era to –380 ppm V at present and potentially to 700 ppm V
towards the end of the twenty-first century (IPCC, 2007).
Similarly, other greenhouse gases like CH4, N2O and tropospheric
ozone (O3) increased 152%, 18% and 36% respectively. The high global
warming potential (GWP) of CH4 [GWP = 23 for the 100- year horizon
(Jain et. al., 2000)] and N2O [GWP = 296 for the 100-year horizon (Jain
et. al., 2000)] relative to CO2 [GWP = 1] amplifies the effect of these
gases on climate.
As a consequence of the build-up of atomspheric CO2 and other
greenhouse gases in the atomsphere, Earth’s surface temperature has
increased by 0.74oC since 1850 and is expected to increase by another
1.1oC-6.4oC by the end of this century (IPCC,2007)

9. Carbon Cycle

10. Carbon Work Flow Process

11. Sequestration and the Carbon Cycle

12. Schematic summary of major regulatory
mechanisms that lead to either positive or negative
feedbacks of terrestrial C cycles to climate warming

13. • Discussions on biospheric feedbacks to climatic disruption have been
influenced by the perspective that temperature is the minant limiting factor
of respiration, whereas photosynthesis is limited by multiple factors
including light, CO2 concentration, water stress and nutrient availability.
• It is argued that respiration of terrestrial ecosystems including microbial
decomposition of SOM would be more sensitive to global warming than
would gross primary productivity.
• Global warming would thus lead to a net increase of C release to the
atmosphere by the terrestrial biosphere or less net C uptake from the
atmosphere by the terrestrial biosphere.
•However, in the absence of a consensus on the temperature sensitivity of
decomposition of a large fraction of soil C stocks, the significance of this
positive feedback continues to be debated.
Evidence for a decomposition feedback to warming

14.  The stocks of organic matter in soils result from the balance between inputs and
outputs of carbon within the belowground environment.
Soils contain a ‘veritable soup’ of thousands of different organic-C compounds, each
with its own inherent kinetic properties.
Not only do plants produce a wide range of carbon substrates, but plant detritus also
undergoes transformation by microbial degradation or by abiotic condensation reactions
that produce new aromatic structures, larger molecular weights, insolubility, or other
molecular architectures that affect the types and efficacies of enzymes degrading them.
These molecular attributes are characterized by low decomposition rates, high
activation energies and inherently high temperature sensitivity. Secondly, the enzymes
for decomposition may be physically or chemically excluded from many of the organic-
C substrates within the heterogenous environment, causing substrate limiation of
reaction microsites.
Characterization and quantification of plant-derived
C-inputs and externally added inputs on SOC pools
and their environmental linkage

15.  The stocks of organic matter in soils result from the balance between inputs and outputs of
carbon within the belowground environment.
Inputs are primarily from the aboveground (leaf) and belowgroud (root) detritus. Outputs
are dominated by the efflux of CO2 from the soil surface, although CH4 efflux and
hydrological leaching of dissolved and particulate carbon compunds can also be important,
especially under wetland conditions.
The production of CO2 in soils is almost entirely from root respiration and microbial
decomposition of organic matter. For this we intend to quantify the major sources of gaseous-
C efflux (CO2 and CH4) from soils.
This would be achieved by measuring the SOM derived CO2 to include (a) SOM derived
CO2 originating from basal respiration (without root) and (b) SOM derived CO2 from soils
with detritus.
In addition, plant-derived CO2 to include microbial respiration of detritus or added
organic manures, rhizomicrobial respiration and root respiration will be quantified.
Factors controlling decomposition of organic matter

16. Environmental constraints affecting
temperature sensitivities of decomposition
 Environmental constraints that can temporarily or indefinitely affect
apparent temperature sensitivities of decomposition include
 Physical protection in the interior of soil aggregates.
 Chemical protection due to sorbtion onto mineral surfaces through
covalent or electrostatical bonds.
 Negative moisture realtionship lowering substrate availability.
 Flooding to slow down oxygen diffusion to the reaction sites allowing
only anaerobic decompostion

 Low temperature affecting the optimal activity of degrading enzymes.
Each of the environmental constraints affects decomposition reaction
rates, directly or indirectly by decreasing substrate concentrations at
enzymatic reaction sites.

17. Soil organic content in agricultural soils of selected Asian countries
Country No. of
samples
Mean
(g kg-1)
Standard deviation
(g kg-1)
Minimum
(g kg-1)
Maximum
(g kg-1)
Tropical Asia 410 14.1 12.8 1.2 114.0
Bangladesh 53 11.8 8.3 4.7 60.0
Mayanmar 16 12.1 5.0 3.7 23.2
Cambodia 16 10.9 7.7 2.4 28.8
India 73 8.5 3.7 2.8 19.0
Indonesia 44 13.9 7.6 5.0 56.0
West Malayisa 41 33.6 25.3 6.0 114.0
Philippines 54 16.6 6.4 5.2 33.0
Sri Lanka 33 14.1 15.0 1.8 84.9
Thailand 80 10.5 6.7 1.2 29.5
Mediterranean
Countries
62 18.2 14.5 3.5 86.0
Japan 84 33.3 20.2 10.0 113.6

18. Major land use and cereal production in Asia and the World.
World Asia
Area (106 ha) Production (106 t) Area (106 ha) Production (106 t)
Total area 13,422 - 2758 -
Land area 10973 - 2679 -
Agricultural area 4868 - 1259 -
Arable and
permanent pasture
1444 - 459 -
Arable land 1346 - 425 -
Cereal, total 691 1894 307 903
Rice, paddy 147 527 132 482
Wheat 222 564 87 224
Maize 127 470 39 136
Permanent crops 98 - 34 -
Permanent pasture 3424 - 800 -
Forested woodland 3880 - 535 -
(Adapted from FAO, 1994)

19. Estimation of annual C balance in plots without fertilizer N addition in the rice-wheat
long-term experiment in Bhairahawa, Nepal (based on 15 years yield data from
Regmi, 1994)
Source of C Rice
Crop 1
t C ha-1
Rice
Crop 2
t C ha-1
Wheat
t C ha-1
Total
gross
input
t C ha-1
Annual
turnover
%
Annual
mineralizatio
n
t C ha-1
Total
net
input
t C ha-1
Roots 0.08 0.18 0.15 0.41 60 0.24 0.16
Rhizodeposition 0.07 0.15 0.21 0.43 70 0.30 0.13
Total 0.14 0.21 0.36 0.84 - 0.55 0.34
Net change in soil
organic C
- - - - - - -0.45
Soil C-
mineralization
- - - - 4.5 - -0.74

20. Estimation of annual C balances in plots with NPK fertilizer (100 –13 – 25) addition in
the rice-rice-wheat long-term experiment in Bhairahawa, Nepal (based on 15 years
yield data from Regmi, 1994)
Source of C Rice
Crop 1
t C ha-1
Rice
Crop 2
t C ha-1
Wheat
t C ha-1
Total
gross
input
t C ha-1
Annual
turnover
%
Annual
mineralizatio
n
t C ha-1
Total
net
input
t C ha-1
Roots 0.39 0.40 0.60 1.39 70 0.97 0.42
Rhizodeposition 0.38 0.39 0.85 1.62 80 1.29 0.32
Total 0.77 0.78 1.45 3.00 - 2.27 074
Net change in soil
organic C
- - - - - - -0.23
Soil C-
mineralization
- - - - 4.9 - -0.96

21. Effect of cropping system on organic matter content of paddy soils in South China
Location Cropping system Organic matter (g kg-1)
Huber Continuous rice
Rice-dryland crops
20.3 – 21.5
18.5- 19.4
Zhejfang Continuous rice
Rice-cotton
31.1 – 52.1
20.1 – 28.7
Talhu lake region Rice-rice-wheat
Rice-wheat
27.4 + 9.4
24.5 + 10.4
Shanghai suburbs Rice-rice-wheat
Rice-wheat
21.4 + 1.9
15.8 + 1.4

22. Estimated changes in total C balance of three benchmark areas of the “Alternatives to
slash and Burn Project” in Sumatra for 8 years, based on remote sensing data of land
cover and average C contents of each land cover type
Area (ha) Total C loss (t) Total C gain (t) Net C loss
(t)
T C ha-1 yr-1
Rantai Pandan 63,819 2,296,888 3,879,660 -1,583,712 -3.1
Muara Tebo 148,571 11,945,690 3,928,750 8,016,940 6.8
North
Lampung
141,332 13,315,855 3,125,830 10,190,020 9.0

23. Effect of N fertilizer application on shoot and root dry matter, and C and N content of root
and stubble biomass in an irrigated lowland rice double cropped system at the IRRI
research farm in the Philippines
Fert.
N
rate
Above
ground dry
matter at
maturity
(kg ha-1)
Rootb (kg ha-1) Stubblec (kg ha-1)
Composition Composition
Dry
matt
er
C N C/N Dry
matter
C N C/N
0 7530
+ 250
1420
+ 50
357
+ 3
4.9
+ 0.1
73.51 2510
+ 120
313
+ 4
4.6
+ 0.1
68
190 17340
+370
1960
+ 45
330
+ 4
6.5
+0.2 50.77
4400
+ 110
305
+ 11
7.1
+ 0.1
43

24. Effect of long-term fertilization and manuring on soil organic C for different cropping systems in
India.
Cropping system Location Treatment
Initial value
(g kg-1)
Control
(g kg-1)
NPK
(g kg-1)
NPK+FYM
(g kg-1)
Rice-rice Hyderabad 5.1 6.6 8.2 12.5
Rice-rice Bhubaneswar 2.7 4.1 5.9 7.6
Rice-wheat-jute Barrackpore 7.1 4.2 4.5 5.2
Rice-wheat-
cowpea
Pantnagar 14.8 6.0 9.0 14.4
Maize-wheat-
cowpea
Ludhiana 2.1 2.5 2.7 3.7
Maize-wheat Palampur 7.9 6.2 8.3 12.0
Millet-cowpea-
maize
Bangalore 5.5 3.4 4.5 4.8

25.  Most efforts to characterize the kinetics of SOM decomposition have stratified
carbon compounds into ‘pools’that share similar mean residence time (MRT) within
the soil.
The MRT is the inverse of the decomposition rate (k) and therefore reflects a
combination of inherent reactivity of the compound and the environmental constraints
on its decomposition.
 Most of the extrapolations are done through modelling using process-based models
like DNDC or CENTURY.
While these models have proven effective for explaining local and regional variation
in current soil C stocks and changes in stocks due to management and land-use
change, a consensus has not emerged for their applicability to climate change.
Typically most models of soil C dynamics assume that decomposition of all SOM is
nearly equally sensitive to temperature, but this assumption is contrary to the kinetic
theory.
Common approaches for modeling decomposition

26. ·
Microbial diversity in the organic matter
decomposition and its feedback to climate change
 Indigenous resources become gradually depleted in intensively managed
cropping systems.
 N, the most important nutrient in crop production, is depleted not only by crop
harvest, crop residue removal and leaching but also through the extension of
the N cycle into the atmosphere. Similar is true for the C cycle where gaseous
forms of C including CH4 forms an open end in the atmosphere.
 Spatial heterogeneity being a considerable problem in soil microbiology, a
simple differentiation between different microbial groups dwelling in a soil
ecosystem is not enough because within these groups many taxonomic and
functional subgroups do exist that deserve special attention.
 It is thus essential to develop an understanding of the structural and
functional diversity analysis of the microbial isolates in the biogeochemical
cycling, especially of C, N and their feedback to climate change

27. Effect of crop reside management on organic C and total N content of soil under the
rice-wheat cropping system at different locations in the Indo-Gangetic Plain in
India
Reference Type of crop
residue
Duration of
study (Yr.)
Residue
management
Organic C
(%)
Total N
(%)
Beri et al
(1995)
Rice straw in
wheat and wheat
straw in rice
10 Removed
Burned
Incorporated
0.38
0.43
0.47
0.051
0.055
0.056
Sharma et al
(1987)
Rice straw in
wheat and wheat
straw inrice
6 Removed
Incorporated
1.15
1.31
0.144
0.159
Zia et al.
(1992)
Rice straw in rice 3 Removed
Incorporated
0.53
0.63
-
-
Yadvinder
Singh et al
(2000)
Wheat straw,
green manure
(GM), and wheat
straw + GM in rice
6 Removed
Incorporated
GM
Straw+GM
0.38
0.49
0.41
0.47
-
-
-
-

28. Tillage effects on organic carbon distribution in soil
organic matter size fractions of a red clayey soil
Tillage Organic C in SOM size fractions (mg C g -1 soil)
Treatment 212-
2000
μm
coarse
sand
53-212
μm
medium
sand
20-53
μm
fine
sand
5-20
μm silt
0-5 μm
silt
Sum Total
measure
d
%
recovery
Conventional
tillage
0.97 0.95 0.84 1.69 8.1 12.6 14.9 84.6
Mulch
ripping
1.04 1.34 1.00 2.09 9.0 14.5 17.2 84.3
Weedy fallow 4.47 3.57 1.90 3.15 10.4 23.5 27.9 84.2
SED 0.167 0.187 0.091 0.118 0.242

29. Carbon Sequestration
in Soil

30. C sequestration through reduced tillage
simulated change
in Corg (0-20 cm);
maize in USA;
Matson et al. 1998
ca. 5 t C/ ha

31. 0 100 200 300 400
sequestration potential (Mt C yr-1
)
Degraded land
Wetland restor.
Grassland
Agroforestry
Urban land
Rice paddies
Agroforestry
Grazing land
Cropland
Forest
Potential C sequestration through modified land use
ManagementLandusechange
Watson 2001

32. Mitigation of methane emission from soil
Vascular transportBasic requirements
1. Organic C
2. Anaerobic condition

33. Methane
‘Generic’ mitigation options for GHG
emissions from agricultural soils
Modification of irrigation pattern
Management of organic inputs
Change of crop establishment technique

34. Mid-season drainage
Alternate flooding
Aerobic rice
Irrigation Management
More methane Less methane

35. Residue retention (not incorporation) on soil
Manure incorporation in unpuddled soil
Avoiding residue burning
Organic Input Management

36. Dry seeded rice
Bed-planted rice
Crop Establishment
More methane
Less methane

37. Methane Mitigation Practices
(baseline practice is continuous flooding)
Water management Relative
mitigation (%)
Yield impact
(%)
Midseason drainage 23 0-15
Alternate drying 61 0
Pathak and Wassmann (2007)

38. Antagonism of methane and nitrous oxide
emissions
Drainage reduces methane but promotes nitrous
oxide emission
But ?

39. NH4
+
Nitrification
NO3
-
Denitrification
N2
Biological assimilation
and abiological reactions NO NO2
Aqueous phase of soil
Gaseous phase of soil
Atmosphere
NO NO2
Aerobic soil Anaerobic soil
Emission of nitrous oxide from soil
Aerobic-anaerobic
cycle produces more
nitrous oxide

40. Nitrous oxide
‘Generic’ mitigation options for GHG
emissions from agricultural soils
Improving N fertilizer management
Optimizing irrigation practices
Optimizing tillage operations
Managing organic inputs

41. Leaf colour chart
Urea tablets
Smart Nitrogen Management

42. Impact of water management and tillage on yield,
income and GWP in the rice-wheat system
Technology Yield
(kg ha-1)
Income
(US$ ha-1)
GWP (Mg CO2
eq. ha-1)
Cont. Flood 12.2a 563 3.7
Mid. Drying 12.0a 680 3.2
No-till DSR 11.1b 651 2.5
No-till trans. 11.6ab 629 2.7
Pathak et al. (2007)

43. Develop adaptation strategies
Complete mitigation not possible even
with very good management of
• Water
• Nitrogen
• Carbon

44. Adaptation strategies to climate change
Changing land-use management
Developing climate-ready crops
Diversifying crop and livestock
Improving pest management
Harnessing indigenous technical knowledge
Developing insurance and forecast systems

45. Greater absorption of sun light, better root system,
drought tolerant, photo-insensitivity, high yield
Climate-ready crops
New plant type in rice
Past Present Future

46. Waterproof rice provides flood (up to
17 days) relief for farmers
Flood and Drought Tolerant Rice
Drought resilient rice out yield
traditional varieties

47. C3 Anatomy
Change
Biochem
Change
Fine
Tuning+++ = C4
Converting Rice from C3 to C4

48. Conventional way of growing
rice

49. Resource Conserving Technologies (RCT)
1. No-tillage
2. Laser land leveling
3. Direct seeding of rice
4. Leaf colour chart for N
5. Crop diversification
Conventional RCT

50. No-till happy seeder
The machine directly drills seed into a
harvested field (without straw
removal/burning) in a single pass

51. Saves water, labor and diesel
Helps early sowing
Improves soil organic C
Reduces soil compaction
Increases fertilizer use efficiency
Reduced soil erosion
No-tillage is a win-
win technology
0.5
0.6
0.7
0.8
Initial2002
Wheat2002-03
Rice2003
Wheat2003-04
Wheat2004-05
Rice2005
Wheat2005-06
Rice2007
OrganicC(%)
Tilled
No till

52. Tillage
Conventional Unpuddled Raised bed Zero-tillage
Resource conservation technologies in rice-
wheat systems can help
Crop
establishment
Transplanting Direct-drill-seeding

53. RCTs have potential to reduce the global warming
potential (GWP)
Resource Conservation Technologies (RCTs)
How to assess and extrapolate the
GWP of various RCTs?

54. InfoRCT, a Decision Support System
For quantitative evaluation of the RCTs in terms of
Productivity
Resource use efficiency
Cost effectiveness
Environmental impact
N loss
Greenhouse gas emission
Biocide residue

56. Experiment on Rice-wheat system with RCTs
Site: Modipuram, Uttar Pradesh Duration: 4 years

57. 0
1000
2000
3000
4000
FP Mid
drain
Bed
DSR
Bed
TPR
ZT
DSR
ZT
TPR
GWP(kgCO2equi.ha
-1
)
Rice Wheat
Calculated GWP is more in the conventional system because of more methane
emission in continuously submerged condition in rice and more fuel
consumption for tillage and irrigation.
GWP in different RCTs in Modipuram

58. Global warming potential in the RW system of
various districts of Haryana
District RW area (000 ha) GWP (000 t CO2 equiv.)
Ambala 65 181
Yamunanagar 20 53
Kurukshetra 97 255
Kaithal 150 324
Sirsa 32 100
Karnal 161 391
Jind 81 154
Hissar 22 48
Panipat 69 141
Sonepat 62 120
Bhiwani __ 0
Rohtak 17 25
Gurgaon 7 13
Faridabad 18 31
Mahendragarh __ 0
Rewari __ 0
Karnal, Kurukshetra and Kaithal (3K) have more GWP
000 t CO2

59. Impact of RCTs on Yield, Income and GWP in the
RW system in Haryana
Technology Yield
(Mt)
Income
(M US$)
GWP (Mt CO2
equi.)
FP 6.38 352 1.84
Bed DSR 5.45 348 1.29
ZT DSR 5.95 437 1.33

60. Impact of RCTs on Yield, Income and GWP in the
RW system in Haryana
Technology Reduction in GWP
(Mt CO2 equi.)
Income
(M US$)
FP - 352
Bed DSR 0.54 348 + 11*
ZT DSR 0.50 437 +10
*Carbon credit @ US$ 20 per ton CO2 equiv.

61. The RCTs also offer suitable options for
adaptation to climate change
Adaptation to climate change with RCTs

62. No-till wheat is more tolerant to abrupt
temperature rise: A case for adaptation
Conventional No-till

63. Manual and small tractor drawn no-till drills for
small and medium land holdings
Dry drill-seeding without puddling Wet drum-seeding after puddling

64. Adaptation to climate change with water
harvesting and efficient water use
Climate change will
aggravate water scarcity

65. Water Harvesting
Water harvesting through construction of check dams,
ponds and in situ furrows

66. Water Saving Technologies
Laser land leveling -
A Precursor technology
Raised bed
planting
Irrigate when water is 15 cm
below surface

67. Upland and aerobic rice

68. Direct dry-seeded rice is more tolerant to
water stress: A case for adaptation
Direct dry-
seeded
Puddled
transplanted

69. Crop diversification

70. Soil N Supply
Plant N Demand
Synchronize
•Mineral
•Fertilizer
•Organic
•Residue
•GM
How to Improve N Use Efficiency and Minimize
Leakage of N into Environment?

71. Conclusion
Research on carbon sequestration in
various cropping systems in view of its long
term sustainability is needed .
Various processes involved in carbon
sequestration should be understood and
quantified
Consorted efforts should be taken to tackle
the problem in global basis

72. The RCTs mitigate global warming and help in
climate change adaptation.
They increase farmers’ income. With the benefit
of carbon credit, the income can be increased.
The Info RCT decision support system could be
used for a comparative assessment of different
RCTs for productivity, income and
environmental impact.