Microbial Biomass Dynamics Research Articles

Evaluating the ‘triggering response’ in soils, using 13C-glucose, and effects on dynamics of microbial biomass

Very small inputs of labile substrates can cause several more times CO2–C to be rapidly evolved from soil than was contained in the added substrates. This effect, termed the triggering response, does not currently have a conclusive mechanistic explanation. In this work 13C-labeled glucose was added (10 μg glucose C g−1 soil) to two Chinese soils, one from a mulberry plantation and another from a grassland soil. An immediate and significant increase in CO2–C evolution occurred from 0 to 72 h after glucose addition in both soils and, after 7 days of incubation. It was equivalent to 149.2% and 195.4% respectively of the C added as glucose. The dynamics of CO2–C, glucose mineralization, ATP and microbial biomass C (biomass C) were monitored in the amended and nonamended control soils after glucose addition (0–3, 3–5, 5–8, 8–24, 24–72 and 72–168 h). The most rapid increase in cumulative triggered CO2–C, glucose mineralization and ATP concentrations occurred within 3–5 h and the largest changes in concentrations occurred within 72 h. During this period, biomass C concentrations decreased by about 10% in both amended soils. The dominant source of triggered CO2–C in the first 24 h was glucose, whereas from 24 to 72 h, the mineralization of biomass C and soil organic C (SOC) dominated in both soils. All microbial indicators recovered by the end of the incubation (168 h). The overall taxonomic composition of the soil bacteria was little influenced, but co-occurrence patterns of bacterial communities, analysed using network analysis based on statistically significant correlations, showed that co-occurrence associations in bacterial networks increased during the triggering response.

Dynamics of Culturable Soil Bacterial Communities During Pre‐Planting and Growing Soybean Season as Evaluated by Community Level Physiological Profiles

The agricultural practices used today for farming produce crops generate major effects on microbial ecosystems. At the same time, soil microbes can stimulate a wide range of impacts on growing crops. Since changes in soil microbial communities may reflect changes in soil quality or differences in soil management practices, we examined the effects of agricultural farming on the dynamics of soil microbial biomass and community structure. Soil samples were collected prior to planting (May 2019) and during the growing season (September 2019) from a non‐tilled agricultural soybean farm in Greencastle, IN. We quantified microbial biomass using phospholipid phosphate and quantified community structure using community level physiological profiling (CLPP) with Biolog EcoPlates. Soil samples were collected from four subplots in the agricultural field and a control sample from an adjacent woods plot. There was not a significant difference in the C/N ratios between the pooled agricultural plots (9.84) and the woods (9.96) in the pre‐planting season. We also did not see significant differences in C/N ratios among the agricultural subplots. Moisture content (Woods: 36.06% to 42.74%; Farm: 20.18% to 15.46%, from pre‐planting to growing season) was higher in the woods with a stable temperature regime. Consequently, there were no significant differences in the microbial biomass from pre‐planting (37.74 nmol PO□ gdw) to the growing season (41.48 nmol PO□ gdw) in the farm plots, but the woods (Pre‐planting: 44.63 nmol PO□ gdw; Growing: 119.57 nmol PO□ gdw) showed much more temporary fluctuation in biomass. In addition, there was a higher microbial biomass in the control plot compared to the agricultural plots during both the sampling periods. It is possible that seasonal changes are not reflected in microbial biomass on the agricultural plots due to the consistent C/N ratio or the agricultural farming of soybeans. The principal component analysis (PCA) of the CLPP indicated a broad scale of different metabolic functions of the soil microbial communities between the agricultural plots and the control. However, we did not observe any significant difference between the microbial communities of the agricultural plots from pre‐planting to the growing season. The dominant bacterial group present in the agricultural plots was Pseudomonadaceae, a common bacteria in soil, while in the control plot, the most dominant bacterial group was Enterobacteriaceae. Our results imply that a consistent organic input (C/N ratio) might sustain a stable microbial community and thus promote soil health, however, diverse factors such as crop growth stage, residue inputs, and soil physical and chemical conditions may contribute to soil quality and microbial communities. In order to determine the effects of root detritus of soybeans after harvest on soil health and microbial communities, it is recommended that sample collection and analysis occur following the harvest of the soybean crop.Support or Funding InformationScience Research Fellows Program; DePauw University

Temperate peatlands use-management effects on seasonal patterns of soil microbial activity and nitrogen availability

Temperate peatlands are regionally important for farming but long-term cultivation, as well as reforestation after intense agricultural use, can have a significant impact on their soil microbial activity and nitrogen cycles. We studied peatlands in the central part of European Russia, which initially was a swamp forest ecosystem with fairly homogeneous properties of woody peat. Different sites in the area were subsequently under different types of land use. We studied 4 sites in order of increasing management intensity: near-pristine swamp forest, a reforested site after 50 years of intensive cultivation and 2 agricultural sites with 50- and 100-year histories of agricultural use. We examined the dynamics of microbial biomass C and N, dissolved organic C and N and mineral nitrogen during the growing season (May-November). We conclude that land use type can affect the seasonal dynamics of available and microbial nitrogen by changing the vegetation cover. For peatlands covered with natural vegetation, an important feature of the seasonal dynamics of N is microbial immobilization and storage during winter. High activity of β-1,4-glucosidase and low activity of peroxidase indicate that microorganisms consume mainly nitrogen and carbon from fresh plant litter, rather than carbon and nitrogen conserved in peat. Long-term peatland agricultural use has led to significant changes in the dynamics of available and microbial nitrogen and carbon during the growing season, and land management has greatly modified the limitations of the activity of microorganisms from the availability of nitrogen (in the forest) to the availability of carbon (in arable peatland). The changes in peatlands occurred in the first years or decades of their exploitation because we did not find significant differences in any of the indicators between the arable lands used for 50 and >100 years. We found that natural reforestation for 50 years has not yet fully restored microbial activity; however, for some parameters, this site has characteristics close to those of near-pristine swamp forest.

Impact of Land Use Types and Seasonal Variations on Soil Physico-chemical Properties and Microbial Biomass Dynamics in a Tropical Climate, Ghana

Land use conversion significantly impact on sensitive soil quality parameters such as microbial biomass and soil microbial quotient. Therefore, soil microbial biomass and physicochemical properties were compared under three different land use systems namely agricultural land, degraded mine land and an adjacent natural forest in the Newmont Gold Ghana Limited concessional areas, Kenyasi, Ghana. In our field experimentation, an area of 300 m2 was demarcated in each land use type for soil sampling. In each of the land use type, we collected soil 5 samples at a depth of 0-15 cm in both the dry and wet seasons respectively. Parameters we measured included soil bulk density, pH, particle size distribution, organic carbon, total nitrogen, available phosphorus, microbial biomass carbon and nitrogen, and moisture content. Our results revealed that land use type significantly impacted on soil microbial biomass and physicochemical properties. Microbial biomass carbon and nitrogen was higher in the forested land compared to the agricultural land and degraded mine land, which was due to relatively higher amounts of litter inputs. Microbial biomass carbon decreased between 20.23 - 88.36% when land use changed from forested land to other land uses. Significant positive correlation was observed between soil microbial biomass and water content, soil organic carbon, phosphorus, clay, nitrogen. Generally, seasonal variation in our study area did not influence soil physical and chemical properties, however, it significantly affected microbial biomass indices. Findings of our study further revealed the importance of forested area in the maintenance of soil quality parameters.

Influence of organic inputs with mineral fertilizer on maize yield and soil microbial biomass dynamics in different seasons in a tropical acrisol

IntroductionThe practice of co-applying chemical fertilizers (CF) with organic inputs (OIs) as a soil amendment is still low in Ghana, although it has the potential to improve crop yield and soil productivity.ObjectivesIn a two-year study, we evaluated the effects of co-applying contrasting OIs with and without CF on maize yield and soil chemical and microbial composition.MethodsAboveground biomasses of Centrosema pubescens (CEN), Pueraria phaseoloides (PUE), and Zea mays (MZE) were amended to an acrisol at 4 t ha−1 season−1. The combined treatments (CEN+, PUE+, and MZE+) were fertilized with basal NPK 15:15:15 at 40 kg N ha−1, followed by topdressing with [(NH4)2SO4] at 50 kg N ha−1. Sole OI inputs (CEN, PUE, and MZE) did not receive any CF inputs. The controls (CON− and CON+) received 0 and 90 kg N ha−1 season−1.ResultsThe results showed that either sole OIs except for MZE or its combination with CF improved grain yield compared to the CON. Grain yield ranged from 2.1 t ha−1 to 2.6 t ha−1 in the first season versus 0.8 t ha−1 to 1.7 t ha−1 in the second. The MZE+ and CEN+ treatments showed the highest mean grain yields and were similar to CON+. Although CF addition to OIs improved grain yield in all treatments, negative interaction was observed for CEN and PUE as opposed to a positive interaction in the MZE treatment. Co-application of CF with OIs on dissolved organic carbon and nitrogen (DOC) and (EON) dynamics depended on seasonal soil moisture and sampling time. Moreover, co-application of CF with OIs enhanced microbial biomass in CEN but showed minimal and suppressive effects on MZE and PUE amendments, respectively.ConclusionOverall, the increased grain yield in MZE+, CEN+ and CON+ was attributable primarily to the CF addition. Thus, long term evaluations are recommended for sustainable utilization of MZE and CEN given their minimal responses in the short term in the presence of CFs.

Modeling the coupled dynamics of stream metabolism and microbial biomass

AbstractEstimating and interpreting ecosystem metabolism remains an important challenge in stream ecology. Here, we propose a novel approach to model, estimate, and predict multiseasonal patterns of stream metabolism (gross primary production [GPP] and ecosystem respiration [ER]) at the reach scale leveraging on increasingly available long‐term, high‐frequency measurements of dissolved oxygen (DO). The model uses DO measurements to estimate the parameters of a simple ecosystem model describing the underlying dynamics of stream autotrophic and heterotrophic microbial biomass. The model has been applied to four reaches within the Ybbs river network, Austria. Even if microbial biomasses are not observed, that is, they are treated as latent variables, results show that by accounting for the temporal dynamics of biomass, the model reproduces variability in metabolic fluxes that is not explained by fluctuations of light, temperature, and resources. The model is particularly data‐demanding: to estimate the 11 parameters used in this formulation, it requires sufficiently long, for example, annual, time series, and significant scouring events. On the other hand, the approach has the potential to separate ER into its autotrophic and heterotrophic components, estimate a richer set of ecosystem carbon fluxes (i.e., carbon uptake, loss, and scouring), extrapolate metabolism estimates for periods when DO measurements are unavailable, and predict how ecosystem metabolism would respond to variations of the driving forces. The model is seen as a building block to develop tools to fully appreciate multiseasonal patterns of metabolic activity in river networks and to provide reliable estimations of carbon fluxes from land to ocean.

Studies on nitrogen dynamics of soil microbial biomass in paddy fields and runoff control in the Lake Biwa basin by environmentally conscious agricultural practices

Studies on nitrogen dynamics of soil microbial biomass in paddy fields and runoff control in the Lake Biwa basin by environmentally conscious agricultural practices

Dynamics, Structure, and Functional Activity of Microbial Biomass in Soils of Restoring Felled Areas in Fir Forests of the Yenisei Ridge

The dynamics, structure, and functional activity of microbial biomass have been studied in soils of felling areas in southern taiga fir forests (the Yenisei Ridge, Krasnoyarsk krai), which are at different stages of natural regenerative successions. The top organomineral horizons of soddy-podzolic soil (Albic Glossic Retisol (Loamic, Cutanic, Ochric)) of the after-felling regeneration succession (with the stage of secondary birch forests) is characterized by an increase in the content of carbon of microbial biomass (Cmic) and in the intensity of basal respiration from new felling to the stage of dense young forest. In the soil of the dense young-wood stage, the total reserves of Cmic (170 g C/m3) and microbial CO2 production (528 mg СО2–С/m3 per hour) are the highest and exceed the control by 80–85%. In the humus-accumulative soil horizon of the studied succession series, there is a tendency for a decrease in the portion of fungal substrate-induced respiration and in the fungi to bacteria ratio in comparison with the control. In the middle-aged deciduous forests with dark-coniferous undergrowth, all the considered parameters of microbial complexes decrease but remain higher than the control. A trend for a decrease in Cmic and basal respiration is revealed in the profile of soddy-podzolic soil of the regeneration series without species change over an eight-year period. At the stage of fir dense young forest, all ecological-functional parameters of the microbial complex become closer to the control small-grass–true-moss fir forest.

Вплив систем удобрення на динаміку мікробної біомаси ясно-сірого лісового поверхнево огленого ґрунту

Вплив систем удобрення на динаміку мікробної біомаси ясно-сірого лісового поверхнево огленого ґрунту

Seasonal Dynamics of Microbial Biomass in Soddy-Podzolic Soil

The seasonal dynamics of the structure of microbial biomass in a soddy-podzolic soil under fallow was assessed using luminescent microscopy. Samples from three soil horizons (P, 5‒15 cm, BEL, 30‒40 cm, and BT2, 50‒60 cm) were sampled monthly from March, 2017 to February, 2018, in the territory of Eldigino experimental station (Moscow oblast). In addition to microbial biomass measurement, soil temperature and moisture were recorded. The microbial biomass at all sampling times was dominated by fungi (up to 93%). Minimal microbial population and biomass were observed in the period from November to March. The biomass of prokaryotes increased twofold in May, the maximal values were observed in August and September. The length of actinomycete mycelium was maximal in July and August, when the soil water content was the lowest. Maximal fungal biomass was observed in July and September. Seasonal changes of microbial biomass were most pronounced in the upper soil horizon P, while they were more even in the BEL and BT horizons. Using regression analysis, we revealed a significant effect of temperature and sampling depth on the fungal and prokaryotic biomass. The results indicate substantial seasonal variations in biomass of soil microbiota, which should be taken into account when comparing soils sampled at different seasons.

Seasonal dynamics of soil microbial biomass C and N of Keteleeria fortunei var. cyclolepis forests with different ages

Soil microbial biomass is an important indicator to measure the dynamic changes of soil carbon pool. It is of great significance to understand the dynamics of soil microbial biomass in plantation for rational management and cultivation of plantation. In order to explore the temporal dynamics and influencing factors of soil microbial biomass of Keteleeria fortunei var. cyclolepis at different stand ages, the plantation of different ages (young forest, 5 years; middle-aged forest, 22 years; mature forest, 40 years) at the Guangxi Daguishan forest station of China were studied to examine the seasonal variation of their microbial biomass carbon (MBC) and microbial biomass nitrogen (MBN) by chloroform fumigation extraction method. It was found that among the forests of different age, MBC and MBN differed significantly in the 0–10 cm soil layer, and MBN differed significantly in the 10–20 cm soil layer, but there was no significant difference in MBC for the 10–20 cm soil layer or in either MBC or MBN for the 20–40 cm soil layer. With increasing maturity of the forest, MBC gradually decreased in the 0–10 cm soil layer and increased firstly and then decreased in the 10–20 cm and 20–40 cm soil layers, and MBN increased firstly and then decreased in all three soil layers. As the soil depth increased, both MBC and MBN gradually decreased for all three forests. The MBC and MBN basically had the same seasonal variation in all three soil layers of all three forests, i.e., high in the summer and low in the winter. Correlation analysis showed that MBC was significantly positively correlated with soil organic matter, total nitrogen, and soil moisture, whereas MBN was significantly positively correlated with soil total nitrogen. It showed that soil moisture content was the main factor determining the variation of soil microbial biomass by Redundancy analysis. The results showed that the soil properties changed continuously as the young forest grew into the middle-aged forest, which increased soil microbial biomass and enriched the soil nutrients. However, the soil microbial biomass declined as the middle-age forest continued to grow, and the soil nutrients were reduced in the mature forest.

Hierarchical drivers of soil microbial community structure variability in \u201cMonte Perdido\u201d Massif (Central Pyrenees)

Microbial activity is highly dependent on climatic factors (moisture and temperature) and edaphic characteristics in temperate ecosystems. Moreover, soil microbial community composition in high mountain areas is less known when compared to plant communities. In this study we investigated the soil microbial community from a functional perspective using PLFA (phospholipid fatty acid) methods in the four aspects of four summits (2,242 – 3,012 m above sea level) in the Spanish Central Pyrenees. Soil organic carbon (C), microbial biomass and nutrient dynamics (N{H}_{4}^{+} + N{O}_{3}^{-}, N mineralization and nitrification potential) were also determined. Microbial biomass C was highest in the lowermost summit and decreased by approximately 50, 14 and 12% with increasing altitude. In each summit soil N{H}_{4}^{+} and N{O}_{3}^{-} concentrations differed significantly among summits and aspects. Soil nitrification potential varied significantly between the factors summit and aspects, e.g., southerly vs. northerly, easterly vs. westerly aspects. Gram negative bacteria and Actinobacteria functional groups dominated the microbial community, with almost 40% of the total PLFA. Non-metric multidimensional scale (NMS) analysis showed that most of the PLFA functional groups were present in all summits and aspects, although with specific biomarkers. A high abundance of biomarkers 16:1ω9c and 16:0 2OH (gram negative bacteria) were obtained in the lowermost summit, while the biomarkers 16.1ω7cDMA (anaerobes) and 19:3ω6c (Eukaryote) were only found in the uppermost summit. Linear mixed model (lmm) analysis was used with summit as fixed effect and aspect as random effect. In general, our results demonstrate a fundamental role for environment, principally moisture, temperature and organic matter in explaining the pattern observed for soil PLFA biomarkers. Under a global change scenario, we need to shed light on the relationships between soil microbial functional groups and soil nutrient-related variables in order to identify the associated patterns of decomposition rates and soil processes driven by microbial communities in mountain areas. The results could thus be used in global predictive models on climate change impact on C or N cycles in these environments.

Seasonal dynamics of soil microbial biomass in fragmented patches of subtropical humid forest of Jaintia hills in Meghalaya, Northeast India

Aim of the study: The aim of the study was to assess the seasonal dynamics of microbial biomass and its contribution to soil system along a fragment size gradient in subtropical humid forest of Meghalaya. Area of study: The study was conducted in forest fragments located at Jarain and adjoining areas in Jaintia Hills of Meghalaya, northeast India.Material and Methods: Forest fragments of sizes ranging from 3.8 to 105 ha were selected for the study and grouped into Small (< 5 ha), Medium (> 5 and < 15 ha), Large (>15 and < 50 ha) and Very Large (105 ha) classes. Three experimental plots each of 20 x 20 m were established at the forest edge and at 50 m distance assigned as ‘interior’ microsite in each of the fragments for sampling of soil. Soil samples (0-10 cm depth) from each of the experimental plots were collected in replicates on seasonal interval and microbial biomass was estimated by the fumigation extraction method.Important findings: Microbial biomass- C, -N and -P varied significantly (p< 0.05) between the fragment sizes, microsites and seasons. The microbial biomass was higher in the interior as compared to the edge. It was also high during the winter season. Overall, soil microbial biomass -C, -N and -P ranged from 260 to 969; 25 to 95 and 8 to 67 µg g-1 respectively. The contribution of microbial biomass -C, -N and -P to soil organic carbon, total Kjeldahl nitrogen and phosphorus ranged from 1.48 to 1.81 %, 2.54 to 4.54 % and 3.41 to 5.22 % respectively. Fragmentation alters the microenvironmental conditions and soil properties that in turn affect the microbial biomass. Highlights: This interaction of plant, soil and microbial community would gradually degrade in the fragments due to change in vegetation composition and structure, microclimatic conditions and soil physical and chemical properties. Our results suggests that microbial mediated ecosystem processes such as nutrient cycling are more susceptible to variation at the edge which may become unstable and unpredictable in forest fragments exposed to various human disturbances.Keywords: fragment size, microbial biomass, microenvironment, subtropical forest.

渤海泥质海岸典型防护林土壤微生物量季节动态变化

PDF HTML阅读 XML下载 导出引用 引用提醒 渤海泥质海岸典型防护林土壤微生物量季节动态变化 DOI: 10.5846/stxb201711021961 作者: 作者单位: 沈阳农业大学,沈阳农业大学,沈阳农业大学,辽宁省林业科学研究院,辽宁省林业科学研究院,沈阳农业大学 作者简介: 通讯作者: 中图分类号: 基金项目: 辽宁省自然科学基金项目（201602663）；辽宁教育厅基金项目（L2014480）；辽宁省农业攻关及产业化资助项目（2015103002）；中央财政林业科技推广项目（辽[2015]TG14号） Seasonal dynamics of soil microbial biomass in typical shelterbelts on the Bohai muddy coast Author: Affiliation: College of Forestry,Shenyang Agricultural University,College of Forestry,Shenyang Agricultural University,College of Forestry,Shenyang Agricultural University,Liaoning Academy of Forestry Science,Liaoning Academy of Forestry Science,College of Forestry,Shenyang Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:土壤微生物生物量碳、氮是研究土壤肥力、土壤养分转化、循环以及环境变化的重要指标。研究渤海泥质海岸白榆、刺槐、白蜡、群众杨、辽宁杨纯林和辽宁杨刺槐混交林及当地自然生灌草地土壤微生物生物量碳、氮的季节动态及与土壤养分含量变化的关系，以期为沿海防护林树种的选择及林地管理提供科学依据。结果表明：造林能显著增加土壤微生物生物量含量，其中白榆（25 a）土壤微生物生物量碳、氮最高，是对照的2.50倍和2.09倍。0-10 cm土壤层微生物生物量碳、氮大于10-30 cm土层，季节动态变化差异显著。在0-10 cm土层内，渤海泥质海岸典型防护林土壤微生物生物量碳、氮季节动态多表现为春秋两季较高，夏季较低的"V"字型变化；在10-30 cm土层内，防护林土壤微生物生物量碳季节变化规律与0-10 cm土层一致，表现为夏季较低春秋较高的"V"字型，微生物生物量氮主要表现有"V"字型、倒"V"字型与直线型3种变化形式。在0-30 cm土层内，白榆（25 a）、刺槐、白蜡、群众杨、辽宁杨刺槐混交林、白榆（10 a）、辽宁杨及灌草地微生物生物量碳对土壤有机碳的平均贡献率分别为1.59%、1.68%、1.42%、1.54%、2.29%、1.80%、2.02%和1.12%，土壤微生物生物量氮对土壤全氮的平均贡献率分别为1.85%、1.30%、1.08%、1.35%、2.49%、1.57%、2.08%和2.32%。不同类型防护林地土壤微生物量碳、氮之间显著正相关，它们与土壤全氮、有机碳显著正相关，与土壤电导率显著负相关，另外，土壤微生物量碳还与土壤速效磷含量显著正相关。从不同土层微生物量碳、氮季节动态来看，造林可以增加泥质海岸土壤微生物生物量，但是夏季地下水位升高，盐碱上扬，加之树木生长大量利用养分，土壤微生物生物量夏季较低。综合分析土壤微生物生物量和土壤营养库的贡献率，白榆纯林和辽宁杨刺槐混交林更有利于泥质海岸土壤微生物群落功能恢复和营养固定。 Abstract:Soil microbial biomass carbon and nitrogen are the important indicators to study soil fertility, soil nutrient transformation and circulation, and environmental changes. During this research, the seasonal dynamics of soil microbial biomass C and N contents and their relation with the changes of soil nutrients content in Ulmus pumila forest[25 years old (UPM), 10 years old (UP)], Robinia pseudoacacia forest (RP), Fraxinus chinensis forest (FC), Populus popularis forest (PP), P.×liaoningensis forest (PL), mixed forest of P.×liaoningensis and R. pseudoacacia (PR) and CK (naturally occurring shrub-grassland) were investigated. The purpose of this study is to provide a scientific basis for selection of coastal shelterbelt tree species and forest management in this area. The results showed that soil microbial biomass increased significantly by afforestation. Among all the forest types, UPM has the highest soil microbial biomass C and N contents, which are 2.50 and 2.09 times than CK. The microbial biomass C and N contents in soil layer of 0-10 cm were larger than those in 10-30 cm soil layer, and the seasonal dynamic change of soil microbial biomass in two soil layers varied significant differently. In the 0-10 cm soil layer, the seasonal dynamics of soil microbial biomass C and N contents in the typical shelterbelts on Bohai muddy coast were higher in spring and autumn, and lower in summer, with a "V" shape trend. The change trend of soil microbial biomass C in the typical shelterbelt under 10-30 cm soil layer was consistent with that of 0-10 cm soil layer, which showed a lower in summer, and a higher in spring and autumn, also with a "V" shape trend. There are mainly three forms of microbial biomass N variation:"V", inverted "V", and straight line. In the 0-30 cm soil layer, the average contribution rates of soil microbial biomass C to soil organic carbon in UPM, RP, FC, PP, PR, UP, PL, and naturally occurring shrub-grassland were 1.59%, 1.68%, 1.42%, 1.54%, 2.29%, 1.80%, 2.02%, and 1.12%, respectively, and in the 0-30 cm soil layer, the contribution rates of soil microbial biomass N to soil total nitrogen were 1.85%, 1.30%, 1.08%, 1.35%, 2.49%, 1.57%, 2.08%, and 2.32%, respectively. The correlation of soil microbial biomass C and N in all forest types were significantly positive, and soil microbial biomass C and N had significantly positive correlation with soil total nitrogen and organic matter, and had significantly negative correlation with soil conductivity. In addition, soil microbial biomass C had significantly positive correlation with soil available P. From the results of seasonal dynamics of microbial biomass C and N in different soil layers, it could be drew the conclusion that microbial biomass increased by afforestation in muddy coastal soil, but ground water was rose in summer, accompanied by the increment of salt and alkali content, moreover, trees utilize large quantities of nutrients to maintain growth, thus, the soil microbial biomass was lower. Based on the comparison of soil microbial biomass C and N content and their contributions to soil N pools among all forest types, the conclusion can be made that UPM and PR are the most conducive tree species to the recovery of soil microbial function and nutrient fixation on the Bohai muddy coast. 参考文献 相似文献 引证文献

Nitrogen Mineralization and Microbial Biomass Dynamics in Different Tropical Soils Amended with Contrasting Organic Resources

The use of location-specific and underutilized organic residues (OR) as soil amendments in small-holder agro-ecosystems is promising. Six ORs (Leucaena leucocephala, Centrosema pubescens, Gliricidia sepium, Pueraria phaseoloides, Azadirachta indica, and Theobroma cacao) were amended to three tropical soils each at 24 mg g−1 dry soil in 120-day incubation study to estimate their nitrogen (N) mineralization and microbial biomass carbon (C) dynamics. Inorganic N contents varied among ORs, soil type and incubation days. Regardless of soil type, Gliricidia had the highest inorganic N among the studied ORs. Mineralization rate of 1.4 to 1.5 mg N kg−1 soil day−1 was observed for Lego and Tec soils, respectively, and was twice higher than Nya soil. However, Nya soil released higher inorganic N than Tec and Lego soils, implying high N mineralization efficiency in the former. Consistent soil pH increase was respectively observed for Theobroma and Pueraria treatments in all soils. Moreover, Theobroma and Pueraria amendments showed the highest soil microbial biomass C (MBC) at the end of the incubation. The assessed soil properties likely affected by the dominant edaphic factors and management influenced differences in MBC and dissolved organic carbon (DOC) while OR quality indices controlled N mineralization. Thus, we conclude that soil properties and OR type are important factors for optimal utilization of organic resources.

Mineralization of Organic Residues, Dynamics of Microbial Biomass and Enzyme Activities in an Aridisol and Alfisol Soil under Rain-Fed Dry Farming

This study was planned with hypothesis to quantify mineralization rate of wheat and groundnut straw spiked in Kahuta and Guliana soil series. Results revealed that groundnut and wheat strawspiked soils had increased quantum of microbial biomass carbon (Cmic), biomass nitrogen (Nmic) and biomass phosphorous (Pmic) and activities of enzyme dehydrogenase (DHA) and alkaline phosphatase (APA) than un-amended soils. Initially, the contents of soil Cmic, Nmic, Pmic, DHA, and APA increased gradually during 2-14th days of incubation (DAI), again increased significantly at 28th DAI and then decreased slowly at 60th DAI in all treatments under both series. Hence, the addition of groundnut straw mineralized better than to other organic sources in both soil series. These results suggested that groundnut straw must be incorporated in soil one month before sowing of crop to enhance crop yield under rain-fed dry farming.Key words: Crop Residues, Microbial Biomass, Soil Enzymes, Aridisol, Alfisols

Mineralization of Organic Residues, Dynamics of Microbial Biomass and Enzyme Activities in an Aridisol and Alfisol Soil under Rain-Fed Dry Farming

This study was planned with hypothesis to quantify mineralization rate of wheat and groundnut straw spiked in Kahuta and Guliana soil series. Results revealed that groundnut and wheat strawspiked soils had increased quantum of microbial biomass carbon (Cmic), biomass nitrogen (Nmic) and biomass phosphorous (Pmic) and activities of enzyme dehydrogenase (DHA) and alkaline phosphatase (APA) than un-amended soils. Initially, the contents of soil Cmic, Nmic, Pmic, DHA, and APA increased gradually during 2-14th days of incubation (DAI), again increased significantly at 28th DAI and then decreased slowly at 60th DAI in all treatments under both series. Hence, the addition of groundnut straw mineralized better than to other organic sources in both soil series. These results suggested that groundnut straw must be incorporated in soil one month before sowing of crop to enhance crop yield under rain-fed dry farming.Key words: Crop Residues, Microbial Biomass, Soil Enzymes, Aridisol, Alfisols

Mineralization of Organic Residues, Dynamics of Microbial Biomass and Enzyme Activities in an Aridisol and Alfisol Soil under Rain-Fed Dry Farming

This study was planned with hypothesis to quantify mineralization rate of wheat and groundnut straw spiked in Kahuta and Guliana soil series. Results revealed that groundnut and wheat strawspiked soils had increased quantum of microbial biomass carbon (Cmic), biomass nitrogen (Nmic) and biomass phosphorous (Pmic) and activities of enzyme dehydrogenase (DHA) and alkaline phosphatase (APA) than un-amended soils. Initially, the contents of soil Cmic, Nmic, Pmic, DHA, and APA increased gradually during 2-14th days of incubation (DAI), again increased significantly at 28th DAI and then decreased slowly at 60th DAI in all treatments under both series. Hence, the addition of groundnut straw mineralized better than to other organic sources in both soil series. These results suggested that groundnut straw must be incorporated in soil one month before sowing of crop to enhance crop yield under rain-fed dry farming.Key words: Crop Residues, Microbial Biomass, Soil Enzymes, Aridisol, Alfisols

Effects of snowfall depth on soil physical–chemical properties and soil microbial biomass in moss–dominated crusts in the Gurbantunggut Desert, Northern China

Winter snowfall is an important source of moisture that may influence the growth and development of biological soil crusts (BSCs) in temperate desert regions of China. Yet there is still limited empirical knowledge about the effect of snowfall on BSCs. In this study, moss crusts from the Gurbantunggut Desert were exposed to five snow depths to evaluate how snowfall affected the physical–chemical properties (pH; electric conductivity, EC; soil organic carbon, SOC; total nitrogen, TN; available nitrogen, AN; available phosphorus, AP; available potassium, AK) and microbial biomass (soil microbial biomass carbon, SMBC; soil microbial biomass nitrogen, SMBN; soil microbial biomass phosphorus, SMBP) of soil in the BSCs, before (in October 2016: representing three consecutive years of snow manipulation) and after winter (in April 2017). Results showed that the soil water content increased significantly as snowfall depth increased (p < 0.05) in October 2016 and April 2017. Most of the soil physical–chemical features (EC, SOC, TN, AN, AP, and AK) and microbial biomass (SMBC and SMBN) showed an increase with an increase of snowfall depth after three consecutive years of snow manipulation. Moreover, for most experimental treatments, after a winter of melting snow (in April 2017) most of the soil properties were significantly higher (p < 0.05) than found in October 2016. Together, these results showed that the dynamics of soil nutrients and microbial biomass in moss BSCs were affected by snowfall depth in Gurbantunggut Desert. Different snowfall depths can have different effects on the dynamics of soil nutrients and microbial biomass of moss crusts, an impact that may alter the future growth and development of BSCs. Thus, we suggest that the potential influence of snowfall depth on soil nutrients and microbial biomass dynamics in BSCs require consideration when discussing the effects of moisture on ecological functions of BSCs in arid and semi–arid regions.

Two contrasting seasonal patterns in microbial nitrogen immobilization from temperate ecosystems

Ecosystems with seasonal snow cover and soil frost comprise more than half of the terrestrial ecosystems. Recent studies have reported peak microbial biomass carbon (MBC) and nitrogen (MBN) in late winter in alpine and arctic regions, followed by a rapid decline when soil temperatures rise to 0 °C. In these snow-covered ecosystems, the N incorporated into microbes from soil during winter is considered vital for plant nutrient uptake in the following growing seasons. However, evidence from temperate ecosystems has rarely been reported. We studied 24 ecosystems from two forest-steppe ecotones (Saihanba and Saihanwula) with similar climatic conditions, but different soil properties, to comprehensively analyze the seasonal dynamics of microbial biomass and its controlling factors. MBC consistently reached its annual peak in winter, and this seasonal trend was not influenced by different vegetation types or study areas. In contrast, the seasonal dynamics of MBN were strongly influenced by the study area. There were minimum values of winter MBN observed in the Saihanba area while maximum values of winter MBC observed in the Saihanwula area. Soil properties showed poor nutrient status in the Saihanba area compared with the Saihanwula area. Our results suggest winter microbes in the Saihanba area invest N to produce extracellular enzymes, rather than retaining in biomass. We argue that it is a possible strategy to cope with nutrient stress caused by plant competition in the following spring. However, the peak of MBN occurred in the winter in the Saihanwula area, suggesting a potential resource for spring plant N uptake in this area. We also found the magnitude of MBN was positively related to the soil water content under different vegetation types in the Saihanwula area. Our study demonstrates two contrasting seasonal patterns of soil MBN, suggesting that the general conceptual model of N cycle based on the studies from alpine and arctic areas may not be applicable to temperate ecosystems.