1、Lecture 9.Carbon Sequestration in Agricultural Soils1.The role of soil carbon sequestration 2.Soil C sequestration process 3.Soil carbon sequestration strategies and management practices 4.Methods of increasing soil carbon sequestration 5.Carbon sequestration potential in USThe role of soil sequestr
2、ation in reducing GHG emissions 1).Soil carbon is a major global carbon poolGlobal estimates of soil organic carbon(SOC)pool0-1 m(Pg)0-2 m(Pg)0-3 m(Pg)Jobbagy and Jackson(2000)150219932344(Source:Jobbagy and Jackson(2000),Ecol.App.10:423-436)Global estimates of soil inorganic carbon(SIC)poolReferenc
3、eSIC pool(Pg)Batjes(1996)695-748Eswaran et al.(2000)940Schlesinger(1982)780-9302)Direct link between soil and the atmospheric carbon pool-cultivation of virgin soils or conversion of natural to agriculturalecosystems leads to depletion of SOC with the emission of GHGs(CO2 and CH4)e.g.the reduction i
4、n SOC pool by 1Pg is equivalent to an atmospheric enrichment of CO2 by 0.47 ppm 3).Misuse agricultural soils can be a major sources of GHGse.g.From 1850 to 1998,global CO2 emissions are estimated to have been:from land use change:13655Pgfrom soil cultivations:78 17Pg During the 1990s,about 25%of glo
5、bal GHGs emissions came from land-use change and soil cultivation(IPCC,1996)The C Cycle in Agricultural EcosystemsCropped soils have been historically depleted in SOC,which can be regained with improved managementC Sequestration and ManagementErosionManage.WaterManage.NutrientManage.ConservationMana
6、ge.EcosystemrestorationWinter cover cropsRestorationof eroded soilsAdoption of recommended management practicesIdentification and implementation of appropriate policiesStrategies for enhancing C sequestration and reducing GHG emissionsin Agricultural SoilsPast Agricultural Practices:-Erosion-Intensi
7、ve tillage-Residue removal-Low productivityImproved Agricultural Practices:-Conservation buffers-Conservation tillage-Cover crops-Improved rotationCRPNo-till:excludes full-width primary,secondary,and subsurface tillage.Sundance system for incorporation on semi-permanent bedsShallow MT:refers to oper
8、ate such as Sundance System thatuses disks and lister bottom to incorporate crop residues andcultivate the tops and sides of the beds in a single pass.Deep MT:is intended to reduce soil compaction.CRP(Conservation Reserve Program):Lands eligible for inclusion with CRP were those with annual erosion
9、rate of 42.8 MT/ha(19.1 tons/acre),which is 3 times the nationalaverage rate soil erosion.About 24%of all us cropland is eligible for inclusion in CRP(currently 14.75Mha)Objective:to convert highly erodible land from active crop production to Permanent vegetation cover for a 10-year period.Soil Orga
10、nic MatterInterpretations of Article 3.4Narrow definitionNarrow definitionBroad definitionBroad definitionUSA definitionUSA definitionForest ManagementCropland ManagementGrazing land ManagementCase Study:South Dakota Carbon Sequestration ProjectBadlandsCuster State ParkSturgis RallyBlack Hills Fores
11、tsMt RushmoreC-Lock project goalsTo develop an internet-based registration system that links to a Geographic Information System(GIS)coupled to soil carbon models to estimate carbon sequestration for agricultural and forest landsTo quantify and certify Carbon Emission Reduction Credits(CERC)that can
12、be generated and sold by individual producers in South Dakota.The South Dakota Carbon Sequestration Project HOME PAGEContact:Carbon Sequestration C-Lock Project Strategy Determine carbon cycle drivers Develop a geographically-referenced database Establish links among observations and models Test mod
13、els at endpointCentury 4.0FarmersTillage Affects on SOCSpink County(SD)CENTURY4.0 model run Soil carbon(kg C/acre)CRP(no grazing)No TillMinimum TillageStatus Quo(Con.Tillage)(Con.Tillage)(Con.Tillage)Management PracticesWheatCarbon Sequestration Potential(Corn-CT(2P)050010001500200025003000350019751
14、980198519901995200020052010201520202025YearSOC(gm-2)CHI3/C7_S3CHI6/C7_S3Convent.TillageContinue Convent.Tillage15 ton/ha/yr29 ton/ha/yrSimulated Soil Carbon Using CENTURY 4.0 ModelConservation Reserve Program(CRP)(Spink County:Climate zone 7 Sandy loam soil)Corn“Cash for Carbon:The Soil Bank in South Dakota”Total for SD:$157 million(assumed price$40/ton)Agricultural Soil Carbon Sink and ManagementReduce fallow,tillageGood grazing managementGood fertilization practicesPlant green manure cropsPlant cover cropsRestore degraded landsAgroforestry(e.g.plant shelterbelts)Summary:
