The potential to increase soil carbon stocks through reduced tillage or organic material additions in England and Wales: A case study

Results from the UK were reviewed to quantify the impact on climate change mitigation of soil organic carbon (SOC) stocks as a result of (1) a change from conventional to less intensive tillage and (2) addition of organic materials including farm manures, digested biosolids, cereal straw, green manure and paper crumble. The average annual increase in SOC deriving from reduced tillage was 310 kg C ± 180 kg C ha⁻¹ yr⁻¹. Even this accumulation of C is unlikely to be achieved in the UK and northwest Europe because farmers practice rotational tillage. N₂O emissions may increase under reduced tillage, counteracting increases in SOC. Addition of biosolids increased SOC (in kg C ha⁻¹ yr⁻¹ t⁻¹ dry solids added) by on average 60 ± 20 (farm manures), 180 ± 24 (digested biosolids), 50 ± 15 (cereal straw), 60 ± 10 (green compost) and an estimated 60 (paper crumble). SOC accumulation declines in long-term experiments (>50 yr) with farm manure applications as a new equilibrium is approached. Biosolids are typically already applied to soil, so increases in SOC cannot be regarded as mitigation. Large increases in SOC were deduced for paper crumble (>6 t C ha⁻¹ yr⁻¹) but outweighed by N₂O emissions deriving from additional fertiliser. Compost offers genuine potential for mitigation because application replaces disposal to landfill; it also decreases N₂O emission.     

Simulated dynamics of carbon stocks driven by changes in land use, management and climate in a tropical moist ecosystem of Ghana

Sub-Saharan Africa is large and diverse with regions of food insecurity and high vulnerability to climate change. This project quantifies carbon stocks and fluxes in the humid forest zone of Ghana, as a part of an assessment in West Africa. The General Ensemble biogeochemical Modeling System (GEMS) was used to simulate the responses of natural and managed systems to projected scenarios of changes in climate, land use and cover, and nitrogen fertilization in the Assin district of Ghana. Model inputs included historical land use and cover data, historical climate records and projected climate changes, and national management inventories. Our results show that deforestation for crop production led to a loss of soil organic carbon (SOC) by 33% from 1900 to 2000. The results also show that the trend of carbon emissions from cropland in the 20th century will continue through the 21st century and will be increased under the projected warming and drying scenarios. Nitrogen (N) fertilization in agricultural systems could offset SOC loss by 6% with 30 kg N ha⁻¹ year⁻¹ and by 11% with 60 kg N ha⁻¹ year⁻¹. To increase N fertilizer input would be one of the vital adaptive measures to ensure food security and maintain agricultural sustainability through the 21st century.     

Organic carbon stock in topsoil of Jiangsu Province, China, and the recent trend of carbon sequestration

Data collection of soil organic carbon(SOC) of 154 soil series of Jiangsu, China from the second provincial soil survey and of recent changes in SOC from a number of field pilot experiments across the province were collected. Statistical analysis of SOC contents and soil properties related to organic carbon storage were performed. The provincial total topsoil SOC stock was estimated to be O. 1 Pg with an extended pool of 0.4 Pg taking soil depth of 1 m, being relatively small compared to its total land area of lOl?00 km^2. One quarter of this topsoil stock was found in the soils of the Taihu Lake region that occupied 1/6 of the provincial arable area. Paddy soils accounted for over 50% of this stock in terms of SOC distribution among the soil types in the province. Experimental data from experimental farms widely distributed in the province showed that SOC storage increased consistently over the last 20 years despite a previously reported decreasing tendency during the period between 1950--1970. The evidence indicated that agricultural management practices such as irrigation, straw return and rotation of upland crops with rice or wheat crops contributed significantly to the increase in SOC storage. The annual carbon sequestration rate in the soils was in the range of 0.3-3.5 tC/(hm^2. a), depending on cropping systems and other agricultural practices. Thus, the agricultural production in the province, despite the high input, could serve as one of the practical methods to mitigate the increasing air CO2.     

长期施肥对棕壤有机碳储量及固碳速率的影响

利用棕壤肥料长期定位试验,研究了不同施肥条件下棕壤有机碳在0~60 cm土层的含量和储量特征以及土壤固碳速率.试验共设6个处理,即氮磷肥有机肥配施(M_2NP)、氮肥有机肥配施(M_2N)、单施有机肥(M_2)、单施氮肥(N)、氮磷肥配施(NP)和不施肥处理(CK).结果表明:经过31年长期不同施肥,各处理土壤有机碳(SOC)含量和储量的剖面分布均呈现随土层深度增加而显著降低的规律.本试验条件下M_2NP、M_2N、M_2、NP、N、CK处理的耕层有机碳富集系数分别为0.465、0.455、0.407、0.48_2、0.393、0.471,表明耕层土壤对有机碳的保持强度最强.在0~60 cm土层土壤有机碳储量表现为M_2NP、M_2NM_2、NPNCK,有机肥和化肥配施能够显著提高土壤有机碳含量和储量.与试验前相比,CK处理各土层土壤有机碳含量和储量均显著降低.各处理碳库管理指数(CPMI)表现为M_2NPM_2NM_2NNPCK.分析不同施肥处理土壤固碳速率可知,与试验前相比,CK处理表现为碳的净释放,固碳速率达-401.4 kg·hm~(-_2)·a~(-1);固碳速率最高的为M_2NP,M_2N,分别达到489kg·hm~(-_2)·a~(-1)、440._2 kg·hm~(-_2)·a~(-1).综合结果表明,化肥、有机肥配施所产生交互效应更有利于棕壤有机碳储量的增加及固碳速率的提高.     

Potential for carbon sequestration in Canadian forests and agroecosystems

The potential for carbon (C) sequestration was examined in selectedCanadian forest settings and prairie agroecosystems under severalmanagement scenarios. A simple C budget model was developed toquantitatively examine C sequestration potential in living biomass of forestecosystems, in associated forest-product C pools, and in displaced fossil-fuelC. A review of previous studies was conducted to examine C sequestrationpotential in prairie agroecosystems. In the forest settings examined, ourwork suggests that substantial C sequestration opportunities can be realizedin the short term through the establishment of protected forest-C reserves.Where stands can be effectively protected from natural disturbance, peaklevels of biomass C storage can exceed that under alternative managementstrategies for 200 years or more. In settings where it is not feasible tomaintain protected forest-C reserves, C sequestration opportunities can berealized through maximum sustained yield management with harvestedbiomass put towards the displacement of fossil fuels. Because there is afinite capacity for C storage in protected forest-C reserves, harvesting forestbiomass and using it to displace the use of fossil fuels, either directlythrough the production of biofuels or indirectly through the production oflong-lived forest products that displace the use of energy-intensive materialssuch as steel or concrete, can provide the greatest opportunity to mitigategreenhouse gas emissions in the long term. In Canadian prairieagroecosystems, modest C sequestration can be realized while enhancingsoil fertility and improving the efficiency of crop production. This can bedone in situations where soil organic C can be enhanced without relianceupon ongoing inputs of nitrogen fertilizer, or where the use of fossil fuelsin agriculture can be reduced. More substantial C offsets can be generatedthrough the production of dedicated energy crops to displace the use offossil fuels. Where afforestation or reconstruction of native prairieecosystems on previously cultivated land is possible, this represents thegreatest opportunity to sequester C on a per unit-area basis. However,these last two strategies involve the removal of land from crop production,and so they are not applicable on as wide a scale as some other Csequestration options which only involve modifications to currentagricultural practices.     

Analysis of leakage in carbon sequestration projects in forestry: a case study of upper magat watershed,Philippines

The role of forestry projects in carbon conservation and sequestration is receiving much attention because of their role in the mitigation of climate change. The main objective of the study is to analyze the potential of the Upper Magat Watershed for a carbon sequestration project. The three main development components of the project are forest conservation: tree plantations, and agroforestry farm development. At Year 30, the watershed can attain a net carbon benefit of 19.5 M tC at a cost of US$ 34.5 M. The potential leakage of the project is estimated using historical experience in technology adoption in watershed areas in the Philippines and a high adoption rate. Two leakage scenarios were used: baseline and project leakage scenarios. Most of the leakage occurs in the first 10 years of the project as displacement of livelihood occurs during this time. The carbon lost via leakage is estimated to be 3.7 M tC in the historical adoption scenario, and 8.1 M tC under the enhanced adoption scenario.     

重庆市农田土壤有机碳时空变化与固碳潜力分析

区域土壤有机碳库、固碳潜力的估算,对全球气候变化中的碳循环研究具有重要意义.本研究基于1978—1979年全国第二次土壤普查和2007—2011年农业部"测土配方施肥"项目的数据,并结合大量前人调研资料和田间试验数据进行整理与比较分析.同时,采取土壤类型法估算了重庆市农田土壤碳库储量和碳密度;基于GIS分析了重庆市农田土壤碳密度的空间分布特征;对30年来各区县农田土壤碳量变化趋势进行拟合分析,估算了农田土壤固碳潜力.结果表明,土壤表层有机碳库总储量为233.54×106t,土壤有机碳密度平均值为3.08 kg·m-2;渝西南、渝东北和渝东南的农田土壤有机碳密度较高,长江干流沿岸及附近低山丘陵地区土壤有机碳密度较低;重庆市农田土壤固碳潜力约为30.82 Tg(以C计),农田土壤单位面积固碳潜力平均值为6.71 t·hm-2.     

退耕植茶对川西低山丘陵区土壤活性有机碳组分的影响

为探讨退耕植茶对土壤活性有机碳组分的影响,选取退耕2~3年(RT 2~3)、9~10年(RT 9~10)和16~17年(RT 16~17)的茶园为研究对象,以邻近撂荒地为对照(CK),测定其土壤颗粒有机碳(POC)、微生物量碳(MBC)、水溶性有机碳(WSOC)、可矿化有机碳(MOC)含量,并分析其分配比例随退耕植茶年限推移的变化.结果表明,POC、MBC和WSOC对退耕植茶的响应较为一致,与对照相比,退耕植茶初期(RT 2~3),各组分含量均降低,但随着植茶时间的推移,各组分含量逐渐增加,在植茶9~10或16~17年后显著高于撂荒地;退耕植茶后MOC含量显著降低,总体表现为CKRT 16~17RT 9~10RT 2~3,0~10 cm土层,RT 2~3、RT 9~10和RT 16~17土壤MOC含量分别较对照显著下降35.25%、23.89%和16.87%,10~20 cm土层中分别下降32.31%、13.09%和23.22%,20~40 cm土层中分别下降36.43%、28.79%和30.76%.植茶后,土壤活性有机碳在总有机碳中的比例整体现为0~10 cm高于20~40 cm,相较于表层土壤,深层土壤碳库的稳定性更强.退耕植茶有利于土壤肥力的保持,对提升土壤有机质水平起到积极作用,且随植茶时间的推移,土壤对碳的固持作用增强,土壤质量得到提升.     

Socioeconomic potential of carbon sequestration through agroforestry in the West African Sahel

The recognition of agroforestry as a greenhouse-gas mitigation strategy under the Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) offers an opportunity to agroforestry practitioners to benefit from the global Carbon (C) credit market. Our knowledge on this important topic from the semiarid regions such as the West African Sahel (WAS) is, however, very limited. In order to fill this gap, this study was undertaken in the Ségou region of Mali (annual temperature, 29°C; annual rainfall, 300–700 mm in 60 to 90 days), focusing on two improved agroforestry systems (live fence and fodder bank) along with traditional parkland agroforestry systems of the region. A cost–benefit analysis was conducted to assess the economic profitability and risks associated with the systems considering them as 25-year projects and their potential for participation in C credit market. The traditional systems had high C stock in their biomass and soil, but little potential for sequestering additional C; on the other hand, the improved systems had low C stock, but high sequestration potential. For the standard size live fence (291 m) and fodder bank (0.25 ha) projects, the estimated net present values (NPV) were $ 96.0 and $158.8 without C credit sale, and $109.9 and $179.3 with C sale, respectively. From the C sale perspective, live fence seemed less risky and more profitable than fodder bank. Carbon credit sale is likely to contribute to economic development of the subsistence farmers in the WAS.

中国森林碳汇潜力与增汇成本评估——基于Meta分析方法

准确评估中国森林碳汇潜力与增汇成本的经济可行性,是科学制定碳中和林业行动方案的基础。然而针对中国森林碳汇潜力与增汇成本的不同结果差异明显,可靠性需要进一步验证。为此,基于相关文献,采用Meta分析方法,对中国森林碳汇潜力与增汇成本及其导致差异的原因展开评估。研究表明：(1)中国森林碳汇量呈现不断增长的态势,但不同研究对森林碳汇潜力测度结果存在较大差异。(2)中国森林增汇的平均成本为220.45元/t CO_2e(区间值为3.9～1457.02元/t CO_2e),与工业减排成本相比,中国森林增汇更具有经济可行性,但波动幅度较大。(3)评估方法采用、碳库数量选择等因素是导致已有森林碳汇潜力文献估计结果差异的关键因素;森林增汇成本差异则主要受碳汇成本测度研究方法、成本收益数据来源等因素影响。(4)中国森林增汇对碳中和的贡献将会持续增加。基于研究结果,提出进一步深化森林碳汇潜力与成本测算相关研究等方面的政策建议。     

土地利用变化对土壤有机碳的影响研究进展

研究土地利用变化对土壤有机碳及其动态变化规律,有助于掌握全球气候变化与土地利用变化之间的关系。本文分别从土地利用及其管理方式变化的角度,综合阐述了土地利用变化对土壤有机碳的影响过程与机理。     

Soil carbon sequestration and associated economic costs for farming systems of the Indo-Gangetic Plain: A meta-analysis

Soil organic carbon sequestration rates over 20 years based on the Intergovernmental Panel for Climate Change (IPCC) methodology were combined with local economic data to determine the potential for soil C sequestration in wheat-based production systems on the Indo-Gangetic Plain (IGP). The C sequestration potential of rice-wheat systems of India on conversion to no-tillage is estimated to be 44.1 Mt C over 20 years. Implementing no-tillage practices in maize-wheat and cotton-wheat production systems would yield an additional 6.6 Mt C. This offset is equivalent to 9.6% of India's annual greenhouse gas emissions (519 Mt C) from all sectors (excluding land use change and forestry), or less than one percent per annum. The economic analysis was summarized as carbon supply curves expressing the total additional C accumulated over 20 year for a price per tonne of carbon sequestered ranging from zero to USD 200. At a carbon price of USD 25 Mg C⁻¹, 3 Mt C (7% of the soil C sequestration potential) could be sequestered over 20 years through the implementation of no-till cropping practices in rice-wheat systems of the Indian States of the IGP, increasing to 7.3 Mt C (17% of the soil C sequestration potential) at USD 50 Mg C⁻¹. Maximum levels of sequestration could be attained with carbon prices approaching USD 200 Mg C⁻¹ for the States of Bihar and Punjab. At this carbon price, a total of 34.7 Mt C (79% of the estimated C sequestration potential) could be sequestered over 20 years across the rice-wheat region of India, with Uttar Pradesh contributing 13.9 Mt C.     

不同水分条件沼泽湿地土壤轻组有机碳与微生物活性动态

通过野外实验与室内分析,对三江平原生长季内毛果苔草(Carex lasiocapa)沼泽湿地生物量及0~20cm土壤不同有机碳组分进行观测,分析了不同水分条件下毛果苔草湿地土壤轻组有机碳(LFOC)与微生物量碳(MBC)的变化动态.结果表明,随水位增加毛果苔草群落地上生物量积累明显,与10~20cm积水条件相比,17~30cm水位状况下湿地土壤具有较高的轻组有机质含量与比例.生长季初期冻融过程提高了土壤轻组分(LF)有机碳含量与LFOC含量,之后随植物生长毛果苔草沼泽湿地土壤重组有机碳(HFOC)含量增长快于LFOC,说明毛果苔草沼泽湿地土壤具有较高的重组有机质持有能力.此外不同水位条件下毛果苔草沼泽湿地微生物活性受到土壤有机碳含量影响不同,低水位条件下微生物量碳与SOC呈显著正相关关系(R2=0.859),17~30cm水位条件下二者关系不显著,并且高水位毛果苔草沼泽湿地具有较低的MBC与微生物熵,表明该条件下土壤碳库具有较高的稳定性.     

Protective shade, tree diversity and soil properties in coffee agroforestry systems in the Atlantic Rainforest biome

Sustainable production and biodiversity conservation can be mutually supportive in providing multiple ecosystem services to farmers and society. This study aimed to determine the contribution of agroforestry systems, as tested by family farmers in the Brazilian Rainforest region since 1993, to tree biodiversity and evaluated farmers’ criteria for tree species selection. In addition, long-term effects on microclimatic temperature conditions for coffee production and chemical and biological soil characteristics at the field scale were compared to full-sun coffee systems. A floristic inventory of 8 agroforests and 4 reference forest sites identified 231 tree species in total. Seventy-eight percent of the tree species found in agroforests were native. The variation in species composition among agroforests contributed to a greater γ-diversity than α-diversity. Monthly average maximum temperatures were approximately 6 °C higher in full-sun coffee than in agroforests and forests. Total soil organic C, N mineralization and soil microbial activity were higher in forests than in coffee systems, whereas the chemical and biological soil quality in agroforests did not differ significantly from full-sun coffee after 13 years. Given its contribution to the conservation of biodiversity and its capacity to adapt coffee production to future climate change, coffee agroforestry offers a promising strategy for the area.     

广东省人为源BC、OC排放清单建立与校验

根据收集的人为源活动水平数据和最新的排放因子,采用"自下而上"和"自上而下"相结合的排放因子法建立了广东省2012年人为源BC、OC排放清单.结果显示,2012年广东省人为源BC、OC排放量分别为53.5×103、78.8×103t.BC排放主要来自道路移动源和生物质燃烧源,贡献率分别为30.1%和29.4%,生物质燃烧源和餐饮源是主要的OC排放贡献源,贡献率分别为48.5%和16.9%.建立的BC、OC排放源清单仍然具有较大的不确定性,分别为-66%~154%和-63%~126%.其中,道路移动源和生物质燃烧源是主要的不确定贡献源,餐饮源和扬尘源次之,不确定性主要来自由质量分数间接得到的BC和OC排放因子.最后,采用清单结果横向比较法和基于环境监测浓度结果对比法2种方法对本研究的结果进行了校验,结果表明,本研究清单结果基本合理.建议统一不同排放源成分谱的建立方法,加强排放源颗粒物测试,并重视清单结果校验的研究以降低不确定性,从而改进BC、OC排放源清单.     

土壤团聚体制备方法对其稳定性及固碳潜力评价的影响研究

为探讨不同土壤团聚体制备方法对评价城市土壤固碳潜力的影响,本研究采集北京市两种典型的不同利用类型土壤—城市绿地土壤和城郊农田土壤,分别采用干筛法和湿筛法制备土壤团聚体,对其团聚体组成、有机碳含量以及稳定碳同位素特征进行了解析.结果表明:干筛法制备的机械稳定性团聚体均以>0.25mm的大团聚体为主(城市绿地土壤:69.80%;农田土壤:71.36%);而湿筛法制备的水稳性团聚体均以<0.25mm微团聚体为主(城市绿地土壤:57.70%;农田土壤:52.14%).红外光谱解析发现,不同制备方法下,两类土壤中微团聚体中均是稳定有机碳比活性有机碳相对含量高;北京城郊农田土壤中稳定芳香碳的相对含量较多,而脂肪碳相对含量较少;城市绿地土壤则具有相反特征,说明城市绿地土壤中有机碳具有更高活性易在一定条件下被释放.结合稳定碳同位素比值解析发现,湿筛制备方法下¹³C在<0.053mm团聚体颗粒组中富集,更符合土壤团聚体胚胎发育模型,说明在土壤固碳潜力研究中,湿筛法比干筛法制备团聚体更具有实际评价价值,本研究为进一步评价我国城市土壤的固碳潜力具有参考意义.     

黄土丘陵区不同有机碳水平侵蚀坡面土壤微生物量碳的分布特征

通过分析5种不同有机碳水平侵蚀坡面上土壤微生物量碳的空间分布特征及其影响因素,探究了不同土壤有机碳水平下侵蚀和土壤微生物量碳的"压力-响应"关系.结果表明:10~20 cm土层土壤微生物量碳含量随土壤有机碳水平的增加而增加.0~10 cm土层土壤微生物量碳含量比10~20 cm土层更易受坡面有机碳背景的影响,且对侵蚀的响应较敏感;2土壤微生物碳含量随着土层深度的加深而减少,当坡面有机碳水平为5.68 g·kg-1时,土壤微生物量碳的剖面分布差异最大.土壤微生物量碳的水平分布表现为沉积区对照区侵蚀区,当坡面有机碳含量在4.92~5.65 g·kg-1范围内,其水平分布差异较大.即在中等有机碳水平的侵蚀坡面上,土壤微生物量碳的空间分布差异较大,对侵蚀的响应较敏感;3土壤微生物量碳的空间分布主要受坡面土壤有机碳水平的影响;其次受坡位、土壤平均含水量、土壤容重等的影响.     

成都碳质气溶胶变化特征及二次有机碳的估算

利用2020年6月~2021年5月在成都市观测的碳质气溶胶小时分辨率数据,分析了气溶胶中总碳(TC)、有机碳(OC)、元素碳(EC)和二次有机碳(SOC)的变化特征.结果表明:观测期间m(TC)、m(OC)、m(EC)和r(OC/EC)的年均值分别为(9.5±4.4)μg/m³,(6.4±3.2)μg/m³,(3.2±1.1)μg/m³,2.2±0.5.成都m(TC)、m (OC)、m (EC)均表现冬为季最高((15.8±8.2),(11.1±5.8),(4.6±2.5)μg/m³),春秋次之,夏季最低((6.1±0.9),(4.5±2.0),(2.7±1.4)μg/m³)的特征.r(OC/EC)季节均值(1.9~2.6)以及四个季节的m(TC)、m(OC)、m(EC)呈现早(07:00~09:00)晚(22:00~01:00)“双峰”的日变化特征,表明机动车排放源对成都碳质气溶胶的影响较大.春夏季OC与EC的相关性小于秋冬季,表明春夏季OC、EC来源差异较大.由EC示踪法和最小相关性法得到m(SOC),r(SOC/OC)在夏季最大(40.4%),冬季最小(27.3%).春、夏季SOC与O₃呈显著正相关,表明较强的光化学反应对SOC生成有重要贡献.选取各季节连续高m(TC)时段与季节平均作对比,发现碳质气溶胶有明显夜间积累过程,夏季高浓度时段二次生成使得m(OC)增长显著高于m(EC),r(OC/EC)也迅速上升.     

Soil-profile distribution of carbon and associated properties in no-till along a precipitation gradient in the central Great Plains

No-till (NT) farming is considered as a potential strategy for sequestering C in the soil. Data on soil-profile distribution of C and related soil properties are, however, limited, particularly for semiarid regions. We assessed soil C pool and soil structural properties such as aggregate stability and strength to 1 m soil depth across three long-term (≥21 year) NT and conventional till (CT) experiments along a precipitation gradient in the central Great Plains of the USA. Tillage systems were in continuous winter wheat (Triticum aestivum L.) on a loam at Hutchinson and winter wheat-sorghum [Sorghum bicolor (L.) Moench]-fallow on silt loams at Hays and Tribune, Kansas. Mean annual precipitation was 889 mm for Hutchinson, 580 mm for Hays, and 440 mm for Tribune. Changes in profile distribution of soil properties were affected by differences in precipitations input among the three sites. At Hutchinson, NT had 1.8 times greater SOC pool than CT in the 0-2.5-cm depth, but CT had 1.5 times greater SOC pool in the 5-20-cm. At Hays, NT had 1.4 times greater SOC pool than CT in the 0-2.5-cm depth. Differences in summed SOC pool for the whole soil profile (0-1 m depth) between NT and CT were not significant at any site. The summed SOC pool with depth between NT and CT were only significant above the 5 cm depth at Hutchinson and 2.5 cm depth at Hays. At Hutchinson, NT stored 3.4 Mg ha⁻¹ more SOC than CT above 5 cm depth. At Hays, NT stored 1.35 Mg ha⁻¹ more SOC than CT above 2.5 cm depth. Moreover, NT management increased mean weight diameter of aggregates (MWDA) by 3 to 4 times for the 0-5-cm depth at Hutchinson and by 1.8 times for the 0-2.5-cm depth at Hays. It also reduced air-dry aggregate tensile strength (TS) for the 0-5-cm depth at Hutchinson and Hays and for the 0-2.5-cm depth at Tribune. The TS (r = −0.73) and MWDA (r = 0.81) near the soil surface were more strongly correlated with SOC concentration at Hutchinson than at Hays and Tribune attributed to differences in precipitation input. Results suggested NT impacts on increasing SOC pool and improving soil structural properties decreased with a decrease in precipitation input. Changes in soil properties were larger at Hutchinson (880 mm of precipitation) than at Hays and Tribune (≤580 mm). While NT management did not increase SOC pool over CT for the whole soil profile, the greater near-surface accumulation of SOC in NT than in CT was critical to the improvement in soil structural properties. Overall, differences in precipitation input among soils appeared to be the dominant factor influencing NT impacts on soil-profile distribution of SOC and soil structural properties in this region.     

东湖沉积物中微生物量与碳、氮、磷的相关性

对武汉东湖3个采样点柱状沉积物中总氮、总磷、总有机碳及微生物量的垂向分布进行了测定,并对生源要素与微生物量之间垂向分布的相关性进行了研究.结果表明,东湖柱状沉积物中总有机碳与总氮之间存在明显的同步变化趋势,其含量随着沉积物深度的增加而不断降低,处于纳污区的1号点的各种营养盐含量均显著高于其它各点.沉积物中的有机质有着明显的双重来源,1号点含有较高的陆源有机质成分,而远离排污口部分的2号和3号点的有机质来源则以水生生物为主.微生物量在沉积物表层最高,随着沉积物深度的增加而不断下降.微生物量与有机质含量之间存在极显著的相关性,但是受有机质来源不同的影响,微生物量与总氮、总磷之间仅在远离排污口部分存在极显著相关性.