It is about the importance of Soil carbon.The ways for enhancing the soil carbon and how these soil carbon changes over period of time under different land use systems.

2. SOIL ORGANIC CARBON DYNAMICS: IMPACT OF LAND
USE CHANGES AND MANAGEMENT PRACTICES
Sathisha G S
IInd PhD
Dept. Of Agronomy
UAHS, SHIVAMOGGA

3. Sequence of presentation
• Introduction
• Soil organic carbon fractions
• Factors affecting soil organic carbon dynamics
• Land use changes and soil organic carbon
dynamics
• Agriculture practices and soil organic carbon
dynamics
• Research studies

4. Carbon – The Element of Life
carbon is the simplest element on the periodic table
that also has four valence electrons

5. Table.1 Carbon stores: magnitude
Location Total carbon % Carbon forms
Lithosphere 99.985 Sedimentary rocks
Organic carbon
Fossil fuels
Marine sediments
Hydrosphere 0.0076 Carbonate ions
Bicarbonate ions
Dissolved CO2
Pedosphere 0.0031 Soil organisms
Plant remains
Cryosphere 0.0018 Frozen masses
Atmosphere 0.0015 Gaseous carbon
Biosphere 0.0012 Living plants and animals

6. CARBON CYCLE

7. POPULATION
FOOD DEMAND WATER DEFORESTATION
INTENSIVE & EXTENSIVE CULTIVATION
VEHICLES
GHG’s
GLOBAL WARMING
INDUSTRIALIZATION

8. Source of carbon dioxide emission

9. Fig.1. Global green house gas emission by different sectors
IPCC (2016)

10. China, 8.1
The U.S., 5.7
India, 1.83
Russia, 1.78
Japan, 1.26
Billion metric tons perAnnumCO2
Fig.2. Carbon dioxide emission from different countries
IPCC (2016)

11. Potential climate change impact

12. Strategies to Reduce
Atmospheric CO2
Strategies
Reduce fossil
fuel
consumption
Improve
efficiency
Renewable
energy
sources
Identify sinks and
sequestration
rate
Terrestrial
Soils Plants
Aquatic
Geologic

13. Fig.3. Components of soil

15. Soil Organic
matter
Soil organic
carbon
40 %60 %
Ca, H, O, N
etc.,

16. Soil organic carbon
• Soil organic carbon is a measureable component of soil organic matter.
• Organic matter makes up just 2–10% of most soil's mass and has an
important role in the physical, chemical and biological function of
agricultural soils.
• Soils with less than 0.5% organic C are mostly limited to desert areas.
• Soils containing greater than 12 - 18% organic carbon are generally
classified as organic soils.
• Organic matter which contains C, H, O, N etc., So Carbon is one of the
part of soil organic matter which is considered as soil organic carbon.
• Organic matter (%) = Total organic carbon (%) x 1.72

17. Sources of Soil organic matter

18. plants
elements
compounds
Fig 4. Elemental and different compounds composition of Plant dry matter

19. Sugars, starches
Crude proteins
Hemicellulose
Cellulose
Fats, waxes
Lignins, phenols
Compounds
Rapid decomposition
Very slow decomposition
Rate of decomposition of different compounds
Highly resistant compounds are formed which remain in the soil for long periods: “humification”
Less rapid decomposition

20. Total Soil
Carbon
Soil organic
Carbon
Soil Inorganic
Carbon
Active
Slow
Passive

21. For Agriculture which organic pool is more
important?
Active Passive
Active

22. Soil organic carbon fractions
• Total carbon, total inorganic carbon and total organic carbon
• Potassium dichromate oxidizable carbon (PDOC)
• Potassium permanganate oxidizable carbon (PPOC)
• Cold water extractable carbon
• Hot water extractable carbon
• Soil microbial biomass carbon
• Particulate organic carbon
• Water stable aggregate associated carbon
• Light fraction organic carbon
• Mineralizable organic carbon

23. Soil organic
carbon dynamics
Climate related factors Soil related factors
Temperature
Rainfall
Parent material Soil texture
Soil pH Soil moisture
Soil microbes

24. Soil organic carbon in different land use system

25. Active and passive soil organic carbon pools as
affected by different land use types in Mizoram,
Northeast India.
Uttam kumar et al., 2017Mizoram, India

26. Management practices of different land uses.
Land uses Age
(year)
Dominant species Management practices
Forest 41 Engelhardtia spicata, Oryxylum indicum,
Helicia excelsia,
Quercus oblongata, Quercus floribunda,
Rhododendron
arboretum, Schima wallichi
Mild anthropogenic disturbances for
occasional tree felling,
frequent collection of fuelwood and other
non-timber forest
products
Agroforestry 10 to 17 Parkia timoriana, Mangifera indica,
Artocarpus heterophyllus
Regular weeding and harvest of above
ground biomass
Wet Rice
Cultivation
30 Oryza sativa Application of fertilizer.
Plantation 7 to 50 Areca nut, Mangifera indica, Elaeis
guineensis, Citrus reticulata,
Pinus roxburghii, Tectona grandis
Intercultural operations like weeding.
Current Jhum 2 Musa accuminata, Carica papaya,
Callicarpa arborea
Annual harvest of above ground biomass,
thereafter
subjected to burning.
Grassland 23 Eulalia trispicata, Imperata cylindrica,
Cyrondon dactylon
Subjected to annual burning.
Jhum fallow 7 Musa sylvestris Conservation tillage and dibbling method
of planting
Mizoram, India Uttam kumar et al., 2017

27. Fig 5. Litter inputs in different land use systems.
Mizoram, India Uttam kumar et al., 2017

28. Table 2. Soil organic carbon concentration (%) of varying lability
in different land use types (0-45 cm soil depth) of Mizoram.
Land uses Very labile Labile Less labile Non-labile Active pool
(VL+L)
Passive pool
(LL+NL)
Forest 1.07±0.21a 0.54±0.09a 0.58±0.11a 0.58±0.11a 1.61±0.29 a 1.13±0.22 a
Agroforestry 0.79±0.25ab 0.39±0.13ab 0.39±0.12ab 0.39±0.12ab 1.18±0.38ab 0.78±0.23ab
Wet Rice
Cultivation
0.67±0.03ab 0.33±0.02ab 0.32±0.02ab 0.32±0.02ab 1.00±0.08ab 0.62±0.01ab
Plantation 0.68±0.07ab 0.33±0.13ab 0.34±0.02ab 0.34±0.02ab 1.07±0.25ab 0.70±0.07ab
Current Jhum 0.55±0.05b 0.26±0.02 b 0.30±0.03b 0.30±0.03 b 0.82±0.07 b 0.56±0.05 b
Grassland 0.52±0.14ab 0.26±0.08ab 0.26±0.06ab 0.27±0.07ab 0.78±0.22ab 0.53±0.12ab
Jhum fallow 0.58±0.18ab 0.27±0.09ab 0.30±0.11ab 0.30±0.11ab 0.85±0.26ab 0.56±0.18ab
Uttam kumar et al., 2017Mizoram, India

29. Table 3. Soil carbon fraction under different land use systems in different soil
depths of Virajpet taluk, Kodagu district
PDOC: Potassium Dichromate organic carbon, PPOC: Potassium Permanganate Organic Carbon, CWEC: Cold Water
Extractable Carbon, SMBC: Soil Microbial Biomass Carbon, TOC: Total Organic Carbon, TC: Total Carbon and TIC:
Total Inorganic Carbon
Pradeepa et al., 2018UAHS, Shivamogga

30. Table 4. Effect of different land use systems on soil carbon pools in
vertisols of Central India
Land use Depth of
sample
(cm)
SOC (g kg-1) WSC (ug g-1) MBC (ug g-1) AC (ug g-1)
Forest (>40 yrs)
Madhuka longifolia and Diospyros
melanoxylon dominant
0-15 38.0a 101.6a 430.7a 1816.8a
Agriculture (soybean–wheat system) (9 yrs)
Control plot (No application of mineral
fertilizer and organic manure)
10-20 8.9e 13.8e 88.9e 311.8e
Organic plot (24 t Farm yard manure ha-
1 y-1)
0-15 14.0c 36.1c 257.8c 621.2c
Recommended dose of fertiliser (100 %
NPK based on crop specific general
recommendation)
0-15 11.0d 18.3b 201.5c 555.5c
Horticulture (25 yrs)
Mango orchard
0-15 22.0b 70.6b 355.5b 719.8b
Pramod et al., 2012Bhopal
0-15 cm is surface soil, 10-20 cm is sub surface soil

31. Table 5. Soil carbon pools and their mean residence time
under different land use systems
Land use Active pool (g
kg-1)
Mean
residence time
(Days)
Slow pool (g
kg-1)
Mean residence
time (Years)
Forest (>40 yrs)
Madhuka longifolia and Diospyros melanoxylon
dominant
2.88a 67.2a 9.70a 38.5a
Agriculture (soybean–wheat system) (9 yrs)
Control plot (No application of mineral
fertilizer and organic manure)
0.30d 24.8c 1.63c 2.30c
Organic plot (24 t Farm yard manure ha-1 y-1) 1.34b 44.9b 3.33b 17.5a
Recommended dose of fertiliser (100 % NPK
based on crop specific general
recommendation)
0.62c 39.9c 3.06b 4.50b
Horticulture (25 yrs)
Mango orchard
1.40b 35.1c 5.56d 4.80b
Pramod et al., 2012Bhopal

32. Table 6. Total organic C, Water extractable organic C, hot water soluble C, soil
microbial biomass carbon in soils of agroforestry, rice-wheat, and maize-wheat systems
in the Rupnagar district of Indian Punjab.
Land-use TOC (g kg-1) WEOC (ug g-1) HWC (ug g-1) MBC (ug g-1)
Agroforestry 8.35a 33a 335a 203a
Maize-wheat 8.06a 29a 300a 185a
Rice-wheat 6.50a 22a 173b 104b
LSD (0.05) NS NS 70 18
Benbi et al., 2012Punjab

33. Fig 6. Soil microbial biomass carbon (SMBC) under different cropping systems and
nutrient management practices.
Ghosh et al., 2003IIPR, Kanpur, UP

34. Table 7. Oxidisable organic C fractions (Mg ha-1 soil) in soils in different
layers (m) of 6-year-old orchards at EPH region of India
Sushanth et al., 2016ICAR research complex, Jharkhand

35. Table 8. Active and Passive carbon pool in soils in different layers (m) of
6-year-old orchards at plateau in EPH region of India
Orchard
Active carbon pool (Mg ha-1) Passive carbon pool (Mg ha-1)
0–0.15 0.15–0.30 0.30–0.45 0.45–0.60 Total 0–0.15 0.15–0.30 0.30–0.45 0.45–0.60 Total
Control 10.57b 7.67b 7.08a 5.38a 30.72b 7.92a 5.77b 4.72a 4.15a 22.56b
Litchi 10.94ab 8.96ab 7.53a 5.68a 33.12a 8.21a 6.94a 5.64a 4.31a 25.20a
Guava 11.88a 9.30a 7.96a 6.10a 35.42a 8.28a 6.96a 5.72a 4.63a 25.52a
Mango 12.06a 10.06a 7.89a 6.36a 36.38a 8.60a 7.26a 5.74a 4.69a 26.27a
Mean 11.36 9.00 7.62 5.88 33.87 8.25 6.73 5.46 4.45 24.89
Sushanth et al., 2016ICAR research complex, Jharkhand

36. Table 9. Total organic carbon (mg g-1) as affected by different shifting
cultivation fallow period and cultural operations at 0-10 cm surface soil
P BB AB H Mean
F23 38.8 ± 2.0 31.0 ± 1.7 28.6 ± 0.4 32.8a
F21 36. 6± 2.1 31.2 ± 2.1 25.4 ± 0.5 31.1a
F14 32.1 ± 1.8 27.9 ± 1.4 25.3 ± 0.3 28.4b
F10 25.6 ± 1.5 21.8 ± 1.6 20.7 ± 0.8 22.7c
F6 25.1 ± 1.6 22.7 ± 1.5 20.0 ± 0.3 22.6c
F3 24.1 ±2.0 21.8 ± 1.5 19.0 ± 0.4 21.6d
Mean 30.4a 26.1b 23.2c
Langmuana et al., 2014Mizoram
P, fallow period; BB, before burning; AB, after burning; H, harvesting; F23: 23-year fallow;
F21, 21-year fallow; F14, 14-year fallow; F10, 10-year fallow; F6, 6-year fallow; F3, 3-year
fallow

37. Table 10. Active carbon pool (mg g-1) and passive carbon pool (mg g-1) as affected by
different shifting cultivation fallow period and cultural operations at 0-10 cm surface
soil
Active carbon pool (mg g-1) Passive carbon pool (mg g-1)
P BB AB H Mean BB AB H Mean
F23 27.8 ± 0.7 17.3 ± 0.3 15.4 ± 0.4 20.1a 15.0 ± 1.9 13.1 ± 0.3 11.5 ± 1.7 13.2a
F21 25.1 ± 0.3 16.3 ± 0.5 15.2 ± 0.6 18.9ab 13.7 ± 2.1 11.2 ± 0.5 10.2 ± 1.8 12.1a
F14 23.0 ± 0.6 16.2 ± 0.7 15.0 ± 0.8 18.1b 11.6 ± 1.8 10.2 ± 0.7 9.1 ± 1.8 10.3ab
F10 18.1 ± 0.2 15.3 ± 0.3 13.4 ± 0.5 15.6c 10.1 ± 1.6 8.8 ± 0.8 7.5 ± 2.0 8.8b
F6 17.8 ± 0.6 14.2 ± 0.3 11.5 ± 1.1 14.6c 8.5 ± 1.4 7.6 ± 1.2 7.3 ± 1.5 7.8b
F3 17.0 ± 0.2 11.6 ± 0.7 10.2 ± 0.5 13.0d 7.4 ± 1.3 7.4 ± 1.1 7.1 ± 1.2 7.4b
Mean 21.5a 15.2b 13.5c 10.9a 9.7ab 8.9b
Mizoram Langmuana et al., 2014

38. Agronomic practices which improves soil
organic carbon
TILLAGE
RESIDUE MANAGEMENTNUTRIENT MANAGEMENT
IRRIGATION

39. Table 11. Total organic carbon, Permanganate oxidizable carbon as
influenced by irrigation, mulching and N management at 0–5 and 5–15 cm
soil depth after harvest of maize.
Treatments Total organic carbon (g/kg) Permanganate oxidizable
carbon (mg/g)
0–5 cm 5–15 cm 0–5 cm 5–15 cm
Irrigation effect
Rainfed (I0) 4.2b 4.0a 0.39a 0.41a
Irrigated (I+) 5.9a 4.1a 0.31b 0.32b
Mulch effect
Without mulch (M0) 4.7b 4.0a 0.38a 0.38a
With wheat residue
mulch @ 10 t/ha (M+)
5.4a 4.1a 0.32b 0.36a
Nitrogen effect
Control (N0) 4.5b 3.9a 0.39a 0.39a
75 kg N/ha (N75) 5.1a 4.0a 0.35b 0.38a
150 kg N/ha (N150) 5.5a 4.1a 0.31b 0.34b
Sumantha et al., 2013IARI, New Delhi

40. Table 12. Water stable aggregate associated carbon (g/kg) after maize harvest
as influenced by irrigation, mulching and N management.
Treatment Soil organic carbon (g/kg) in water stable aggregates
Large macro
aggregates
(> 2000 μm)-SOC
Small macro
aggregate
(250–2000 μm)-SOC
Micro aggregate
(53–250 μm)-SOC
Irrigation effect
Rainfed (I0) 3.1b 2.4b 1.7b
Irrigated (I+) 3.7a 2.8a 1.9a
Mulch effect
Without mulch (M0) 3.0b 2.4b 1.7b
With wheat residue
mulch @ 10 t/ha (M+)
3.5a 2.9a 1.9a
Nitrogen effect
Control (N0) 3.2b 2.3b 1.6b
75 kg N/ha (N75) 3.5a 2.7a 2.0a
150 kg N/ha (N150) 3.7a 2.8a 2.1a
Sumantha et al., 2013IARI, New Delhi

41. Fig. 8. Soil microbial biomass carbon after harvest of maize at 0–15 cm soil depth
as influenced by irrigation, mulch and nitrogen management
Sumantha et al., 2013IARI, New Delhi

42. Table 13. Effect of 10 years of reduced tillage and nutrient
sources on soil carbon fractions at the 0–20 cm depth.
Treatment TOC
(Mg ha-1)
OOC
(Mg ha-1)
VLC
(Mg ha-1)
LC
(Mg ha-1)
LLC
(Mg ha-1)
NLC
(Mg ha-1)
POC
(Mg ha-1)
MBC
(mg g-1)
CT 11.14c 2.52 2.02b 0.29bc 0.21a 8.62 0.55c 83.92c
RT 12.65b 3.28 2.72a 0.31c 0.25a 9.38 1.07b 105.40b
MT 14.42a 3.66 2.84a 0.55a 0.27a 10.76 1.58a 122.31a
100% OS 14.02g 3.59 2.77g 0.47g 0.35g 10.43 1.12g 117.84g
50% OS +50%
IOS
12.51hi 3.27 2.66g 0.39gh 0.26h 9.24 0.85i 95.71hi
100% IOS 11.69i 2.59 2.04h 0.29h 0.22gh 9.10 0.83hi 88.12i
Fallow 23.70 6.19 3.64 0.34 2.21 17.51 2.72 73.22
No fertilizer 9.66 3.73 1.50 0.37 1.86 5.93 0.53 138.94
Prasad et al., 2010UAS, Bangalore
OOC- Oxidizable organic carbon, POC-Particulate organic carbon, MBC-Microbial biomass carbon

43. Tillage practices adopted in various tillage treatments.
Tillag
e
No. of
tillage
operation
s taken up
Timing of tillage
operation
Purpose of
the
operation
Number of
inter
cultivation
s
Timing of tillage
operation
Purpose of
the operation
CT 3 Summer season, before
sowing after the receipt of
rains and just before
sowing
Moisture
conservation,
seedbed
preparation,
3 Thrice during
vegetative growth
depending on
rainfall and weed
growth
Weeding,
moisture
conservation
RT 2 Before sowing after the
receipt of rains and just
before sowing
Moisture
conservation,
seedbed
preparation,
2 Twice during
vegetative growth
depending on
rainfall and weed
growth
Weeding,
moisture
conservation
MT 1 Before sowing Opening of
the furrow
for sowing
1 Once during
vegetative growth
depending on weed
growth
Weeding

44. Experimental details, crops cultivated during the study
period.
Year Rainfall (mm)
received during the
cropping season
(June– December)
Crop grown during the
rainy season (June–
December)
Recommended
dose of NPK
(kg ha-1)
2000 454.2 Finger millet 50:40:25
2001 486.6 Horsegram 12.5:25:12.5
2002 220.0 Finger millet 50:40:25
2003 419.7 Finger millet 50:40:25
2004 719.8 Pigeonpea 25:50:25
2005 1049.0 Finger millet 50:40:25
2006 405.6 Pigeonpea 25:50:25
2007 742.4 Finger millet 50:40:25
2009 525.1 Finger millet 50:40:25
2010 733.4 Pigeonpea 25:50:25

45. Table 15. Effect of levels of biochar on TOC, labile soil organic carbon
pools at panicle initiation stage and harvest under aerobic rice cultivation
Treatment
s
TOC (g kg-1) PDOC (g kg-1) PPOC (mg kg-1) SMBC (mg kg-1) CWEC (mg kg-1)
Panicle
initiation
Harvest Panicle
initiation
Harvest Panicle
initiation
Harvest Panicle
initiation
Harvest Panicle
initiation
Harvest
T1 4.64 5.24 4.10 5.00 431.86 369.10 269.50 212.61 164.34 243.43
T2 5.08 5.31 4.15 5.40 429.12 356.41 236.70 191.67 210.14 297.68
T3 8.29 8.74 7.12 5.93 639.43 686.39 479.40 496.78 332.41 373.17
T4 8.36 8.95 7.37 6.10 710.61 690.41 494.50 507.71 363.17 397.08
T5 8.48 9.90 4.90 7.39 467.38 621.38 312.70 529.79 263.67 330.61
T6 8.70 9.94 7.39 7.47 498.21 676.43 329.40 546.79 278.67 347.83
T7 8.80 10.90 5.90 7.63 563.89 717.34 336.70 576.08 309.41 360.03
T8 8.87 13.21 6.12 7.98 584.09 768.41 358.80 580.81 310.96 390.96
T9 8.94 11.17 6.28 8.07 681.40 786.31 381.40 598.61 316.61 408.63
T10 8.93 11.78 6.63 8.29 693.07 841.36 409.40 603.09 320.43 416.18
T11 9.04 12.13 6.92 8.58 709.36 873.12 439.30 618.13 361.67 435.61
T12 9.42 13.90 7.05 8.92 718.01 891.43 440.67 671.01 368.18 457.31
T13 9.49 12.70 7.14 8.97 723.61 901.63 477.61 656.41 393.17 445.00
T14 9.54 13.28 7.21 9.21 738.37 928.18 485.30 673.73 395.63 449.00
T15 9.64 13.75 7.42 9.36 757.46 941.67 494.50 680.09 401.43 455.18
T16 9.93 14.87 7.62 9.79 773.43 996.67 512.61 709.30 403.71 475.00
S. Em± 1.35 1.55 0.99 0.14 85.35 12.22 63.87 8.85 51.09 45.38
C.D.
(p=0.05)
NS NS NS 0.40 NS 35.28 NS 25.56 NS NS
Arun kumar et al., 2018UAHS, Shivamogga

46. Treatment details
T1: Absolute Control
T2: 100:50:50 NPK kg ha-1 (Only RDF)
T3: FYM @ 5 t ha-1
T4: FYM @ 10 t ha-1 (POP)
T5: CS - Biochar @ 2 t ha-1
T6: CS - Biochar @ 4 t ha-1
T7: CS - Biochar @ 6 t ha-1
T8: CS - Biochar @ 8 t ha-1
T9: CS - Biochar @ 2 t ha-1 + FYM @ 5 t ha-1
T10: CS - Biochar @ 4 t ha-1 + FYM @ 5 t ha-1
T11: CS - Biochar @ 6 t ha-1 + FYM @ 5 t ha-1
T12: CS - Biochar @ 8 t ha-1 + FYM @ 5 t ha-1
T13: CS - Biochar @ 2 t ha-1 + FYM @ 10 t ha-1
T14: CS - Biochar @ 4 t ha-1 + FYM @ 10 t ha-1
T15: CS - Biochar @ 6 t ha-1 + FYM @ 10 t ha-1
T16: CS - Biochar @ 8 t ha-1 + FYM @ 10 t ha-1

47. Fig. 9. Changes in Walkley and Black organic carbon as influenced by application of FYM
and fertilizers after wheat grown in a 6-year-old pearl millet–wheat cropping system.
Manohara et al., 2010IARI, New Delhi

48. Fig. 10. Changes in microbial biomass carbon as influenced by application of FYM and
fertilizers after wheat grown in a 6-year-old pearl millet–wheat cropping system.
(mgkg-1)
Manohara et al., 2010IARI, New Delhi

49. Treatment details
Main plot
FYM =Application of farmyard manure to rice,
RS=Incorporation of rice straw before seeding wheat
FYM+RS =application of farmyard manure to rice and incorporation of
rice straw before seeding wheat
CK =A control with no addition of organic amendment
In Sub plot four rates of fertilizer N, 0, 60, 120, and 180 kg N ha−1,
applied as urea to both rice and wheat.
• All treatments received a basal application of 26 kg P ha−1 as single
superphosphate and 25 kg K ha−1 as potassium chloride to wheat each
year.
• In the FYM and FYM+RS plots, farmyard manure (dry weight basis)
at 15 Mg ha−1 during the first three years and 10 Mg ha−1 thereafter
was applied three weeks before transplanting rice each year.

50. Table 16. Influences of organic amendments and fertilizer N rates on soil total organic C , water-
extractable organic C, hot water-soluble organic C, and KMnO4-oxidizable organic C in the surface
(0–7.5 cm) soil layers after 11 years of rice-wheat cropping
Treatment TOC
(Mg C ha-1)
WEOC
(kg C ha-1)
HWOC
(kg C ha-1)
KMnO4-C
(kg C ha-1)
Organic amendment
CK (Control) 5.58a 20.9a 179a 130a
FYM application to rice 7.46b 37.6b 246b 420c
RS (Rice residue incorporation before wheat seeding ) 7.46b 34.2b 231b 303b
FYM + RS 10.24c 38.3b 311c 538d
N rate
0 7.45a 30.6a 236a 353a
60 7.71a 33.4a 237a 352a
120 7.77a 31.1a 235a 325a
180 7.81a 31.1a 260a 364a
LSD 0.05
Organic amendment 0.45 4.2 31.3 49.6
N rate NS NS NS NS
Organic amendment × N rate NS NS NS NS
Dinesh et al., 2010PAU, Ludhiana

51. Table 17. Influences of organic amendments and fertilizer N rates on basal soil
respiration (BSR), mineralizable C (Cmin), microbial biomass C (MBC) in the surface
(0-7.5 cm) soil after 11 years of rice-wheat cropping
Treatment BSR mg CO2-C kg-1 h-1 Cmin mg C kg−1 MBC mg C kg−1
Organic amendment
CK 0.22a 185a 115a
FYM 0.26ab 261b 185c
RS 0.22a 246b 147b
FYM + RS 0.30b 355c 272d
N rate
0 0.24a 281a 167a
60 0.24a 281a 175a
120 0.26a 281a 184a
180 0.22a 281a 192a
LSD 0.05
Organic amendment 0.04 45 30
N rate NS NS 20
Organic amendment × N
rate
NS NS NS
PAU, Ludhiana Dinesh et al., 2010

52. Treatment details
4 years experiment
4 Nutrient regimes
I. Control (CK)
II. Exclusively chemical fertilizers (CF)
III. Integration of chemical fertilizers with farmyard manure (FYM) (CM)
IV. Combined application of chemical fertilizers and wheat straw (CS)
• 150 kg N ha -1, 45 kg P2O5 ha -1 and 60 kg K2O ha -1 for each plot
• FYM and wheat straw in the treatment CM and CS were 1500 and 2500 kg
ha -1 each year, respectively
2 soil water regimes
I. Continuous waterlogging (CWL): plots were flooded to a depth of 3–5
cm throughout the rice growth period,
II. Alternate wetting and drying (AWD): plots were allowed to dry up for 2
weeks before submerged (3–5 cm above the soil surface) for 3 weeks
after transplanting, and then re-flooded to waterlogging for 2 weeks.

53. Table 19. Effect of soil nutrient and moisture regimes on paddy soil total
organic carbon, easily oxidizable organic carbon (EOC), particulate organic
carbon (POC) and light fraction organic carbon (LFOC) (g kg-1)
Nutrient
regimes
TOC (g kg-1) EOC (g kg-1) POC (g kg-1) LFOC (g kg-1)
CWL AWD CWL AWD CWL AWD CWL AWD
CK 11.01e 10.32e 2.29c 2.47c 3.09c 3.01c 3.93cd 3.57d
CF 13.57d 12.13de 2.91b 2.63c 3.72c 3.69c 4.65c 4.42c
CM 19.43ab 17.10bc 4.01b 5.12a 4.75b 6.08a 6.28b 7.50a
CS 21.73a 17.89c 4.13b 5.95a 5.82ab 6.35a 6.78ab 7.58a
Changming et al., 2005Beijing, China.

54. CONCLUSION