The Role of Soil Organic Matter in the Global Carbon Cycle

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1 The Role of Soil Organic Matter in the Global Carbon Cycle R. Lal Carbon Management and Sequestration Center The Ohio State University Columbus, Ohio USA

2 The Carbon Civilization World Primary Energy Consumption, Quad = 1.06 EJ

3 Energy Release by Fossil Fuel Combustion C + O 2 CO kj/mole The addiction of C civilization

4 Price of Oil 2001 May 2008 Story, 2008

5 The March of Oil Price Story, 2008

6 The Energy Cost Increase in oil price by $1/barrel means additional $7.4 billion cost to the cardriven culture of the U.S.

7 World Population Growth and CO 2 Emissions Global population Atmospheric carbon dioxide Yea CO2 (ppm)

8 Population growth and CO 2 emissions in China Population CO 2 Emissions CO2 Emission (Million metric ton, Tg/yr) Population (millions) Years

9 Population growth and CO 2 emissions in India Population CO 2 Emissions CO2 Emission (Million metric ton, Tg/yr) Population (millions) Years

10 Energy Use and CO 2 Emission a. 1 MWh of energy = Mg C b. Total emissions: I. Between 1850 and 2000 = 300 Pg II. Between 2000 and 2100 = Pg c. Rate of emission: I = 5.5 Pg/yr II = Pg/yr

11 Global Carbon Budget Parameter 1980 s 1990 s 2000 s Pg C/yr I. Sources Fossil Fuel Combustion Land Use Conversion TOTAL II. Known Sinks Atmosphere Ocean Land TOTAL III. Fugitive CO 2 IV. CO 2 ppm s s s

12 Fossil Fuel Combustion and Atmospheric CO 2 4 Pg of fossil C combustion = 1ppm of CO 2 in the atmosphere Stabilization of atmospheric CO 2 at 580 ppm = ( ) x 4 = 800 Pg of C emission 1 Pg of SOC pool = 0.47ppm CO 2 in the atmosphere

13 Biota 560 Gt MRT = 5Yr 60 Gt/yr Soils 2,500 Gt (i) SOC - 1,550 Gt (ii) SIC Gt MRT = 25Yr Gt/yr Deforestation Gt/yr (photosynthesis) Plant respiration Gt/yr 60 Gt/yr (soil respiration) Accelerated soil erosion Gt/yr (erosion) Gt/yr (deposition) Biofuel offset? MRT = 6Yr Atmosphere 780 Gt +3.3 Gt/yr 90 Gt/yr 92.3 Gt/yr 7.5 Gt/yr Fossil fuel combustion Ocean 38,400 Gt Gt/yr (i) Surface layer: 670 Gt (ii) Deep layer: 36,730 Gt (iii) Total organic: 1,000 Gt Fossil Fuels 4,130 Gt (i) Coal: 3,510 Gt (ii) Oil: 230 Gt (iii) Gas: 140 Gt (iv) Other: 250 Gt Mean Residence Time (MRT) = 400Yr

14 Biotic Pool = 600 Pg SOC Pool = 1550 Pg SIC Pool = 950 Pg

15 Terrestrial and Geologic Sequestration Geologic Sequestration (EOR, CBM) Geologic Pool Fossil Fuel Combustion 7.5 Pg/yr Anthropogenic Emissions 9.4 Pg/yr Atmospheric Enrichment 4.1 Pg/yr Terrestrial Pool Deforestation Soil Cultivation 1.9 Pg/yr Terrestrial Sequestration

16 Uses of Crop/Agricultural Residues Agricultural Residues Retention on Soil Fodder Burning/ Biochar Incorporating Mulching (NT) Stall Feeding Manure Management Grazing Fuel Traditional Fuel Modern Fuel Co- Combustion Cellulosic Ethanol

17 Managing Crop Residues for Carbon Sequestration Carbon Sequestration With Crop Residue Management Soil Application Biofuel Burial Under Ocean Humification 10-15% Off-Setting Emissions Energy Cost of Transport Erosion Loss of Nutrients

18 CO 2 Utilization and Recycling Rather than treating it as a waste (garbage) to be disposed of underground or under the ocean, industrially emitted CO 2 is a resource and an important raw material for: (i) chemical and biological products (bio-economy) (ii) Photosynthetic products (terrestrial/marine biosphere)

19 Residence Time in Soil Atmospheric C pool = 760 Pg (+ 3.5 Pg yr -1 ) Link between terrestrial and atmospheric C pool Terrestrial C Pool = 2860 Pg Pg C/yr SOC = 1550 Pg SIC = 750 Pg Biotic Pool = 560 Pg (-1.6 Pg yr 1 )

20 Adverse Impacts of Depletion of Soil Organic Matter on Soil Quality and Ancillary Ecosystem Services Depletion of Soil Organic Matter Decline in Soil Structure Disruption in Elemental Cycling Decline in Productivity of Aquatic Ecosystems Reduction in Soil Fauna & Flora Decline in Biomass Input into Soil Crusting Compaction Decline in Microbial Processes Depletion of Soil Fertility Reduction in NPP Increase in Nonpoint Source Pollution and Hypoxiaa Runoff and Erosion Loss of Soil Biodiversity Elemental Imbalance Adverse Effects on Plant Growth Decline in Quantity and Quality of Water Resources Soil Physical Degradation Soil Biological Degradation Soil Chemical Degradation Decline in Soil Quality

21 Management Conservation Tillage Prescribed Grazing Land Use Integrated Nutrient Management Change High Biomass Rotations (Bioenergy Plantations) Soil Quality SOC Soil Organisms Water Holding Capacity Infiltration Rate Soil Structure Ecosystem Services Air Quality Water Quality Productivity Fewer Pollutants Less Dust Less Sediment Drought and Disease Resistance Mitigation of climate change Managing soil organic matter as the key to soil, air, and water quality (Redrawn from Andrews et al., 2006)

22 Estimates of Global and Regional Potential of Soil C Sequestration 1. World: Pg C yr USA: Tg C yr India: Tg C yr Iceland: Tg C yr Brazil: Tg C yr Western Europe: Tg C yr -1

23 Terrestrial Carbon Sink Capacity Prehistoric C loss = 320 Pg (Ruddiman, 2003) Loss since 1850 = 136 Pg (IPCC, 2000) Total loss = 456 Pg = 114 ppm CO 2 (Boeckert, 2007) Assuming recovery of 40-50% = ppm (50 ppm)

24 Soil C Dynamics Relative Magnitude of SOC Pool land use conversion subsistence farming, none or low off-farm input, soil degradation new equilibrium adoption of RMPs soil C sink capacity Rate X Y Maximum potential Attainable potential Accelerated erosion Innovative technology II Innovative technology I Time (Yrs) Fig. 3 A schematic of the soil C dynamics upon conversion from a natural to agricultural ecosystem, and subsequent adoption of recommended management practices (RMPs). In most cases, the maximum potential equals the magnitude of historic C loss. Only in some soil-specific situations, the adoption of RMPs can increase SOC pool above that of the natural system. An example of this is acid savanna soils of South America (Llanos, Cerrados) where alleviation of soil-related constraints can drastically enhance the SOC pool.

25 Production Agriculture: A Success Story Agronomic Pedosphere Biosphere Production

26 Linked Cycles in the Soil-Plant Plant- Atmosphere Continuum Carbon Cycle Nitrogen Cycle Atmosphere Water Cycle Soil KEY PROCESSES Photosynthesis Respiration Biomass Decompositions Humus Formation (SSSA, 1992) Precipitation Evapotranspiration Infiltration Runoff Fixation Mineralization Decomposition Leaching Loss

27 Linked Cycles in the Soil- Plant-Atmosphere Continuum Carbon Cycle Nitrogen Cycle Atmosphere Water Cycle Soil KEY PROCESSES Photosynthesis Respiration Biomass Decompositions Humus Formation (SSSA, 1992) Precipitation Evapotranspiration Infiltration Runoff Fixation Mineralization Decomposition Leaching Loss

28 Strategies for Soil C Sequestration Baseline Mulch Farming Soil Carbon Sequestration Residence Analysis Soil Aggregation No-till NPP Life Cycle Analysis Root Turnover INM Microbial Processes Depth Distribution Humification Illuviation Water/Soil Conservation Cover Cropping Soil Quality Nutrient Cycling Coupled Cycling Complex Systems Measurement & Monitoring Processes Practices Impact

29 Recommended Agricultural Practices and Soil Carbon Recommended practices Conservation tillage Winter cover crop Soil fertility management Elimination of summer fallow Forages based rotation Use of improved varieties Organic amendments Water table management/irrigation Lal et al., 1998 CCX=500 lbs CO 2 /acre/yr C sequestration potential (Mg C/ha/yr)

30 Rates of Soil C Sequestration in Ohio No-Till Farming = kgc/ha/yr NT + Cover Cropping = kgc/ha/yr NT+CC+Manure = kgc/ha/yr

31 U. S. Millennium Goals (2015) 1. Eradicate extreme poverty and hunger 2. Achieve universal primary education 3. Promote gender equality and empower women 4. Reduce child health 5. Improve maternal health 6. Combat HIV/AIDS, malaria and other diseases 7. Ensure environmental sustainability 8. Develop a global partnership for development

32 Food Versus Fuel Converting corn grains and soybeans into biofuel is creating competition between 1 billion hungry stomachs and car tanks

33 Crop yield and productivity effects of SOC pool Fertilized Crop Yield Unfertilized Yield SOC Pool SOC Pool

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35 U.S. and Global Energy Needs 1 Quad = BTU Current U.S. Energy Consumption = 100 Quads/yr Projected Increase in Demand = 1.5%/yr in the U.S. World Energy Consumption = 400 Quads/yr Projected Increase in Demand = 2.5%/yr

36 Biofuels From Crop Residue Modern agriculture can generate = 10 Mg/ha of biomass Biomass energy value = 16x10 6 BTU/Mg Tal cereal residue produced in the U.S. = 350 Tg/yr Gross biofuel energy value of residues = 6 Quads/yr Net energy value = 3 Quads/yr Energy Value of 33% of the residue = 1 Quad/yr Energy conservation can save upto 30% of energy use

37 One Billion Ton Cellulosic Feedstock The goal is to produce 1 billion ton of lignocellulosic feedstock 2030 vision: 30% biofuel by 2030

38 Rates of Corn Stover Retention and Soil Properties at Coshocton, OH Soil Property/yield Regression equation R 2 Middens (#/m 2) Hydraulic conductivity (mm/h) Bulk density (g/cm 3 ) Organic Carbon (Mg/ha) Corn Height (cm) Grain yield (t/ha) Y= 1.7x Y= x x Y= 0.003x x Y= -0.11x x Y= -0.81x x Y= -0.06x x Blanco-Canqui, Lal and Owen (2006).

39 Biofuel From Industrial CO 2 and SOC Sequestration Bioreactors Bioenergy Algae Ethanol Biodiesel Biochemicals Residues Nutrient- Enriched & Biochar/ Compost Cynobacteria Soil Carbon Sequestration Application on Ag. Soils

40 Ecological Footprints of Crop Residues Removal for Biofuel Production Cellulosic ethanol Decomposition of lignin and cellulose CO 2 evolution Microbial Processes Sugar Fermentation Conversion of starch to sugar Grain-based ethanol

41 Energy Efficiency vs. Residue Removal Meeting 1% of energy needs can seriously jeopardize nations/world soil and water resources Improving energy use efficiency can reduce demand by 20-30%

42 Carbon Debt Upon Conversion of Native Ecosystems to Biofuel Plantations (Fargione et al., 2008) Former Ecosystem Tropical Rainforest Peatland Rainforest Tropical Rainforest Cerrado Wooded Cerrado Woodland Central Grassland Abandoned Cropland Abandoned Cropland Marginal Cropland Biofuel Palm Biodiesel Palm Biodiesel Soybean Biodiesel Sugarcane Ethanol Soybean Biodiesel Corn Ethanol Corn Ethanol Corn Ethanol Prairie Biomass Ethanol Carbon Debt (Mg C/ha) Soil Biomass Total Debt Allocated to Biofuel (%) Annual Payment (Mg C/ha/yr) Time to Repay C Debt (yr) No debt

43 The Economist $ food index Economist, 2007

44 Estimates of Under-Nourished People (FAO, 2006) Region India Sub-Saharan Africa Asia/Pacific China Latin America/Caribbean Near East/North Africa Transition Countries Industrialized Countries TOTAL Developing Countries Population (10 6 ) % of Total

45 Estimates of Under-Nourished People (FAO, 2006) 1% 1% India 6% 4% 26% SSA Asia/Pacific 18% China 19% 25% Latin America/Caribbean Near East/North Africa Transition Countries Industrialized Countries

46 Mean Crop Yield in India, Kenya and Developed Countries (FAO, 2005) Crop Rice Wheat Maize Sorghum Cowpea Chickpea Ethiopia Yield (kg/ha) India Developed Countries

47 Areas where current population exceeds potential agricultural capacity

48 Economics of Residue Removal for Biofuel

49 Estimated Increase in Food Production in Africa by Increase in SOC Pool by 1 Mg C/ha/yr (Lal, 2006) Type Grains Roots and Tubers Total Total Annual Increase (10 6 Mg/yr)

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51 Commodification of soil C How can soil C be made a commodity that can be traded like any other farm product?

52 The value of soil carbon Value to farmer: for soil quality enhancement Value to society: for ecosystem services

53 Societal value of soil carbon Reduction in erosion and sedimentation of water bodies. Improvement in water quality. Biodegradation of pollutants. Mitigation of climate change.

54 On-farm value of soil carbon The quantity of NPK, Zn, Cu etc. and H 2 O retention in humus. Improvements in soil structure and tilth. Decrease in losses due to runoff, leaching and erosion. ~ $200/ton

55 Need for determining a just value of soil carbon Under valuing a resource can lead to its abuse. It is important to identify criteria for determining the societal value of soil C, and using it for trading purposes.

56 Trading C Credits The C market may reach $ trillion by We need to make this market accessible to land managers.

57 Trading Carbon

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59 Tragedy of Crop Removal Indiscriminate removal of crop residue is taking soil for granted and treating it as dirt. Why is this so?

60 Taking Soils for Granted Is it because: We are seduced by the short-term economic gains? Our knowledge of soil processes is fragmentary and distorted? We forget history (e.g., The Dust Bowl)? We are desperate about the energy needs? and We are not cognizant of the basic laws of ecology?

61 Four Laws of Ecology 1. Everything is connected to everything else. 2. Everything must go somewhere. 3. Nature knows best. 4. There is no such thing as a free lunch.... Barry Commoner (1971)

62 Soil and Survival Upon this handful of soil our survival depends. Husband it and it will grow our food, our fuel, and our shelter and surround us with beauty. Abuse it and the soil will collapse and die, taking humanity with it. From Vedas Sanskrit Scripture 1500 BC

63 The Balancing Act We may utilize the gifts of Nature just as we choose, but in Her books, the debits are always equal to the credits. M.K. Gandhi

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