1. The Societal Value of Soil Carbon Sequestration Rattan Lal Director, Carbon Management and Sequestration Center The Ohio State University, Columbus, Ohio

2. Global Climate Change ∆T over the 20th century………….+0.6+0.2°C Rate of ∆T increase since 1950……+0.17°C/decade Sea level rise over 20th century…..+0.1-0.2 m Change in precipitation…………..+0.5-1%/decade Extreme events…………………….+2-4% ………..IPCC (2001)

3. Atmospheric Concentration of Trace Gases Between 1750 and 1999 IPCC (2001)

4. Global Carbon Budget IPCC (2001)

6. How Much C is in Soil? (i) Soil organic C = 1550 Pg Soil inorganic C = 750 Pg Total= 2300 Pg (ii) Atmosphere= 720 Pg (iii) Biota= 560 Pg (iv) Ocean= 38,000 Pg SOC pool = 40 - 100 Mg/ha

7. Soil vs. Atmospheric C 1 Pg (billion tonnes) of soil C = 0.47 ppm of CO 2

8. Mean Residence Time of C in Different Pools The average atom of C spends about: 5 yrs in the atmosphere, 10 yrs in vegetation (including trees), 35 yrs in soil, and 100 yrs in the sea. Residence time = pool / flux The residence time is longer in soils of high latitude.

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15. Depressed oxidation of CH 4 C burial Effects of Soil Erosion and Redistribution on Trace Gases Emissions. CO 2 CH 4 N 2 O C burial DOC CH 4 N 2 O Erosion Redistribution Depression

16. Soil erosion and C emission

17. 1.14 x 10 15 g/yr decomposition and emission to the atmosphere 3.99 x 10 15 g/yr stored within the terrestrial ecosystem 0.57 x 10 15 g/yr transported to the ocean 5.7 x 10 15 g/yr C displaced due to erosion 1500 x 10 15 C in world soil C sequestratio n Global soil erosion and dynamics of soil organic carbon (Lal, 1995).

18. Historic Soil C Loss World soils…….. 66-90 Pg U.S. soils……….. 5 Pg Recoverable C…. 50-75% Time horizon……25-50 yrs

19. The magnitude of soil C loss 30-40 Mg/ha Agricultural soils now contain lower SOC pool than their potential, and thus have a C sink capacity.

20. Anthropogenic emissions (1850-2000) 1. Fossil fuel:270 + 30 Pg 2. Land use change:136 + 55 Pg Soil:78 + 12

21. Soils and Global Warming Can we use soils and vegetation for scrubbing a dirty atmosphere?

22. Carbon Sequestration It is the net removal of CO 2 from the atmosphere into the long-lived pools of C such as vegetation and soil by biotic and abiotic processes.

23. A New Definition of Agriculture It is an anthropogenic manipulation of carbon through: uptake, fixation, emission and transfer. C U + C F = C E + C T

24. How to Increase Soil C A.Increase (i)density of C in the soil (ii)depth of C in the profile B.Decrease (i)decomposition of C (ii)losses due to erosion

25. Increasing Density of C in Soil PlowNo till Residue removedResidue return Bare fallowCover crops Low inputJudicious input (precision farming, IPM) No water controlWater conservation and supplemental irrigation Fence to fence croppingForestation/vegetation on marginal lands/CRP

27. Disposition of Organic Residues CO 2 60-80% 3-8% 10-30% Biomass (soil organisms) Nonhumic compounds (polyuronides, acids, etc.) Complex humic compounds Humus 10-35% Organic residues 100 grams

28. Mulch Rate and SOC Content in Ohio No till: SOC (Mg ha -1 ) = 15.2 + 0.321 MR = 0.68 Plow till: SOC (Mg ha -1 ) = 11.9 + 0.266 MR = 0.72

29. Cover Crop and SOC Pool in a Miamian Soil in Ohio TreatmentSOC (0-30 cm) Kg/m 3 Relative SOC (5 yr) Continuous corn Corn-soybean Continuous soybean Corn-soybean-wheat Alfalfa Birdsfoot trefoil White clover Kentucky blue grass Tall fescue Smooth bromegrass Fallow 2.30 2.34 2.37 2.36 2.33 2.45 2.36 2.28 2.72 2.75 2.58 100 102 103 101 107 103 118 120 112 Lal (1998)

34. SOC pool in 0-30 cm depth over a 60-year period at Coshocton, OH (Hao, Lal, Owen, 2002)

35. Biofuel vs. Fossil Fuel 1 gallon of biofuel = 0.5 gallon of oil/diesel saving

36. Global Cooling Potential GCP = (GWP) -1 Conservation tillage Cover crops Nutrient management Soil restoration CRP/WRP Land use and afforestation 100-1000 Kg C/ha/y

37. Land Use and Soil C Sequestration in the U.S.

38. U.S. Emissions and Soil C Sequestration Total U.S. gas emissions……………….1500 MMTC/yr Emission from agricultural activities…133 MMTC/yr Net soil C sequestration potential……..332 MMTC/yr

39. Agricultural Soils and Mitigation of GHE 1 bbl of diesel = 220 L 1 L of diesel = 0.73 Kg C  1 ton of C = 1370 L of diesel = 6.2 bbl of diesel C sequestration potential of ag soils = 2 billion barrels/yr

40. Potential of Global Soil C Sequestration 1-2 Pg C/yr or 24% of the total emissions by fossil fuel combustion.

41. Is Soil C Sequestration A Free Lunch? Not really! Additional N, P, S etc. are needed for humification of residue C. There are hidden C costs of RMPs.

42. Building Blocks of Humus C is only one of several constituents of humus. Other constituents are H, O, N, P, S and micronutrients.

43. Nutrients Needed for Humification How much N, P and S are needed to convert residue into humus? How to adjust fertilizer use for desired productivity and converting residue into humus?

44. Elemental Composition of Humus and Crop Residues RatioHumusCrop Residue C:N C:P C:S 10-15 40-60 60-80 70-100 200-400 400-800

45. Additional Nutrients Required to Convert 10,000kg of Carbon into Humus NutrientQuantity needed (kg) NPSNPS 833 200 143

47. Energy-based Input and C Sequestration 1. What is the carbon budget in relation to: (i) Fertilizer use (ii) Manure application (iii) Tillage practices (iv) Irrigation (v) Liming of acid soils 2.C sequestration occurs only if output > input.

48. Hidden C costs of tillage methods

49. Hidden C cost of fertilizers

50. Hidden C cost of pesticides

51. Hidden C cost of irrigation

52. Farming Carbon 1.Commodification of C (price) 2.Incentives

53. Societal Value of Carbon Nutrients and H 2 O contained in 1 kg of humus = $0.2  Rational price = $200/ton

54. Undervaluing a Commodity Undervaluing carbon has and will perpetuate its misuse.

55. 01020304050 0 40 30 10 20 Time after conversion (yrs) Cumulative C sequestration (M/ha)

57. Economics of C Sequestration 1.Assessing economics of C by itself is not adequate. 2.Evaluate the entire package of benefits: (i) To the farmer (ii) To the society

58. Can soil C sequestration mitigate the greenhouse effect?

59. Dependency on Carbon Modern civilization is hooked on carbon. It needs rehabilitation, in a big way.

60. Role of soil and biomass C in global C management. Source: The Global Energy Technology Strategy, Battelle, Washington, D.C., 1998

61. Soil C Sequestration It is a:Development challenge in the tropics and sub-tropics. Policy reform and implementation challenge in developed countries.

62. A Bridge to the Future C sequestration in soil and vegetation is a bridge to the future. It buys us time while alternatives to fossil fuel take effect. It is a good thing to do, regardless of what happens to the climate. It is truly a win-win strategy.