Sustainable Management and Carbon Sequestration in Soils of Africa

Transcription

1 Sustainable Management Carbon Sequestration in Soils of Africa Dr. Rattan Lal Carbon Management The Ohio State University Marrakesh, Morocco November

2 SOC AND SOIL HEALTH Physical I. Water Increase retention Decreases drought Reduces runoff erosion Decreases infiltration Improves filtration II. Structure Increases aggregation Improves aeration Reduces crusting compaction Improves tilth Eco-physical Ecological I. Elemental Cycling Improves cycling (N, P, S) Increase physio-chemical activity Increases use efficiency of N, P, S, H 2 O II. Productivity Increases productivity Improves produce quality Enhances stability Soil Organic Carbon Chemical I. Soil Fertility Reservoir of plant nutrients Increases N, P, S II. CEC Increases buffering Decreases leaching Increases surface area Biochemical Biological I. Biodiversity Improves soil biota Increases cycling Provides energy II. Activity Increase MBC Increases biopores Lal (2016) 2

3 THRESHOLD/CRITICAL LEVEL Threshold/Critical Level/Tipping Point: Soil processes properties have threshold levels.beyond threshold level, re is a drastic regime change. What is threshold level of SOC in root zone profile for major soils of Africa for principal l uses? 3

4 CROP YIELD INCREASE WITH INCREASE IN SOC BY 1Mg C/ha Crop Yield Increase (kg/ha/mg C) Maize Soybean Wheat Rice Sorghum Millet Beans Lal,

5 SOIL EROSION AS A CARBON SOURCE World 1.1 Pg C/y USA.. 15 Tg C/y Brazil 60 Tg C/y India Tg C/y Icel Tg C/y ( Tg C/1000 yr) Emission Avoidance by Conservation- Effective Measures 5

6 GLOBAL POTENTIAL OF SOC SEQUESTRATION (Pg C/YR) Cropl: Grazing l: Salt-affected soils: Desertified soils: Total: Lal (2010) 6

7 CREATING POSITIVE C BUDGET Losses Gains Gains Losses Biochar Compost Cover Crops Root Biomass Crop Residues Erosion Leaching Decomposition Residue Compost Root Biomass Erosion Leaching Decomposition Soil Carbon Sequestration Soil Carbon Depletion 7

8 TECHNOLOGICAL OPTIONS FOR SOIL CARBON SEQUESTRATION Conservation Agriculture No till Residue mulch Integrated nutrient management Cover cropping Use of Organic Amendments Compost Manure Biochar Vermiculture Technological Options to Create a Positive Soil C Budget Complex Farming Systems by Integration of Cropping with: 1. Livestock 2. Trees 3. Urban Ecosystems 4. Biofuel Plantations Restoration of Degraded Ls Eroded lscapes Salinized ls Mined ls Depleted ls 8

9 SOIL MICROAGGREGATE FORMATION (<250 µm) AND SOM STABILIZATION(MRT) Strongly sorbed polymer Cation bridges Carbon Management Organic Matter OH C O C = C = (Redrawn from Tisdall Oades, Soil Sci 33: ) C C C = O OH OH O O OH OH O O OH Fe Al Ca 9

10 Traditional Knowledge & Modern Innovations 9. Engine of Economic Development 8. Soil as Sink for Atmospheric CO2 Causes of Soil Degradation 2. Soil Sustainable Soil Management 7. Soil vs. Germplasm Carbon Management Stewardship & Human 3. Suffering Nutrient, Carbon, & Water Bank 6. Soil Carbon & GHG Effect 4. Marginality Principle 5. Organic vs. Inorganic Nutrients Sustainable The potential management of management elite varieties of soils ofout can soil is be implies engine only use ofthrough economic of if is grown modern Soil are integral to any strategy of mitigating warming Mining Csoils has same onof global warming wher it is It issustainable not possible topoverty take more a realized soil than what put in itinnovations Plants cannot differentiate nutrients supplied The Marginal biophysical cultivated process ofeffect with soil marginal degradation inputs isglobal driven produce by economic, social When people are stricken, desperate starving, y under built upon soil traditional conditions. knowledge. political forces. without degrading its quality. development, political stability transformation rural communities improving environment. through mineralization of soil organic matter of extractive inorganic fertilizers orsupport organic amendments. marginal yields marginal living. pass onoptimal ir sufferings to l. Evenby elitetovarieties cannot extract water nutrients in Vulnerability degradation depends how rar than what is grown. Only replacing what is taken can a on soil be kept fertile, developing countries. farming or burning fossil fuels or draining peat soils. The strategy is of producing more from less. from any soil where y dotonot exist. 10 responsive productive, Soil can be a source or sink management of GHGs depending on l use management

11 LONG-TERM COMMUNITY-BASED GLOBAL BENCHMARK SITES ON LINKING SOIL CARBON SEQUESTRATION TO FOOD, CLIMATE AND OTHER ECOSYSTEM SERVICES The answer lies in harnessing power of agriculture, soil, natural resources. Improved Agriculture Matters Through targeted efficient use of existing resources 11

12 PRIORITIES FOR AAA Priorities for SOC research in Africa are to establish: 1. Critical levels for diverse l uses eco-regions, 2. Rates of net SOC sequestration societal value, 3. Ecosystem services provisioned by SOC, 4. Transects across l uses ecoregions, 5. Synergies between 4PT AAA 12

13 ADVANCING GLOBAL PEACE Lal (2016) 13