不同植被群落土壤水溶性有机碳的变化特征

[目的]对比天然次生林和人工林土壤水溶性有机碳的含量、季节变化特征及与土壤理化性质的相关性,评估不同植被恢复模式对土壤碳库的影响。[方法]以浙江省凤阳山不同植被群落为对象,在野外调查和实验测定的基础上,通过相邻样地比较法进行研究。[结果]不同植被群落0—60cm土层平均水溶性有机碳含量的大小关系为:35a杉木人工林(0.299 7g/kg)40a常绿阔叶次生林(0.271 7g/kg)35a针阔混交次生林(0.258 6g/kg)40a杉木人工林(0.252 9g/kg)30a柳杉人工林(0.252 8g/kg)30a针阔混交次生林(0.248 0g/kg),相邻样地基本表现为人工林大于天然次生林;不同植被群落土壤水溶性有机碳含量的最小值均出现在夏季。[结论]土壤水溶性有机碳含量与土壤总有机碳、全氮、有效磷、速效钾呈极显著或显著正相关,与土壤pH值及容重呈极显著或显著负相关。     

不同森林植被下土壤活性有机碳含量及其季节变化

通过对湖南省会同县地区不同季节地带性常绿阔叶林、杉木纯林、火力楠纯林以及杉木火力楠混交林土壤各活性有机碳的含量测定,分析了森林植被对土壤活性碳库及其季节变化的影响.结果表明,常绿阔叶林转变为人工林后,土壤活性有机碳含量明显降低;与杉木纯林相比,火力楠与杉木混交可提高土壤活性有机碳含量,但只有土壤水溶性有机碳含量显著提高;各林地土壤活性有机碳具有明显的季节变化,一年中土壤水溶性有机碳含量的大小始终为常绿阔叶林>杉木火力楠混交林>火力楠纯林>杉木纯林,土壤微生物量碳、热水浸提有机碳和碳水化合物则表现为常绿阔叶林>火力楠纯林>杉木火力楠混交林>杉木纯林.与杉木纯林相比,杉木火力楠混交林可提高林地质量,但不同林地活性有机碳的季节变化规律表现不尽一致,表明土壤活性有机碳的季节差异不仅与温度、降雨等气候因素有关,还受到植被类型的影响.     

不同状态高寒草原主要土壤活性有机碳组分的变化

对藏北高原正常、轻度和严重退化高寒草原表层(0 ～ 10 cm)、亚表层(10～20 cm)活性有机碳(Active soil organic carbon,ASOC)主要组分变化,以及土壤微生物对ASOC的影响进行了研究,结果表明:(1)易氧化有机碳(Readily oxidizable organic carbon,ROC)、微生物生物量碳(Microbial biomass carbon,MBC)、轻组有机碳(Light fraction organic carbon,LFOC)和水溶性有机碳(Water-soluble organic carbon,WSOC)对土壤环境变化的敏感度显著不同,平均分配比率分别为11.10％、0.57％、0.04％和0.03％,高原寒旱环境对WSOC、LFOC的形成与积累极为不利.(2)不同状态高寒草原亚表层ASOC各组分含量均显著高于表层;与正常草原ASOC各组分含量相比,退化草原表层、亚表层分呈小幅增加和大幅下降,但轻度退化草原变化幅度大于严重退化草原;因此,0～20 cm土层ASOC各组分含量均呈正常草原＞严重退化草原＞轻度退化草原.(3)不同状态草原中,纤维素分解酶活性对ASOC组分的形成均具极显著(R2:0.731 ～0.960)的促进作用,土壤放线菌、真菌对纤维素分解酶活性(Cellulolytic enzyme activity,CEA)则具有较大影响.(4)草原严重退化阶段,土壤微生物可能已完成向抗逆能力、纤维素分解酶分泌能力更强生理种群的演替,其相对较高的SOC、ASOC含量表征着土壤有机残体的较大消耗.     

黄土高原半干旱区不同土地利用下的土壤有机碳、碳组分和土壤营养

Cropland (CP), native grassland (NG) and two shrub land treatments which were converted from cropland in 1985:seabuckthorn (Hippophae rhamnoides L. ) (ST), and branchytamarisk (Tamarix ramosissima) (BT) were investigated to evaluate effects of land use conversion on soil organic carbon (SOC) and soil nutrients in the semi-arid region of the Loess Plateau of China. Total organic carbon (TOC), light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), total N (TN), nitrate nitrogen (NO₃^--N) and nitrite nitrogen (NO₂^--N), ammonium nitrogen (NH₄⁺-N), total P, and available P (AP) were measured. The results showed that SOC in NG, ST and BT were 12.7%, 27.7% and 34.8% higher than that of the cropland, respectively. LFOC, light fraction (LF) dry matter, ratio of TOC to TN (C/N) and the ratio of TOC to AP (C/P) were higher in the shrub land or native grassland than in the cropland. Cropland had the highest TN, the sum of NO₃^--N and NO₂^--N, TP and AP due to the use of chemical fertilizers. TOC significantly correlated with LFOC, HFOC and C/N. LFOC significantly correlated with dry matter of the LF and C/N. TN, the sum of NO₃^--N and NO₂^--N and AP were significantly negatively correlated with TOC and LFOC. Therefore, land use conversion from cropland to shrub land, or maybe grassland, contributed to SOC sequestration and improved soil nutrients stabilization.     

黄河三角洲盐碱地不同混交林土壤可溶性有机碳氮的研究

对黄河三角洲盐碱地刺槐纯林、刺槐+白蜡、刺槐+白榆和刺槐+臭椿混交林土壤可溶性有机碳(DOC)和土壤可溶性氮(TNS)进行了研究。结果表明,4种人工林中,腐殖质层DOC和TSN含量显著大于0-20和20-40cm层土壤。刺槐+臭椿混交林的DOC含量最高,为257.70mg/kg。另外,总氮(TN)和TSN含量分别为1065.79和55.80mg/kg,均显著高于其他三种林型。各层土壤DOC和TSN含量由高到底的顺序依次为：刺槐+臭椿混交林 > 刺槐+白榆混交林 > 刺槐纯林 > 刺槐+白蜡混交林。相关分析结果表明,土壤DOC和TSN与土壤的全氮、有效磷、速效钾和含盐量相关性显著。     

不同施肥模式下褐土的有机碳组分及碳固存效应变化

【目的】基于长期定位试验,研究长期有机无机肥配施下褐土有机碳含量及其组分构成的演变特征,以深入了解有机肥对土壤碳固存能力的影响机制,为通过科学养分管理实现褐土生态环境稳定和提高生产力提供理论依据。【方法】有机无机肥配施试验于1992年在山西寿阳旱地农业生态系统国家野外科学观测研究站进行,种植制度为一年一季玉米。试验采用氮、磷、有机肥三因素四水平正交设计,共18个处理,本研究选择其中的9个处理：N₀P₀M₀、N₁P₁M₀、N₂P₂M₀、N₃P₃M₀、N₄P₄M₀、N₂P₁M₁、N₃P₂M₃、N₄P₂     

不同利用方式下复垦土壤的有机碳组分空间分布特征

以济宁市粉煤灰充填复垦中的园地、耕地和林地为研究对象,研究不同利用方式对复垦土壤的有机碳组分空间分布的影响。通过现场分层采集土样和室内化验指标,研究有机碳组分(WDOC、POC、MOC、LFOC、HFOC、MBC)在不同利用方式土壤中的空间分布特征。结果表明:(1)3种利用方式的全碳(TC)、土壤有机碳(SOC)和土壤有机碳密度(SOCD)均偏低于对照耕地。不同利用方式之间TC、SOC和SOCD的大小关系均为复垦园地复垦林地复垦耕地。(2)不同利用方式之间有机碳组分差异明显(P0.05),SOC与各组分之间均表现为极显著正相关,且关系密切。通过对组分进行相关性分析、比重分析和敏感性分析发现,MOC和HFOC的含量偏低是导致复垦土壤有机碳低于对照耕地的根本原因。(3)根据有机碳组分丰富度指数发现,复垦园地的组分在0—40cm土层恢复较好,复垦林地在40—60cm土层恢复较好,复垦耕地恢复效果一般。在0—60cm土层的综合指数上表现为复垦园地复垦林地复垦耕地。通过对3种利用方式的有机碳组分空间分布特征进行分析后发现,在济宁市平阳寺镇的粉煤灰充填复垦地中,利用成园地效果最好,值得进一步推广。     

不同施肥处理红壤生物活性有机碳变化及与有机碳组分的关系

采用物理分组方法对长期不同施肥处理的旱地红壤有机碳组分进行了区分,布置室内培育试验观测了培养过程中土壤有机碳的矿化动态,通过拟合一级动力学方程计算土壤生物活性有机碳库量.研究结果表明,不同施肥处理的土壤中,轻组有机碳(LF-C)、团聚体包裹的粗颗粒有机碳(iPOMc-C)及细颗粒有机碳(iPOMf-C)、矿物结合态有机碳(mSOC)分别占总有机碳的7%～10%、0.5%～1.5%、4%～7%、76%～85%,并与总有机碳(TOC)含量显著相关;厩肥处理显著增加了各组分含量,其作用优于绿肥处理和单施无机肥处理(CK);培养过程中土壤有机碳矿化动态符合一级反应动力学方程;有机无机肥配施处理的土壤生物活性有机碳库(C0)显著提高;和绿肥相比,厩肥处理中生物活性有效碳库(C0)增加幅度更大,但其周转速率常数k更小;各组分有机碳含量与C0含量均达到极显著(p＜0.01)相关,但除LF-C外其余有机碳组分占TOC的百分率均与C0达到极显著水平.     

土壤活性有机碳不同组分对保护性耕作的响应

为分析保护性耕作措施对旱作农田土壤活性有机碳的影响以及对土壤有机碳的敏感响应指标进行归纳总结,探讨适合西南丘陵区紫色土农田生态系统在保护性耕作下的有机碳分组方法和活性碳有效指标提供科学依据,进而为土壤固碳减排、提高土壤质量奠定理论基础。在重庆北碚西南大学试验农场对平作(traditional tillage,T)、垄作(ridge tillage,R)、平作+秸秆覆盖(traditional tillage+straw mulching,TS)和垄作+秸秆覆盖(ridge tillage+straw mulching,RS)4种处理下、西南紫色土丘陵区"旱三熟"种植模式下的土壤总有机碳(Total soil organic carbon,TOC)、颗粒有机碳(Particulate organic carbon,POC)、水溶性有机碳(Dissolved organic carbon,DOC)、易氧化有机碳(Readily oxidized organic carbon,ROC)、可矿化有机碳(Mineralized organic carbon,MOC)以及微生物量有机碳(Microbial biomass carbon,MBC)进行了测定和分析。结果表明,秸秆覆盖不仅增加了表层土壤的TOC,也有利于20cm以上的耕层TOC的增加,而垄作对TOC的影响很小。秸秆覆盖处理下各土层POC均显著高于传统耕作,而单纯的垄作处理对5cm以下土层的POC没有影响,却显著地降低了0-5cm土层POC含量。DOC含量随土层的加深逐渐降低,且不同处理的差异主要出现在表层0-5cm土壤中,5cm以下土壤的DOC含量不易受到耕作措施的影响。TS、RS与对照相比均显著提高0-5cm土层的ROC含量,R与T之间差异不显著,秸秆覆盖只对土壤表层ROC影响很大。T、R、TS、RS处理全年日均土壤呼吸分别为1.84,1.65,2.22,2.21μmol/(m2·s),年土壤呼吸总量分别为696.31,624.41,840.12,836.33g/m2。与对照相比,垄作对土壤呼吸的影响不大,秸秆覆盖加速了土壤呼吸速率。秸秆覆盖处理显著提高了MBC含量,而垄作处理的影响不大。MBC与土壤呼吸速率呈显著正相关,R2介于0.756~0.919之间,P0.05。通过对土壤总有机碳及各组分之间的相关分析分析结果显示,TOC、POC、DOC和ROC在0-5cm土层表现显著的正相关,其他土层没有明显的规律。TOC、POC、DOC、ROC和MBC对耕作措施的响应变化基本一致,表现为对垄作处理的响应不显著,而受秸秆覆盖的影响很大,其中颗粒有机碳占总有机碳的35.74%~49.66%,二者显著正相关,可以作为反映土壤有机碳变化的敏感指标。     

不同有机厩肥输入量对土壤团聚体有机碳组分的影响

土壤是重要的有机碳库,其微小变化可能引起大气CO2浓度水平的较大变异。土壤团聚体对土壤有机碳具有物理保护作用。有机厩肥的输入既可以提高土壤有机碳含量,又可以促进土壤团聚体的形成,对土壤有机碳的截获和保持有重要意义。本实验采用湿筛的方法分离土壤团聚体,并对团聚体进行有机碳组分分离。通过对连续8年施加不同量有机厩肥试验的研究发现:适量的有机厩肥施用可以显著地提高土壤的平均质量直径(MWD),改善土壤结构;过量施用有机厩肥则明显降低了>2 000μm团聚体含量。潮棕壤有机碳主要分布在250～53μm和2 000～250μm团聚体中,两者相加约占有机碳全量的73.7%～78.5%。并且随着有机碳输入量的增加,土壤有机碳主要贮存在2 000～250μm团聚体中。有机厩肥的施加明显地加快了>2 000μm团聚体的更新速率。土壤轻组分有机碳含量也随有机厩肥输入量的增加而不断增加,高量有机厩肥下占全量的22.1%。土壤固定有机碳的能力有限,存在明显的等级饱和现象。因此,在有机质匮乏的土壤施用有机肥意义重大,应尽量减少向高有机质土壤输入有机碳。     

Soil organic matter content and chemical composition under two rotation management systems in a Mediterranean climate

The crop rotation system in organic farming is a determinant factor to accumulate and preserve soil organic matter (SOM), and in depth knowledge on its effects is still lacking. Tillage intensity in particular is crucial to maintain soil aggregates and protect SOM from degradation. The evolution of SOM was tested in two adjacent fields under two different rotation cropping systems (low-intensity tillage and high-intensity tillage), and the effect of a further cultivation of legume in both fields was evaluated using ¹³carbon (C)-nuclear magnetic resonance (NMR) and elemental analysis of samples isolated through combined aggregate size and density fractionation. The two adjacent fields had been managed using the following organic farming methods for 13 seasons since 1998: i) alfalfa-based, with nitrogen (N) enrichment and low-frequency tillage with alfalfa (Medicago sativa) (9 seasons), winter wheat (Triticum durum) (3 seasons), and broad bean (Vicia faba) (1 season) and ii) cereal-based, with N depletion and annual tillage with barley (Hordeum vulgare) (7 seasons), sunflower (Helianthus annuus) (2 seasons), broad bean (Vicia faba) (3 seasons), and bare fallow (1 season). Soil sampling was carried out at the end of the 13-year rotation (T0, November 2011) and after winter wheat and chickpea cultivation in both fields over two subsequent years (T1, July 2013). Bulk organic C was significantly higher in the alfalfa-based system than in the cereal-based system at both T0 and T1, with SOM occluded in soil aggregates and associated with mineral particles. In terms of the macroaggregates heavy fraction at T0, the alfalfa-based field contained twice the organic C of that in the cereal-based field, as well as three times the organic C in the occluded particulate organic matter (POM). The occluded POM (oPOM) had a lower aryl/O-alkyl C ratio in the alfalfa-based system than in the cereal-based system, suggesting that oPOM undergoes a lower degree of decomposition during low-intensity management. The aryl/O-alkyl C ratios of the macro-and microaggregate oPOM decreased from T0 to T1 in the cereal-based system, suggesting increased protection of these fractions by soil aggregates. Thus, including legumes in crop rotation appears to positively affect the accumulation of SOM associated with mineral particles and within soil aggregates.     

Carbon mineralization in soils of different textures as affected by water-soluble organic carbon extracted from composted dairy manure

The water-soluble organic C in composted manure contains a portion of labile C which can stimulate soil microbial activity. The objective of this experiment was to evaluate the effects of water-soluble organic C extracted from composted dairy manure on C mineralization in soil with different textures. Three soils with textures varying from 3 to 54% clay were amended with 0 to 80 mg water-soluble organic C kg^–1 soil extracted from a composted dairy manure and incubated for 16 weeks at 23°C. The total amount of C mineralized was greater than the amount of C added in the three soils. Differences in mineralizable C with and without added water-soluble organic C were approximately 13–16 times, 4.8–8 times, and 7.5–8 times greater than the amount of C added to clay, loam, and sand soils, respectively. The results of this experiment suggest that immediately following composted manure applications, C mineralization rates increase, and that most of the C mineralized comes mainly from the indigenous soil organic C pool.CLBRR contribution No. 94-71     

Effect of tillage and rotation on organic carbon forms of chernozemic soils in Saskatchewan

The effects of selected tillage and rotation systems on soil organic carbon and its fractions were studied on Chernozemic soils in south‐western and east‐central Saskatchewan. After practicing a no‐till fallow unfertilized‐wheat rotation for 7 years on an Orthic Brown Chernozem in south‐western Saskatchewan, total soil organic carbon (TOC) in the 0 – 5 cm and 5 – 10 cm layers was slightly lower than the tillage fallow‐unfertilized wheat comparable treatment. However, light fraction of organic carbon (LFOC) was similar in the two treatments. Comparison of the tillage fallow‐unfertilized wheat to a treatment involving conversion to a fertilized continuous cropping system for 10 years showed TOC increased slightly in the two depths and LFOC increased by 24 % and 29 % in the 0 – 5 cm and 5 – 10 cm layer, respectively, of the continuous cropping treatment. Microbial biomass carbon (MB‐C) was increased significantly at the 5 – 10 cm depth. After conversion of fallow‐wheat to alfalfa as perennial forage for 10 years, TOC increased by 80 % and 27 %, LFOC by 245 % and 286 %, and HFOC by 63 % and 20 % at 0 – 5 cm and 5 – 10 cm depths, respectively, compared to the tilled cereal‐fallow system. Meanwhile, water soluble organic carbon (WSOC) was not affected but MB‐C increased significantly. In an Orthic Black Chernozem in east‐central Saskatchewan, the depletion and restoration of organic carbon was observed when native sod was changed into cropland and then back to grassland. For example, the TOC of cropland under cereal‐fallow rotation for 62 years decreased by 42 % and 33 % at 0 – 5 cm and 5 – 10 cm depths, respectively, compared to native sod. The LFOC decreased by 79 % and 74 % in the layers, and reductions in WSOC and MB‐C were even greater. After cropland was re‐seeded to grassland for 12 years, the concentration of total organic carbon was increased by 16 % and 22 % while the mass of organic carbon was the same as the cropland in the two layers. The LFOC and MB‐C amounts in the grass seed‐down were double that of the cropped land, but the amounts of TOC, LFOC, and MB‐C in grass seed‐down were still significantly lower than the native sod.     

Soil microbial biomass and organic matter composition in soils under cultivation

To determine whether there is a relationship between the composition of soil organic matter and the activity of the soil microbial biomass, the composition of the organic matter in 12 typical arable soils in Northwest Germany was investigated by wet chemical analysis and CPMAS cross polarization magic angle spinning ¹³C-NMR spectroscopy. The data were correlated with the microbial biomass as estimated by substrate-induced respiration. A strong correlation between the microbial biomass and alkylic C compounds was observed (r=-0.960^***). Recalcitrant substances were enriched in this fraction, which were classified as humic acids according to the wet chemical procedure. The microbial decomposition of these humic acids is probably retarded, due to their chemical structure and/or physical bonding, when the soil microbial biomass activity is limited.     

长期不同施肥下我国4种典型土壤活性有机碳及碳库管理指数的变化特征

研究长期不同施肥处理对3种旱作土壤(黑土、潮土和红壤)及1种水田土壤(水稻土)活性有机碳含量(LOC)及碳库管理指数(CMI)的影响,为优化施肥管理措施提供科学依据。结果表明:水田土壤总有机碳含量(TOC)和LOC含量高于旱作土壤。单施化肥(NPK),旱作3种土壤TOC、LOC较不施肥对照(CK)显著增加,而水田较CK无显著差异。化肥配施秸秆处理(NPKS),旱作和水田土壤TOC、LOC、活性有机碳占总有机碳的比例(LOC/TOC)及CMI均显著增加,潮土TOC和LOC含量增加最多,增加比例分别为37.6%和66.9%。化肥配施有机肥处理(NPKM),旱作和水田土壤的TOC、LOC、LOC/TOC及CMI均显著增加,其中黑土增加比例最大,分别为90.3%、140.9%、5.1%及277%。旱作和水田土壤的活性有机碳及碳库管理指数均对施肥响应敏感,具有相对一致的响应特征,即长期有机无机肥配施能显著提高土壤活性有机碳含量及碳库管理指数,且效果优于化肥配施秸秆和单施化肥处理。     

Changes in soil organic carbon fractions and bacterial community composition under different tillage and organic fertiliser application in a maize−wheat rotation system

ABSTRACT

The objective of this study was to assess the impact of different tillage and organic fertiliser regimes on soil carbon fractions and bacterial community composition within a maize–wheat cropping system. We conducted a six-year experiment on the Huang-Huai-Hai Plain of China. Six treatments were established: deep tillage (DT), shallow tillage (ST), no-tillage (NT), deep tillage with organic fertiliser (DTF), shallow tillage with organic fertiliser (STF), and no-tillage with organic fertiliser (NTF). Results indicated that during the winter wheat growing season, the highest contents of soil organic carbon (SOC) and easily-oxidised organic carbon (EOC) were in the STF treatment. During the summer maizegrowing season, the DTF treatment had the highest SOC and EOC contents. Compared with the other treatments, the NTF treatment had higher Chao1 and Shannon indices for bacteria; however, the relative abundance of Proteobacteria is highest in all treatments. A redundancy analysis (RDA) revealed that bacterial community composition was correlated with variation of the SOC, DOC, EOC, and microbial biomass carbon (MBC). Our results showed that combining the two components of the SOC fractions and bacterial community composition, STF practice in a maize–wheat rotation was a sustainable approach to optimising soil structure and improving soil quality.     

Influence of tillage and rotation systems on distribution of organic carbon associated with particle-size fractions in Chernozemic soils of Saskatchewan, Canada

The effects of several dominant tillage and rotation systems on soil organic C content of different particle-size fractions were studied in Chernozemic soils from southwestern and east-central Saskatchewan, Canada. In an Orthic Brown Chernozem in southwestern Saskatchewan, 7 years of no-till cereal–fallow, imposed on a long-term tillage fallow–wheat rotation soil, resulted in 0.1 Mg C ha⁻¹ more organic C mass in the sand + organic matter (OM) fraction of the 0- to 5-cm layer, whereas organic C associated with coarse silt (CS), fine silt (FS), coarse clay, and fine clay of 0- to 5- and 5- to 10-cm layers was less than that of the comparable tilled cereal–fallow system. Conversion of tilled fallow–wheat rotation soil to continuous cropping had a slight effect, whereas the organic C mass in all the size fractions was significantly increased in both 0- to 5- and 5- to 10-cm layers after alfalfa was introduced on tilled fallow–wheat as perennial forage for 10 years. In an Orthic Black Chernozem in east-central Saskatchewan that was cultivated and tilled using a cereal–fallow rotation for 62 years, organic C mass decreased in sand + OM, CS, and FS of 0- to 10-cm depth. Conversion of the tilled cereal–fallow cropland soil back to seeded grassland resulted in significantly more soil organic C in sand + OM fraction after 12 years of grass seed-down. The sand + OM fraction appears to be the size fraction pool initially most sensitive to adoption of management practices that are liable to sequester carbon in the soil.     

黑土根际土壤有机碳及结构对长期施肥的响应

由于人类农业措施的干扰,氮肥和畜禽粪污大量输入到黑土中,对土壤有机碳库产生了较大负面影响。根际有机碳在调控土壤碳循环和养分转化中发挥着重要的作用。探明根际有机碳对不同养分的生态响应,可为不同施肥处理下黑土农田生态系统碳固持和农田可持续利用提供理论依据。该研究以黑土长期定位试验为基础,采集长期不施肥（CK）、常量氮（N）、二倍量氮（N2）、常量有机肥（M）、二倍量有机肥（M2）、常量有机肥+常量氮（MN）、二倍量有机肥+二倍量氮（M2N2）7个处理下大豆根际土壤,分析了根际有机碳和活性有机碳特征,同时利用固态核磁共振技术分析其光谱特征。结果表明,N、M2、MN和M2N2处理的根际土壤有机碳含量显著高于非根际水平,且以MN和M2N2处理的根际效应最显著,分别比非根际增加了18.3%和26.7%。分析核磁共振光谱显示,与非根际土壤相比,根际土壤具有较高的烷氧基碳比例和较低芳香碳比例,表明根际效应能够改变土壤有机碳结构比例。与不施肥处理相比,大部分施肥处理提升了黑土根际有机碳含量,其中以氮肥马粪配施和二倍量马粪（M2N2）处理提升幅度最高。由核磁共振图谱可知,M2和M2N2处理均增加根际土壤难降解成分烷基碳比例、芳香基碳比例、烷基碳与烷氧基碳比值、芳香碳与总碳比值,而MN处理仅增加烷基碳比例、烷氧基碳比例以及烷基碳与烷氧基碳比值。二倍量氮肥（N2）处理降低烷基碳比例、芳香碳比例和烷氧基碳比例,根际土壤难降解成分降低,不利于土壤固碳,同时证明固态 13C-核磁共振技术结合半定量分析能够准确地分析不同有机碳结构组分变化,深刻认识根际土壤有机碳的稳定机制。     

施肥对板栗林土壤活性碳库和温室气体排放的影响

在浙江省临安市典型板栗林试验地,利用静态箱-气相色谱法测定了不同施肥条件下板栗林土壤CO2和N2O排放速率,同时测定了土壤水溶性有机碳（WSOC）和微生物量碳（MBC）含量。初步探讨了施肥对板栗林土壤活性碳库与温室气体排放速率的影响,以及土壤温室气体排放速率与活性碳库之间的关系。本试验设置不施肥（CK）、 无机肥（IF）、 有机肥 （OF）和有机无机混合肥（OIF,1/2无机肥和1/2有机肥）4个施肥处理。结果表明, 施肥1个月后,与不施肥（CK）处理相比,无机肥（IF）、 有机肥（OF）和有机无机混合肥（OIF）处理下土壤CO2排放速率分别增加了87%、 38%和61%, N2O排放速率分别增加了101%、 67%和95%; 而施肥6个月后,与CK处理相比,IF、 OF和OIF处理下土壤CO2 排放速率分别增加了51%、 43%和64%,N2O排放速率分别增加了21%、 29%和47%。同时,施肥显著增加板栗林土壤WSOC和MBC含量（P＜0.05）。此外,土壤CO2和N2O排放速率与WSOC含量均呈显著正相关（P0.05）,而与MBC含量没有显著的相关性。因此,施肥引起板栗林地土壤WSOC含量增加可能是导致板栗林地土壤温室气体排放增加的重要原因之一。     

有机物料还田对华北小麦玉米两熟农田土壤有机碳及其组分的影响

中国农业废弃物种类多、数量大、利用率低、污染重。将有机物料还田,是实现废弃物资源化利用的重要途径。该研究以循环农业理念为指导,选择代表农田内循环的秸秆以及代表农沼循环、农牧循环、农菌循环、农工循环的废弃物沼渣、猪粪、菌渣和酒渣为试验材料,开展了等碳量还田定位试验,分析各有机物料还田后对土壤有机碳及其组分的影响。结果表明:1)连续施用有机物料提高了土壤总有机碳(TOC)、易氧化有机碳(LOC)、微生物量碳(MBC)和可溶性有机碳(DOC)含量。随着有机物料还田年限的增加,土壤TOC、LOC和MBC含量均不同程度地增加,年平均增幅分别为:15.57%~22.82%、20.00%~38.31%和16.30%~50.56%。还田5年后各有机物料处理土壤TOC、LOC、MBC和DOC含量平均分别是无机肥处理的1.24~1.62、2.07~3.19、1.20~2.06和1.05~3.36倍。2)不同有机物料中均利于土壤TOC含量的提高,秸秆提升效果相对最差,沼渣、菌渣、猪粪、酒渣和秸秆还田处理的0~20cm土壤TOC含量平均增长速率分别为:22.82%、21.88%、16.42%、16.13%和15.57%。