Carbon Sequestration and Greenhouse Gas Fluxes from Cropland Soils – Climate Opportunities and Threats

摘要: Globally, soils contain approximately 1500 Pg (1 = 1Gt 1015 g) of organic carbon (C) (Batjes 1996), roughly three times the amount in vegetation and twice atmosphere (IPCC 2001). The annual uxes dioxide (CO2) from to land (global Net Primary Productivity [NPP]) (respiration re) are order 60 Cyr−1 during 1990s, fossil fuel combustion cement production emitted 6.3 ± 1.3 atmosphere, while land-use change accounted for 1.6 0.8PgCyr−1 (Schimel et al. 2001; IPCC 2001).Atmospheric C increased at a rate 3.2 0.1PgCyr−1, oceans absorbed 2.3 therewas an estimated terrestrial sink 1.3PgCyr−1 stored globally is, therefore, very large compared gross net biosphere, pools vegetation. Human intervention, via cultivation disturbance, has also decreased soil relative store typically achieved under native Historically, these processes have caused loss between 40 90 (Paustian 1998; Houghton 1999; Lal 1999). Hence, increasing size global pool by even small proportion potential sequester amounts carbon, thus help mitigate climate change.