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1、Soil Carbon Sequestration Impacts on Global Climate Change and Food Security,Tutor:Prof.ZHENGSpeaker:DongXiaogangDate:2012-05-10,R.Lal,et al.2004 Science 304,1623,土壤碳固定对全球气候变化和粮食安全的影响,2.Soil Carbon Sequestration,3.Soil Carbon Sequestration for Mitigating Climate Change,4.Soil Carbon Sequestration an
2、d Global Food Security,5.Conclusions,1.Background,Content,The global soil carbon(C)pool of 2500 gigatons(Gt)includes about 1550 Gt of soil organic carbon(SOC)and 950 Gt of soil inorganic carbon(SIC).,1.Background,The soil C pool is 3.3 times the size of the atmospheric pool(760 Gt)and 4.5 times the
3、size of the biotic pool(560Gt,fig.S1).,25000亿吨的全球土壤碳库由15500亿吨的土壤有机碳和9500亿吨的土壤无机碳组成。,土壤碳库的容量是大气碳库的3.3倍，是生物碳库的4.5倍。,Fig.1.Processes affecting soil organic carbon(SOC)dynamics.,The SOC pool represents a dynamic equilibrium of gains and losses(Fig.1).土壤碳库处于收支动态平衡。,Severe depletion of the SOC pool degrad
4、es soil quality,reduces biomass productivity,and adversely impacts water quality,and the depletion may be exacerbated by projected global warming.,The depletion is exacerbated when the output of C exceedsthe input and when soil degradation is severe.,当输出超过输入和土壤退化严重时土壤碳库的耗竭将加剧。,土壤碳库的严重耗竭使得土壤质量退化，生物产量
5、降低，影响水质量，预测的全球变暖可能会加剧土壤碳库的耗竭。,The estimates of historic SOC loss range widely,from 44 to 537 Gt,with a common range of 55 to 78 Gt(3).以往的土壤有机碳的损失量的估算值变化范围广大约从440到5370亿吨，而共识的损失量是550到780亿吨。,2.Soil Carbon Sequestration,Carbon sequestration implies transferring atmospheric CO2 into long-lived pools and
6、storing it securely so it is not immediately reemitted.Thus,soil C sequestration means increasing SOC and SIC stocks through judicious land use and recommended management practices(RMPs).,土壤碳固定意味着将大气中的CO2转移到长期存在的土壤库中并安全地储存它，因此使碳不能立即释放到大气中。因此土壤碳固定意味着通过精确的土地使用和推荐的管理措施(RMPs)增加了土壤有机和无机碳库的容量。,The SOC seq
7、uestration is caused by those management systems that add high amounts of biomass to the soil,cause minimal soil disturbance,conserve soil and water,improve soil structure,enhance activity and species diversity of soil fauna,and strengthen mechanisms of elemental cycling(Fig.2,table S2).,土壤有机碳的固定是由向
8、土壤中增加高生物量，使土壤受到最小的扰动，保持水土，提高土壤结构，增强土壤动物的种类和多样性的活性，增强元素循环而实现的。(Fig.2,table S2),2.Soil Carbon Sequestration,Fig.2.,具有高的土壤碳固定潜能的态系统有:农田，放牧的草地，退化的或沙漠化土地,灌溉的土壤放牧的草地的生态系统的土壤碳固定潜力不包括在全球的土壤碳固定中，这是因为它部分的被覆盖在其它生态系统下以及具有很大的不确定性。,Common RMPs that lead to SOC sequestration are mulch farming,conservation tillage,
9、agroforestry and diverse cropping systems,cover crops(Fig.3),and integrated nutrient management,including the use of manure,compost,biosolids,improved grazing,and forest management.,通常导致土壤有机碳固定的RMPs措施是：覆盖农业，保护性耕作，混农林和多样性种植系统(Fig.3)，和包括由粪肥、堆肥、生物固体、改善的放牧模式和林地管理的使用的综合养分管理。,2.Soil Carbon Sequestration,F
10、ig.3.Important recommended management practices are no-till farming,cover crops,manuring and agroforestry.(A:Long-term no-till plots B:Agroforestry),The rate of SIC sequestration as secondary carbonates is low(5 to 150 kg C/ha per year)and is accentuated by biogenic processes and leaching of carbona
11、tes into the groundwater(11,12),especially in soils irrigated with water containing low carbonates.,作为处于次要地位的碳酸盐，土壤无机碳的固定的速率是很低的(每年5到150kgC/ha)，土壤无机碳作为生命必须的过程和碳酸盐向地下水的淋洗过程被重视，(11,12)特别是在含有低碳酸盐的水中的土壤灌溉区。,2.Soil Carbon Sequestration,土壤无机碳的固定,3.Soil Carbon Sequestration for Mitigating Climate Change 土壤
12、碳固定对气候变化的缓解,Estimates of the total potential of C sequestration in world soils vary widely from a low of 0.4 to 0.6 Gt C/year(9)to a high of 0.6 to 1.2 Gt C/year(13).Thus,the potential is finite in capacity and time.Nonetheless,soil C sequestration buys us time until the alternatives to fossil fuel
13、take effect.,Some issues related to this strategy are as follows:,全球土壤碳固定总的潜力的估算值是非常广泛的，从低的0.4 to 0.6 Gt C/year(9)到高的0.6 to 1.2 Gt C/year(13)。因此，这种固定的潜力在容量和时间上是有限的。尽管如此，直到我们能找到化石燃料的替代品时，土壤碳固定为我们争取了时间。,(1).Agricultural chemicals 农化用品,Most RMPs involve C-based input.,However,inputs are needed not for
14、soil C sequestration per se,but for increasing food production and ensuring sustainable use of soil and water resources.,(1).Agricultural chemicals,然而输入不仅是为了土壤碳固定自身，也是增加了粮食生产，确保水土资源使用的可持续。,(2).Nutrients required 养分需求,It is estimated that sequestration of 1 Gt of C in world soils would require 80 mil
15、lion tons(Mt)of N,20 Mt of P,and 15 Mt of K.In comparison,the global fertilizer use in 2000 was 136 Mt(17).,据计算，世界土壤中10亿吨的碳固定需要8000万吨的N，2000万吨的P，1500万吨的K。与此相比，2000年全球肥料的施用量为1.36亿吨（17）。,One ton of cereal residue contains 12 to 20 kg N,1 to 4 kg P,7 to 30 kg K,4 to 8 kg Ca,and 2 to 4 kg Mg.Annually,3
16、Gt of residues of grain crops are produced globally(table S3),which if recycled rather than removed for fuel and other uses,would improve soil quality and sequester C.,一吨的禾谷类作物残渣含有12到20Kg的N，1到4Kg的P，7到30Kg的K,4到8Kg的Ca以及2到4Kg的Mg。每年全球有30亿吨的禾谷类作物残渣被生产(table S3)，这些作物残渣如果是循环利用而不是用于燃料和其它方面的使用，将提高土壤质量和固定碳。,(
17、2).Nutrients required,Crop residue is also a potential source of energy by direct combustion,or for production of ethanol or H2.It can be used either for biofuel production or to sequester C and improve soil quality.The economics of these two competing uses need to be assessed.,作物残渣通过直接的燃烧也是能源的一个潜在的
18、库，或者也可以作为乙醇或氢气的生产原料。作物残渣既可以用于生物燃料的生产或用于碳的固定以提高土壤质量。这二者的竞争使用的经济效益需要被评估。,(3).Soil erosion and deposition 土壤的侵蚀和沉积,The SOC is preferentially removed by wind-and water-borne sediments through erosional processes.Some of the SOC-enriched sediments are redistributed over the landscape,others are deposited
19、 in depressional sites,and some are carried into the aquatic ecosystems(Fig.1).,Yet,an effective soil erosion control is essential to sustainable use of agricultural soils and improving environment quality.,土壤有机碳是通过侵蚀过程优先被风传和水传沉淀的。一些是在陆地在分布，一些是在作用位点被沉积，而另一些是被移动到水生生态系统中(Fig.1)。,然而，一个有效的土壤的侵蚀的控制对于农业土壤
20、的可持续使用和改善环境质量来说是很重要的。,Fig.1.Processes affecting soil organic carbon(SOC)dynamics.,(4).Extractive farming practices 传统的农业措施,The annual depletion rate of nutrients for sub-Saharan Africa(SSA)caused by low-input/subsistence farming is estimated to be 40 kg of NPK/ha of cultivated land since the mid-196
21、0s(20).,Therefore,RMPs must enhance rather than deplete SOC pool and soil fertility,increase rather than maintain or decrease crop yield per unit use of fertilizer and other inputs,and improve rather than degrade soil quality.,由于低投入或自给农业引起的SSA每年的养分耗竭速率从20世纪60年代的耕地开始被估算为每公顷40KgNPK（20）。,因此，RMPs一定是提高而不
22、是耗竭土壤有机碳库和土壤肥力，增加而不是保持和减少每单位作物的产量通过肥料和其它方面的投入，提高而不是退化土壤质量。,(5).Societal value and hidden benefits 社会价值和潜在的效益,Carbon trading markets have existed since 2002,especially in European Union countries(21).,the price of soil C must be based on both on-site and off-site societal benefits(table S4).Undervalu
23、ing soil C can lead to a“tragedy of the commons.”,从2002年开始碳交易市场开始存在，特别是在欧盟国家(21)。,土壤碳的价格必须基于社会各方面的利益。低估土壤碳会导致一个常识性的悲剧。,(6).Hydrologic and carbon cycles 水文学和碳循环,Because renewable freshwater is scarce,a projected increase in cereal production by 56%between 1997 and 2050(23)must occur on the same or sm
24、aller land area and with the same or less water.Thus,linking the hydrologic and C cycles through conservation of water resources is crucial to improving agronomic yields and to soil C sequestration in dryland.,Enhancing SOC stock in dryland ecosystems through notill farming is important to drought m
25、anagement:a truly win-win option(24).,由于可更新的新鲜的水很少，预测在1997年到2050年间禾谷类作物的产量将增长56%（23），而要实现这个目标需要现有相同或比现有耕地面积小的耕地以及现有相同或比现有水小的水用量。因此通过水资源的保护将水文学和碳循环联系起来以提高农作物产量和在旱地上的土壤碳固定是非常重要的。,(7).Soil C sequestration and global warming,Soil C sequestration is a related but separate issue with its own merits of inc
26、reasing productivity,improving water quality,and restoring degraded soils and ecosystems,irrespective of the global-warming debate.,Furthermore,soil C sequestration is a bridge across three global issues climate change,desertification,and biodiversity and a natural link among three UN conventions.,G
27、lobal warming is a“century-scale”problem and a“global commons”issue.,(8).Other greenhouse gases 其它的温室气体,Enhancing SOC stock increases the soils capacity to oxidize CH4,especially under no-till farming(25),but may also exacerbate emission of N2O(26).,增加土壤有机碳的同时也增强了土壤氧化CH4的能力，特别是在免耕农业系统中(25)，可能也加剧了N2O
28、的排放(26)。,(9).Soils of the tropics 热带地区的土壤,Because of its severe depletion and degradation,the C sink capacity of soils of the tropics may be high,but the rate of sequestration can be low.The need for enhancing soil quality is also more urgent in soils of the tropics than in soils of high latitudes b
29、ecause of low crop yields.,Soil-restorative farm policies must be implemented to mitigate soil degradative trends.,由于严重的养分耗竭和土壤退化，热带地区的土壤碳库的容量可能是很高的，但是土壤碳固定的速率是很低的。增加土壤质量的需要在热带地区的土壤比在高纬度地区的土壤是更紧急的，因为热带地区的作物产量是很低的。,(10).Permanence 持久性,Soil C sequestration is a natural,cost-effective,and environment f
30、riendly process.,Soil sink capacity and permanence are related to clay content and mineralogy,structural stability,landscape position,moisture and temperature regimes,and ability to form and retain stable microaggregates.,土壤碳固定是一个自然的，划算的和环境友好的过程。,土壤碳库的容量和持久性是与粘粒含量和矿物学、结构的稳定性，地理位置，水分和温度状态，以及稳定性团聚体的形成
31、和保持的能力联系紧密的。,4.Soil Carbon Sequestration and Global Food Security 土壤碳固定和全球粮食安全,Global hotspots of soil degradation with a high priority for soil restoration and C sequestration include SSA,central and south Asia,China,the Andean region,the Caribbean,and the acid savannas of South America.,As a sourc
32、e of nutrients for growing crops,the SOC pool is a mean of production in subsistence farming systems of SSA,which accounts for only 2.5%of the fertilizer consumption and 2%of the worlds irrigated land area,both essential to SOC sequestration.,当生长的作物作为养分的一个源时，在SSA的自给农业中土壤有机碳库是作物生产的一种手段。(SSA仅占世界肥料消耗的2
33、.5%，占世界灌溉土地的2%，而这些对于土壤有机碳的固定是很重要的。),4.Soil Carbon Sequestration and Global Food Security,Fertilizer application is an important strategy of increasing crop yield in SSA(27),but its effectiveness is enhanced when used in conjunction with crop residue mulch(28)or trees(20).,肥料的施用对于在SSA的作物产量的增加是一个非常重要的
34、策略(27)，但是当通过使用作物残渣的覆盖(28)或是固氮的豆科乔木休耕(20)与施肥手段相结合时，它的效益将提高。,4.Soil Carbon Sequestration and Global Food Security,An increase of 1 ton of soil carbon pool of degraded cropland soils may increase crop yield by 20 to 40 kilograms per hectare(kg/ha)for wheat,10 to 20 kg/ha for maize,and 0.5 to 1 kg/ha fo
35、r cowpeas.,在退化的耕地土壤上每增加1吨的土壤有机碳可以使小麦的产量每公顷增加20到40Kg，玉米的产量每公顷增加10到20Kg，豇豆的产量每公顷增加0.5到1Kg。,4.Soil Carbon Sequestration and Global Food Security,Fig.4.The vicious cycle of deletion in soil organic matterdecline in crop yieldfood insecuritysoil and environmental degradation can be broken by improving so
36、il fertility.,5.Conclusions,As well as enhancing food security,carbon sequestration has the potential to offset fossil-fuel emissions by 0.4 to 1.2 gigatons of carbon per year,or 5 to 15%of the global fossil-fuel emissions.,Soil organic carbon is an extremely valuable natural resource.,Yet,the close link between soil C sequestration and world food security on the one hand and climate change on the other can neither be overemphasized nor ignored.,Thanks for your time!,
