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。     

荒地不同压砂年限对土壤微生物区系、酶活性与土壤理化性状的影响

以宁夏中卫市香山地区荒地压砂3,8,15,25 a和邻近未压砂(对照)的土壤为研究对象,研究了压砂对土壤微生物区系、酶活性和土壤理化性状的影响.结果表明,与对照相比,压砂后微生物总数减少;土壤脲酶活性随着压砂年限的延长呈下降趋势;前15 a压砂地土壤有机碳、全氮、碱解氮和速效钾随着压砂年限的延长呈下降趋势;压砂地土壤含水量高于对照;压砂地全盐含量远远低于对照;说明荒地压砂种植能蓄水保墒,防止土壤次生盐碱化,但连续种植肥力下降,微生物量减少.     

沼液对河西绿洲葡萄园土壤微生物功能多样性的影响

为探明使用沼液对土壤质量的影响，明确土壤微生物功能多样性对沼液使用量和使用年限的响应，在甘肃祁连葡萄观光园进行等氮量替代和增施沼液处理，采用Biolog方法测定土壤微生物功能多样性。结果表明：（1）100%等氮量沼液处理的土壤微生物群落代谢活性最小，替代33%氮量处理的土壤微生物群落代谢活性最高，连续两年使用沼液的处理间差异大于一年。（2）试验地土壤微生物利用的主要碳源为碳水化合物类，使用沼液能够显著提高土壤微生物对氨基酸类和羧酸类碳源的利用率。连续两年使用沼液条件下，增施沼液处理（133%和167%）效果优于等氮量替代处理。（3）与单施化肥对照相比，使用沼液处理仅在提高土壤微生物均一度指数方面存在优势，且增施沼液处理（133%和167%）效果优于等氮量替代处理。（4）主成分分析表明，沼液使用量和使用年限对土壤微生物碳源利用水平以及代谢多样性的影响有差异，且使用年限增加能使各处理间变异程度增大。（5）碳水化合物类和氨基酸类碳源是引起不同沼液用量处理土壤微生物功能群分异的主要碳源，其中碳水化合物类是使用年限增加后土壤微生物群落变化的敏感碳源。（6）Pearson相关性分析表明，该试验地土壤微生物功能多样性与土壤有机质、碱解氮呈正相关关系，与速效磷、速效钾呈负相关关系。综上，长期使用沼液（尤其是沼液与化肥配施）有利于提高土壤微生物代谢活性和土壤微生物群落功能多样性，且当沼液使用量较大时能达到完全取代化肥的效果。     

福建安溪不同年限茶树土壤养分与微生物Biolog功能多样性的差异分析

茶园提早衰老退化是制约茶叶经济效益的一个关键性问题。以1年生、6年生与20年生茶树土壤为研究对象,对不同年限的茶树土壤养分与微生物多样性进行研究。结果表明:根据《茶叶产地环境技术条件》(NY/T8 53—2004)的pH和各项肥力指标,1年生茶树土壤的pH为4.73,处于Ⅱ级水平,6年生茶树土壤的pH为4.41,接近Ⅱ级水平,都符合优质、高效、高产茶园土壤的酸碱指标;20年生茶树土壤pH为4.15,接近4.0,呈酸化。6年生茶树土壤的有机质、碱解氮和速效磷都达到肥力Ⅰ级,速效钾处于肥力Ⅲ级,整体肥力水平最好;1年生茶树土壤的速效磷丰富,达到肥力Ⅰ级,碱解氮达到肥力Ⅱ级,有机质和速效钾处于肥力Ⅲ级,肥力处于中等水平;20年生茶树土壤的有机质达到肥力Ⅱ级,碱解氮、速效磷和速效钾都处于肥力Ⅲ级,整体肥力水平最差。基于Biolog平板法的微生物功能多样性研究表明,6年生茶树土壤的微生物群落利用碳源的能力最好,20年生茶树土壤微生物对6类碳源的利用程度都不高,1年生茶树土壤微生物对6类碳源的利用处于中等水平。多样性指数分析表明,6年生茶树土壤微生物群落的Shannon、Brillouin、均匀度、丰富度指数均最高;20年生茶树土壤最低。总之,与6年生和1年生茶树土壤相比,20年生茶树土壤呈现较强酸化,有机质含量比6年生茶树土壤下降47.81%,微生物群落的生理活性最低,生理功能多样性急剧减少。     

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。     

宁夏环香山地区压砂地土壤微生物结构及功能多样性研究

对压砂地不同利用年限下的土壤微生物群落结构及功能多样性进行了分析。研究结果表明,压砂地不同利用年限的土壤微生物群落总菌数整体上明显低于农田对照,且随着压砂利用年限的增加土壤微生物总菌数呈逐年下降的趋势。压砂利用1~3a,5~10a,10~15a之间均存在显著差异<0.05)。压砂第1a对土壤微生物的功能影响很大,能明显提高微生物对C源的利用能力。压砂1a后,随着压砂利用年限的增加土壤微生物的功能明显下降,且不同压砂年限间的微生物功能差异不显著,说明农田压砂初期由于土地利用方式的改变,提高了土壤蓄水保墒及增温效果,使得土壤微生物物功能和利用强度增加,随着压砂地利用年限的增加作物对土壤养分消耗增大,而土壤中养分得不到补充,使得压砂地土壤微生物环境逐步恶化。     

黄顶菊(Flaveria bidentis)入侵对土壤微生物功能多样性的影响

外来植物入侵对土壤生物多样性的影响已成为生态学领域的研究热点之一。运用Biolog技术和氯仿熏蒸浸提法研究了黄顶菊入侵对土壤微生物群落功能多样性及土壤微生物量的影响。结果表明,黄顶菊入侵后土壤微生物代谢活性显著升高;土壤微生物群落平均吸光值(AWCD)的变化趋势为:入侵地根际土(RPS)入侵地根围土(BS)未入侵地(CK),且差异显著;而CK的功能多样性指数(H)高于BS,RPS亦高于BS,差异均显著(P0.05)。主成分分析结果表明,黄顶菊入侵使土壤微生物群落的碳源利用方式和代谢功能发生改变。对不同碳源利用的分析结果表明,糖类、氨基酸类、羧酸类和聚合物为土壤微生物利用的主要碳源。入侵样地BS和RPS的微生物量碳分别比CK高27.05%、121.52%;BS和RPS的微生物量氮分别比CK高37.40%、79.80%。相关性分析表明,AWCD与微生物量碳和微生物量氮均呈极显著正相关(P0.01)。由此可知,黄顶菊入侵增强了入侵地土壤微生物代谢活性,降低了土壤微生物群落的功能多样性,增加了土壤微生物量碳、氮水平。     

马铃薯连作栽培对土壤微生物多样性的影响

为阐明马铃薯连作对土壤微生物群落结构和功能多样性的影响,揭示马铃薯连作障碍机制,本试验采用BIOLOG技术结合丛枝菌根真菌(AMF)形态学鉴定方法,就连作0(迎茬)、2 a、4 a、6 a、10 a的马铃薯田块土壤进行研究。结果表明:土壤养分含量随马铃薯连作年限增加有一定程度下降,其中,连作10 a马铃薯根际土壤的全磷、速效磷、速效钾和碱解氮与连作4 a相比分别下降61.32%、26.86%、26.87%和17.24%,但没有明显的养分亏缺和不均衡现象。土壤微生物群落结构发生了较大变化,放线菌、真菌数量显著随连作年限的延长先增加后减少,呈单峰型变化趋势;细菌数量随连作年限的延长呈逐步减少趋势,但差异不显著。连作4~6 a土壤微生物群落依然有较强的功能多样性,培养120 h后,连作6 a较迎茬AWCD值提高3.89%;群落组成中随连作年限的延长以碳水化合物、氨基酸类为碳源的微生物类群代谢能力明显下降,但代谢功能多样性趋于一致。连作马铃薯土壤AM真菌优势种发生改变,迎茬土壤为沙漠球囊霉(Glomus deserticola),连作2 a土壤为扭形球囊霉(Glomus delhiense)和福摩萨球囊霉(Glomus formosanum),连作10 a土壤为球泡球囊霉(Glomus globiferum)。多元分析结果表明,土壤微生物结构与功能多样性、AM真菌多样性变化受土壤p H、全磷含量、放线菌数量、细菌数量及土壤中以碳水化合物、氨基酸类等为碳源基质的微生物类群影响。说明长期连作栽培会影响土壤真菌、放线菌的数量,使真菌群落中AM真菌种的多样性显著下降,优势种发生改变,打破了微生物群落结构与功能平衡,引起土壤微生物群落结构与功能的失调。     

模拟氮沉降对滨海湿地土壤微生物功能多样性的影响

为全面了解大气氮沉降条件下滨海湿地土壤微生物碳源利用特点,本研究在江苏盐城滨海湿地建立模拟氮沉降实验平台,设置N1(N,0 g/(hm~2·a),对照)、N2(N,3 g/(hm~2·a),低氮)和N3(N,6 g/(hm~2·a),高氮)3个处理,采用Biolog微平板法,分析了土壤微生物功能多样性在不同氮处理下的变化规律和特点。结果表明:不同氮沉降处理间土壤微生物功能多样性差异显著,AWCD值随培养时间延长而增加;Shannon和Mc Intosh多样性指数也随施氮增加呈现升高的趋势,且不同处理间多样性指数差异显著;物种多样性和功能多样性表现出相同的变化规律。土壤微生物对6大类碳源利用强度存在差异,各处理间土壤微生物对碳水化合物类碳源利用率最高,为优势碳源;主成分分析结果显示,不同处理间土壤微生物在碳源利用上有明显的空间分异,土壤微生物功能多样性的差异主要体现在对羧酸类、酚酸类和胺类碳源的利用上,其中胺类尤为突出;此外,对不同施氮处理土壤微生物群落功能多样性与土壤理化因子进行相关分析,结果显示全氮、铵态氮、全磷会对滨海湿地土壤微生物组成和功能活性产生重要影响。     

矿区侵蚀土壤的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矿区侵蚀土壤的微生物活性以及微生物群落功能多样性研究,结果表明:人为开矿使矿区土壤环境呈现不同层次的加速侵蚀特征。矿区侵蚀土壤的几种重金属含量比无明显侵蚀土壤有明显的增加,且其基本理化性质相应变差。矿区侵蚀土壤微生物特征发生了显著的变化,与无明显侵蚀土壤相比,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。Biolog测试结果显示,随着土壤侵蚀程度的加剧,其微生物群落结构亦发生了相应改变,侵蚀土壤微生物群落的丰富度、多样性指数、均匀度均显著低于对照土壤,且几项指标都达极显著水平差异(P<0.001),表明矿区水土流失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,最终导致土壤微生物群落结构和功能多样性发生变化。     

脱硫废弃物施用对盆栽油葵碱化土壤微生物多样性的影响

在宁夏平罗西大滩前进农场,利用盆栽试验以油葵为指示植物设置了脱硫废弃物5个不同施用量处理改良碱化土壤,采用Biolog Eco-plate技术对土壤微生物群落功能多样性进行了分析.结果表明:脱硫废弃物施用处理都能够降低土壤pH值0.06～0.29个单位;降低土壤全盐含量0.72～1.35 g/kg;脱硫废弃物施用能够明...     

Crop rhizospheric microbial community structure and functional diversity as affected by maize and potato intercropping

Field trials were conducted to evaluate the effects of different cropping patterns (maize monocropping, maize and potato intercropping, potato monocropping) on microbial abundance, community structure, and microbial functional diversity using plate culture and Biolog technique. Results showed that compared with monocropping, intercropping increased the abundance of soil bacteria, fungi, and actinomyces in rhizosphere surrounding maize and potato. The average well color development (AWCD) and Shannon index (H) were higher in intercropping soil than that found in monocropping soil. The ability of rhizospheric soil microorganisms in utilizing six types of carbon sources had definite differences, and the most dominant community structure was the carbohydrates metabolic groups. Principal component analysis demonstrated that intercropping changed significantly soil microbial community functional diversity depending mainly on carbohydrates and carboxylic acids. Our findings suggested that maize–potato intercropping has positive effects on the improvement of soil microbial abundances, activity, and functional diversity.     

Plant biomass, soil water content and soil N:P ratio regulating soil microbial functional diversity in a temperate steppe: A regional scale study

Soil microorganisms are influenced by various abiotic and biotic factors at the field plot scale. Little is known, however, about the factors that determine soil microbial community functional diversity at a larger spatial scale. Here we conducted a regional scale study to assess the driving forces governing soil microbial community functional diversity in a temperate steppe of Hulunbeir, Inner Mongolia, northern China. Redundancy analysis and regression analysis were used to examine the relationships between soil microbial community properties and environmental variables. The results showed that the functional diversity of soil microbial communities was correlated with aboveground plant biomass, root biomass, soil water content and soil N: P ratio, suggesting that plant biomass, soil water availability and soil N availability were major determinants of soil microbial community functional diversity. Since plant biomass can indicate resource availability, which is mainly constrained by soil water availability and N availability in temperate steppes, we consider that soil microbial community functional diversity was mainly controlled by resource availability in temperate steppes at a regional scale.     

Capacity of fatty acid profiles and substrate utilization patterns to describe differences in soil microbial communities associated with increased salinity or alkalinity at three locations in South Australia

 Fatty acid methyl ester (FAME) profiles, together with Biolog substrate utilization patterns, were used in conjunction with measurements of other soil chemical and microbiological properties to describe differences in soil microbial communities induced by increased salinity and alkalinity in grass/legume pastures at three sites in SE South Australia. Total ester-linked FAMEs (EL-FAMEs) and phospholipid-linked FAMEs (PL-FAMEs), were also compared for their ability to detect differences between the soil microbial communities. The level of salinity and alkalinity in affected areas of the pastures showed seasonal variation, being greater in summer than in winter. At the time of sampling for the chemical and microbiological measurements (winter) only the affected soil at site 1 was significantly saline. The affected soils at all three sites had lower organic C and total N concentrations than the corresponding non-affected soils. At site 1 microbial biomass, CO₂-C respiration and the rate of cellulose decomposition was also lower in the affected soil compared to the non-affected soil. Biomarker fatty acids present in both the EL- and PL-FAME profiles indicated a lower ratio of fungal to bacterial fatty acids in the saline affected soil at site 1. Analysis of Biolog substrate utilization patterns indicated that the bacterial community in the affected soil at site 1 utilized fewer carbon substrates and had lower functional diversity than the corresponding community in the non-affected soil. In contrast, increased alkalinity, of major importance at sites 2 and 3, had no effect on microbial biomass, the rate of cellulose decomposition or functional diversity but was associated with significant differences in the relative amounts of several fatty acids in the PL-FAME profiles indicative of a shift towards a bacterial dominated community. Despite differences in the number and relative amounts of fatty acids detected, principal component analysis of the EL- and PL-FAME profiles were equally capable of separating the affected and non-affected soils at all three sites. Redundancy analysis of the FAME data showed that organic C, microbial biomass, electrical conductivity and bicarbonate-extractable P were significantly correlated with variation in the EL-FAME profiles, whereas pH, electrical conductivity, NH₄-N, CO₂-C respiration and the microbial quotient were significantly correlated with variation in the PL-FAME profiles. Redundancy analysis of the Biolog data indicated that cation exchange capacity and bicarbonate-extractable K were significantly correlated with the variation in Biolog substrate utilization patterns. Received: 8 March 2000     

铜污染土壤线虫多样性的PCR-DGGE分析

A wheat pot experiment was conducted under greenhouse conditions to assess the effect of copper contamination on soil nematode diversity by polymerase chain reaction-denaturing gradient gel electrophoresis （PCR-DGGE） method and morphological analysis. The soil was treated with CuSO4.5H2O at the following concentrations： 0, 50, 100, 200, 400, and 800 mg kg^-1 dry soil, and the soil samples were collected at wheat jointing and ripening stages. Nematode diversity index （H′） from morphological analysis showed no difference between the control and the treated samples in either of the sampling dates. At the wheat ripening stage, nematode diversity obtained by the PCR-DGGE method decreased noticeably in the Cu800 treatment in comparison with the control. With optimization of the method of nematode DNA extraction, PCR-DGGE could give more information on nematode genera, and the intensity of the bands could reflect the abundance of nematode genera in the assemblage. The PCR-DGGE method proved promising in distinguishing nematode diversity in heavy metal coritaminated soil.     

生物质炭对连作参地土壤肥力及微生物特性的影响

为分析生物质炭用于老参地土壤修复的可行性,本研究采用Biolog、高通量测序等技术研究了3种生物质炭对连作参地人参品质、土壤肥力、微生物群落结构与功能多样性变化的影响。结果显示,增施不同生物质炭均有助于两年生重茬人参生物量及总皂苷含量的积累。结合生物质炭对土壤性质的影响研究结果发现,不同生物质炭对土壤有效磷、有机碳含量具有稳定的提升效果,增幅分别为47.04%~237.73%、8.09%~38.71%。增施生物质炭促进了土壤微生物的代谢活性,增加了土壤对聚合物类、酚酸类、氨基酸类、羧酸类碳源的利用效率,其中以酚酸类物质为底物的功能微生物种群数量显著增加。高通量测序结果显示,老参地土壤细菌物种数、丰度与多样性均呈下降趋势,细菌优势门类减少,单个门类优势度上升。生物质炭处理下土壤中细菌丰度与多样性增加,调控了变形菌门、厚壁菌门、疣微菌门、芽单胞菌门的优势度,使其数量变化趋势趋向于新林土。上述分析表明,重茬人参生物量和品质的提高与生物质炭提升土壤中人参生长的关键肥力指标,促进微生物代谢,调控细菌群落结构变化趋势有关。综上,生物质炭对老参地土壤表现出良好的修复、改良作用,适量增施生物质炭有利于老参地土壤质量的调节与恢复。     

Land-use intensification and agroforestry in the Kenyan highland: Impacts on soil microbial community composition and functional capacity

This study investigates microbial communities in soil from sites under different land use in Kenya. We sampled natural forest, forest plantations, agricultural fields of agroforestry farms, agricultural fields with traditional farming and eroded soil on the slopes of Mount Elgon, Kenya. We hypothesised that microbial decomposition capacity, biomass and diversity (1) decreases with intensified cultivation; and (2) can be restored by soil and land management in agroforestry. Functional capacity of soil microbial communities was estimated by degradation of 31 substrates on Biolog EcoPlates™. Microbial community composition and biomass were characterised by phospholipid fatty acid (PLFA) and microbial C and N analyses. All 31 substrates were metabolised in all studied soil types, i.e. functional diversity did not differ. However, both the substrate utilisation rates and the microbial biomass decreased with intensification of land use, and the biomass was positively correlated with organic matter content. Multivariate analysis of PLFA and Biolog EcoPlate™ data showed clear differences between land uses, also indicated by different relative abundance of PLFA markers for certain microorganism groups. In conclusion, our results show that vegetation and land use control the substrate utilisation capacity and microbial community composition and that functional capacity of depleted soils can be restored by active soil management, e.g. forest plantation. However, although 20–30 years of agroforestry farming practises did result in improved soil microbiological and chemical conditions of agricultural soil as compared to traditional agricultural fields, the change was not statistically significant.     

Seasonal, soil type, and alternative management influences on microbial communities of vegetable cropping systems

Microbial community responses to alternative management may be indicative of soil quality change. In this study, soils were collected from research plots over 2 years and from commercial grower fields over 1 year. Treatments at the sites included 1-9 years of either winter cover cropping or winter fallow practices. Soils were assayed for microbial fatty acid methyl esters (FAMEs), direct count microscopy and Biolog substrate utilization potentials to assess management and environmental influences on soil communities. The strongest influence was season. Soils in early spring (prior to termination of the cover crop) utilized fewer carboxylic acids and generally were enriched in eukaryotic FAMEs, whereas proportionally more bacterial FAMEs were detected in soils at canopy closure and harvest of the summer vegetable crop. Within a season, community FAME and Biolog patterns were related to field properties. FAME profiles from grower fields in early spring and harvest were correlated significantly with soil texture, cation exchange capacity, and carbon content. Changes in community structure and Biolog potential occurred in some soils in response to winter cover crops, although effects were not observed until cover crop incorporation. Greater amounts of fungal and protozoan FAME markers were detected in some cover-cropped soils compared to winter fallow soils. Cover crop residues increased FAME diversity at one research station and Biolog diversity at two research stations and the grower fields. Although seasonal and field-dependent factors are major determinants of microbial community structure, shifts can occur as soil physical and chemical properties change in response to alternative practices, as demonstrated by this study.