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Journal articles on the topic 'Soil enrichment'
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Wang, Bai, Liu, Zhang, Chen, and Lu. "Enrichments of Cadmium and Arsenic and Their Effects on the Karst Forest Area." International Journal of Environmental Research and Public Health 16, no. 23 (November 22, 2019): 4665. http://dx.doi.org/10.3390/ijerph16234665.
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An understanding of the enrichment mechanisms of cadmium (Cd) and arsenic (As) in the process of rock weathering and soil formation is essential to develop agriculture according to local conditions. However, the enrichments of soil Cd and As under natural background conditions in karst areas are still uncertain. The enrichment factor, geo-accumulation index, redundancy analysis, and other methods were used to analyze the enrichment degree and the influencing factors of Cd and As on 5 rock–soil profiles and 15 topsoil samples, which were collected from a karst forest area in Libo County, Guizhou Province. The results showed that the enrichment process was divided into three stages. In the first stage, Cd and As were enriched in carbonate rocks, and their mean concentrations were 1.65 and 3.9 times those of the corresponding abundance of the crust. In the second stage, the enrichment of the parent rock into the soil, the enrichment factors of Cd and As in the parent material horizon relative to the bedrock horizon were 9.2 and 2.82, respectively. The third stage refers to the enrichments of Cd and As in the topsoil, where Cd enrichment was more obvious than that of As. Soil organic matter (SOM) and phosphorus (P) are important factors that influenced the enrichments of Cd and As in the topsoil. The functional groups of SOM were complexed with Cd and As; P easily formed precipitates with Cd, and the tree litter was fed back to the topsoil, which may be the reason for the surface enrichment of Cd and As. This study will help the scientific community understand the enrichment mechanisms of soil Cd and As in karst areas.
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Wawrik, Boris, Lee Kerkhof, Jerome Kukor, and Gerben Zylstra. "Effect of Different Carbon Sources on Community Composition of Bacterial Enrichments from Soil." Applied and Environmental Microbiology 71, no. 11 (November 2005): 6776–83. http://dx.doi.org/10.1128/aem.71.11.6776-6783.2005.
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ABSTRACT Soil is a highly heterogeneous matrix, which can contain thousands of different bacterial species per gram. Only a small component of this diversity (maybe <1%) is commonly captured using standard isolation techniques, although indications are that a larger proportion of the soil community is in fact culturable. Better isolation techniques yielding greater bacterial diversity would be of benefit for understanding the metabolic activity and capability of many soil microorganisms. We studied the response of soil bacterial communities to carbon source enrichment in small matrices by means of terminal restriction fragment length polymorphism (TRFLP) analysis. The community composition of replicate enrichments from soil displayed high variability, likely attributable to soil heterogeneity. An analysis of TRFLP data indicated that enrichment on structurally similar carbon sources selected for similar bacterial communities. The same analysis indicated that communities first enriched on glucose or benzoate and subsequently transferred into medium containing an alternate carbon source retained a distinct community signature induced by the carbon source used in the primary enrichment. Enrichment on leucine presented a selective challenge that was able to override the imprint left by primary enrichment on acetate. In a time series experiment community change was most rapid 18 hours after inoculation, corresponding to exponential growth. Community composition did not stabilize even 4 days after secondary enrichment. Four different soil types were enriched on four different carbon sources. TRFLP analysis indicated that in three out of four cases communities enriched on the same carbon source were more similar regardless of which soil type was used. Conversely, the garden soil samples yielded similar enrichment communities regardless of the enrichment carbon source. Our results indicate that in order to maximize the diversity of bacteria recovered from the environment, multiple enrichments should be performed using a chemically diverse set of carbon sources.
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Tesfahunegn, G. B., and P. G. L. Vlek. "Assessing sediment enrichment ratio in Mai-Negus catchment, northern Ethiopia." Soil and Water Research 9, No. 1 (January 23, 2014): 38–45. http://dx.doi.org/10.17221/16/2013-swr.
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Soil degradation is a threat to sustainable development in Ethiopia. However, degradation indicators, such as sediment enrichment ratio (SER), are not adequately documented in literature. This study aims to investigate the SER of different erosion-status sites (aggrading, stable, eroded) in various landforms in Mai-Negus catchment, northern Ethiopia. The erosion-status sites in the landforms were identified using field indicators, and soil samples were collected for analysis of selected soil parameters. In this study, due to the ratio of aggrading to eroded or stable sites at catchment and landform levels, the SER of soil nutrients and fine soil particles was > 1. But due to the ratio of aggrading to eroded sites in the landforms the average SER of the soils were higher (1.42–7.22) as compared to the ratios of aggrading to stable sites (1.10–3.66). The SER significantly (P ≤ 0.05) differed among the landforms, which indicated differences in the effect of erosion. The relationships between the SER of fine soil particles and soil nutrients were strong. Thus, priority for introducing appropriate anti-erosion measures should be given to sources of high SER sites such as the mountainous and central ridge landforms in the catchment using the limited resources available.
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DRURY, C. F., D. A. TEL, and E. G. BEAUCHAMP. "15N ANALYSIS OF HIGHLY ENRICHED SAMPLES ON A MASS SPECTROMETER." Canadian Journal of Soil Science 67, no. 4 (November 1, 1987): 779–85. http://dx.doi.org/10.4141/cjss87-075.
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Mass spectrometer analysis of highly enriched 15N samples underestimated the 15N enrichment. Conventional 15N analysis utilizes a ratiometer procedure in which the ratio of 29N2 to 28N2 ions is determined. Samples containing high enrichments had a low quantity of 28N2 ions and it appeared background contamination of 28N2 produced erroneous results with this procedure. Therefore, results obtained with the ratiometer procedure were compared to those obtained with a scanning procedure which measured the 28N2, 29N2 and 30N2 peak heights. The 15N enrichment was determined by the scanning procedure by using all three N2 peaks (28/29/30 method), the 28N2 and 29N2 peaks (28/29 method), and 29N2 and 30N2 peaks (29/30 method). These four methods were compared over a range of enrichments from 0.366 to 99 atom % 15N in samples containing 0.5, 1.0 and 1.5 mg N. Samples with enrichments less than 10 atom % 15N were best estimated by the ratiometer method. Enrichments greater or equal to 10 atom % 15N were most accurately determined by the 29/30 method. Background contamination during sample preparation produced 28N2 peaks which had a negligible effect on samples containing low enrichments, but was a source of error in highly enriched samples. Since natural levels of 29N2 and 30N2 in air are very low, the 29/30 method was found to closely estimate the expected 15N enrichment in standard samples greater than 10 atom % and had the lowest standard deviation. Key words: High 15N enrichment, mass spectrometer, ratiometer procedure, peak scanning procedure
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Shim, J. H., H. H. Powers, C. W. Meyer, A. Knohl, T. E. Dawson, W. J. Riley, W. T. Pockman, and N. McDowell. "Hydrologic control of the oxygen isotope ratio of ecosystem respiration in a semi-arid woodland." Biogeosciences 10, no. 7 (July 23, 2013): 4937–56. http://dx.doi.org/10.5194/bg-10-4937-2013.
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Abstract. We conducted high frequency measurements of the δ18O value of atmospheric CO2 from a juniper (Juniperus monosperma) woodland in New Mexico, USA, over a four-year period to investigate climatic and physiological regulation of the δ18O value of ecosystem respiration (δR). Rain pulses reset δR with the dominant water source isotope composition, followed by progressive enrichment of δR. Transpiration (ET) was significantly related to post-pulse δR enrichment because the leaf water δ18O value showed strong enrichment with increasing vapor pressure deficit that occurs following rain. Post-pulse δR enrichment was correlated with both ET and the ratio of ET to soil evaporation (ET/ES). In contrast, the soil water δ18O value was relatively stable and δR enrichment was not correlated with ES. Model simulations captured the large post-pulse δR enrichments only when the offset between xylem and leaf water δ18O value was modeled explicitly and when a gross flux model for CO2 retro-diffusion was included. Drought impacts δR through the balance between evaporative demand, which enriches δR, and low soil moisture availability, which attenuates δR enrichment through reduced ET. The net result, observed throughout all four years of our study, was a negative correlation of post-precipitation δR enrichment with increasing drought.
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Shim, J. H., H. H. Powers, C. W. Meyer, A. Knohl, T. E. Dawson, W. J. Riley, W. T. Pockman, and N. McDowell. "Hydrologic control of the oxygen isotope ratio of ecosystem respiration in a semi-arid woodland." Biogeosciences Discussions 10, no. 1 (January 2, 2013): 1–48. http://dx.doi.org/10.5194/bgd-10-1-2013.
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Abstract. We conducted high frequency measurements of the δ18O value of atmospheric CO2 from a juniper (Juniperus monosperma) woodland in New Mexico, USA, over a four-year period to investigate climatic and physiological regulation of the δ18O value of ecosystem respiration (δR). Rain pulses reset δR with the dominant water source isotope composition, followed by progressive enrichment of δR. Transpiration (ET) was significantly related to post-pulse δR enrichment because leaf water δ18O value showed strong enrichment with increasing vapor pressure deficit that occurs following rain. Post-pulse δR enrichment was correlated with both ET and the ratio of ET to soil evaporation (ET / ES). In contrast, soil water δ18O value was relatively stable and δR enrichment was not correlated with ES. Model simulations captured the large post-pulse δR enrichments only when the offset between xylem and leaf water δ18O value was modeled explicitly and when a gross flux model for CO2 retro-diffusion was included. Drought impacts δR through the balance between evaporative demand, which enriches δR, and low soil moisture availability, which attenuates δR enrichment through reduced ET. The net result, observed throughout all four years of our study, was a negative correlation of post-precipitation δR enrichment with increasing drought.
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Grosser, Robert J., Michael Friedrich, David M. Ward, and William P. Inskeep. "Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Different Enrichment Conditions Influence Bioavailability and Selection of Phenanthrene-Degrading Isolates." Applied and Environmental Microbiology 66, no. 7 (July 1, 2000): 2695–702. http://dx.doi.org/10.1128/aem.66.7.2695-2702.2000.
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ABSTRACT The sorption of organic contaminants by natural organic matter (NOM) often limits substrate bioavailability and is an important factor affecting microbial degradation rates in soils and sediments. We hypothesized that reduced substrate bioavailability might influence which microbial assemblages are responsible for contaminant degradation under enrichment culture conditions. Our primary goal was to characterize enrichments in which different model organic solid phases were used to establish a range of phenanthrene bioavailabilities for soil microorganisms. Phenanthrene sorption coefficients (expressed as log KD values) ranged from 3.0 liters kg−1 for Amberlite carboxylic acid cation-exchange resin (AMB) to 3.5 liters kg−1 for Biobeads polyacrylic resin (SM7) and 4.2 liters kg−1 for Biobeads divinyl benzene resin (SM2). Enrichment cultures were established for control (no sorptive phase), sand, AMB, SM7, and SM2 treatments by using two contaminated soils (from Dover, Ohio, and Libby, Mont.) as the initial inocula. The effects of sorption by model phases on the degradation of phenanthrene were evaluated for numerous transfers in order to obtain stable microbial assemblages representative of sorptive and nonsorptive enrichment cultures and to eliminate the effects of the NOM present in the initial inoculum. Phenanthrene degradation rates were similar for each soil inoculum and ranged from 4 to 5 μmol day−1 for control and sand treatments to approximately 0.4 μmol day−1 in the presence of the SM7 sorptive phase. The rates of phenanthrene degradation in the highly sorptive SM2 enrichment culture were insignificant; consequently, stable microbial populations could not be obtained. Bacterial isolates obtained from serial dilutions of enrichment culture samples exhibited significant differences in rates of phenanthrene degradation performed in the presence of SM7, suggesting that enrichments performed in the presence of a sorptive phase selected for different microbial assemblages than control treatments containing solid phase phenanthrene.
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Friedrich, M., R. J. Grosser, E. A. Kern, W. P. Inskeep, and D. M. Ward. "Effect of Model Sorptive Phases on Phenanthrene Biodegradation: Molecular Analysis of Enrichments and Isolates Suggests Selection Based on Bioavailability." Applied and Environmental Microbiology 66, no. 7 (July 1, 2000): 2703–10. http://dx.doi.org/10.1128/aem.66.7.2703-2710.2000.
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ABSTRACT Reduced bioavailability of nonpolar contaminants due to sorption to natural organic matter is an important factor controlling biodegradation of pollutants in the environment. We established enrichment cultures in which solid organic phases were used to reduce phenanthrene bioavailability to different degrees (R. J. Grosser, M. Friedrich, D. M. Ward, and W. P. Inskeep, Appl. Environ. Microbiol. 66:2695–2702, 2000). Bacteria enriched and isolated from contaminated soils under these conditions were analyzed by denaturing gradient gel electrophoresis (DGGE) and sequencing of PCR-amplified 16S ribosomal DNA segments. Compared to DGGE patterns obtained with enrichment cultures containing sand or no sorptive solid phase, different DGGE patterns were obtained with enrichment cultures containing phenanthrene sorbed to beads of Amberlite IRC-50 (AMB), a weak cation-exchange resin, and especially Biobead SM7 (SM7), a polyacrylic resin that sorbed phenanthrene more strongly. SM7 enrichments selected for mycobacterial phenanthrene mineralizers, whereas AMB enrichments selected for a Burkholderia sp. that degrades phenanthrene. Identical mycobacterial andBurkholderia 16S rRNA sequence segments were found in SM7 and AMB enrichment cultures inoculated with contaminated soil from two geographically distant sites. Other closely relatedBurkholderia sp. populations, some of which utilized phenanthrene, were detected in sand and control enrichment cultures. Our results are consistent with the hypothesis that different phenanthrene-utilizing bacteria inhabiting the same soils may be adapted to different phenanthrene bioavailabilities.
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Hardy, Kathleen R., and Gary M. King. "Enrichment of High-Affinity CO Oxidizers in Maine Forest Soil." Applied and Environmental Microbiology 67, no. 8 (August 1, 2001): 3671–76. http://dx.doi.org/10.1128/aem.67.8.3671-3676.2001.
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ABSTRACT Carboxydotrophic activity in forest soils was enriched by incubation in a flowthrough system with elevated concentrations of headspace CO (40 to 400 ppm). CO uptake increased substantially over time, while the apparent Km (app Km ) for uptake remained similar to that of unenriched soils (<10 to 20 ppm). Carboxydotrophic activity was transferred to and further enriched in sterile sand and forest soil. The app Km s for secondary and tertiary enrichments remained similar to values for unenriched soils. CO uptake by enriched soil and freshly collected forest soil was inhibited at headspace CO concentrations greater than about 1%. A novel isolate, COX1, obtained from the enrichments was inhibited similarly. However, in contrast to extant carboxydotrophs, COX1 consumed CO with an app Km of about 15 ppm, a value comparable to that of fresh soils. Phylogenetic analysis based on approximately 1,200 bp of its 16S rRNA gene sequence suggested that the isolate is an α-proteobacterium most closely related to the genera Pseudaminobacter, Aminobacter, andChelatobacter (98.1 to 98.3% sequence identity).
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Zhou, Wenxiang, Guilin Han, Man Liu, Chao Song, and Xiaoqiang Li. "Geochemical Distribution Characteristics of Rare Earth Elements in Different Soil Profiles in Mun River Basin, Northeast Thailand." Sustainability 12, no. 2 (January 7, 2020): 457. http://dx.doi.org/10.3390/su12020457.
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Exploring the distributions of rare earth elements (REEs) in soil profiles is essential to understanding how natural and anthropogenic factors influence the geochemical behaviors of REEs. This study aimed to learn about the distribution characteristics of REEs in soils, including their fractionation and enrichment, and to explore the influence of soil pH and soil organic carbon (SOC) on REEs. One hundred and three samples were collected from six soil profiles under different land uses (paddy field: T1, T3; forest land: T2, T6; wasteland: T4; building site: T5) in the Mun River Basin, Northeast Thailand. The average total REE contents (∑REE) are much lower (<80 mg kg−1) than that of Earth’s crust (153.80 mg kg−1) in soil profiles T2, T3, T4, and T6. The contents of REEs tend to increase slightly with depth in all soil profiles. The ratios of (La/Yb)N range from 0.35 to 0.96 in most samples, indicating that the enrichment of heavy REEs (HREEs) relative to light REEs (LREEs) is the main fractionation pattern. Samples from profile T2 show relatively obvious negative Ce anomalies (0.55–0.78) and positive Eu anomalies (1.41–1.56), but there are almost no anomalies of Ce and Eu in other soil profiles. Enrichment factors of LREEs (EFLREEs) range from 0.23 to 1.54 and EFHREEs range from 0.34 to 2.27, which demonstrates that all soil samples show no LREE enrichment and only parts of samples show minor HREE enrichment. Soil organic carbon (SOC) contents positively correlate with the enrichment factors of REEs (EFREE) in soil profiles T1 (R = 0.56, p < 0.01) and T6 (R = 0.71), while soil pH values correlate well with EFREE in soil profiles T2 (R = 0.75) and T4 (R = −0.66, p < 0.01), indicating the important influence of soil pH and SOC on the mobility of REEs in some soil profiles.
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Garten Jr., Charles T. "Relationships among forest soil C isotopic composition, partitioning, and turnover times." Canadian Journal of Forest Research 36, no. 9 (September 1, 2006): 2157–67. http://dx.doi.org/10.1139/x06-115.
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The purpose of this research was to test the hypothesis that vertical enrichment of soil δ13C values is related to rates of soil C turnover in undisturbed, mature forest ecosystems. Soil C and N were measured at nine sites along an altitudinal gradient in the southern Appalachian Mountains (Tennessee and North Carolina, USA). Measurements indicated greater labile and total soil C stocks with increasing altitude. Laboratory incubations (3 days) of rewetted, air-dry soils indicated potential soil C mineralization (µg CO2 produced·g1 soil C) declined with elevation. A principal component analysis indicated N availability increased with altitude. At each site, there was a significant relationship between δ13C and log-transformed C concentrations in the soil profile (30 cm deep). Enrichment factors (ε) from the Rayleigh equation were also equally useful for describing soil δ13C profiles at each site. Soil C partitioning and turnover times along the gradient were correlated with 13C-enrichment factors. Greater rates of change in δ13C through the soil profile were correlated with faster soil C turnover. Environmental factors, soil C partitioning, and the rate of vertical change in soil 13C abundance are interrelated such that δ13C measurements are a potential indicator of C dynamics in undisturbed forest soils.
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Perveen, Nazia, Mariam Ayub, Tanvir Shahzad, Muhammad Rashid Siddiq, Muhammad Sohail Memon, Sébastien Barot, Hamid Saeed, and Ming Xu. "Soil carbon mineralization in response to nitrogen enrichment in surface and subsurface layers in two land use types." PeerJ 7 (July 8, 2019): e7130. http://dx.doi.org/10.7717/peerj.7130.
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Atmospheric nitrogen (N) deposition increases N availability in soils, with consequences affecting the decomposition of soil carbon (C). The impacts of increasing N availability on surface soil C dynamics are well studied. However, subsurface soils have been paid less attention although more than 50% soil C stock is present below this depth (below 20 cm). This study was designed to investigate the response of surface (0–20 cm) and subsurface (20–40 cm and 40–60 cm) C dynamics to 0 (0 kg N ha−1), low (70 kg N ha−1) and high (120 kg N ha−1) levels of N enrichment. The soils were sampled from a cropland and a grass lawn and incubated at 25 °C and 60% water holding capacity for 45 days. Results showed that N enrichment significantly decreased soil C mineralization (Rs) in all the three soil layers in the two studied sites (p < 0.05). The mineralization per unit soil organic carbon (SOC) increased with profile depth in both soils, indicating the higher decomposability of soil C down the soil profile. Moreover, high N level exhibited stronger suppression effect on Rs than low N level. Rs was significantly and positively correlated with microbial biomass carbon explaining 80% of variation in Rs. Overall; these results suggest that N enrichment may increase C sequestration both in surface and subsurface layers, by reducing C loss through mineralization.
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Taylor, M. D., and N. D. Kim. "Dealumination as a mechanism for increased acid recoverable aluminium in Waikato mineral soils." Soil Research 47, no. 8 (2009): 828. http://dx.doi.org/10.1071/sr09053.
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This paper assesses a potentially interesting soil process, dealumination, as the mechanism for the increase observed in strong acid recoverable Al and associated elements in farmed soils compared with background soils in the Waikato Region of New Zealand. Waikato Regional Council has been measuring an established set of 7 soil quality chemical and physical parameters and concentrations of 33 elements as part of a Regional Soil Quality Monitoring program since 2003. Statistical comparison of farmed to background soils, relative surface enrichments, and inter-element correlations enable us to infer likely and potential sources of those elements which show some form of enrichment. Acid-recoverable Al is 1.5 times higher (P < 0.0001) in the Waikato region’s farmed soils than its background soils. This increase is not readily explained as an external source of recoverable Al (due to lack of enrichment at the soil surface). However, it could be explained as an increase in the concentration of acid-recoverable Al as a result of accelerated weathering or chemical attack of primary crystalline and short-range order aluminosilicates. In keeping with this interpretation, acid recoverable concentrations of several trace elements that are normally retained inside aluminosilicates (in residual phases) are also significantly higher in farmed than background soils but are not selectively enriched at the soil surface. These include (with enrichment-to-background factors) Li (2.5), La (2.1), Mn (1.5), and Ag, Bi, Mo, Sn, and Tl (1.4). Also, this process may contribute one-quarter of the observed increase in acid-recoverable U. If it is occurring, accelerated Al weathering may be a normal part of an increase in soil productivity, or may be facilitated by an external agent capable of attacking crystalline aluminosilicates. A candidate in the latter category is the F (and/or possibly free HF) in phosphate fertilisers, because this substantially increases Al species in soil porewater. Two specific mechanisms that could favour Al mobilisation from clay surfaces include partial dissolution by local areas of high acidity associated with fertiliser granules, and surface complexation and extraction by the fluoride and residual hydrofluoric acid present in phosphate fertilisers. Based on the high reactivity between F and both Al and Si, potential exists for significant production of SiF4(g) as another side-effect of phosphate fertiliser use.
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Ngole, V. M. "Using soil heavy metal enrichment and mobility factors to determine potential uptake by vegetables." Plant, Soil and Environment 57, No. 2 (February 17, 2011): 75–80. http://dx.doi.org/10.17221/125/2010-pse.
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This study investigated copper (Cu) and lead (Pb) enrichment factor (EF) and mobility factor (MF) as possible indicators of their uptake by spinach (Spinaceae oleraceae) and carrots (Daucus carota) grown on a sludge-amended luvisol (SAL). Sewage sludge was applied to luvisol at different rates and spinach and carrots planted. Enrichment of Cu and Pb in SAL was determined, and values regressed with those of Cu and Pb concentrations in spinach and carrots. Concentration of Cu and Pb in vegetables was calculated using the regression model obtained, and calculated values compared with actual values. Pb MF were higher than Cu MF but Cu and Pb EFsoil values were < 3.0, indicating minor enrichment from sludge addition. EF had 10% reliability in predicting Cu and Pb uptake in vegetables. MF was more than 70% reliable in predicting carrot Cu uptake and spinach Pb uptake. EF and MF are not effective as predictors of heavy metal uptake by vegetables. The role of other soil components including root exudates and by-products from microbial activities should also be investigated.
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Hu, Shuijin, Mary K. Firestone, and F. Stuart Chapin. "Soil microbial feedbacks to atmospheric CO2 enrichment." Trends in Ecology & Evolution 14, no. 11 (November 1999): 433–37. http://dx.doi.org/10.1016/s0169-5347(99)01682-1.
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Monard, C., F. Binet, and P. Vandenkoornhuyse. "Short-Term Response of Soil Bacteria to Carbon Enrichment in Different Soil Microsites." Applied and Environmental Microbiology 74, no. 17 (July 11, 2008): 5589–92. http://dx.doi.org/10.1128/aem.00333-08.
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ABSTRACT The response of bacteria in bulk soil and earthworm casts to carbon enrichment was studied by an RNA stable-isotope probing/terminal restriction fragment length polymorphism strategy with 13C-labeled glucose and acetate. Both the soil microsite status and the carbon enrichment selected rapidly for different active bacterial communities, which resulted in different degradation kinetics. Our study clearly illustrates the biases that are generated by adding C substrates to detect metabolically active bacteria in soil.
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Corstanje, R., and K. R. Reddy. "Microbial Indicators of Nutrient Enrichment." Soil Science Society of America Journal 70, no. 5 (September 2006): 1652–61. http://dx.doi.org/10.2136/sssaj2004.0070.
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Li, Yong, Jian Sun, Dashuan Tian, Jinsong Wang, Denglong Ha, Yuxi Qu, Guangwei Jing, and Shuli Niu. "Soil acid cations induced reduction in soil respiration under nitrogen enrichment and soil acidification." Science of The Total Environment 615 (February 2018): 1535–46. http://dx.doi.org/10.1016/j.scitotenv.2017.09.131.
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Zhou, Wenxiang, Guilin Han, Man Liu, Chao Song, Xiaoqiang Li, and Fairda Malem. "Vertical Distribution and Controlling Factors Exploration of Sc, V, Co, Ni, Mo and Ba in Six Soil Profiles of The Mun River Basin, Northeast Thailand." International Journal of Environmental Research and Public Health 17, no. 5 (March 7, 2020): 1745. http://dx.doi.org/10.3390/ijerph17051745.
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Exploring the enrichment and controlling factors of heavy metals in soils is essential because heavy metals can cause severe soil contamination and threaten human health when they are excessively enriched in soils. Soil samples (total 103) from six soil profiles (T1 to T6) in the Mun River Basin, Northeast Thailand, were collected for the analyses of the content of heavy metals, including Sc, V, Co, Ni, Mo, Ba. The average contents of soil heavy metals decrease in the following order: Ba, V, Ni, Sc, Co, and Mo (T1, T3, T4 and T5); Ni, V, Ba, Co, Sc, Mo, and Ba (T2); Ba, V, Sc, Ni, Mo, and Co (T6). An enrichment factor (EF) and geoaccumulation index were calculated to assess the degree of heavy metal contamination in the soils. The EFs of these heavy metals in most samples range from 0 to 1.5, which reveals that most heavy metals are slightly enriched. Geoaccumulation indexes show that only the topsoil of T1 and T2 is slightly contaminated by Ba, Sc, Ni, and V. Soil organic carbon (SOC), soil pH and soil texture are significantly positively correlated with most heavy metals, except for a negative correlation between soil pH and Mo content. In conclusion, the influence of heavy metals on soils in the study area is slight and SOC, soil pH, soil texture dominate the behavior of heavy metals.
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Lorenz, Marcel, Delphine Derrien, Bernd Zeller, Thomas Udelhoven, Willy Werner, and Sören Thiele-Bruhn. "The linkage of 13C and 15N soil depth gradients with C:N and O:C stoichiometry reveals tree species effects on organic matter turnover in soil." Biogeochemistry 151, no. 2-3 (November 12, 2020): 203–20. http://dx.doi.org/10.1007/s10533-020-00721-3.
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AbstractThe knowledge of tree species dependent turnover of soil organic matter (SOM) is limited, yet required to understand the carbon sequestration function of forest soil. We combined investigations of 13C and 15N and its relationship to elemental stoichiometry along soil depth gradients in 35-year old monocultural stands of Douglas fir (Pseudotsuga menziesii), black pine (Pinus nigra), European beech (Fagus sylvatica) and red oak (Quercus rubra) growing on a uniform post-mining soil. We investigated the natural abundance of 13C and 15N and the carbon:nitrogen (C:N) and oxygen:carbon (O:C) stoichiometry of litterfall and fine roots as well as SOM in the forest floor and mineral soil. Tree species had a significant effect on SOM δ13C and δ15N reflecting significantly different signatures of litterfall and root inputs. Throughout the soil profile, δ13C and δ15N were significantly related to the C:N and O:C ratio which indicates that isotope enrichment with soil depth is linked to the turnover of organic matter (OM). Significantly higher turnover of OM in soils under deciduous tree species depended to 46% on the quality of litterfall and root inputs (N content, C:N, O:C ratio), and the initial isotopic signatures of litterfall. Hence, SOM composition and turnover also depends on additional—presumably microbial driven—factors. The enrichment of 15N with soil depth was generally linked to 13C. In soils under pine, however, with limited N and C availability, the enrichment of 15N was decoupled from 13C. This suggests that transformation pathways depend on litter quality of tree species.
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Irfan, Mohd, Shamsul Hayat, Aqil Ahmad, and Mohammed Nasser Alyemeni. "Soil cadmium enrichment: Allocation and plant physiological manifestations." Saudi Journal of Biological Sciences 20, no. 1 (January 2013): 1–10. http://dx.doi.org/10.1016/j.sjbs.2012.11.004.
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Zhu, Xiao Long, Guo Juan Gan, Hang Zhou, Yan Liu, Xiao Deng, Hong Bo Hou, and Pei Qin Peng. "Transfer Characteristics of Cd in Paddy Soil-Rice System under Field Condition." Applied Mechanics and Materials 737 (March 2015): 367–73. http://dx.doi.org/10.4028/www.scientific.net/amm.737.367.
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It is important to control Cadmium (Cd) content in rice and ensure the grain security. The transfer characteristics of Cd in paddy soil-rice system between different soil types (red soil and purple soil) under field condition were researched to provide a theoretical basis for Cd environmental management in paddy. In this study, many rice plant samples and corresponding paddy soil samples were collected from fields around the industrial and mining area in central Hunan province in 2011 and 2012. The Cd concentration of samples was analyzed, and the degree of Cd contamination was evaluated. Moreover, the differences of enrichment factor and influencing factors in paddy soil-rice system between red soil and purple soil were discussed. The results revealed that paddy soils and brown rice in the survey area were serious contaminated by Cd. The Cd content and enrichment factor were arranged in the order of root> straw >chaff >brown rice. The Cd content and enrichment factor were in the order of red soil >purple soil. In addition, multivariate linear regression was analyzed and predictions models of Cd concentration of brown rice are based on different types of soil were worked out. It showed that total Cd of soil, organic matter and clay were the main factors that affecting the content of Cd in brown rice. In conclusion, the contamination characteristics, transfer disciplinarian and influencing factors of Cd in the soil-rice system are different between red soil and purple soil. So it needs to pay more attention to the characteristics of different soil parent material when making environmental management related to Cd contamination in soil-rice system.
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Ge, Zhiwei, Ran An, Shuiyuan Fang, Pengpeng Lin, Chuan Li, Jianhui Xue, and Shuiqiang Yu. "Phragmites australis+Typha latifoliaCommunity Enhanced the Enrichment of Nitrogen and Phosphorus in the Soil of Qin Lake Wetland." Scientifica 2017 (2017): 1–9. http://dx.doi.org/10.1155/2017/8539093.
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Aquatic plants play an essential role and are effective in mitigating lake eutrophication by forming complex plant-soil system and retaining total nitrogen (TN) and phosphorus (TP) in soils to ultimately reduce their quantities in aquatic systems. Two main vegetation types (Phragmites australiscommunity andP. australis+Typha latifoliacommunity) of Qin Lake wetland were sampled in this study for the analysis of TN and TP contents and reserves in the wetland soils. The results showed that (1) the consumption effect of Qin Lake wetland on soluble N was much more significant than on soluble P. (2) The efficiency of TN enrichment in wetland soil was enhanced by vegetation covering ofP. australisandT. latifolia. (3) Wetland soil P was consumed byP. australiscommunity and this pattern was relieved with the introduction ofT. latifolia. (4) According to the grey relativity analysis, the most intensive interaction between plants and soil occurred in summer. In addition, the exchange of N in soil-vegetation system primarily occurred in the 0–15 cm soil layer. Our results indicated that vegetation covering was essential to the enrichment of TN and TP, referring to the biology-related fixation in the wetland soil.
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Perumal, Mugunthan, Mohd Effendi Wasli, Ho Soo Ying, Jonathan Lat, and Hamsawi Sani. "Association between Soil Fertility and Growth Performance of Planted Shorea macrophylla (de Vriese) after Enrichment Planting at Rehabilitation Sites of Sampadi Forest Reserve, Sarawak, Malaysia." International Journal of Forestry Research 2017 (2017): 1–16. http://dx.doi.org/10.1155/2017/6721354.
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A study was conducted to determine the status of soil properties after enrichment planting in comparison to an adjacent secondary forest and to evaluate the effect of enrichment planting of Shorea macrophylla (de Vriese) on the soil fertility status with special reference to Soil Fertility Index (SFI) and Soil Evaluation Factor (SEF) at Sampadi Forest Reserve, Sarawak. The study sites were stands rehabilitated in different years (1996: SM96; 1997: SM97; 1998: SM98; 1999: SM99) and secondary forest (SF). Findings indicated that the soils at rehabilitation sites and SF were strongly acidic in nature, with pH less than 5.50, poor soil exchangeable bases, and nutrient status. The soils were relatively of sandy clay loam to sandy clay. Principal Component Analysis revealed the three most significant components of the soil properties which explained 76.3% of the total variation. At surface soils, SFI was correlated with tree growth parameters of S. macrophylla, indicating that SFI is an applicable soil quality index as compared to SEF. Notwithstanding, a significant association was found between soil available phosphorus and planted S. macrophylla, indicating that soil phosphorus is a better indicator than SFI. Further studies on other environmental factors influencing tree growth performance, early establishment of experimental reforestation at nursery, and field should be implemented to obtain the initial data on seedling growth performance prior to outplanting.
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Sansupa, Chakriya, Sara Fareed Mohamed Wahdan, Terd Disayathanoowat, and Witoon Purahong. "Identifying Hidden Viable Bacterial Taxa in Tropical Forest Soils Using Amplicon Sequencing of Enrichment Cultures." Biology 10, no. 7 (June 22, 2021): 569. http://dx.doi.org/10.3390/biology10070569.
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This study aims to estimate the proportion and diversity of soil bacteria derived from eDNA-based and culture-based methods. Specifically, we used Illumina Miseq to sequence and characterize the bacterial communities from (i) DNA extracted directly from forest soil and (ii) DNA extracted from a mixture of bacterial colonies obtained by enrichment cultures on agar plates of the same forest soil samples. The amplicon sequencing of enrichment cultures allowed us to rapidly screen a culturable community in an environmental sample. In comparison with an eDNA community (based on a 97% sequence similarity threshold), the fact that enrichment cultures could capture both rare and abundant bacterial taxa in forest soil samples was demonstrated. Enrichment culture and eDNA communities shared 2% of OTUs detected in total community, whereas 88% of enrichment cultures community (15% of total community) could not be detected by eDNA. The enrichment culture-based methods observed 17% of the bacteria in total community. FAPROTAX functional prediction showed that the rare and unique taxa, which were detected with the enrichment cultures, have potential to perform important functions in soil systems. We suggest that enrichment culture-based amplicon sequencing could be a beneficial approach to evaluate a cultured bacterial community. Combining this approach together with the eDNA method could provide more comprehensive information of a bacterial community. We expected that more unique cultured taxa could be detected if further studies used both selective and non-selective culture media to enrich bacteria at the first step.
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Swęd, Maciej, and Przemysław Niedzielski. "Geochemistry and mineralogy of technogenic soils developed on old mine heaps of abandoned iron ore mines in the Ławęczna area (Holy Cross Mountains, south-central Poland)." Soil Science Annual 69, no. 1 (March 1, 2018): 28–38. http://dx.doi.org/10.2478/ssa-2018-0004.
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Abstract The article presents the results of preliminary geochemical and mineralogical studies of technogenic soils (Technosols) of abandoned iron ore mines on the Ławęczna Hill near Miedziana Góra in the Holy Cross (Świętokrzyskie) Mountains, southcentral Poland. The results of chemical analyses (XRF) were used to calculate the soil enrichment factors of arsenic, copper, iron, lead and zinc, and compare the element concentrations to their levels in uncontaminated soils across Poland and in the city of Kielce. The highest values of soil enrichment factors of metals (As 27.699, Ni 26.455, Cu 9.353, Zn 3.344, Pb 0.62) were recorded for the sand fraction composed of iron oxyhydroxides and hematite, whereas the lowest (Ni 0.22, Cu 0.069, Zn 0.007, Pb 0.028) for the clay–silt and sand fractions, which were primarily composed of calcite and quartz as well as for gravel fraction. The clay-silt fraction shows the highest enrichment in arsenic (27.69). The examined metals and arsenic show positive geochemical anomalies.
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Perelman, Adi, Naftali Lazarovitch, Jan Vanderborght, and Andreas Pohlmeier. "Quantitative imaging of sodium concentrations in soil-root systems using magnetic resonance imaging (MRI)." Plant and Soil 454, no. 1-2 (July 25, 2020): 171–85. http://dx.doi.org/10.1007/s11104-020-04628-8.
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Abstract Aims Demonstrating the potential of MRI as a 3D, non-invasive and continuous measurement technique to map Na+ concentration distributions in soil and around roots. Methods Dissolved NaCl in soil and soil-plant systems was mapped by 3D 23Na-MRI. The lower limit of detectability in saturated and unsaturated porous media was evaluated, followed by evaporation experiments to test the quantification. Finally, Na+ enrichment around tomato roots, irrigated with saline solution under low/high transpiration rates (LT, HT), was imaged in parallel to the root system,. Results A spin echo pulse sequence allowed the quantitative mapping of the volume concentration of NaCl in sandy porous medium. Evaporation experiments showed slight enrichment in the top surface layer, plus uniform temporal enrichment in the deeper layers. In the tomato experiments, enrichment was more distinct under HT than under LT. Concentration-distance correlation curves revealed thin enrichment zones ranging a few mm around the roots. Conclusions MRI can map Na+ non-invasively in 3D at relevant concentrations for root activity. Visualizing water content, roots and Na+ on the same scale is possible, despite limitations of different scanning times and resolution. This opens a route for further quantitative investigations of salt enrichment processes in soil and soil-plant systems.
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Sharmila, M., K. Ramanand, and N. Sethunathan. "Effect of yeast extract on the degradation of organophosphorus insecticides by soil enrichment and bacterial cultures." Canadian Journal of Microbiology 35, no. 12 (December 1, 1989): 1105–10. http://dx.doi.org/10.1139/m89-185.
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Soil enrichment cultures were prepared by repeated additions of methyl parathion to flooded alluvial and laterite soils incubated at 35 °C. These cultures were tested for their ability to degrade methyl parathion in a mineral salts medium in the presence and absence of yeast extract. Addition of yeast extract (0.05% w/v) accelerated the degradation of methyl parathion by both enriched cultures. Methyl parathion was degraded by the enrichment culture from alluvial soil essentially by hydrolysis in the absence of yeast extract and by nitro group reduction in its presence. The enrichment culture from laterite soil degraded methyl parathion (by hydrolysis) only in the presence of yeast extract. A Bacillus sp., isolated from laterite soil, degraded methyl parathion essentially by hydrolysis in the presence of a concentration (w/v) of yeast extract of 0.05%, by both hydrolysis and nitro group reduction at 0.1 and 0.25%, and exclusively by nitro group reduction at 0.5%. A similar trend was also noticed with parathion. However, fenitrothion was degraded by Bacillus sp. mainly by hydrolysis at all concentrations of yeast extract, whereas diazinon was not degraded.Key words: organophosphorothioates, biodegradation, yeast extract dependent pathway.
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Duarte, Gabriela Frois, Alexandre Soares Rosado, Lucy Seldin, Welington de Araujo, and Jan Dirk van Elsas. "Analysis of Bacterial Community Structure in Sulfurous-Oil-Containing Soils and Detection of Species Carrying Dibenzothiophene Desulfurization (dsz) Genes." Applied and Environmental Microbiology 67, no. 3 (March 1, 2001): 1052–62. http://dx.doi.org/10.1128/aem.67.3.1052-1062.2001.
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ABSTRACT The selective effects of sulfur-containing hydrocarbons, with respect to changes in bacterial community structure and selection of desulfurizing organisms and genes, were studied in soil. Samples taken from a polluted field soil (A) along a concentration gradient of sulfurous oil and from soil microcosms treated with dibenzothiophene (DBT)-containing petroleum (FSL soil) were analyzed. Analyses included plate counts of total bacteria and of DBT utilizers, molecular community profiling via soil DNA-based PCR-denaturing gradient gel electrophoresis (PCR-DGGE), and detection of genes that encode enzymes involved in the desulfurization of hydrocarbons, i.e., dszA, dszB, and dszC.Data obtained from the A soil showed no discriminating effects of oil levels on the culturable bacterial numbers on either medium used. Generally, counts of DBT degraders were 10- to 100-fold lower than the total culturable counts. However, PCR-DGGE showed that the numbers of bands detected in the molecular community profiles decreased with increasing oil content of the soil. Analysis of the sequences of three prominent bands of the profiles generated with the highly polluted soil samples suggested that the underlying organisms were related to Actinomyces sp.,Arthrobacter sp., and a bacterium of uncertain affiliation.dszA, dszB, and dszC genes were present in all A soil samples, whereas a range of unpolluted soils gave negative results in this analysis. Results from the study of FSL soil revealed minor effects of the petroleum-DBT treatment on culturable bacterial numbers and clear effects on the DBT-utilizing communities. The molecular community profiles were largely stable over time in the untreated soil, whereas they showed a progressive change over time following treatment with DBT-containing petroleum. Direct PCR assessment revealed the presence of dszB-related signals in the untreated FSL soil and the apparent selection of dszA- and dszC-related sequences by the petroleum-DBT treatment. PCR-DGGE applied to sequential enrichment cultures in DBT-containing sulfur-free basal salts medium prepared from the A and treated FSL soils revealed the selection of up to 10 distinct bands. Sequencing a subset of these bands provided evidence for the presence of organisms related to Pseudomonas putida, a Pseudomonassp., Stenotrophomonas maltophilia, and Rhodococcus erythropolis. Several of 52 colonies obtained from the A and FSL soils on agar plates with DBT as the sole sulfur source produced bands that matched the migration of bands selected in the enrichment cultures. Evidence for the presence of dszB in 12 strains was obtained, whereas dszA and dszC genes were found in only 7 and 6 strains, respectively. Most of the strains carrying dszA or dszC were classified asR. erythropolis related, and all revealed the capacity to desulfurize DBT. A comparison of 37 dszA sequences, obtained via PCR from the A and FSL soils, from enrichments of these soils, and from isolates, revealed the great similarity of all sequences to the canonical (R. erythropolis strain IGTS8)dszA sequence and a large degree of internal conservation. The 37 sequences recovered were grouped in three clusters. One group, consisting of 30 sequences, was minimally 98% related to the IGTS8 sequence, a second group of 2 sequences was slightly different, and a third group of 5 sequences was 95% similar. The first two groups contained sequences obtained from both soil types and enrichment cultures (including isolates), but the last consisted of sequences obtained directly from the polluted A soil.
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Miller, J. J., T. Curtis, D. S. Chanasyk, S. Reedyk, and W. D. Willms. "Effectiveness of soil in vegetated buffers to retain nutrients and sediment transported by concentrated runoff through deep gullies." Canadian Journal of Soil Science 96, no. 2 (June 1, 2016): 154–68. http://dx.doi.org/10.1139/cjss-2015-0038.
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Little research has evaluated naturally vegetated buffers to retain pollutants in soil from concentrated runoff through deep (2–14 m) gullies. Soil enrichment in the flow path of 11 naturally vegetated gullies in southern Alberta, Canada, was used as a long-term signature of filtering during concentrated flow. Soil was sampled at three depth intervals (0–2.5, 2.5–5, and 5–10 cm) along two 50-m transects inside and outside the flow path of the vegetated gullies in each of 3 yr (2011–2013). The influence of soil type, flow path (inside vs. outside), distance into vegetated flow path, depth, and their interactions on enrichment of nutrients (NH4–N, NO3–N, soil test P (STP), total P) and particle size fractions (clay, silt, and sand) was determined. Significantly (P ≤ 0.05) greater enrichment of nutrients and specific particle size fractions inside than outside the flow path of the vegetated gully suggested that greater deposition occurred inside the concentrated flow path. In contrast, there was little evidence for enrichment of nutrients and sediment at the front or inlet of the buffer (except STP), or for infiltration of more soluble nutrients into the subsoil. Soil enrichment in buffers may reveal long-term filtering processes that may not be shown with short-term runoff experiments.
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Liu, X., S. J. Herbert, K. Baath, and A. M. Hashemi. "Soybean (Glycine max) seed growth characteristics in response to light enrichment and shading." Plant, Soil and Environment 52, No. 4 (November 15, 2011): 178–85. http://dx.doi.org/10.17221/3363-pse.
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Seeds are the primary sinks for photosynthates during reproductive growth. Variation in light intercepted during and after seed initiation has been found a major environmental determinant of soybean [Glycine max(L.) Merrill] seed size. We investigated the influence of light enrichment and shading on seed growth rate, effective filling, cotyledon cell number, cell volume and endogenousABA concentrations of cotyledons/testas during seed filling of soybean. Evans, an indeterminate Group 0 soybean, was subjected to light reduction and enrichment treatments from the beginning of pod formation until final harvest for two years inMassachusetts. Higher rates of seed growth, greater seed dry weight, and higher cotyledon cell number were all observed with light enrichment. There was a reduction in seed growth rate and cotyledon cell number, along with a significant lowering of endogenousABA levels in testa and cotyledon with shade. The level ofABAin cotyledon during seed development was significantly correlated with seed growth rates only under shade treatments. Both the growth rates and seed filling duration were influenced by variation in light interception by the soybean canopy. The effects of varying light treatment on seed size, within one genotype, were most likely due to the differences in seed growth rate and cotyledon cell number.
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WILLIAMS, L. K., L. C. SAIT, T. A. COGAN, F. JØRGENSEN, R. GROGONO-THOMAS, and T. J. HUMPHREY. "Enrichment culture can bias the isolation ofCampylobactersubtypes." Epidemiology and Infection 140, no. 7 (September 19, 2011): 1227–35. http://dx.doi.org/10.1017/s0950268811001877.
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SUMMARYEnrichment culture is often used to isolateCampylobacter. This study compared isolation ofCampylobacterspp. from 119 broiler chicken environments from two farms, using Preston and modified Exeter (mExeter) and modified Bolton (mBolton) enrichments. mExeter was significantly more effective in isolatingCampylobacterspp. from the environmental samples compared to Preston (P<0·001) and mBolton (P<0·04) broths but there was no significant difference between the latter two methods (P>0·05). Enrichment broth type did not affect isolation from chicken faecal or soil and litter samples.C. jejuniwas isolated from significantly more environmental samples using mExeter broth compared to Preston (P<0·01) and mBolton (P<0·003) broths; there was no difference between the latter two methods or between all methods for detection ofC. coli(P>0·05). OnlyC. coliwas isolated from the soil and litter samples and although bothC. jejuniandC. coliwere recovered from the faecal samples there was no effect of using different enrichment broths. The majority of samples where the same species had been isolated yielded the same or closely related genotypes as defined by pulsed-field gel electrophoresis. Isolates recovered using Preston and mBolton broths were less genetically diverse than those from mExeter broth. We conclude that the enrichment method used affects both the number and species ofCampylobacterisolated from naturally contaminated samples.
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Stepanova, L. P., E. V. Yakovleva, and A. V. Pisareva. "Spatio-Temporal Dynamics of Soil Geochemical Anomalies in the Zone of Impact of Slag Residuals." Ecology and Industry of Russia 23, no. 3 (March 12, 2019): 44–48. http://dx.doi.org/10.18412/1816-0395-2019-3-44-48.
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The 13-year-old (from 2003 to 2016) dynamics of soil contamination for the content of heavy metals in the area of the village of Bolshoye Dumchino of the Mtsensk District in the territory adjacent to the slag dump of Mtsensk Foundry was studied. It is shown that on the territory of the placement of slag residuals a techno geochemical anomaly is formed, in which the contained heavy metals are of technogenic and genetic (natural geochemical) nature. To identify the effect of anthropogenic factor on soil pollution with heavy metals, was determined the refined enrichment factor of heavy metals (EFHM) in light gray forest soils at different distances from the slag dump, allowing to calculate the proportion of technogeneity of metals as a percentage of its total content. The technogenic origin of heavy metals as pollutants and the role of humus soil horizons in fixing these metals in the soil profile have been proven. Analysis of the results characterizing the degree of enrichment of the genetic horizons of light gray forest soils with heavy metals for the period 2003–2016 convincingly proves the effect of maximum accumulation of slag residuals in the dump on the accumulation intensity and fixation of the studied metals, both in the upper humus layer and their distribution in the profile soil. The established patterns in changing the degree of enrichment and technogenicity of heavy metals in the profile of light-gray forest soil are caused not only by the impact of the slag dump as a source of pollution, but also by the peculiarities of using the soils of the studied territories. It is shown that the toxic load for the analyzed period not only did not decrease, but even increased.
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Dadrasnia, Arezoo, and Salmah Binti Ismail. "Bio-Enrichment of Waste Crude Oil Polluted Soil: Amended with Bacillus 139SI and Organic Waste." International Journal of Environmental Science and Development 6, no. 4 (2015): 241–45. http://dx.doi.org/10.7763/ijesd.2015.v6.598.
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Mosier, A. R., E. Pendall, and J. A. Morgan. "Effect of water addition and nitrogen fertilization on the fluxes of CH<sub>4</sub>, CO<sub>2</sub>, NO<sub>x</sub>, and N<sub>2</sub>O following five years of elevated CO<sub>2</sub> in the Colorado Shortgrass Steppe." Atmospheric Chemistry and Physics 3, no. 5 (October 13, 2003): 1703–8. http://dx.doi.org/10.5194/acp-3-1703-2003.
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Abstract. An open-top-chamber (OTC) CO2 enrichment (~720 mmol mol-1) study was conducted in the Colorado shortgrass steppe from April 1997 through October 2001. Aboveground plant biomass increased under elevated CO2 and soil moisture content was typically higher than under ambient CO2 conditions. Fluxes of CH4, CO2, NOx and N2O, measured weekly year round were not significantly altered by CO2 enrichment over the 55 month period of observation. During early summer of 2002, following the removal of the open-top-chambers from the CO2 enrichment sites in October 2001, we conducted a short term study to determine if soil microbial processes were altered in soils that had been exposed to double ambient CO2 concentrations during the growing season for the past five years. Microplots were established within each experimental site and 10 mm of water or 10 mm of water containing the equivalent of 10 g m-2 of ammonium nitrate-N was applied to the soil surface. Fluxes of CO2, CH4, NOx and N2O fluxes within control (unchambered), ambient CO2 and elevated CO2 OTC soils were measured at one to three day intervals for the next month. With water addition alone, CO2 and NO emission did not differ between ambient and elevated CO2 soils, while CH4 uptake rates were higher and N2O fluxes lower in elevated CO2 soils. Adding water and mineral N resulted in increased CO2 emissions, increased CH4 uptake and decreased NO emissions in elevated CO2 soils. The N addition study confirmed previous observations that soil respiration is enhanced under elevated CO2 and N immobilization is increased, thereby decreasing NO emission.
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Kadlec, V., O. Holubík, E. Procházková, J. Urbanová, and M. Tippl. "Soil organic carbon dynamics and its influence on the soil erodibility factor." Soil and Water Research 7, No. 3 (July 10, 2012): 97–108. http://dx.doi.org/10.17221/3/2012-swr.
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The effect of erosion and erosion control measures on changes in the amount of organic matter in soil was studied. We investigated the influence of organic matter inputs into the soil on surface runoff, soil erosion and soil erodibility (K-factor), including the monitoring of carbon dynamics, as a result of torrential rains. The research was conducted on experimental plots in Třebsín site. Erosion leads to soil carbon loss and subsequently to increasing concentrations of carbon in sediments (enrichment ratio). We can conclude from the results that the input of organic matter into the soil (especially farmyard manure) significantly contributes to a decrease in surface runoff and soil loss and also to a reduction of carbon leaching into sediments; so it contributes to carbon sequestration into the soil.
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Kachanoski, R. Gary. "Estimating soil loss from changes in soil cesium-137." Canadian Journal of Soil Science 73, no. 4 (November 1, 1993): 629–32. http://dx.doi.org/10.4141/cjss93-060.
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A simple power-function equation was developed to relate changes in soil 137Cs with time to an average annual soil-loss rate. The equation accounts for tillage dilution of the concentration of 137Cs in the surface plow layer and for enrichment in the eroding soil. The predictions from the relationship were similar to values for a more complicated model and to measured values given in previous studies. Key words: Erosion rate, prediction, cesium-137
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Mosier, A. R., P. Pendall, and J. A. Morgan. "Soil-atmosphere exchange of CH<sub>4</sub>, CO<sub>2</sub>, NO<sub>x</sub>, and N<sub>2</sub>O in the Colorado Shortgrass Steppe following five years of elevated CO<sub>2</sub> and N fertilization." Atmospheric Chemistry and Physics Discussions 3, no. 3 (May 20, 2003): 2691–706. http://dx.doi.org/10.5194/acpd-3-2691-2003.
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Abstract. An open-top-chamber (OTC) CO2 enrichment study was conducted in the Colorado shortgrass steppe to determine the effect of elevated CO2 (~720 mmol mol−1) on plant production, photosynthesis, and water use of this mixed C3/C4 plant community, soil nitrogen (N) and carbon (C) cycling and the impact of changes induced by \\CO2 on trace gas exchange. Weekly measurements of CO2, CH4, NOx and N2O fluxes within control (unchambered), ambient CO2 and elevated CO2 OTCs and soil water and temperature were measured at each flux measurement time from early April 1997, year round, through October 2001. Even though both aboveground plant biomass increased under elevated CO2 and soil moisture content was typically higher than under ambient CO2 conditions, none of the trace gas fluxes were significantly altered by CO2 enrichment over the 55 month period of observation. During early summer of 2002, following the removal of the open-top-chambers from the CO2 enrichment sites in October, we conducted a short term study to determine if soil microbial processes were altered in soils that had been exposed to double ambient CO2 concentrations during the growing season for the past five years. Microplots were established within each experimental site and 10 mm of water or 10 mm of water containing the equivalent of 10 g m−2 of ammonium nitrate-N was applied to the soil surface. Fluxes of CO2, CH4, NOx and N2O fluxes within control (unchambered), ambient CO2 and elevated CO2 OTCs soils at one to three day intervals for the next month. With water addition alone, CO2 and NO emission did not differ between ambient and elevated CO2 soils, while CH4 uptake rates were higher and N2O fluxes lower in elevated CO2 soils. Adding water and mineral N resulted in increased CO2 emissions, increased CH4 uptake and decreased NO emissions in elevated CO2 soils. The N addition study confirmed previous observations that soil respiration is enhanced under elevated CO2 and N immobilization is increased, thereby decreasing NO emission.
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Palis, R. G., C. W. Rose, and P. G. Saffigna. "Soil erosion and nutrient loss. IV." Soil Research 35, no. 4 (1997): 907. http://dx.doi.org/10.1071/s92061.
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The effect of slope length on runoff and soil loss, and the loss and enrichment ratio of nitrogen from steep slopes planted to pineapple, were studied under natural field conditions over 3 sampling dates at Imbil, Gympie, Queensland. The experiments were conducted on 3 sites, with each site having 3 slope lengths of 9, 15 and 23 m, each replicated twice. The mean slope gradient was 32% with extreme variation from 24 to 37%. During sampling for soil loss measurement, subsamples were also collected, air-dried, weighed, and analysed for total nitrogen concentrations. Samples of the original soil (uneroded) were also taken and analysed and the concentration of total nitrogen in the original soil was used for enrichment ratio and nutrient nitrogen loss determination. The runoff per unit area was not significantly affected by slope length. Total soil loss per unit area in each erosion event increased with increasing slope length. The relationship between soil loss (Y ) and slope (L) is well fitted by the function: The measured sediment concentrations (in the case of site 3) for different slope lengths were higher than those for the estimated sediment concentration at the transport limit assuming either uniform overland flow, or furrow or rill geometry. The estimated sediment concentration at the transport limit provided evidence for the occurrence and importance of rilling which increased soil loss per unit area. Furthermore, sediment concentration estimated at the transport limit assuming rill or furrow geometry was higher than uniform overland flow and increased as slope length increased from 9 to 23 m. The enrichment ratio for total nitrogen decreased with increasing eroded sediment. The eroded sediment was found to contain a nitrogen concentration very similar to that of the original soil, resulting in the enrichment ratio, in some cases, being close to or slightly below unity. Total nitrogen loss per unit area showed a similar trend to total soil loss and it increased with increasing slope length. The relationship between total soil loss in the event (SL) and enrichment ratio (ER) for total nitrogen for all slope lengths is represented by the logarithmic function
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Chalmers, A., S. McIntyre, R. D. B. Whalley, and N. Reid. "Grassland species response to soil disturbance and nutrient enrichment on the Northern Tablelands of New South Wales." Australian Journal of Botany 53, no. 6 (2005): 485. http://dx.doi.org/10.1071/bt04211.
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An experiment was established in an area of long-grazed temperate grassland on the Northern Tablelands of New South Wales to investigate individual species response to mechanical soil disturbance and nutrient enrichment. Grazing was excluded for the duration of the experiment. The total species pool available in the experiment included 56 native and 24 exotic species recorded in the plots, as well as seven exotic species that were artificially introduced (i.e. sowing treatment). Eighteen months after treatment, total species richness was significantly lower under high soil disturbance (mean of 14.7 ± 0.85 species m–2) than under low (21.1 ± 0.67 species m–2) and moderately (21.7 ± 0.77 species m–2) disturbed conditions. Total species richness was not significantly affected by nutrient enrichment or sowing. Most of the annuals analysed were exotic and their relative cover increased with nutrient enrichment (Aira cupaniana Guss., Briza minor L. and Vulpia spp.), but was unresponsive to soil disturbance. Perennials showed varied responses, with the abundance of most decreasing with high soil disturbance and being unaffected by moderate soil disturbance levels. All four perennials favoured by high soil disturbance were exotic (Dactylis glomerata L., Lolium perenne L., Hypochaeris radicata L. and Sanguisorba minor Scop.); three of these were sown. Most perennials showed no significant response to nutrient enrichment, although the occurrence of a small number was either reduced (Aristida ramosa R.Br., A. warburgii Mez., H. radicata and S. minor) or increased (Carex inversa R.Br., D. glomerata, Fimbristylis dichotoma (L.) Vahl., Sporobolus creber De Nardi and Tricoryne elatior R.Br.). Most interactions (i.e. species response to one experimental factor depends on another experimental factor) occurred because few individuals survived on the severely soil-disturbed plots to respond to nutrient enrichment. However, in this particular grassland, the short-term response of most species to soil disturbance was independent of the level of nutrient enrichment.
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Garten Jr., Charles T., and Helga Van Miegroet. "Relationships between soil nitrogen dynamics and natural 15N abundance in plant foliage from Great Smoky Mountains National Park." Canadian Journal of Forest Research 24, no. 8 (August 1, 1994): 1636–45. http://dx.doi.org/10.1139/x94-212.
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We tested the hypothesis that naturally occurring nitrogen (N) isotope ratios in foliage (from plants that do not symbiotically fix atmospheric N2) are an indicator of soil N dynamics in forests. Replicate plots were established at eight locations ranging in elevation from 615 to 1670 m in Great Smoky Mountains National Park in eastern Tennessee, U.S.A. The locations selected ranged from N-poor (low-elevation) to N-rich (high-elevation) forest stands. Soils were sampled in June 1992; plants, forest floors, and upper mineral soils were sampled in August 1992. Net N mineralization and net nitrification potentials for surface mineral soils and organic matter layers at each site were determined by aerobic laboratory incubations. Soils and organic layers from high-elevation sites had greater net N mineralization and nitrification potentials than soils from low-elevation sites. There were significant (P ≤ 0.05) differences between study sites in soil 15N abundance. Therefore, we examined correlations between measures of soil N availability and both mean foliar δ15N values and mean enrichment factors (εp−s = δ15Nleaf − δ15Nsoil). In evergreens, maples, and ferns, mean foliar δ15N values and mean enrichment factors were positively correlated with net N mineralization and net nitrification potentials in soil. The observed relationships between natural 15N abundance in plant leaves and soil N availability were explained by a simple model of soil N dynamics. The model predicts how the isotopic composition of plant N is affected by the following factors: (i) varying uptake of soil NH4-N and NO3-N, (ii) the isotopic composition of different soil N pools, and (iii) relative rates of soil N transformations.
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Pintar, Marina, Spela Velikonja Bolta, and Franc Lobnik. "Nitrogen isotope enrichment factor as an indicator of denitrification potential in top and subsoil in the Apače Valley, Slovenia." Soil Research 46, no. 8 (2008): 719. http://dx.doi.org/10.1071/sr07123.
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Denitrification is still a poorly explained process in soil nitrogen cycles. Nitrogen isotope analyses, in combination with conventional soil-science methods (i.e. rate measurements), permit the tracing and quantification of several turn-over and transfer processes in soils. The aim of the presented investigations is to determine the 15N isotope enrichment factor (ε) in a laboratory experiment during denitrification in the topsoil and subsoil layer of a Eutric Fluvisol (FAO classification) from the Apače Valley (NE Slovenia). Intact soil cores taken from depths of 0.10–0.20 m and 0.90–1.00 m were incubated under anaerobic conditions at a temperature of 18°C. A nitrate dose of 116 mg N-NO3/L was added to the topsoil layer and 58 mg N-NO3/L to the subsoil material. Glucose (250 mg) was added to each soil column. After the initial 24 h of incubation, water samples were taken every 8 h. The isotope enrichment factor for denitrification in the upper soil-layer columns was –7.60 ± 1.28‰ and for subsoil columns –34.91 ± 1.77‰ (n = 3). The isotope enrichment factor close to zero demonstrated that microorganisms easily consumed abundant substrate in the topsoil layer. Added nitrate and glucose exceeded the capacity of the microbial population in the subsoil and the process was limited by a low microbial population for which a high ε is characteristic.
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GUPTA, UMESH C., K. A. WINTER, and K. B. McRAE. "SELENIUM ENRICHMENT OF CROPS THROUGH FOLIAR APPLICATIONS." Canadian Journal of Soil Science 68, no. 3 (August 1, 1988): 519–26. http://dx.doi.org/10.4141/cjss88-050.
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A field study was conducted, at two locations on Prince Edward Island, over a 5-yr period to determine the effects of foliar applications of sodium selenite on the Se concentration in barley (Hordeum vulgare L.) grain and in alfalfa (Medicago sativa L.) and timothy (Phleum pratense L.) foliage. Applications of 10–20 g Se ha−1 resulted in barley kernels and forage plant Se levels that would be adequate to prevent Se deficiency in most livestock. The highest rate of Se, at 80 g ha−1, resulted in plant Se concentrations of 706 μg kg−1 in timothy. The measured plant Se concentrations, to the same applications, varied from year to year but the responses to applied Se levels were generally in the same proportions. For similar application rates Se concentrations were lower in barley grain than in the forages. Tissue Se levels in the second cuts of alfalfa and timothy were lower than in the first cut. High levels of foliar-applied Se did not result in a carryover effect the following crop year. Annual foliar applications of Se would be required to raise the Se levels in crops into the sufficiency range for livestock feeds. Key words: Selenium content, foliar spray, cereals, forages, Podzol soils
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Swallow, Mathew J. B., and Sylvie A. Quideau. "Evidence of rapid non-targeted effects of cycloheximide on soil bacteria using 13C-PLFA analysis." Canadian Journal of Soil Science 100, no. 4 (December 1, 2020): 356–62. http://dx.doi.org/10.1139/cjss-2019-0152.
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Stable isotope probing of phospholipid fatty acids (PLFA-SIP) is useful when studying bacterial contributions to soil processes, and it is an effective way to separate fungal and bacterial activity by linking 13C enrichment to specific PLFAs. Distinguishing bacterial contributions to soil processes often employs selective inhibitors; however, studies demonstrating their efficacy when using PLFA-SIP are less common. Here, we determined the effect of the fungal inhibitor cycloheximide (4.8 mg g−1 dry soil) and the bacterial inhibitor bronopol (0.48 mg g−1 dry soil) on microbial communities white spruce [Picea glauca (Moench) Voss] forest floor by measuring the uptake of 13C-enriched glucose (2 mg g−1 dry soil) in microbial PLFAs. We targeted [13C]glucose uptake by the bacterial community conditioned to a stable soil environment of 23 °C for over 2 wk rather than new bacteria generated from active colony growth caused by glucose addition. Nearly all bacterial PLFAs exhibited pronounced inhibition of 13C enrichment in the presence of bronopol. Limited inhibition of 13C enrichment in the presence of cycloheximide was observed as bacterial PLFA affected by cycloheximide had roughly one third less 13C enrichment than samples emended with [13C]glucose alone. Inhibitory effects only reduced 13C enrichment and did not affect total PLFA concentrations, implying that the inhibitors in the concentrations applied were impeding bacterial activity without causing cell death. Based on this work, we conclude that bronopol is an effective inhibitor for bacteria. Additionally, non-targeted effects of cycloheximide on soil bacteria must be accounted for when it is used in soil incubations.
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Niu, Huan, Ziqin Pang, Nyumah Fallah, Yongmei Zhou, Caifang Zhang, Chaohua Hu, Wenxiong Lin, and Zhaonian Yuan. "Diversity of microbial communities and soil nutrients in sugarcane rhizosphere soil under water soluble fertilizer." PLOS ONE 16, no. 1 (January 22, 2021): e0245626. http://dx.doi.org/10.1371/journal.pone.0245626.
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The dynamics of soil microbial communities are important for plant health and productivity. Soil microbial communities respond differently to fertilization. Organic water soluble fertilizer is an effective soil improver, which can effectively improve soil nutrient status and adjust soil pH value. However, little is known about the effects of water soluble fertilizers on soil microbial community, and the combined effects on soil nutrients and sugarcane productivity. Therefore, this study sought to assess the effects of water soluble fertilizer (1,050 kg/hm2 (WS1), 1,650 kg/hm2 (WS2)) and mineral fertilizer (1,500 kg/hm2 (CK)) on the soil microbial community, soil nutrients and crop yield of sugarcane. The results showed that compared with CK, the application of water soluble fertilizers (WS1 and WS2) alleviated soil acidity, increased the OM, DOC, and AK contents in the soil, and further improved agronomic parameters and sugarcane yield. Both WS1 and WS2 treatments significantly increased the species richness of microorganisms, especially the enrichment of beneficial symbiotic bacteria such as Acidobacteria and Planctomycetes, which are more conducive to the healthy growth of plants. Furthermore, we found that soil nutrient contents were associated with soil microbial enrichment. These results indicate that water soluble fertilizer affects the enrichment of microorganisms by improving the nutrient content of the soil, thereby affecting the growth and yield of sugarcane. These findings therefore suggest that the utilization of water soluble fertilizer is an effective agriculture approach to improve soil fertility.
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Wilson, Sandra L., Paul Grogan, and Virginia K. Walker. "Prospecting for ice association: characterization of freeze–thaw selected enrichment cultures from latitudinally distant soils." Canadian Journal of Microbiology 58, no. 4 (April 2012): 402–12. http://dx.doi.org/10.1139/w2012-010.
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Freeze–thaw stress has previously been shown to alter soil community structure and function. We sought to further investigate this stress on enriched microbial consortia with the aim of identifying microbes with ice-associating adaptations that facilitate survival. Enrichments were established to obtain culturable psychrotolerant microbes from soil samples from the latitudinal extremes of the Canadian Shield plateau. The resulting consortia were subjected to consecutive freeze–thaw cycles, and survivors were putatively identified by their 16S rRNA gene sequences. Even though the northerly site was exposed to longer, colder winters and large spring-time temperature fluctuations, the selective regime similarly affected both enriched consortia. Quantitative PCR and metagenomic sequencing were used to determine the frequency of a subset of the resistant microbes in the original enrichments. The metagenomes showed 22 initial genera, only 6 survived and these were not dominant prior to selection. When survivors were assayed for ice recrystallization inhibition and ice nucleation activities, over 60% had at least one of these properties. These phenotypes were not more prevalent in the northern enrichment, indicating that regarding these adaptations, the enrichment strategy yielded seemingly functionally similar consortia from each site.
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Sheppard, S. C., and W. G. Evenden. "Contaminant Enrichment and Properties of Soil Adhering to Skin." Journal of Environmental Quality 23, no. 3 (May 1994): 604–13. http://dx.doi.org/10.2134/jeq1994.00472425002300030029x.
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Jackson, R. B., J. H. Manwaring, and M. M. Caldwell. "Rapid physiological adjustment of roots to localized soil enrichment." Nature 344, no. 6261 (March 1990): 58–60. http://dx.doi.org/10.1038/344058a0.
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Bordean, Despina-Maria, Dragos V. Nica, Monica Harmanescu, Ionut Banatean-Dunea, and Iosif I. Gergen. "Soil Manganese Enrichment from Industrial Inputs: A Gastropod Perspective." PLoS ONE 9, no. 1 (January 14, 2014): e85384. http://dx.doi.org/10.1371/journal.pone.0085384.
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Jackson, R. B., and M. M. Caldwell. "Kinetic responses of Pseudoroegneria roots to localized soil enrichment." Plant and Soil 138, no. 2 (December 1991): 231–38. http://dx.doi.org/10.1007/bf00012250.
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