铅锌银尾矿区土壤微生物活性及其群落功能多样性研究

通过对浙江省天台铅锌银尾矿区土壤微生物活性指标以及微生物群落功能多样性研究 ,结果表明 ,尾矿污染区土壤几种重金属含量比非矿区土壤有明显的增加。尾矿区土壤微生物特征发生了显著的变化 ,微生物生物量和可培养细菌数量显著降低 ,但土壤基础呼吸和微生物代谢商 (qCO2 )值却明显升高。Bi olog测试结果显示 ,随着重金属污染程度的加剧其土壤微生物群落结构发生了相应变化 ,尾矿区土壤微生物群落代谢剖面 (AWCD)及群落丰富度、多样性指数均显著低于非矿区土壤 ,且供试土壤间均达极显著水平差异 (p <0 .0 1) ,表明尾矿区重金属污染引起了土壤微生物群落功能多样性的下降 ,减少了能利用有关碳源底物的微生物数量、降低了微生物对单一碳源底物的利用能力     

长江三角洲地区污水污泥与健康安全风险研究Ⅴ.污泥施用对土壤微生物群落功能多样性的影响

利用BIOLOG测试方法对长江三角洲地区施污泥土壤的微生物群落功能多样性进行了初步探讨。研究结果表明,施用污泥后土壤微生物群落代谢剖面、多样性指数、动力学参数均发生了变化,说明微生物对单一碳源底物的利用能力发生了改变。微生物群落功能多样性动力学研究结果发现,供试土壤的微生物群落代谢剖面(AWCD)与培养时间之间呈非线性关系,其变化过程符合微生物种群生长动态模型(S型)。除滩潮土的杭州新鲜消化污泥和杭州风干污泥处理外,其他污泥处理均使土壤微生物群落功能多样性动力学参数K和r值降低,S值增大。土壤微生物群落功能多样性特征的变化可以较好地显示施用污泥后土壤微生物群落对碳源利用能力和模式的差异,反映施用污泥特定生境土壤微生物群落功能多样性的变化。     

转Bt基因棉叶对土壤微生物多样性的影响

应用Biolog方法研究了转Bt基因棉粉碎叶腐解对土壤微生物群落结构功能多样性的影响。取腐解10d、25d、40d、55d、70d土样分析土壤微生物群落多样性指数及土壤微生物对聚合物、胺类、氨基酸、糖、羧酸和其他类碳源利用情况。结果表明:在腐解过程中,转Bt基因棉粉碎叶土壤微生物群落丰富度下降,群落多样性显著降低,而群落优势集中性明显提高;转Bt基因棉粉碎叶影响了土壤微生物群落对碳源的利用程度,表现为可显著增加对糖类、胺类和氨基酸类碳源的利用,初期显著降低对羧酸类碳源的利用,对聚合物类和其他类碳源的利用率无显著影响;主成分分析表明转Bt基因棉粉碎叶对土壤微生物群落原有结构功能影响具有持续性。     

长江三角洲地区污水污泥与健康安全风险研究V．污泥施用对土壤微生物群落功能多样性的影响

利用BIOLOG测试方法对长江三角洲地区施污泥土壤的微生物群落功能多样性进行了初步探讨。研究结果表明，施用污泥后土壤微生物群落代谢剖面、多样性指数、动力学参数均发生了变化，说明微生物对单一碳源底物的利用能力发生了改变。微生物群落功能多样性动力学研究结果发现，供试土壤的微生物群落代谢剖面（AWCD）与培养时间之间呈非线性关系，其变化过程符合微生物种群生长动态模型（S型）。除滩潮土的杭州新鲜消化污泥和杭州风干污泥处理外，其他污泥处理均使土壤微生物群落功能多样性动力学参数K和r值降低，S值增大。土壤微生物群落功能多样性特征的变化可以较好地显示施用污泥后土壤微生物群落对碳源利用能力和模式的差异，反映施用污泥特定生境土壤微生物群落功能多样性的变化。     

重金属复合污染下土壤微生物群落功能多样性动力学特征

用碳素利用法对浙江省天台铅锌银尾矿区重金属复合污染土壤微生物群落功能多样性动力学特征进行了初步探讨。研究结果表明 ,矿区重金属复合污染降低了供试土壤的微生物群落代谢剖面 ,且群落代谢剖面值与培养时间之间呈非线性关系 ,其变化过程符合微生物种群生长动态模型 (S形 )。随着重金属复合污染程度的加剧 ,土壤微生物群落功能多样性动力学参数K和r值越低 ,参数s值所需的时间则越长。上述动力学参数与群落代谢剖面各自的主成分分析结果显示 ,微生物群落功能多样性的动力学参数K值和s值能够很好地区分矿区土壤重金属污染程度 ,并且其区分效果比微生物群落代谢剖面值好。土壤微生物群落功能多样性动力学特征的变化可以较好地显示矿区重金属复合污染土壤微生物群落对碳源利用模式的差异 ,反映矿区特定生境土壤微生物群落功能多样性的变化 ,在一定程度上揭示重金属胁迫下环境微生物种群作用机理。     

转Bt基因棉粉碎叶对土壤微生物群落功能多样性的影响

采用Biolog GN2微平板法,研究转Bt基因棉粉碎叶添加到土壤后,对土壤微生物群落功能多样性的影响。结果表明,在转Bt基因棉粉碎叶添加到土壤后,第10天和第40天的平均颜色变化率(AWCD)显著提高,表明微生物群落的代谢加快,活动强度加大;土壤微生物群落对糖类、胺类、氨基酸类和羧酸类4类碳源的优势利用顺序发生明显变化,表明土壤微生物群落结构及其功能多样性发生了一定改变;土壤微生物群落对聚合物类和其他类碳源的利用率无显著影响,但显著提高对糖类、胺类和氨基酸类碳源的利用率,并仅在第10天显著降低对羧酸类碳源的利用率,表明降解糖类、胺类和氨基酸类碳源的微生物可能是转Bt基因棉粉碎叶影响的主要土壤微生物类群。     

玉米秸秆覆盖还田量对黑土微生物碳代谢活性与多样性的影响

  目的  针对东北黑土区长期集约化耕作导致的土壤退化问题,开展不同秸秆覆盖还田量对土壤微生物碳代谢特征的影响及其驱动因素的研究。  方法  采用MicroRespTM方法结合土壤碳氮含量等理化性质,测定土壤微生物碳代谢能力及其影响因素,使用Past v2.16、Canoco 5.0等软件对微生物群落功能多样性、结构差异以及土壤理化性质和微生物群落碳代谢特征间的关系进行分析。  结果  秸秆连续覆盖还田14年后,土壤微生物对羧酸类与氨基酸类碳源的代谢活性显著降低,但对外源碳底物的代谢多样性显著增强。67%和100%秸秆还田显著改变了土壤微生物群落碳源代谢结构,100%秸秆还田下微生物对芳香酸类碳源的相对代谢活性提高。土壤微生物对碳源的代谢活性主要与土壤碳氮含量显著相关,土壤可溶性碳与碱解氮含量分别是影响土壤微生物碳源代谢多样性和结构的主要理化因子。  结论  长期秸秆还田可以通过降低土壤微生物对易利用碳源的代谢需求、提高对碳源的代谢多样性而改善免耕土壤微生物碳代谢功能。本研究可为优化东北黑土区保护性耕作管理模式、促进该地区农业可持续发展提供微生物学参考。     

甘肃中部沿黄灌区马铃薯连作对土壤化学和生物学性质的影响

甘肃中部沿黄灌区是全国重要的加工型马铃薯和种薯生产基地,但集约化种植带来的连作障碍问题已严重影响到产业的健康发展。设置不同连作年限(0~5年)马铃薯种植处理,通过田间试验评估连作对土壤化学和生物学性质的影响,探讨马铃薯连作的土壤障碍因子。结果表明:土壤有机碳含量随连作年限延长逐渐降低,而碱解氮和速效钾含量以及电导率与之相反;连作显著增加土壤速效磷含量,但对全氮含量、碳氮比和p H无明显影响。长期连作(3~5年)较非连作(0年)土壤平均酶活性显著降低33.07%~61.78%,脲酶、蔗糖酶和脱氢酶活性亦随连作年限延长逐渐降低。长期连作降低土壤微生物生物量碳含量,土壤基础呼吸量和FDA水解活性与连作年限呈极显著负相关。Biolog ECO分析显示,长期连作显著降低土壤微生物总活性和功能多样性,Shannon多样性指数较非连作降低11.75%~13.65%。碳源利用图谱分析表明,连作明显改变土壤微生物群落结构,碳水化合物是区分不同连作年限土壤微生物群落结构差异的最敏感碳源类型;长期连作显著降低土壤微生物对碳水化合物类、氨基酸类、羧酸类和胺类碳源的相对利用率,且土壤微生物对单一碳源的利用呈现集中化的趋势。线性逐步回归分析和通径分析表明,土壤微生物群落结构、微生物生物量碳、全氮和脱氢酶对块茎产量有显著影响,以微生物群落结构贡献最大,微生物生物量碳次之。土壤微生物因子变化可能是导致甘肃中部沿黄灌区马铃薯连作障碍发生的重要原因。     

种植方式对玉米不同生长期土壤微生物群落功能多样性的影响

为探讨玉米不同种植方式下土壤微生物群落功能多样性的差异,进行田间定点试验,采用Biolog方法分别研究了4行轮作、4行连作、8行轮作和8行连作的种植方式对玉米种植前、拔节期、抽穗期和收获期土壤微生物功能多样性的影响。结果表明:4种种植方式的土壤微生物均在种植前代谢活性最弱、功能多样性最低,在玉米抽穗期土壤微生物代谢活性最强,功能多样性最高。在种植玉米前,轮作的土壤微生物代谢活性和功能多样性高于连作,8行轮作和4行轮作土壤微生物的物种多样性指数分别比相应的连作高22.93%和11.42%;4行轮作的土壤微生物物种多样性指数比8行轮作低3.17%,而4行连作比8行连作高6.83%。在玉米拔节期、抽穗期及收获期连作土壤微生物功能多样性略高于轮作,且有4行连作大于8行连作的趋势,但差异均未达显著水平。种植前,4种种植模式的土壤微生物对6大类碳源的利用程度整体上都较低,降解碳水化合物类、羧酸类和聚合物类碳源的微生物是种植方式影响的主要土壤微生物类群;随着玉米的生长,土壤微生物对6大类碳源的利用都逐渐增强,玉米拔节期、抽穗期和收获期之间土壤微生物特征碳源没有较大差异,4种种植方式的土壤微生物对聚合物类碳源利用程度差异都不显著。PLS-EDA分析结果表明种植方式对土壤微生物产生较大影响,种植前8行轮作和4行连作的土壤微生物碳源利用模式具有相似性;种植玉米后4种种植方式的土壤微生物对碳源的利用模式存在较大差异,其中4行连作的土壤微生物在玉米拔节期和收获期对碳源的利用模式与其他3种种植方式差异最大。试验说明作物长期连作栽培会影响土壤微生物群落功能,降低土壤微生物物种多样性,引起土壤微生物群落结构与功能的失调。     

基于BIOLOG指纹解析土壤可培微生物对铀污染的响应

为考察铀污染对土壤微生物群落的影响,以50、100、150 mg·L-1铀处理的土壤为研究对象,未处理的土壤为对照(CK),采用BIOLOG-ECO微孔板技术考察土壤微生物群落的功能多样性和碳源利用动力学特征等的变化。根据微孔板中的孔平均颜色变化率(AWCD)可知,铀污染对土壤微生物的生理活性呈现显著的抑制作用;采用Shannon多样性指数、Simpson指数、Mc Intosh指数描述微生物功能多样性,结果表明,铀处理组与CK的微生物群落功能多样性差异在3个多样性指数上均达到显著水平;土壤微生物对各类碳源的利用能力有所不同,以氨基酸类和胺类碳源为主;铀处理后,6类碳源相对利用率均比CK显著降低,其中羧酸类和多聚物类的利用率下降50%以上。主成分分析结果表明,铀污染后的土壤微生物特异利用的碳源主要有β-甲基-D-葡萄糖苷、D-半乳糖酸-γ-内脂、L-精氨酸等。因此,铀污染改变了土壤微生物的群落结构,导致微生物生理代谢等功能特性的变化。BIOLOG-ECO技术结合数学统计分析方法可以较为直观、快捷地反映土壤微生物的生物多样性,研究结果为评估和修复铀污染生态环境提供了理论依据。     

Effects of tetracycline on the soil microflora: function,diversity, resistance

Background  Tetracycline is a widely used antibiotic in animal production. Significant amounts of the substance reach the soil via feces, urine and manure application. As tetracycline is a persistent compound with antibacterial activity, its presence in soil may have undesired direct and indirect effects. These have been investigated so far focusing on effects on selected microbial functions. Objectives  The aim of the present study was to obtain comprehensive information on potential effects of tetracycline on the soil microflora under environmentally relevant conditions. The investigations included function and structure of the microbial biocoenosis and the distribution of resistance genes. Methods  Pig manure rich in tetracycline resistance genes was applied to a sandy soil. This soil as well as an unamended soil were additionally treated with several concentrations of tetracycline. The spiked soils were incubated in outdoor lysimeters for several months. Substrate induced respiration, PLFAs, ten selected resistance genes, and the concentrations of tetracycline were determined. Results  The test concentrations, though far exceeding environmental relevance, caused only small effects. An establishment of resistance could not be detected. Applied resistance genes were not detectable at the end of the study even in the presence of added tetracycline. Conclusion  Due to the high sorption capacity of the antibiotic, environmentally relevant concentrations of tetracycline do not seem to cause undesired effects on the soil microflora.     

Substrate inputs and pH as factors controlling microbial biomass, activity and community structure in an arable soil

Our aim was to determine whether the smaller biomasses generally found in low pH compared to high pH arable soils under similar management are due principally to the decreased inputs of substrate or whether some factor(s) associated with pH are also important. This was tested in a soil incubation experiment using wheat straw as substrate and soils of different pHs (8.09, 6.61, 4.65 and 4.17). Microbial biomass ninhydrin-N, and microbial community structure evaluated by phospholipid fatty acids (PLFAs), were measured at 0 (control soil only), 5, 25 and 50 days and CO₂ evolution up to 100 days. Straw addition increased biomass ninhydrin-N, CO₂ evolution and total PLFA concentrations at all soil pH values. The positive effect of straw addition on biomass ninhydrin-N was less in soils of pH 4.17 and 4.65. Similarly total PLFA concentrations were smallest at the lowest pH. This indicated that there is a direct pH effect as well as effects related to different substrate availabilities on microbial biomass and community structure. In the control soils, the fatty acids 16:1ω5, 16:1ω7c, 18:1ω7c&9t and i17:0 had significant and positive linear relationships with soil pH. In contrast, the fatty acids i15:0, a15:0, i16:0 and br17:0, 16:02OH, 18:2ω6,9, 17:0, 19:0, 17:0c9,10 and 19:0c9,10 were greatest in control soils at the lowest pHs. In soils given straw, the fatty acids 16:1ω5, 16:1ω7c, 15:0 and 18:0 had significant and positive linear relationships with pH, but the concentration of the monounsaturated 18:1ω9 PLFA decreased at the highest pHs. The PLFA profiles indicative of Gram-positive bacteria were more abundant than Gram-negative ones at the lowest pH in control soils, but in soils given straw these trends were reversed. In contrast, straw addition changed the microbial community structures least at pH 6.61. The ratio: [fungal PLFA 18:2w6,9]/[total PLFAs indicative of bacteria] indicated that fungal PLFAs were more dominant in the microbial communities of the lowest pH soil. In summary, this work shows that soil pH has marked effects on microbial biomass, community structure, and response to substrate addition.     

Correlation among microbial biomass s,soil properties,and other biomass nutrients

The soil physicochemical characteristics and amounts of microbial biomass C, N, and S in 19 soils (10 grassland, 2 forest, and 7 arable soils) were investigated to clarify the S status in granitic regosols in Japan, in order to determine the relationships between biomass S and other soil characteristics and to estimate approximately the annual Sand N flux through the microbial biomass. Across the sites, the amount of biomass C ranged from 46 to 1,054, biomass N from 6 to 158, and biomass S from 0.81 to 13.44 mg kg_-1 soil with mean values of 438.8, 85.8, and 6.15 mg kg_-1 soil, respectively. Microbial biomass Nand S accounted for 3.4–7.7% and 1.1–4.0% of soil total Nand S, respectively. The biomass C: N, C : S, and N : S ratios varied considerably across the sites and ranged from 3.0–10.4, 32.5–87.7, and 5.0–18.8, respectively. Microbial biomass S was linearly related to biomass C and biomass N. The regression accounted for 96.6% for biomass C and 92.9% for biomass N of the variance in the data. The amounts of biomass C, N, and S were positively correlated with a number of soil properties, particularly with the contents of organic C, total N, SO₄-S, and electrical conductivity and among themselves. The soil properties, in various linear combinations showed a variability of 84–97% in the biomass nutrients. Stepwise multiple regression indicated that biomass C, N, and S were also dependent on SO₄-S as a second factor of significance which could limit microbial growth under the conditions prevailing at the study sites. Annual flux of Nand S was estimated through the biomass using the turnover rates of 0.67 for Nand 0.70 for S to be approximately 129 kg Nand 9.7 kg S ha^-1 y^-l, respectively, and was almost two times higher in grassland than arable soils.     

土壤微生物对不同粒径、不同表面和孔隙性质生物炭的响应

Biochars are known for their heterogeneity, especially in pore and surface structure associated with pyrolysis processes and sources of feedstocks. The surface area of biochar is likely to be an important determinant of the extent of soil microbial attachment, whereas the porous structure of biochar is expected to provide protection for soil microorganisms. Potential interactions between biochars from different sources and with different particle sizes were investigated in relation to soil microbial properties in a short-term incubation study. Three particle size(sieved) fractions(0.5–1.0, 1.0–2.0 and 2.0–4.0 mm) from three woody biochars produced from jarrah wood,jarrah and wandoo wood and Australian wattle branches, respectively, were incubated in soil at 25?C for 56 d. Observation by scanning electron microscopy(SEM) and characterisation of pore and surface area showed that all three woody biochars provided potential habitats for soil microorganisms due to their high porosity and surface areas. The biochars were structurally heterogeneous,varying in porosity and surface structure both within and between the biochar sources. After the 56-d incubation, hyphal colonisation was observed on biochar surfaces and in larger biochar pores. Soil clumping occurred on biochar particles, cementing and covering exposed biochar pores. This may have altered surface area and pore availability for microbial colonisation. Transient changes in soil microbial biomass, without a consistent trend, were observed among biochars during the 56-d incubation.     

玉米地土壤微生物量碳、氮及微生物熵对不同物料还田的响应

在四川丘陵区紫色土上进行田间试验,以无物料还田为对照,对比分析了蚕豆秸秆、油菜秸秆、猪粪3种物料还田对夏玉米吐丝期和收获期0—20,20—40cm土层土壤有机碳、全氮、微生物量碳氮含量及微生物熵的影响,以期为农业废弃有机物料的综合利用及四川丘陵区土壤质量的提升提供理论参考。结果表明:(1)尽管有机物料还田于0—20cm土层中,0—20,20—40cm土层土壤有机碳(SOC)、全氮(TN)、微生物量碳(SMBC)、微生物量氮(SMBN)含量均受到有机物料的深刻影响。各处理0—20cm土层SOC、TN、SMBC、SMBN含量均显著高于20—40cm土层,且上下2层土壤SOC、TN、SMBC和SMBN含量在生育时期间均表现为吐丝期>收获期。(2)在2个生育时期,3种物料还田均能提高0—20,20—40cm土层SOC、TN、SMBC、SMBN含量。与对照相比,物料还田处理的SOC、TN、SMBC、SMBN含量分别提高2.6%~141.2%,1.9%~33.0%,5.1%~114.7%,41.5%~98.7%,其中收获期各处理0—20,20—40cm土层SOC、SMBC、SMBN均表现为油菜秸秆>蚕豆秸秆>猪粪>对照,TN表现为蚕豆秸秆>猪粪>油菜秸秆>对照。(3)各处理SMBC/SMBN、qMB、SMBN/TN分别为3.74~10.53,0.86%~2.19%,1.01%~3.41%,且物料还田降低SMBC/SMBN,提高土壤qMB和SMBN/TN值。相关分析表明,SMBC、SMBN与SOC、TN之间均存在极显著正相关关系。因此,农业生产中可通过物料还田提供给微生物足够的碳氮营养,提高土壤SMBC、SMBN、SOC、TN含量和qMB值,维持较高的农田生产力,提升土壤质量,但具体施用物料时还需寻求土壤肥力提升、玉米产量增加以及环境效益之间的平衡。     

Effects of glucose,cellulose, and humic acids on soil microbial eco‐physiology

Microbial eco‐physiology in soils is regulated by substrate quality of the organic matter. This regulation was studied for a forest and an agricultural soil by the combination of activity and biomass techniques. Soil respiration was stimulated by the substrate quality in the order, humic acid < cellulose < glucose over 20 days. Concurrently, substrate addition increased the respiratory quotient (RQ), defined as the ratio of mol CO₂ evolution per mol O₂ uptake. Anabolic processes were mainly induced by glucose addition. Soil preconditioned with glucose showed a decrease in the RQ value during glucose‐induced microbial growth in comparison to non‐amended control. The decrease in the RQ value induced by preconditioning with cellulose and humic acid was lower. Glucose, cellulose, and humic acid addition modified the microbial biomass as estimated by fumigation‐extraction (FE), substrate‐induced respiration (SIR), and ATP content. Since each biomass estimate refers to specific microbial components, shifts in microbial eco‐physiology and community structure induced by substrate quality were reflected by SIR : FE and SIR : ATP ratios. The active and glucose‐responsive biomass in the forest soil which was earlier suggested as being dominated by K‐strategists was increased in the order, humic acid < cellulose < glucose.     

Land use effects on the dynamics of soil C, N and microbes in the water-wind erosion crisscross region of the northern Loess Plateau, China

The water-wind erosion crisscross region of the northern Loess Plateau in China is under constant pressure from severe erosion due to its windy and dry climate and intensive human activities. Identifying sustainable land use patterns is key to maintaining ecosystem sustainability in the area. Our aim was to appraise the impacts of different land use regimes on the dynamics of soil total organic C (TOC), total N (TN), and microbes in a typical watershed in the northern Loess Plateau to identify suitable land use types that can maintain soil fertility and sustainability. A field experiment was performed in Liudaogou watershed in Shenmu City, Shaanxi Province, China, where the dynamics of soil TOC and TN, microbial biomass C and N, microbial respiration, and net N mineralization in six typical land use types, dam land, rainfed slope land, deciduous broadleaf forest, evergreen coniferous forest, shrubland, and grassland, were measured in three different growing seasons. Land use type and season significantly affected TOC, TN, and the dynamics of microbial biomass and activity. As the most anthropogenically disturbed land use pattern, dam land was an optimal land use pattern for TOC sequestration due to its higher TOC and TN, but lower microbial activity. Soil TOC, TN, and microbial properties demonstrated a decreasing trend after natural grassland was converted to shrubland, forest, and rainfed slope land. Shrubland with exotic N-fixing Korshinsk peashrub (Caragana korshinskii Kom.) can maintain TOC, TN, and microbial properties similar to those in grassland. Soil TOC, NH₄⁺-N, TN, moisture, and extractable C were the principal indexes for soil microbial biomass and activity and explained 88.90% of the total variance. Thus, grassland was the optimal land use pattern in the water-wind erosion crisscross region of the northern Loess Plateau to maintain ecosystem stability and sustainability.     

Effects of microbial inoculations on soil chemical,biochemical and microbial biomass carbon of cassava (Manihot esculenta Crantz) growing Vertisols

Cassava is an important subsidiary food in the tropics. In Tamil Nadu, India, microbial cultures were used to eradicate the tuberous root rot of cassava. Hence, an experiment was conducted for two consecutive years to test the effects of coinoculation of microbes on soil properties. The surface soil from the experimental site was analysed for soil available nutrients, soil enzyme activities and microbial biomass carbon. The treatment of Azospirillum with Trichoderma at the 50% recommended N:P₂O₅:K₂O (NPK) rate (50:25:50 kg ha^?1) significantly increased soil available nitrogen (142.81 kg ha^?1) by 72.66% over uninoculated control. There was a significant increase in available phosphorus in soil by the inoculation of AM (arbuscular mycorrhizal) fungi with Trichoderma at the 50% recommended NPK rate (41.04 kg ha^?1) compared to other treatments. The application of Pseudomonas fluorescens with Trichoderma at the 50% recommended NPK rate significantly increased available iron (19.34 µg g^?1) in soil. The treatment of Azospirillum with Trichoderma increased urease enzyme activity at the recommended NPK rate (816.32 μg urea hydrolyzed g^?1 soil h^?1). Soil application of all cultures at the 50% recommended NPK rate significantly increased dehydrogenase activity (88.63 μg TPF g^?1 soil) and β-glucosidase activity (48.82 μg PNP g^?1 soil) in soil. Inoculation of Trichoderma alone at the 50% recommended NPK rate significantly increased microbial biomass carbon (3748.85 μg g^?1 soil). Thus, the microbial inoculations significantly increased soil available nutrient contents, enzyme activities such as urease, dehydrogenase and β-glucosidase activity and microbial biomass carbon by reducing the amount of the required fertilizer.     

Bacterial communities are more dependent on soil type than fertilizer type, but the reverse is true for fungal communities

The soil microbial community is strongly influenced by a wide variety of factors, such as soil characteristics and field management systems. In order to use biological indicators based on microbial community structure, it is very important to know whether or not these factors can be controlled. The present study aimed to determine whether soil type or fertilization has a greater influence on the soil microbial community based on denaturing gradient gel electrophoresis (DGGE) analysis of 12 experimental field plots containing four different soil types, Cumulic Andosol, Low-humic Andosol, Yellow Soil and Gray Lowland Soil, kept under three different fertilizer management systems since 2001 (the application of chemical fertilizer, the application of rice husk and cow manure, and the application of pig manure). Bacterial DGGE analysis using 16S rRNA genes and fungal DGGE analysis using 18S rRNA genes revealed that the bacterial community was related to the soil type more than the fertilization; however, the fungal community was related to the fertilization more than the soil type. These results might suggest that the fungal community is easier to control by fertilization than the bacterial community. Thus, we propose that indicators based on the fungal community might be more suitable as microbial indicators for soil quality.     

川西平原土壤微生物生物量碳氮磷含量特征及其影响因素分析

本文通过区域调查采样和统计分析，探讨了川西平原土壤微生物生物量碳（MBC）、土壤微生物生物量氮（MBN）和土壤微生物生物量磷（MBP）含量特征及其对气候、海拔、母质和土地利用等因素的响应，揭示了其关键影响因素，以期为川西平原地区土壤质量管理提供参考。结果表明，不同土壤类型的MBC、MBN和MBP含量表现为冲积土显著高于水稻土、潮土和黄壤（P<0.05），潮土MBC/MBN显著高于水稻土。气候和海拔的影响为：MBC、MBN和MBP含量随着≥ 0℃积温、≥ 10℃积温、年均温和年均降水量的增加呈指数减少，而随干燥度和海拔增加呈线性增加。不同成土母质中，MBC、MBN和MBP含量均为灰色冲积物显著高于老冲积物。不同土地利用方式下，三者含量为草地显著高于水田和旱地，水田、旱地和林地差异不显著。皮尔森相关分析和冗余分析表明，MBC和MBN均与≥ 0℃积温、年均温呈极显著负相关（P<0.01），与海拔呈极显著正相关关系，MBP与母质呈现极显著负相关关系。逐步回归分析表明，MBC主要受年均温、干燥度、年均降水量和母质的影响；MBN主要受海拔、干燥度和年均降水量的综合影响；MBP主要受母质、年均温、≥ 10℃积温和年均降水量的调控。因此，川西平原土壤MBC、MBN、MBP能灵敏地反映不同采样点气候的变化，可为该区气候变化下土壤碳、氮、磷的响应预测提供参考。