不同施肥管理措施对土壤碳含量及基础呼吸的影响

连续7年试验研究了施用15t/hm2和7.5t/hm2有机肥(包括EM堆肥、EM鸡粪肥和传统堆肥)、化肥和对照处理对土壤碳含量与基础呼吸的影响,结果表明:随有机肥施用量的提高,土壤可溶性碳、总有机碳、微生物生物量碳和土壤的基础呼吸随之增加。施用化肥可一定程度提高土壤可溶性碳、总有机碳、微生物生物量碳和土壤的基础呼吸。不同施肥措施对土壤有机碳、微生物生物量碳和土壤基础呼吸的影响趋势为EM堆肥处理>传统堆肥处理>化肥处理>对照,施肥对土壤微生物代谢商的影响趋势为EM堆肥处理<传统堆肥处理<化肥处理<对照。土壤微生物生物量碳与可溶性碳、总有机碳及土壤基础呼吸之间呈极显著正相关。土壤微生物代谢商与土壤可溶性碳、总有机碳、微生物生物量碳及基础呼吸之间呈极显著负相关。     

铅锌矿区污染土壤微生物活性研究

通过野外调查和采样分析，研究了浙江衢州铅锌矿区土壤的微生物、土壤酶活性及植物重金属积累特性。结果表明：矿区污染区土壤Ph、Zn、Cd、Cu全量的平均值分别是对照土壤的267．8倍、132．6倍、41．8倍、17．0倍。矿区植物体内重金属含量与土壤重金属全量和有效态含量呈显著正相关。矿区土壤随着重金属含量的增加，土壤微生物生物量碳逐渐降低，而土壤基础呼吸、微生物代谢商则升高，矿区中心污染土壤微生物生物量碳只有对照土壤的72％，而基础呼吸和微生物代谢商分别是对照土壤的1．6倍和2．3倍。铅锌矿口附近污染区土壤酶活性较低，对照土壤的各种酶活性最高。其中土壤脱氧酶的活性变化最大，作为矿区重金属污染的指标更灵敏。     

土壤-水稻系统中铅的生态效应

采用盆栽试验研究了土壤—水稻系统中不同铅浓度下(CK,100,300,500,700,900 mg/kg)2种水稻土壤的酶活性、微生物量碳、水稻生理指标及生物量的变化。结果表明:低浓度的铅处理时,土壤酶活性、微生物量碳及水稻生物量有一定的激活效应,而当铅浓度超过500 mg/kg时,多数指标转为抑制作用,其影响程度受土壤性质(如颗粒组成,有机质含量等)制约。水稻叶绿素含量在黄松田水稻土中开始随铅处理浓度的增大而增加,到铅浓度达700 mg/kg时出现峰值,然后随铅浓度的增加而降低;而在黄红壤水稻土中变化差异不明显。铅处理诱导了水稻中脯氨酸含量和过氧化物酶活性的缓慢上升。种植水稻比未种水稻具有较高的土壤微生物量碳,揭示了水稻生长具有一定的解毒作用。在土壤—铅—水稻相互作用的系统中,土壤酶活性、土壤微生物量和水稻生理指标是较好地反映铅污染的敏感指标,并且相互间存在一定的相关性,其大小因土壤类型而异。     

添加木醋液对沙地土壤微生物生物量和酶活性的影响

[目的]探讨沙地添加木醋液后土壤微生物生物量和酶活性的变化,为沙地土壤生物学质量的改良提供理论依据。[方法]采用盆栽植草培养法,以添加自来水为对照,对沙地添加不同稀释倍数(200,150,100,50,20)木醋液后的土壤可溶性有机碳、氮和酚,土壤微生物生物量碳氮以及土壤酶活性进行研究。[结果]向沙土添加木醋液可以显著降低土壤pH值,显著提高土壤易氧化碳、土壤水溶性碳氮、土壤可溶性酚以及无机氮的含量。在添加木醋液稀释高于50倍范围内,随木醋液稀释倍数降低,土壤微生物生物量碳氮增加以及β-糖苷酶、碱性磷酸酶和脱氢酶活性提高。添加稀释20倍的木醋液,导致土壤微生物生物量碳氮以及β-糖苷酶、碱性磷酸酶和脱氢酶活性有所降低。在高于20的稀释倍数范围内,随着施用木醋液稀释倍数的降低,α-糖苷酶、亮氨酸氨基肽酶、酸性磷酸酶和酚氧化酶的活性有显著增加的趋势。[结论]添加不同稀释倍数的木醋液会影响沙地土壤微生物生物量和酶活性。     

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。     

阿特拉津除草剂对土壤微生物生态特征的影响

采用实验室培养试验研究了阿特拉津除草剂对土壤微生物生态特征的影响。结果表明：阿特拉津除草剂10mg／kg浓度处理释放的CO2与对照无明显差异,根据危害系数法的分级方法,其属于无实际危害级农药;阿特拉津除草剂10mg／kg浓度处理在初始阶段,明显降低土壤微生物生物量碳和微生物生物量氮,随培养时间推移土壤微生物生物量碳和生物量氮有所恢复,随后又有所下降,30d后土壤微生物生物量变化趋于平缓;阿特拉津除草剂对土壤微生物多样性产生一定影响．其影响随培养时间而异。在一定程度上反映出土壤微生物生态特征指标可作为除草剂污染土壤环境质量变异的参考指标。     

冀北辽河源油松天然林土壤微生物碳代谢特征研究

本文以冀北辽河源地区不同林龄油松天然林为研究对象,研究其土壤微生物生物量碳、微生物呼吸及微生物代谢熵随油松林龄的变化趋势。结果表明:随着油松天然林林龄的增加,土壤微生物生物量碳逐渐增加;而土壤微生物呼吸则呈现出先减小后增加的趋势;微生物代谢熵表现为随油松林林龄的增加而降低。相关性分析表明,土壤微生物生物量碳、微生物呼吸分别与微生物代谢熵之间呈现高度的极显著线性负相关。微生物生物量碳与微生物呼吸呈极显著正相关,但线性相关程度较弱。土壤微生物生物量碳和微生物呼吸与土壤温度和含水量均呈极显著正相关,而土壤微生物代谢熵则与土壤温度、土壤含水量呈极显著负相关。上述结果表明,在冀北辽河源地区,土壤微生物生物量碳、微生物呼吸、微生物代谢熵与油松天然林林龄密切相关。随着油松天然林林龄的增加,其土壤微生物活性增强,碳代谢效率增加,土壤质量及可持续利用潜力更高,土壤生态体系更加成熟。     

镉胁迫对洞庭湖湿地土壤微生物数量与活性的影响

为探讨Cd污染胁迫与洞庭湖湿地土壤微生物学特性之间的内在关系,通过野外土样采集和室内模拟胁迫相结合的方法,研究Cd污染胁迫对洞庭湖湿地土壤微生物数量和微生物活性的影响。结果表明,当Cd胁迫浓度为3 mg kg~(-1)时对洞庭湖湿地土壤细菌、微生物总数及土壤微生物生物量碳(SMBC)刺激作用显著,当Cd胁迫浓度为6 mg kg~(-1)时对真菌有显著的刺激作用,而对细菌、放线菌、微生物总数及微生物生物量氮(SMBN)均表现出抑制作用,且随Cd胁迫浓度的进一步增加对细菌、真菌、放线菌、微生物总数及SMBC、SMBN的抑制作用增强;土壤脲酶、蔗糖酶、过氧化氢酶、磷酸酶和脱氢酶活性随Cd胁迫浓度的增加而降低;土壤基础呼吸(SBR)与代谢墒(qCO_2)随Cd胁迫浓度的增加呈上升趋势。放线菌、SMBC、SMBN、土壤脲酶活性、蔗糖酶活性、过氧化氢酶活性、磷酸酶活性、脱氢酶活性、SBR及qCO_2与Cd胁迫浓度相关显著或极显著;Cd胁迫条件下脱氢酶活性的变异系数最大为50.0%,表明脱氢酶活性的变化对Cd胁迫反映最为敏感,可作为洞庭湖湿地Cd污染土壤质量评价的灵敏指标。     

西双版纳不同森林类型土壤微生物生物量的变化

土壤微生物生物量在森林生态系统保护以及养分循环转化中具有重要的作用。本文研究了西双版纳5种森林类型(热带季节雨林、热带季风常绿阔叶林、曼安次生林、鸡血藤次生林和沟谷林次生林)的土壤微生物生物量以及微生物碳氮利用效率的变化。与热带季节雨林和热带季风常绿阔叶林相比,3种次生林具有较高的土壤微生物生物量碳。沟谷林次生林的土壤微生物生物量碳氮含量显著高于其它4种林型。土壤微生物生物量碳氮与土壤含水量、土壤有机碳、土壤总氮显著正相关,与土壤碳氮比显著负相关。热带季节雨林和沟谷林次生林有更高的微生物商,表明热带季节雨林和沟谷林次生林具有更高的微生物碳氮利用效率。微生物商的变化与土壤有机碳以及土壤总氮没有显著相关关系,与土壤微生物生物量显著正相关。本研究可为更好地评价不同森林类型土壤活性提供理论依据。     

重金属Cu的土壤微生物毒性研究

Cu进入土壤后的早期阶段 ,低浓度对土壤微生物生物量有刺激作用 ,而高浓度则起抑制作用 ;表现在微生物呼吸强度升高 ,微生物生理生态参数代谢商 qCO2 增大 ,微生物生物量碳与有机碳的比值 (Cmic/Corg)降低 ;但土壤对Cu高强的结合容量导致该效应随时间而变得不显著 ;Biolog数据表明 ,在Cu的胁迫下 ,不仅微生物的群落结构有所改变 ,而且对碳源的优先利用种类发生了转移 ,碳源消耗量增加 ,消耗速度变快 ,同时这样的损伤效应具有长期性。     

喀斯特峡谷区不同恢复阶段土壤微生物量及呼吸商

土壤微生物生物量、土壤微生物呼吸及微生物商值（微生物商qMB、微生物呼吸商qCO2）是土壤质量的敏感性指标。对喀斯特峡谷区不同植被恢复阶段土壤微生物生物量、土壤微生物呼吸及其qMB、qCO2进行研究,结果表明：在植被恢复过程中,土壤微生物生物量、土壤微生物呼吸及qMB均表现为从退耕地到草本群落下降,从草本到灌木群落上升,从灌木到乔木群落略微上升或者趋于稳定;qCO2的变化规律与它们相反。在同一恢复阶段,土壤微生物生物量,土壤微生物呼吸,qMB值均随土层加深而减小。土壤微生物生物量、微生物呼吸及其qMB、qCO2与土壤总有机碳、全氮、全磷具有显著的线性相关关系（p〈0.05）,可用来评价土壤质量。     

黄土高原中国松人工林演替过程中的土壤微生物和酶活性

Successional and seasonal effects on soil microbial and enzymatic properties were studied in Chinese pine (Pinus tabu- laeformis) plantations in an age sequence of 3-, 7-, 13-, 21- and 28-year-old in northern Ziwuling region in the middle of Loess Plateau, China. The results indicated that plantation age and season affected soil microbial and enzymatic parameters significantly. Soil organic C, total N, microbial biomass C, microbial quotient, basal respiration, dehydrogenase, N-α-benzoyl-L-argininamide (BAA)-protease, urease and β-glucosidase increased quickly and tended to be highest at PF21 (21-year plantation), thereafter they remained nearly at a constant level, whereas the metabolic quotient (qCO 2 ) showed an initial increase and then decreased gradually. Measures of these soil properties showed significant seasonal fluctuations except for organic C and total N, which were found to be relatively stable throughout the study period, and the seasonal distributions were autumn spring summer winter for microbial biomass C, microbial quotient, dehydrogenase, and β-glucosidase; autumn summer spring winter for BAA-protease and urease; and summer autumn spring winter for basal respiration and qCO 2 . Significant season × age interaction was observed for biomass C, basal respiration, dehydrogenase and BAA-protease.     

Effects of Epigeic Earthworms on Decomposition of Wheat Straw and Nutrient Cycling in Agricultural Soils in a Reclaimed Salinity Area:A Microcosm Study

Earthworms,one of the most important macroinvertebrates in terrestrial ecosystems of temperate zones,exert important influences on soil functions.A laboratory microcosm study was conducted to evaluate the influence of the earthworm Eisenia fetida on wheat straw decomposition and nutrient cycling in an agricultural soil in a reclaimed salinity area of the North China Plain.Each microcosm was simulated by thoroughly mixing wheat straw into the soil and incubated for 120 d with earthworms added at 3 different densities as treatments:control with no earthworms,regular density(RD)with two earthworms,and increased density(ID)with six earthworms.The results showed that there was no depletion of carbon and nitrogen pools in the presence of the earthworms.Basal soil respiration rates and metabolic quotient increased with the increase in earthworm density during the initial and middle part of the incubation period.In contrast,concentrations of microbial biomass carbon and microbial biomass quotient decreased in the presence of earthworms.Earthworm activity stimulated the transfer of microbial biomass carbon to dissolved organic carbon and could lead to a smaller,but more metabolically active microbial biomass.Concentrations of inorganic nitrogen and NO₃^--N increased significantly with the increase in earthworm density at the end of the incubation(P<0.05),resulting in a large pool of inorganic nitrogen available for plant uptake.Cumulative net nitrogen mineralization rates were three times higher in the ID treatment than the RD treatment.     

The effect of converting tropical native savanna to Eucalyptus grandis forest on soil microbial biomass

The aim of this work was to investigate the effect of converting native savanna to Eucalyptus grandis forest on soil microbial biomass in tropics. Soil samples were collected from three sites: undisturbed native savanna (savanna), the site of a 1‐year‐old E. grandis forest (1 y), and the site of a 2‐year‐old E. grandis forest (2 y). Soil microbial biomass C (MBC), basal respiration, substrate induced respiration (SIR), soil organic carbon (SOC), microbial, and respiratory quotients were evaluated in soil samples collected from 0–20 cm depth. One year converted forest caused a significant reduction in MBC, SIR, and microbial quotient (about 70, 65 and 75 per cent, respectively). However, after 2 years of E. grandis forest growth, there was recovery of these variables. Soil basal respiration and respiratory quotient were significantly higher in 1 y forest (about 4 and 14 times, respectively) than in savanna. The results showed a significant decrease, after 2 years, in soil respiration and respiratory quotient, suggesting a recovery of soil microorganisms as time passes. In the short term, our results showed negative changes in soil microbial biomass following the conversion of native savanna to E. grandis. Copyright © 2010 John Wiley & Sons, Ltd.     

长期重金属胁迫下的土壤微生物特征: 沈阳张士污灌区的案例研究

Soil samples were collected from Zhangshi Wastewater Irrigation Area in the suburb of Shenyang City, China, an area with a 30-year irrigation history with heavy metal-containing wastewater. The chemical properties and microbial characteristics of the soils were examined to evaluate the present situation of heavy metal pollution and to assess the soil microbial characteristics under long-term heavy metal stress. In light of the National Environmental Quality Standards of China, the soil in the test area was heavily polluted by Cd and to a lesser degree by Zn and Cu, even though wastewater irrigation ceased in 1993. Soil metabolic quotient （qCO2） had a significant positive correlation, while soil microbial quotient （qM） had a negative correlation with content of soil heavy metals. Soil microbial biomass carbon （MBC） had significantly negative correlation with Cd, but soil substrate~induced respiration （SIR）, dehydrogenase activity （DHA）, cellulase activity, and culturable microbial populations had no persistent correlations with soil heavy metal content. Soil nutrients, except for phosphorous, showed positive effects on soil microbial characteristics, which to a certain degree obscured the adverse effects of soil heavy metals. Soil Cd contributed more to the soil microbial characteristics, but qM and qCO2 were more sensitive and showed persistent responses to heavy metals stress. It could be concluded that qM and qCO2 can be used as bioindicators of heavy metal pollution in soils.     

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.     

酞酸酯污染土壤微生物效应与过氧化氢酶活性的变化特征

采用室内模拟污染土壤,研究了邻苯二甲酸二(乙基-己基)酯和邻苯二甲酸二丁酯两种酞酸酯类化合物对农田土壤微生物生物量碳、土壤基础呼吸与土壤过氧化氢酶活性及其反应动力学参数的影响。结果表明,DBP土壤浓度在10 mg/kg,DEHP土壤浓度在20 mg/kg以下,与对照相比,微生物生物量碳、土壤基础呼吸以及过氧化氢酶活性没有明显影响。土壤浓度为20 mg/kg的DBP处理对土壤基础呼吸有明显的激活作用。两种化合物在高浓度处理的土壤中,均对微生物生物量碳、土壤基础呼吸以及过氧化氢酶活性表现抑制效应,抑制作用随处理浓度的增加而加强,其中两种化合物土壤浓度为100 mg/kg时,在培养期内三者均没有表现出明显的恢复趋势。对过氧化氢酶Km与Vmax以及Vmax/Km等动力学参数分析表明,DBP与DEHP没有对过氧化氢酶促反应速率以及酶与底物亲和力产生明显影响。