全球碳循環(huán)_Carbon-Sequestration-in-Agricultural-Soils-_課件

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 se

2、questration 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 ca

3、rbon (SIC) poolReferenceSIC 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 (CO

4、2 and CH4)e.g. the reduction in 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 17

5、Pg During the 1990s, about 25% of global 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.Wat

6、erManage.NutrientManage.ConservationManage.EcosystemrestorationWinter cover cropsRestorationof eroded soilsAdoption of recommended management practicesIdentification and implementation of appropriate policiesStrategies for enhancing C sequestration and reducing GHG emissionsin Agricultural SoilsPast

7、 Agricultural Practices:- Erosion- Intensive 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 incorpora

8、tion on semi-permanent bedsShallow MT: refers to operate 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

9、 for inclusion with CRP were those with annual erosion 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

10、 to Permanent vegetation cover for a 10-year period. Soil Organic MatterCase Study :South Dakota Carbon Sequestration ProjectBadlandsCuster State ParkSturgis RallyBlack Hills ForestsMt RushmoreC-Lock project goalsTo develop an internet-based registration system that links to a Geographic Information

11、 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 be generated and sold by individual producers in South Dakota.The South Dakota Carbon Sequestration Project HOME PAG

12、EContact: Carbon Sequestration - 1994-2001 - SDSM&T - All Rights Reserved. v4.0.7.1 C-Lock Project Strategy Determine carbon cycle drivers Develop a geographically-referenced database Establish links among observations and models Test models at endpointLANDUSESOIL PROPERTIESSOIL CARBONCROPCLIMATECen

13、tury 4.0FarmersTillage Affects on SOCIntensive Tillage increases soil temperature causing higher rate of decomposition resulting in reduction of SOCConservation Tillage retains crop residues lowering soil temperature and protection from erosion.Spink 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 PracticesWheat(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)Agricul