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1.
Purpose
The purposes of this study were to identify the influence of a severe drought period on the impact of a subsequent heat–drought disturbance on the microbial community of a Mediterranean agricultural soil and particularly to highlight the long-term effects on the microbial catabolic profiles.Materials and methods
We performed an experiment in microcosms and applied the MicroResp? method on soil microbial communities.Results and discussion
A 21-day combined heat–drought disturbance had less impact on soil microbial communities pre-exposed to a 73-day severe drought than on those that were not pre-exposed. These differences were observed not only for biomass and physiological traits (basal respiration, qCO2), but also for catabolic microbial structure evolution during the recovery time.Conclusions
These observations suggest that the physiological stress imposed by the initial severe drought changed the microbial catabolic structure or physiological state and favoured a portion of the microbial community best adapted to cope with the final heat–drought disturbance. Consequently, the initial severe drought may have induced a community tolerance to the subsequent heat wave. In this study, we also note that resilience was, more than resistance, an indicator of pre-exposure to stress. In the context of assessing the effects of extreme climatic events on soil microbial processes, these results suggest that future studies should take into account the historic stress of habitats and resilience parameters.2.
Soil microbial biomass, activity and community composition in adjacent native and plantation forests of subtropical Australia 总被引：2，自引：0，他引：2
Joanne Burton Chengrong Chen Zhihong Xu Hossein Ghadiri 《Journal of Soils and Sediments》2010,10(7):1267-1277
Purpose
Soil nitrogen (N) availability is a critical determinant of plantation productivity in subtropical Australia and is influenced by the soil microbial community. The size, structure and function of the soil microbial community can be impacted by land-use change and residue management. The objectives of this study were to examine the impact of land-use change from (1) native forest (NF) to first rotation (1R) hoop pine plantation and (2) 1R hoop pine plantation to second rotation (2R) hoop pine plantation on the soil microbial community. The impact of residue management on the soil microbial community was also investigated in the 2R forest, where soil microbial parameters were measured in tree rows (2R-T) and windrows (2R-W). In addition, relationships between soil microbial parameters and soil N parameters were investigated.Materials and methods
Each of the four treatments (NF, 1R, 2R-T and 2R-W) had five 24-m2 replicate plots from which 15 soil cores were collected and bulked at three depths (0–10, 10–20, 20–30 cm). Microbial biomass carbon (MBC) and N (MBN) and soil respiration were measured on field moist soils. In addition, carbon (C) source utilisation patterns were assessed using the whole soil MicroResp? technique (Campbell et al. 2003).Results and discussion
Results indicate that the land-use change from NF to 1R hoop pine plantation significantly reduced MBC, respiration rate, soil total C and total N. Furthermore, the land-use change appeared to have a significant impact on the soil microbial community composition measured using MicroResp? profiles. Land-use change from 1R to 2R hoop pine plantation resulted in a decline in total C and MBN and a shift in microbial community composition. When compared to the 2R-T soils, the 2R-W soils tended to have a greater microbial biomass and respiration rate. Residue management also influenced the microbial community composition measured in the MicroResp? profiles.Conclusions
Results indicate that land-use change had a significant impact on the soil microbial community, which was likely to be related to shifts in the quality and quantity of organic inputs associated with the change in land use. This may have significant implications for the long-term productivity of the soil resource. Further studies are required to confirm a difference in microbial community composition associated with residue management. In addition, long-term experiments in subtropical Australia are necessary to verify the results of this snapshot study and to improve our understanding of the impact of single-species plantation forestry and residue management on the soil microbial community, soil N dynamics and ultimately the long-term sustainability of the soil resource. 相似文献3.
Background, aim, and scope
Bamboo (Phyllostachy pubescens Mazel ex Lehaie), a unique fast-growing tree species, is an important forest resource in southern China. Because of its high economic value and short rotation period, intensive management practices such as fertilization, weeding, and deep tilling are extensively utilized. These practices significantly increase the production of mature timber and young shoots. In this paper, bamboo stands under intensive management with short-term (STIP) and long-term (LTIP) practices were compared with those managed conventionally (CON) to study the effects of intensive management practices on soil biological properties.Materials and methods
We measured the soil microbial biomass carbon (MBC), basal respiration carbon (BRC), and the specific ability of soil microbiota to consume a range of carbon (C) substrates, measured by Biolog ECO MicroPlate.Results
Intensive management practice significantly decreased (P?<?0.05) soil MBC (in the order of CON > STIP > LTIP), but increased soil BRC (in the order of STIP ≈ LTIP > CON). Under intensive management practices, soil microbial activity, and diversity of C sources utilized by microbial communities decreased (P?<?0.05), as characterized by average well color development (AWCD). Shannon and McIntosh indexes tended to decline with intensive management practices. Intensive management practice also caused much lower (P?<?0.05) utilization of 2-hydroxy benzoic acid and a-cyclodextrin.Discussion
Soil biological properties were proved to be sensitive indicators of soil quality in response to the intensive management practices, with decreases in soil MBC, microbial activity, and diversity of C sources utilized by microbial communities under the continuing intensive management practices in bamboo stands. This indicates that the intensive management practices had resulted in the negative effect on the soil microbial activities.Conclusions
Intensive management practices generally had a negative influence on the soil biological properties. This would have important implications for the sustainable management of bamboo production systems in southern China.Recommendations and perspectives
To minimize the detrimental effect on soil microbial communities, an improved intensive management practice with reducing amounts of mineral fertilizer and increasing organic fertilizer applications are recommended annually so that both high bamboo yield and soil quality can be sustained over a long period. 相似文献4.
Ming Li Lili Jiang Zhaojun Sun Jinzhi Wang Yichao Rui Lei Zhong Yanfen Wang Paul Kardol 《Journal of Soils and Sediments》2012,12(7):1040-1053
Purpose
For an alkaline?Csaline region in Northwest China, we examined the responses of soil microbial communities to flue gas desulfurization gypsum by-products (FGDB), a new ameliorant for alkaline?Csaline soils. In 2009 and 2010, we collected soils from 0?C20?cm and 20?C40?cm depths along an experimental FGDB gradient (0, 0.74, 1.49, 2.25, and 3.00?kg FGDB m?2).Materials and methods
As a measure of microbial community composition and biomass, we analyzed phospholipid fatty acids (PLFAs). We used real-time quantitative polymerase chain reaction (qPCR) to measure abundance of bacterial 16?S rRNA copy numbers. Additionally, physicochemical soil parameters were measured by common laboratory methods.Results and discussion
Microbial community composition differed along the FGDB gradient; however, the microbial parameters did not follow a linear response. We found that, in 2009, total PLFA concentrations, and concentrations of total bacterial and Gram-negative bacterial PLFAs were slightly higher at intermediate FGDB concentrations. In 2010, total PLFA concentrations, and concentrations of total bacterial, Gram-positive bacterial, Gram-negative bacterial, and fungal PLFAs as well as the fungal:bacterial PLFA ratio were highest at 1.49?kg FGDB m?2 and 3.00?kg FGDB m?2. PLFA concentrations often differed between 2009 and 2010; however, the patterns varied across the gradient and across microbial groups. For both years, PLFA concentrations were generally higher at 0?C20?cm depth than at 20?C40?cm depth. Similar results were obtained for the 16?S rRNA copy numbers of bacteria at 0?C20?cm depth. FGDB addition resulted in an increase in soil Ca2+ and NO 3 ? ?CN and a decrease in pH and electrical conductivity (EC). Shifts in PLFA-based microbial community composition and biomass could partly be explained by pH, soil organic carbon, total nitrogen (TN), soil moisture, EC, inorganic nitrogen, C/N, and Ca2+. Indirect effects via shifts in abiotic soil properties, therefore, seem to be an important pathway through which FGDB affect soil microbial communities.Conclusions
Our results demonstrate that addition of FGDB leads to significant changes in soil physicochemical and microbial parameters. As such, addition of FGDB can have large impacts on the functioning of soil ecosystems, such as carbon and nitrogen cycling processes. 相似文献5.
Soil organic matter evolution after the application of high doses of organic amendments in a Mediterranean calcareous soil 总被引：1，自引：0，他引：1
Sergio González-Ubierna Ignacio Jorge-Mardomingo Beatriz Carrero-González María Teresa de la Cruz Miguel ángel Casermeiro 《Journal of Soils and Sediments》2012,12(8):1257-1268
Purpose
We investigate the coevolution of soil organic matter (SOM) and soil properties in a semiarid Mediterranean agroecosystem, as well as the 1-year evolution of the different pools of soil organic and inorganic carbon and their influence on soil respiration after the application of a single high dose of three different organic amendments.Material and methods
We applied a single high dose (160?Mg?ha?1 in dry weight (DW)) of three types of organic amendments: aerobically digested sewage sludge (AE), anaerobically digested sewage sludge (AN), and municipal solid waste compost (MSWC), in a calcareous Mediterranean soil. The study area is located in the southeast of Madrid (Spain), characterized by a Mediterranean climate with a marked seasonal and daily contrast. We analyzed different forms of soil organic and inorganic carbon and soil respiration rates. The measurements have been performed quarterly for 1?year.Results and discussion
The results showed that the coevolution of SOM and soil largely depends on the origin and composition of the organic amendments used. The AN sludge affected the soil chemistry more. The organic matter (OM) provided by AE treatments underwent more intense mineralization processes than AN, with the OM from MSWC being more stable. This behavior could be explained by the different pools of carbon involved in each case. The treatments contributed differently to soil respiration rates following the sequence: AE > AN > MSWC. The application of organic amendments in calcareous Mediterranean soils also modified the inorganic carbon pools.Conclusions
SOM and soil coevolution after organic amendments application depends on the origin and chemical composition of the inputs. The decision-making process of urban organic waste application with regard to agricultural policy must take into account the different behavior in soil of the different types of amendments. 相似文献6.
Rongxiao Che Weijin Wang Jing Zhang Thi Thu Nhan Nguyen Juan Tao Fang Wang Yanfen Wang Zhihong Xu Xiaoyong Cui 《Journal of Soils and Sediments》2016,16(12):2698-2708
Purpose
Understanding soil heterotrophic respiration in relation to microbial properties is not only fundamental to soil respiration modelling, prediction, and regulation through management, but also essential to interpreting microbial community dynamics from an ecologically meaningful perspective. This paper reviewed the recent advances in knowledge and proposed future directions for exploring the respiration-microbe relationships by means of rDNA- or rRNA-based indices (i.e. rDNA copies, rRNA copies, and rDNA- or rRNA-based community structures).Materials and methods
We first elucidated the theoretical basis for using rDNA- or rRNA-based indices to probe into soil microbial respiration. Then, the published studies that simultaneously measured soil microbial respiration and the rDNA- or rRNA-based indices were synthesized, extracted, and analysed to further explore the respiration-microbe relationships. At last, the uncertainties and perspectives for establishing the respiration-microbe links were proposed and discussed.Results and discussion
The rDNA- or rRNA-based indices are theoretically promising for pinpointing the relationships between soil heterotrophic respiration and microbial properties. Our systematic review suggested that the correlations between bacterial rDNA copies and microbial respiration are inconsistent across studies, while the fungal and archaeal rDNA (or ITS) copies showed moderately positive and negative correlations with soil microbial respiration, respectively. Bacterial 16S rDNA-based community structures were significantly correlated with soil microbial respiration in some studies, but not in some short-term situations. Although rRNA copies are widely used as the proxies of microbial activity, no significant correlations between rRNA copies and soil microbial respiration have been found in previous studies. Bacterial 16S rRNA-based community structures were correlated well with the short-term responses of soil microbial respiration to rewetting or labile carbon amendments and clearly outperformed other rDNA- or rRNA-based indices. As respiration-microbe relationships can be affected by many factors, such as soil physicochemical properties and even the analysis methods of microbial indices, the 69 previous studies included in this review actually provided limited information on them, and the aforementioned results still need to be further confirmed in future studies.Conclusions and perspectives
Overall, the relationships between soil microbial respiration and rDNA- or rRNA-based indices are still far from being well established. Future research should be directed to systematically understanding the respiration-microbe links, with more attention to the fungus-, archaea- and RNA-related molecular indices. The relationships between microbial specific lineages and total respiration rates should be explored in future studies, and the effects of edaphic properties on the respiration-microbe relationships should also be evaluated.7.
Sang-Sun Lim Woo-Jung Choi Kwang-Seung Lee Hee-Myong Ro 《Journal of Soils and Sediments》2012,12(9):1299-1308
Purpose
Fly ash can reduce CO2 emission from soils via biochemical (i.e., inhibition of microbial activity) and physicochemical (i.e., carbonation) mechanisms. This study investigated the effects of fly ash amendment on biochemical and physicochemical reduction in CO2 emission from normal and saline soils.Materials and methods
The physicochemical mechanisms of reduction in CO2 emission by fly ash were estimated in a batch experiment with carbonate solution as a CO2 source by the scanning electron microscope (SEM) and inductively coupled plasma analyses. Biochemical mechanisms of reduction in CO2 emission by fly ash were investigated in a 3-day laboratory incubation experiment with normal and saline soils in the absence and presence of fly ash. Finally, the effects of fly ash amendment at a variety rate from 2 to 15?% (w/w) on CO2 emission from normal and saline soils in the presence of additional organic carbon source (glucose) were investigated through a 15-day laboratory incubation study.Results and discussion
In the batch experiment with carbonate solution, both the SEM image of fly ash and changes in soluble Ca and Mg concentrations during reaction with carbonate suggested that the formation of CaCO3 and MgCO3 via carbonation was the principal physicochemical mechanism of carbonate removal by fly ash. In the 3-day incubation study conducted to examine biochemical mechanisms of reduction in CO2 emission by fly ash, microbial respiration of saline soil was inhibited (P?<?0.05) by fly ash due to high pH, salinity, and boron concentration of fly ash; meanwhile, for normal soil, there was no inhibitory effect of fly ash on microbial respiration. In the 15-day incubation with glucose, fly ash application at a variety rates from 2 to 15?% (w/w) reduced CO2 emission by 3.6 to 21.4?% for normal and by 19.8 to 30.3?% for saline soil compared to the control without fly ash. For saline soil, the reduction in CO2 emission was attributed primarily to inhibition of microbial respiration by fly ash; however, for normal soil in which suppression of microbial respiration by fly ash was not apparent, carbonation was believed to play an important role in reduction of CO2 emission.Conclusions
Therefore, fly ash may be helpful in reducing CO2 emission from normal soils via carbonation. For saline soil, however, fly ash needs to be carefully considered as a soil amendment to reduce CO2 emission as it can inhibit soil microbial activities and thus degrade soil quality. 相似文献8.
Electron transfer capacity of soil dissolved organic matter and its potential impact on soil respiration 总被引：1，自引：0，他引：1
Purpose
Soil dissolved organic matter (DOM) as the labile fraction of soil organic carbon (SOC) is able to facilitate biogeochemical redox reactions effecting soil respiration and carbon sequestration. In this study, we took soil samples from 20 sites differing in land use (forest and agriculture) to investigate the electron transfer capacity of soil DOM and its potential relationship with soil respiration.Materials and methods
DOM was extracted from 20 soil samples representing different land uses: forest (nos. 1–12) and agriculture (nos. 13–20) in Guangdong Province, China. Chronoamperometry was employed to quantify the electron transfer capacity (ETC) of the DOM, including electron acceptor capacity (EAC) and electron donor capacity (EDC), by applying fixed positive or negative potentials to a working electrode in a conventional three-electrode cell. The reversibility of electron accepting from or donating to DOM was measured by applying switchable potentials to the working electrode in the electrochemical system with the multiple-step potential technique. Carbon dioxide produced by soil respiration was measured with a gas chromatograph.Results and discussion
Forest soil DOM samples showed higher ETC and electron reversible rate (ERR) than agricultural soil DOM samples, which may be indicative of higher humification rate and microbial activity in forest soils. The average soil respiration of forest soil (nos. 1–12) and agricultural soil (nos. 13–10) was 26.34 and 18.58 mg C g?1 SOC, respectively. Both EDC and EAC of soil DOM had close relationship with soil respiration (p?<?0.01). The results implied that soil respiration might be accelerated by the electroactive moieties contained in soil DOM, which serve as electron shuttles and facilitate electron transfer reactions in soil respiration and SOC mineralization.Conclusions
DOM of forest soils showed higher ETC and ERR than DOM of agricultural soils. As soil represents one of the largest reservoirs of organic carbon, soil respiration affects C cycle and subsequently CO2 concentration in the atmosphere. As one of the important characteristics of soil DOM related to soil respiration, ETC has a significant impact on greenhouse gas emission and soil carbon sequestration but has not been paid attention to. 相似文献9.
Farhan Hafeez Laurent Philippot Aymé Spor Fabrice Martin-Laurent 《Journal of Soils and Sediments》2014,14(1):178-182
Purpose
Soil contamination by pollutants is increasing, urging for remediation strategies but little is known about the functional sustainability of these strategies.Materials and methods
We assessed the resistance and resistance of a microbial respiratory process, denitrification, to two different levels of heat-drought disturbances among (1) thermally treated industrial soil, (2) constructed Technosol made of thermally treated soil, compost, and paper by products, and (3) an arable soil.Results and discussion
We showed that thermal remediation lead to low resistance and resilience after disturbances. However, addition of compost and paper mill sludge improved the stability.Conclusions
This work underlines the relevance of resistance and resilience ecological concepts for assessing remediation strategies. 相似文献10.
Yanfen Wang Yanbin Hao Xiao Yong Cui Haitao Zhao Chengyuan Xu Xiaoqi Zhou Zhihong Xu 《Journal of Soils and Sediments》2014,14(1):99-109
Purpose
Climate change is likely to increase both intensity and frequency of drought stress. The responses of soil respiration (R s) and its components (root respiration, R r; mycorrhizal respiration, R m; and heterotrophic respiration, R h) to drought stress can be different. This work aims to review the recent and current literature about the variations in R s during the period of drought stress, to explore potential coupling processes and mechanisms between R s and driving factors in the context of global climate change.Results and discussion
The sensitivity of soil respiration and its components to drought stress depended on the ecosystems and seasonality. Drought stress depressed R s in mesic and xeric ecosystems, while it stimulated R s in hydric ecosystems. The reductions in supply and availability of substrate decreased both auto- and heterotrophic respirations, leading to the temporal decoupling of root and mycorrhizal respiration from canopy photosynthesis as well as C allocation. Drought stress also reduced the diffusion of soluble C substrate, and activities of extracellular enzymes, consequently, limited microbial activity and reduced soil organic matter decomposition. Drought stress altered Q 10 values and broke the coupling between temperature and soil respiration. Under drought stress conditions, R m is generally less sensitive to temperature than R r and R h. Elevated CO2 concentration alleviated the negative effect of drought stress on soil respiration, principally due to the promotion of plant C assimilation subsequently, which increased substrate supply for respiration in both roots and soil microorganisms. Additionally, rewetting stimulated soil respiration dramatically in most cases, except for soil that experienced extreme drought stress periods. The legacy of drought stress can also regulate the response of soil respiration rate to rewetting events in terrestrial ecosystems through changing abiotic drivers and microbial community structure.Conclusions and perspectives
There is increasing evidence that drought stress can result in the decoupling of the above- and belowground processes, which are associated with soil respiration. However, studies on the variation in rates of soil respiration and its components under different intensities and frequencies of drought stress over the ecosystems should be reinforced. Meanwhile, molecular phylogenetics and functional genomics should be applied to link microbial ecology to the process of R s. In addition, we should quantify the relationship between soil respiration and global change parameters (such as warming and elevated [CO2]) under drought stress. Models simulating the rates of soil respiration and its components under global climate change and drought stress should also be developed. 相似文献11.
Gregor Plestenjak Klemen Eler Dominik Vodnik Mitja Ferlan Matja? ?ater Tja?a Kandu? Primo? Simon?i? Nives Ogrinc 《Journal of Soils and Sediments》2012,12(9):1327-1338
Purpose
The objective of this study is to estimate the contribution of various sources that influence soil CO2 concentrations in calcareous grassland.Materials and methods
The research was performed at the Podgorski Kras plain (45?°33?? N, 13?°55?? E, 400?C430?m.a.s.l.) in the sub-Mediterranean region of Slovenia (SW Slovenia), where many meadows and pastures have been abandoned. In parallel to the measurement of soil respiration R s, soil gas was sampled for stable isotope analysis. Samples were taken biweekly at two sites, Grassland and Invaded, from July 2008 until November 2010. In addition, daily variations in concentration and stable isotope composition of soil CO2 were determined in May 2009. The partitioning of soil CO2 concentrations was performed using stable isotope mass balance calculation.Results and discussion
The concentration and isotope composition of soil CO2 exhibited similar seasonal variations at both sites. Lower ??13CCO2 values, ranging from ?28.2 to ?15.2 ??, which occurred during warm periods and higher values, up to ?12.1 ??, were typical of cold winter periods, from December to March. Organic sources were estimated to constitute between 78 and 99?% of total soil CO2 during warmer periods from May until October. This contribution was lower during the winter, ranging from 46 to 77?%. In winter, the atmospheric component to soil CO2 dominated, constituting up to 60?%. On average, the inorganic contribution was estimated to comprise 12?% of the soil CO2 at all sampling locations. The contribution of this source to soil CO2 concentration, at up to 41?%, was highest in Grassland during the growing season. The inorganic source of soil CO2 was also an important component during daily variations. The highest contribution was observed during the day, in parallel to the highest respiration rates.Conclusions
The inorganic pool is shown to be an important part of soil CO2 in calcareous areas and should be considered as equal to organic CO2 as a source in soil CO2 partitioning. 相似文献12.
Effects of straw amendment and moisture on microbial communities in Chinese fluvo-aquic soil 总被引：2，自引：0，他引：2
Lin Chen Jiabao Zhang Bingzi Zhao Pei Yan Guixiang Zhou Xiuli Xin 《Journal of Soils and Sediments》2014,14(11):1829-1840
Purpose
Returning crop straw into fields is a typical agricultural practice to resolve an oversupply of straw and improve soil fertility. Soil microorganisms, especially eukaryotic microorganisms, play a critical role in straw decomposition. To date, microbial communities in response to straw amendment at different moisture levels in Chinese fluvo-aquic soil are poorly understood. The aim of this study was to explore the effects of straw amendment and moisture on microbial communities in Chinese fluvo-aquic soil.Materials and methods
Two soils (one was applied with organic manure, and the other was not applied with any fertilizer) from a long-term field experiment in the North China Plain were collected. Soils with and without straw amendment at 25 and 55 % of the average water-holding capacities of the two soils were incubated at 25 °C for 80 days. All treatments were sampled 20 and 80 days after the start of incubation. Microbial biomass and community structure were analyzed by phospholipid fatty acids (PLFA) assay, and the eukaryotic diversity and community composition were assessed via barcoded pyrosequencing of the 18S ribosomal RNA (rRNA) gene amplicons.Results and discussion
PLFA analysis showed that straw amendment increased the biomass of Gram-positive bacteria, Gram-negative bacteria, actinobacteria, and fungi and shifted microbial community structure. The varied straw availability resulted in a large variation in microbial community structure. In the presence of straw, actinobacterial and fungal biomass both decreased under high moisture content. 18S rRNA gene pyrosequencing indicated that straw amendment decreased eukaryotic diversity and richness and probably restructured the eukaryotic community. Under identical moisture content, long-term organic manure-fertilized soil had higher eukaryotic diversity and richness than the unfertilized soil. In the amended soils under high moisture content, the relative abundance of dominant fungal taxa (Dikarya subkingdom, Ascomycota phylum, and Pezizomycotina subphylum) decreased.Conclusions
Straw amendment increases microbial biomass, shifts microbial community structure, and decreases eukaryotic diversity and richness. High moisture content probably has a negative effect on fungal growth in the amended soils. In conclusion, microbial communities in Chinese fluvo-aquic soil are significantly affected by straw amendment at different moisture levels. 相似文献13.
Effects of super absorbent polymers on soil microbial properties and Chinese cabbage (Brassica chinensis) growth 总被引：1，自引：0，他引：1
Purpose
New water retention materials, super absorbent polymers (SAPs), have shown the potential to improve some soil physicochemical properties and promote growth of some crop species in arid and semi-arid areas. However, the impacts of SAPs on soil microbial properties are unclear. This study was conducted to clarify the effects of two SAPs on soil microbial properties and Chinese cabbage (Brassica chinensis) growth under different water conditions in the greenhouse.Materials and methods
Experimental conditions included different irrigation conditions and different quantities of SAPs. Chinese cabbage was harvested after 1-month growth in the greenhouse. Meanwhile, soil samples were collected and sieved (<2-mm mesh). Some of the soils were kept at ?4 °C for analysis of soil physicochemical properties, and some at ?20 °C for analysis of soil microbial properties. Chinese cabbage samples were thoroughly washed with deionized water for the measurement of fresh weight, shoot length, and root length.Results and discussion
The effects from SAPs were not obvious under water sufficient (WC1, watered every 2 days, and WC2, watered every 4 days) since plant properties were smaller in some SAP treatments than those in control. However, under water deficit (WC3, watered every 8 days), there were significant differences in plant shoot length and fresh weight between SAP treatments. There were also significant differences in relative soil water content between water condition (WC) or SAP treatments. The SAPs were beneficial for the formation of large aggregates. Under WC3, the soil organic matter (SOM) increased by 16.9 and 11.5 %, soil microbial biomass C (SMBC) by 32.5 and 19.3 %, and soil microbial respiration (SMR) by 52.1 and 37.2 % with Jaguar C (JC) and Jaguar S (JS), respectively. Under WC1 and WC2, significantly higher copy numbers of AOA in bulk treatment of JC were found compared with control treatment in this study. Under water deficit, the abundance of bacteria was significantly increased by application of SAPs. For almost every property of soil and plant, JC was showing better effects than JS.Conclusions
Our results showed that cabbage growth was restricted under water-deficit conditions and the application of SAPs could conserve soil water and be useful for increasing cabbage growth under water deficit, improving SOM, SMBC, and SMR under different WC, and stimulating amoA gene AOA copy numbers and bacterial gene copy numbers. Thus, there should be no adverse effects of SAP application on soil microbial environment and Chinese cabbage growth. 相似文献14.
Purpose
This study aims to evaluate the effects of industrial and agricultural by-products as amendments on soil acidity, soil nutrients, enzymatic and microbial properties, and thus soil quality of an acidic Ultisol under field conditions and to give some index for choosing amendments in acid soils.Materials and methods
A long-term field experiment was established in an acidic Ultisol in the middle China to investigate the ameliorating effect after application of industrial and agricultural by-products for 4 years. There were five treatments including addition of rice chaff, peanut straw, alkaline slag, alkaline slag with rice chaff, and without amendment of control. Top soil samples (0–15 cm) from individual plots per treatment were collected for the analysis of chemical and microbial properties. The relationships between chemical properties and microbial and enzymatic properties were also analyzed with bivariate correlation analyses and stepwise linear regression.Results and discussion
Alkaline slag was more effective than rice chaff and peanut straw in correcting soil acidity and induced more increase in catalase activity, acid phosphatase activity, and microbial quotient, and thus more depress in the metabolic quotient, since soil acidity was an important stress factor for microbial and enzyme activities in the Ultisol. Incorporation of rice chaff and peanut straw markedly increased the soil microbial carbon, urease activity, and basal respiration to a greater extent, by more greatly enriching soil with organic carbon and more balanced nutrients of N, P, and K, which were also significant factors affecting microbial properties. Consequently, the application of alkaline slag and rice chaff together was the most effective in enhancing the geometric mean of enzyme activities (an important index of soil quality) when compared with the single application of alkaline slag, rice chaff, or peanut straw.Conclusions
Soil acidity, organic C, and balanced nutrients of N, P, and K were key factors for affecting soil microbial and enzymatic activities, and thus soil quality in this Ultisol. The combined industrial and agricultural by-products together as amendments would be the better choice to improve soil quality in acidic Ultisols. 相似文献15.
Ching-Yu Huang Shih-Hao Jien Tsai-Huei Chen Guanglong Tian Chih-Yu Chiu 《Journal of Soils and Sediments》2014,14(6):1061-1070
Purpose
Moso bamboo (Phyllostachys edulis), an important economic crop, is distributed from low- to medium-elevation mountains in Taiwan. Bamboo is a fast-growing herbaceous species with an extensive rhizome structure. With the hypothesis that the characteristics of soil organic matter and microbes might change after long-term bamboo plantation, we investigated different fractions of organic C and N as well as soil microbial biomass and activities in five moso bamboo plantations along an elevation gradient in Central Taiwan.Materials and methods
Five soil samples (top 10 cm of soil) were collected from each bamboo plantation (600, 800, 1,000, 1,200, and 1,400 m above sea level (asl)) in January 2011. Soil was processed and analyzed for soil total C and N contents, biologically available C, potentially mineralizable N, soil microbial biomass and soil respiration (CO2). Two extraction methods (2 M KCl and hot-water extraction) were used to estimate soil soluble organic C and N (SbOC and SbON) and soil inorganic N (NH4 + and NO3 ?) concentrations to evaluate the relationship with soil organic matter and microbe characteristics in bamboo plantations.Results and discussion
Soil total C and N contents as well as soil microbial biomass and soil respiration (CO2) of the bamboo plantations increased along the elevation gradient. Temperature changes along elevation contributed to such variations observed among the selected bamboo plantations. The SbON in hot-water extracts was highest in the 1,200-m plantation, then in the 1,400-m plantation, and lowest in the low-elevation plantations (600, 800, and 1,000 m). However, SbON in 2 M KCl extracts did not differ by elevation. The SbON was strongly correlated with soil total N in both 2 M KCl and hot-water extracts, but only SbON in hot-water extracts was strongly correlated with microbial biomass N and potentially mineralizable N. SbOC was strongly correlated with soil total C content, microbial biomass C, and biologically available C in both 2 M KCl and hot-water extracts.Conclusions
Soil total C and N, SbOC and SbON, and microbial biomass characteristics increased in the moso bamboo plantations with increasing elevation. No altitudinal difference in specific soil respiration (CO2) rate suggested that the enhanced potentially mineralizable N and soil respiration (CO2) in the high-elevation plantations were associated with increased microbial biomass rather than microbial activities. 相似文献16.
Soil carbon dioxide emission from intensively cultivated black soil in Northeast China: nitrogen fertilization effect 总被引：1，自引：0，他引：1
Kang Ni Weixin Ding Zucong Cai Yufeng Wang Xilin Zhang Baoku Zhou 《Journal of Soils and Sediments》2012,12(7):1007-1018
Purpose
The aim of this study was to understand the effect of nitrogen fertilization on soil respiration and native soil organic carbon (SOC) decomposition and to identify the key factor affecting soil respiration in a cultivated black soil.Materials and methods
A field experiment was conducted at the Harbin State Key Agroecological Experimental Station, China. The study consisted of four treatments: unplanted and N-unfertilized soil (U0), unplanted soil treated with 225?kg?N?ha?1 (UN), maize planted and N-unfertilized soil (P0), and planted soil fertilized with 225?kg?N?ha?1 (PN). Soil CO2 and N2O fluxes were measured using the static closed chamber method.Results and discussion
Cumulative CO2 emissions during the maize growing season with the U0, UN, P0, and PN treatments were 1.29, 1.04, 2.30 and 2.27?Mg?C?ha?1, respectively, indicating that N fertilization significantly reduced the decomposition of native SOC. However, no marked effect on soil respiration in planted soil was observed because the increase of rhizosphere respiration caused by N addition was counteracted by the reduction of native SOC decomposition. Soil CO2 fluxes were significantly affected by soil temperature but not by soil moisture. The temperature sensitivity (Q 10) of soil respiration was 2.16?C2.47 for unplanted soil but increased to 3.16?C3.44 in planted soil. N addition reduced the Q 10 of native SOC decomposition possibly due to low labile organic C but increased the Q 10 of soil respiration due to the stimulation of maize growth. The estimated annual CO2 emission in N-fertilized soil was 1.28?Mg?C?ha?1 and was replenished by the residual stubble, roots, and exudates. In contrast, the lost C (1.53?Mg?C?ha?1) in N-unfertilized soil was not completely supplemented by maize residues, resulting in a reduction of SOC. Although N fertilization significantly increased N2O emissions, the global warming potential of N2O and CO2 emissions in N-fertilized soil was significantly lower than in N-unfertilized soil.Conclusions
The stimulatory or inhibitory effect of N fertilization on soil respiration and basal respiration may depend on labile organic C concentration in soil. The inhibitory effect of N fertilization on native SOC decomposition was mainly associated with low labile organic C in tested black soil. N application could reduce the global warming potential of CO2 and N2O emissions in black soil. 相似文献17.
Background, Aims and Scope
Bioavailability of toxic compounds in soil can be defined as the fraction able to come into contact with biota and to cause toxic effects. The contact toxicity tests may detect the total toxic response of all bioavailable contaminants present in a sample. The objectives of this study were to evaluate the use of microbial contact toxicity tests for cadmium bioavailability assessment and to evaluate the relationship between sorption, soil characteristics and cadmium bioavailability.Methods
A test soil bacterium,Bacillus cereus, was put in direct contact with the solid sample. Four unpolluted soils were selected to provide solid samples with a variety of physicochemical characteristics. The toxicity and sorption behaviour of cadmium spiked to the soil samples were determined.Results, Discussion and Conclusions
A significant correlation between contact toxicity test results and partitioning of cadmium in the soil samples (r2= 0.79, p <0.05; n = 26) was found. The results confirm that the bioavailability of cadmium in soil depends on its sorption behaviour. Cadmium sorbed to the cation exchange sites associated with fulvic acids is non-bioavailable in the toxicity test employed in this study. It is concluded that the microbial contact toxicity test is a suitable tool for detecting cadmium bioavailablity in the soils used in this study.Outlook
The application of microbial contact toxicity tests for bioavailability assessment can be very useful for the risk identification and remediation of soil-associated contaminants. 相似文献18.
Purpose
Soil microbes contribute significantly to soil respiration (SR) in boreal forests; however, there is limited knowledge on microbial contributions from long field investigations. The objective of this study was to estimate soil microbial respiration, as well as its primary controlling factors, for a period of three consecutive years.Materials and methods
A trenching method was used to distinguish soil microbial respiration (R Mic) in a 55-year-old mature Japanese larch (Larix kaempferi) plantation in Northern Japan; the soil in which developed originally from volcanic soils containing pumice. We used a portable CO2 detection system to measure the soil respiration rate during the growing season. Environmental factors, soil physiochemical characteristics, and soil microbial biomass carbon and nitrogen (MBC and MBN) were analyzed to explain the seasonal variations of SR and R Mic.Results and discussion
The results showed that the estimated contribution of soil microbes to SR was 78, 62, and 55% during the three successive years, respectively. Respiration attributable to decomposition of aboveground litter contributed approximately 19% to SR. The major environmental factor that affected R Mic was soil temperature at 5 cm depth, which accounted for more than 70% of the seasonal variation in R Mic observed. There were close relations among MBC, MBN, and soil water content, but the soil water content showed no significant relation with R Mic.Conclusions
The R Mic to SR varied from 78 to 55% following 3 years of trenching treatments. Our results demonstrated the important role of soil microbes on soil respiration in this larch forest. Soil temperature was the major positive factor that influenced R Mic, while soil water content had no significant effect. Global warming will increase the loss of C into the atmosphere by increasing the R Mic, and could accelerate climate change.19.
Purpose
Carbon (C) flux is largely controlled by the highly bio-reactive labile C (LC) pool, while long-term C storage is determined by the recalcitrant C (RC) pool. Soil nitrogen (N) availability may considerably affect changes of these pools. The aim of this study was to investigate the effects of N treatments on soil LC and RC pools.Materials and methods
A field experiment was conducted in a city lawn soil for 600 days with three N treatments, i.e., the control (0 kg N ha?1 year?1), low-N (100 kg N ha?1 year?1), and high-N (200 kg N ha?1 year?1) treatments. As the N source, NH4NO3 solution was added to soil surface monthly. Measurements of LC, RC, and other soil biochemical properties, including pH, soil respiration rates, microbial biomass, and enzymes activities, were taken during the experiment period.Results and discussion
The low-N and high-N treatments increased 6.3 and 13% of the LC pool, respectively, which was caused by decreased microbial biomass and soil respiration rates under the N treatments. By contrary, the low-N and high-N treatments decreased 5.9 and 12% of the RC pool, respectively. The N addition treatments enhanced phenol oxidase activities. The enhanced oxidase activities decreased new RC input and the increased dissolved organic C stimulated RC pool decomposition. The LC and RC pools were highly influenced by the N treatments, whereas effect of the N treatments on soil organic C was not significant. The N addition treatments also caused soil acidification and reduced bacterial biomass proportion in the soil microbial composition.Conclusions
The N addition increased the LC pool but decreased the RC pool in the soil. These changes should greatly impact soil long-term C storage. 相似文献20.
Soil microbial biomass and bacterial and fungal community structures responses to long-term fertilization in paddy soils 总被引：2，自引：0，他引：2
Hongzhao Yuan Tida Ge Ping Zhou Shoulong Liu Paula Roberts Hanhua Zhu Ziying Zou Chengli Tong Jinshui Wu 《Journal of Soils and Sediments》2013,13(5):877-886