不同种植时间菜园土壤微生物生物量和酶活性变化特征

土壤生物学指标能够反映土壤质量在各种自然和人为作用下的微小变化,是敏感的土壤质量指标。本文以太湖地区高强度开发为背景,研究了不同利用年限的菜园土壤微生物生物量C和酶活性的变化特征。研究结果表明,菜园土壤随着利用年限的不断增加,土壤养分逐渐升高,土壤脲酶活性、土壤微生物生物量C与土壤有机质、全N、全P之间具有良好的线性关系,土壤纤维素酶活性随菜地利用时间增加有上升的趋势,它们能较好地区别不同利用年限的菜地土壤,可以作为敏感的土壤生物学指标。但土壤转化酶活性与土壤养分的变化没有明显的相关性。     

外源营养物质对表征土壤质量的生物学指标的影响

土壤微生物指标(土壤微生物组成和多样性、土壤微生物生物量、土壤微生物活性)、土壤酶活性和土壤动物是表征土壤质量的三大重要生物学指标。这些指标极易受土壤环境因素和人为活动的影响。诸如土壤水分、温度、耕作制度以及外源有机、无机物质等均对它们有较大的影响。本文就外源有机、无机营养物质对上述生物学指标的影响进行了综述。     

不同种植年限酸化果园土壤微生物学性状的研究

土壤微生物学指标能够反映土壤质量,是敏感的土壤质量指标。本文以山东果园土壤急剧酸化为背景,研究了山东5个不同种植年限酸化果园(5a～30a)土壤pH值、土壤的微生物数量、土壤微生物量和酶活性的变化,分析果园土壤微生物学性状与土壤pH值的相关性。结果表明:随着种植年限的延长,除真菌、磷酸酶活性只在一定范围内呈现波动趋势外,土壤pH值与微生物数量,土壤微生物量、土壤酶活性呈现不同程度下降。其中酸化果园土壤pH值与微生物量碳、蔗糖酶、过氧化氢酶之间都存在着极显著相关,相关系数分别为0.92、0.97和0.94。土壤微生物数量、土壤微生物生物量、土壤酶活性之间也存在着某种关联,集中体现在土壤酶活性之间及与土壤微生物生物量之间。     

阿特拉津污染胁迫下土壤微生物生物量对外源有机无机物质的响应

土壤微生物与土壤自净作用密切相关,它直接参与土壤动植物残体、外来有机物质和其它有毒有害有机化合物的降解过程。然而,这些有机物质的存在也同样会影响土壤微生物的活性及其多样性[1] 。土壤生物学性质能敏感地反映出土壤质量和健康的变化,是土壤质量评价不可缺少的指标[2 ]     

贵州茂兰喀斯特森林土壤微生物活性的研究

通过研究不同植被类型下土壤微生物区系、土壤酶活性和土壤生化作用强度 ,分析了贵州茂兰国家级自然保护区喀斯特森林演替过程中土壤微生物活性的变化。结果表明 :随着喀斯特森林退化程度的加剧 ,土壤微生物总数下降、各主要生理类群数量均呈下降趋势 ,土壤酶活性减弱 ,土壤生化作用强度降低 ,对环境反应敏感 ,可作为反映森林生态系统的生物学指标。土壤微生物和酶活性是表征喀斯特森林生态功能的重要特征之一     

重金属污染矿区复垦土壤微生物生物量及酶活性的研究

对铜矿废弃地复垦土壤微生物生物量及酶活性研究结果表明 ,与对照土壤相比 ,矿区复垦土壤微生物生物量C、N和P均有所降低 ,微生物商Cmic Corg可作为矿区重金属污染土壤微生物学敏感指标之一 ;酶活性变化与此相似 ,脲酶、脱氢酶和酸性磷酸酶与对照差异显著 ,其他则与对照差异明显 ,一定程度削弱了矿区土壤中C、N营养元素周转速率和能量循环     

不同退耕还林模式对土壤生物学性质的影响效果评价

在测定土壤微生物、土壤酶活性基础上,应用主成分因子分析法建立了不同退耕还林模式下的土壤生物学性质评价体系。结果表明,土壤放线菌、真菌数量与转化酶、脲酶、纤维素酶、过氧化氢酶活性之间的相关性达到了极显著或显著水平优势微生物中的微球菌与转化酶,芽孢杆菌与纤维素酶,木霉和游动放线菌与过氧化氢酶,酵母菌与脲酶呈显著正相关关系放线菌、真菌及其微生物优势类群多样性指标在评价土壤生物学肥力质量时具有十分重要的作用4种土壤酶活性是土壤生物学肥力质量评价的重要指标而细菌、酵母等生物量较小的微生物对土壤生态肥力评价的贡献较小。用土壤综合肥力指标值(IFI)进一步评价各样地的土壤生物学肥力质量的顺序依次为:苦竹林表层>桦木林表层>农耕地表层>农耕地亚表层>农耕地深层>桦木和苦竹林亚表层>桦木林深层>苦竹林深层。苦竹对退耕地的生态改善效果,如水土保持、水源涵养和土壤生态肥力的增加等方面要优于桦木。     

不同利用方式下红壤微生物生物量及代谢功能多样性的变化

研究了不同农林利用方式下红壤微生物生物量和代谢功能多样性等土壤质量指标的变化.结果表明:不同利用方式对土壤质量各指标造成了显著的影响;稻田的微生物生物量碳、氮最高,林地和草地微生物生物量次之,旱地的微生物生物量碳、氮最低(分别是稻田利用方式的4.3% 和 13.7%);稻田的微生物代谢功能多样性最高,旱地、林地和草地的细菌代谢功能多样性较低,旱地的真菌代谢功能多样性最低;微生物生物量和代谢功能多样性可以作为反映土壤质量变化的早期敏感的指标,用来衡量管理措施的改变对土壤质量造成的影响.     

铅污染对青紫泥微生物活性的影响

土壤微生物量碳、基础呼吸作用、土壤代谢商是表征土壤质量的重要指标,并且与土壤本身的理化性质有关。脱氢酶活性是土壤微生物种群及其活性的重要敏感性指标之一。通过室内培养,研究了不同铅添加水平(200~1 200 mg/kg)对青紫泥田微生物生物量碳及土壤基础呼吸作用、土壤代谢商、土壤脱氢酶的影响。研究表明:随培养时间延长,青紫泥田生物量碳呈下降趋势,基础呼吸作用随铅浓度升高而加强。土壤代谢商随培养时间延长变化趋势不同。外源铅胁迫下土壤脱氢酶活性随铅处理浓度升高明显受抑制。相关分析表明,土壤铅含量与土壤微生物生物量碳、脱氢酶在不同培养时期相关性不同。     

贵州高原喀斯特环境退化过程土壤质量的生物学特性研究

通过研究比较不同植被类型下土壤中微生物区系、土壤酶活性和土壤生化作用强度,分析了贵州高原喀斯特环境退化演变过程中土壤质量的生物学特性变化过程。结果表明:随喀斯特环境退化程度加剧,土壤微生物总数下降,各主要生理类群数量呈下降趋势,土壤酶活性减弱,土壤生化作用强度降低,对环境反应敏感,可作为反映土壤质量的生物学指标。土壤微生物和酶活性是表征喀斯特环境退化演替过程中土壤质量的重要特征之一。     

Effect of cinnamic acid on soil microbial characteristics in the cucumber rhizosphere

In order to elucidate the effect of allelochemicals on soil microbial characteristics in the cucumber rhizosphere, the soil microbial biomass and respiration, community functional diversity and RAPD marker diversity as affected by exogenous cinnamic acid were studied. Exogenous cinnamic acid increased soil microbial respiration and the metabolic quotient, but decreased soil microbial biomass-C. Soil microbial community functional diversity and genetic diversity (as indicated by RAPD markers) were also significantly altered by exogenous cinnamic acid. These results suggest that allelochemicals can change soil microbial genetic diversity, biological activity and microbial metabolic activity, which alter soil microbial ecology and accordingly affect the growth of cucumber with accumulation in the soil of allelochemicals.     

北疆绿洲不同盐分浓度梯度下土壤的生物活性及其功能多样性

土壤盐分类型与含量对土壤生物活性和功能结构多样性会产生重要影响。本文模拟新疆北疆典型硫酸盐盐土,通过设置不同盐分浓度梯度(3、6、10、20和40 g kg-1),研究了土壤5种主要功能酶、土壤微生物量和土壤呼吸等生物性状的变化特征。结果表明:过氧化氢酶、蔗糖酶、β-葡萄糖苷酶和多酚氧化酶4种酶对盐分梯度响应非常敏感,其中过氧化氢酶、蔗糖酶和β-葡萄糖苷酶这3种酶活性与盐分浓度呈负相关,当盐分浓度达到40 g kg-1时,以上3种酶分别较对照降低25.7%、69.6%、30.0%;在3~6 g kg-1盐分浓度范围,多酚氧化酶随盐分浓度而升高,但在10~40 g kg-1时却显著降低,表现出"低盐促进,高盐抑制"的效应;纤维素酶对盐分浓度变化不敏感。土壤盐分与微生物量和微生物商呈显著负相关,与土壤基础呼吸和呼吸商则显著正相关,如40 g kg-1的盐分浓度导致土壤微生物量和微生物商分别较对照降低73.0%和69.5%,呼吸商升高了6.4倍。土壤过氧化氢酶、蔗糖酶、土壤微生物量、微生物商和呼吸商等可作为硫酸盐盐土早期预警生物指标。在40 g kg-1的含盐量下土壤生物功能结构明显区别于其他处理,且多样性指数显著下降。     

Three decades of soil microbial biomass studies in Brazilian ecosystems: Lessons learned about soil quality and indications for improving sustainability

Soil microbial biomass plays important roles in nutrient cycling, plant-pathogen suppression, decomposition of residues and degradation of pollutants; therefore, it is often regarded as a good indicator of soil quality. We reviewed more than a hundred studies in which microbial biomass-C (MB-C), microbial quotient (MB-C/TSOC, total soil organic carbon) and metabolic quotient (qCO₂) were evaluated with the objective of understanding MB-C responses to various soil-management practices in Brazilian ecosystems. These practices included tillage systems, crop rotations, pastures, organic farming, inputs of industrial residues and urban sewage sludge, applications of agrochemicals and burning. With a meta-analysis of 233 data points, we confirmed the benefits of no-tillage in preserving MB-C and reducing qCO₂ in comparison to conventional tillage. A large number of studies described increases in MB-C and MB-C/TSOC due to permanent organic farming, also benefits from crop rotations particularly with several species involved, whereas application of agrochemicals and burning severely disturbed soil microbial communities. The MB-C decreased in overgrazed pastures, but increased in pastures rotated with well-managed crops. Responses of MB-C, MB-C/TSOC and qCO₂ to amendment with organic industrial residues varied with residue type, dose applied and soil texture. In conclusion, MB-C and related parameters were, indeed, useful indicators of soil quality in various Brazilian ecosystems. However, direct relationships between MB-C and nutrient-cycling dynamics, microbial diversity and functionality are still unclear. Further studies are needed to develop strategies to maximize beneficial effects of microbial communities on soil fertility and crop productivity.     

Consequences of forest conversion to pasture and fallow on soil microbial biomass and activity in the eastern Amazon

The main change in soil use in Amazonia is, after slash and burn deforestation followed by annual crops, the establishment of pastures. This conversion of forest to pasture induces changes in the carbon cycle, modifies soil organic matter content and quality and affects biological activity responsible for numerous biochemical and biological processes essential to ecosystem functioning. The aim of this study was to assess changes in microbial biomass and activity in fallow and pasture soils after forest clearing. The study was performed in smallholder settlements of eastern Brazilian Amazonia. Soil samples from depths of 0–2, 2–5 and 5–10 cm were gathered in native forest, fallow land 8–10 yr old and pastures with ages of 1–2, 5–7 and 10–12 yr. Once fallow began, soil microbial biomass and its activity showed little change. In contrast, conversion to pasture modified soil microbial functioning significantly. Microbial biomass and its basal respiration decreased markedly after pasture establishment and continued to decrease with pasture age. The increase in metabolic quotient in the first years of pasture indicated a disturbance in soil functioning. Our study confirms that microbial biomass is a sensitive indicator of soil disturbance caused by land‐use change.     

Does microbial habitat or community structure drive the functional stability of microbes to stresses following re-vegetation of a severely degraded soil?

Re-vegetation of eroded soil restores organic carbon concentrations and improves the physical stability of the soil, which may then extend the range of microhabitats and influence soil microbial activity and functional stability through its effects on soil bacterial community structure. The objectives of this study were (i) to evaluate the restorative effect of re-vegetation on soil physical stability, microbial activity and bacterial community structure; (ii) to examine the effects of soil physical microhabitats on bacterial community structure and diversity and on soil microbial functional stability. Soil samples were collected from an 18-year-old eroded bare soil restored with either Cinnamomum camphora (“Eroded Cc”) or Lespedeza bicolour (“Eroded Lb”). An uneroded soil planted with Pinus massoniana (“Uneroded Pm”) and an eroded bare soil served as references. The effect of microhabitats was assessed by physical destruction with a wet shaking treatment. Soil bacterial community structure and diversity were measured using a terminal restriction fragment length polymorphism (T-RFLP) approach, while soil microbiological stability (resistance and resilience) was determined by measuring short-term (28 days) decomposition rate of added barley (Hordeum vulgare) powder following copper and heat perturbations. The results demonstrated that re-vegetation treatment affected the recovery of physical and biological stability, microbial decomposition and the bacterial community structure. Although the restored soils overshot the Uneroded Pm sample in physical stability, they had lower microbial decomposition and less resilience to copper and heat perturbations than the Uneroded Pm samples. Soil physical destruction by shaking had the same effect on soil physical stability, but different effects on soil microbial functional stability. There were significant effects of vegetation treatment and perturbation type, and interactive effects among vegetation treatment, shaking and perturbation type on bacterial community structure. The destruction of aggregate structure increased resilience of the Eroded Lb sample and also altered its bacterial community structure. Both copper and heat perturbations resulted in significantly different community structure from the unperturbed controls, with a larger effect of copper than heat perturbation. Bacterial diversity (Shannon index) increased following the perturbations, with a more profound effect in the Uneroded Pm sample than in the restored soils. The interactive effects of vegetation treatment and shaking on microbial community and stability suggest that soil aggregation may contribute to the generation of bacterial community structure and mediation of biological stability via the protection afforded by soil organic carbon. Differential effects of re-vegetation treatment suggest that the long-term effects are mediated through changes in the quality and quantity of C inputs to soil.     

Changes of the functional diversity of soil microbial community during the colonization of abandoned grassland by a forest

The impact of secondary succession of grassland communities towards a Norway spruce forest on soil microbial community was studied on a belt transect established in the Pol’ana Mts., Central Europe. Data on understory vegetation, light availability, soil properties and microbial activity were collected on 147 plots distributed over regular grid. Moreover, distributions of functional groups of microorganisms were assessed using BIOLOG analysis on a subset of 27 plots. Mantel partial correlations between microbial community indicators and environmental variables showed that microbial activity generally decreased with increasing tree density and size, whereas it increased with increasing radiation at the soil surface, soil temperature, and cover and diversity of understory vegetation. Functional richness and diversity of microorganisms were positively correlated with solar radiation, but also with plant species richness and diversity. Abundance of several functional groups correlated closely with succession-related variables. Redundance analysis of microbial data provided slightly different outcomes. Forward selection yielded only two environmental variables significantly influencing the composition of the microbial community: tree influence potential and organic carbon content. Abundances of several functional microbial groups correlated with tree influence, documenting that microbial community changes are at least partially driven by the colonization of grassland by trees. Nevertheless, the relative importance of abiotic environment change and plant community succession on microbial community dynamics remains unresolved.     

长期平衡施肥对潮土微生物活性和玉米养分吸收的影响

利用中国科学院封丘农业生态实验站农田生态系统养分平衡长期定位试验地,研究氮磷钾平衡施肥(NPK)与缺素施肥(NK、PK、NP)对土壤微生物生物量、酶活性、呼吸强度以及玉米养分吸收的影响。结果发现,与不施肥对照(CK)相比,NPK处理玉米根系与茎叶生物量、籽粒产量以及植株氮磷钾吸收量均大幅提高,NP处理次之,PK与NK处理则无显著影响;同一处理玉米茎叶与根系养分含量接近,而籽粒的全氮和全磷含量较高、全钾含量偏低;与NPK处理相比,缺施氮、磷或钾肥均直接导致玉米植株相应养分的明显亏缺或其他养分的过量富集,但在根系、茎叶和籽粒部位的累积情况存在一定差异。与CK相比,所有施加磷肥的处理(NPK、NP、PK)土壤微生物生物量(碳、氮、磷)、脱氢酶、转化酶、脲酶与碱性磷酸酶活性以及土壤微生物代谢活性和土壤基础呼吸强度均显著升高(p<0.05),土壤微生物代谢熵则显著下降(p<0.05),而缺施磷肥的NK处理除显著提高脲酶活性外(p<0.05),对其他指标均无显著影响。结果表明,氮磷钾平衡施肥在促进土壤微生物繁育和保育微生物代谢活性以及促进作物生长和保证养分吸收等方面显得非常重要,而缺素施肥中以缺施磷肥的不利影响最为突出。     

藏中矿区重金属污染对土壤微生物学特性的影响

土壤微生物对土壤重金属污染反应敏感,是探讨矿区土壤重金属污染生态效应的有效指标之一。通过野外调查与采样和室内分析,研究了藏中矿区重金属污染对土壤蔗糖酶、脲酶、脱氢酶和酸性磷酸酶活性、微生物生物量C（MBC）、N（MBN）和P（MBP）、土壤基础呼吸、代谢商（qCO2）及可矿化N的影响。研究表明,矿区土壤重金属Cu、Zn、Pb、Cd全量和有效含量均高于对照土壤;随着矿区土壤重金属含量增加,土壤酶活性、微生物量C、N和P、可矿化N均逐渐降低,土壤基础呼吸和qCO2则逐渐升高;土壤重金属与土壤蔗糖酶活性、脲酶活性、脱氢酶活性、酸性磷酸酶活性、MBC、MBN、土壤基础呼吸、qCO2及可矿化N具有显著的线性相关;脱氢酶活性对土壤重金属污染最为敏感,表明脱氢酶活性可作为藏中矿区土壤环境质量变化的有效指标。     

Soil fertility and bacterial community composition in a semiarid Mediterranean agricultural soil under long-term tillage management

This research attempted to investigate a part of the United Nations sustainable development goal 15, dealing with preventing land degradation and halting the loss of microorganisms’ diversity. Since soil deterioration and biodiversity loss in the Mediterranean area are occurring because of intensive management, we evaluated some biochemical and microbiological parameters and bacterial biodiversity under long-term conventional tillage (CT) and no-tillage (NT) practices, in Basilicata, a typical Region of Southern Italy, characterized by a semiarid ecosystem. The highest biological fertility index (BFI) (composed of soil organic matter, microbial biomass C, cumulative microbial respiration during 25 days of incubation, basal respiration, metabolic quotient and mineralization quotient) was determined for the 0–20 cm of NT soil (class V, high biological fertility level). The analysis of the taxonomic composition at the phylum level revealed the higher relative abundance of copiotrophic bacteria such as Proteobacteria, Actinobacteria and Bacteroidetes in the NT soil samples as compared to the CT soil. These copiotrophic phyla, more important decomposers of soil organic matter (SOM) than oligotrophic phyla, are responsible of a higher microbial C use efficiency (CUE) in tilled soil, being microbial community composition, C substrates content and CUE closely linked. The higher Chao1 and Shannon indices, under the NT management, also supported the hypothesis that the bacterial diversity and richness increased in the no-till soils. In conclusion, we can assume that the long-term no-tillage can preserve an agricultural soil in a semiarid ecosystem, enhancing soil biological fertility level and bacterial diversity.