论文检索

总访问量：2724299次

总访客量：122731人

所有论文

26341. 题目: Distribution of prokaryotic communities throughout the Chernozem profiles under different land uses for over a century
文章编号: N180625A1
期刊: Applied Soil Ecology
作者: Mikhail V. Semenov, Timofey I. Chernov, Azida K. Tkhakakhova, Alena D. Zhelezova, Ekaterina A. Ivanova, Tatyana V. Kolganova, Olga V. Kutovaya
更新时间: 2018-06-25
摘要: Land use affects physical, chemical and biological properties and processes in soil. Long-term field experiments were employed to reveal changes of soil characteristics induced by land use. Using high-throughput 16S rRNA gene amplicon sequencing and quantitative PCR, comparative analyses were conducted on prokaryotic community structure in different soil diagnostic horizons of Chernozems under forest, fallow and arable land within a long-term field experiment established by V.V. Dokuchaev in 1892. Soil organic carbon (SOC) was a more sensitive and reliable indicator of changes than microbial diversity indexes. Verrucomicrobia changed most among different prokaryotic phyla. Long-term tillage did not result in detectable changes in α-diversity of Chernozem prokaryotic communities, except for that plow pan horizon that showed a pronounced decrease in microbial diversity. The differences in prokaryotic community structure between soil horizons were more contrasting than between land uses. Analysis of β-diversity indicated that soil microbial communities at different depths formed non-overlapping clusters of A and B horizons, while microbiomes of transitional AB horizons fall in between these two clusters. The sharp decline in α-diversity in the plow pan horizon, as well as significant differences between the communities of A and B horizons indicate that the soil microbiomes are horizon-specific.

26342. 题目: DNA occurrence in organic matter fractions isolated from amended, agricultural soils
文章编号: N180625A0
期刊: Applied Soil Ecology
作者: Claudio Zaccone, Luciano Beneduce, Concetta Lotti, Giulia Martino, César Plaza
更新时间: 2018-06-25
摘要: The persistence of soil organic matter (SOM) constituents as a function of their recalcitrance has been recently questioned, with several papers showing the influence of the combined action of physical protection and chemical stabilization mechanisms as the main factors affecting SOM mean residence time. Using a physical fractionation method, SOM located between aggregates (FR), occluded within macro- (MA) and micro-aggregates (MI), and associated with the mineral fractions (MIN) were isolated from an agricultural soil differently amended (using compost, sewage sludge and biochar), and the occurrence of (total, bacterial and plant) DNA in these SOM pools was investigated. Following physical fractionation, total DNA (tDNA) was recovered from all SOM pools and from all treatments. Independently from the amendment, most tDNA accumulates in the FR fraction (30–70%), followed by the MIN pool (25–55%). The positive correlation between tDNA contents and C/N ratios (both tending to decrease following the order FR, MA and MI) observed for the light SOM fractions, together with the opposite pattern characterizing the heavy, MIN fraction (characterized by relatively high tDNA contents and low C/N ratios), suggests a different origin of the latter SOM pool, i.e., new molecules resulting from microbial transformations rather than highly degraded litter inputs. Therefore, tDNA may represent a promising proxy of organic matter dynamics in mineral soils. Finally, the MI fraction shows the highest number of microbial taxa and diversity, and seems to constitute a separate microbial niche in which different bacterial communities carry out their activity.

26343. 题目: Effect of water table decline on the abundances of soil mites, springtails, and nematodes in the Zoige peatland of eastern Tibetan Plateau
文章编号: N18062599
期刊: Applied Soil Ecology
作者: Xue Wei, Rui Cao, Xinwei Wu, Nico Eisenhauer, Shucun Sun
更新时间: 2018-06-25
摘要: Despite the important role of soil fauna in the decomposition of soil organic matter, the abundance response of soil fauna to environmental changes has been scarcely studied in peatlands, where soil carbon content is exceptionally high. The water table of the Zoige peatland, the largest alpine peatland worldwide, has been declining due to climate change and human drainage in recent decades, which likely induces changes in the abundance of soil fauna. In order to examine the abundance response of soil mites, springtails, and nematodes to water table decline in the Zoige peatland, we conducted an in situ field drainage experiment, consisting of low, intermediate, and ambient water table levels for four consecutive years. We measured the abundances of mites, springtails, and nematodes at five soil depths (0–5, 5–10, 10–15, 15–20, and 20–25 cm), for four times in the third and fourth year of the experiment. Results show that the effect of water table decline on the abundance of soil fauna varied among soil animal groups, soil depths, and the sampling times over the course of the experiment. While mites did not respond significantly to the experimental treatments, the abundance of springtails at soil depths of 0–5, 5–10, and 10–15 cm and that of nematodes at a depth of 15–20 cm were significantly higher in the drained treatments than in the undrained one. Moreover, water table decline increased the proportion of herbivorous nematodes in the top soil (0–5 cm) and decreased the proportion of bacterivorous nematodes at soil depths of 0–5 and 5–10 cm, while fungivorous and omnivorous-predaceous nematodes did not respond significantly. Given the demonstrated importance of soil fauna to soil carbon dynamics, the changes in the abundances of soil mites, springtails, and nematodes depicted here indicate that soil fauna should be further studied in relation to the recently reported rapid loss of soil carbon in the Zoige peatland.

26344. 题目: Effects of permafrost thaw-subsidenceon soil bacterial communities in the southern Qinghai-Tibetan Plateau
文章编号: N18062598
期刊: Applied Soil Ecology
作者: Xiaodong Wu, Lin Zhao, Guimin Liu, Haiyan Xu, Xiaolan Zhang, Yongjian Ding
更新时间: 2018-06-25
摘要: Permafrost thaws cause ground subsidence as the ground ice melts and drains away. Little is known about the effects of this permafrost thaw subsidence on bacterial communities. In this study, using Illumina sequencing methods, we investigated the structure of bacterial communities in the upper 50 cm of the soil in a typical permafrost thaw subsidence area on the southern Qinghai-Tibetan plateau. The micro topographies in the study area were classified as control, collapsing, and subsided types. Results showed that the organic carbon content in the collapsing areas was slightly lower than that in the control areas, while there was a substantial decrease in the subsided areas, with a loss of 23.6 ± 13.2% of organic carbon. The microbial carbon contents showed the highest values in collapsing areas. For all three types of soils, the most abundant microbial groups were Proteobacteria, Acidobacteria, and Bacteroidetes. The Non-metricmultidimensionalscaling (NMDS) results showed that the bacterial communities were different in the subsided areas than in the control and collapsing areas. In the control and collapsing areas, the soil bacterial communities showed a clear vertical distribution pattern with depth, which was not apparent in the subsided areas. The bacterial communities also correlated with soil variables such as carbon, moisture, nitrogen contents, and the C:N ratio. The ground subsidence can greatly change these variables. The results suggested that permafrost thaw subsidence had important effects on microbial communities via the changes of soil properties.

26345. 题目: Incorporation of rice straw carbon into dissolved organic matter and microbial biomass along a 100-year paddy soil chronosequence
文章编号: N18062597
期刊: Applied Soil Ecology
作者: Xiaofen Chen, Ming Liu, Yakov Kuzyakov, Weitao Li, Jia Liu, Chunyu Jiang, Meng Wu, Zhongpei Li
更新时间: 2018-06-25
摘要: Dissolved organic matter (DOM) and microbial biomass (MB) are small but reactive pools of soil organic matter (SOM). The incorporation of carbon (C) from rice residue into DOM and MB in paddy soils under aerobic condition when rice straw remains in the field is poorly understood. A one-year incubation experiment was conducted, in which 13C-labelled rice straw was added to a cultivation chronosequence of paddy soils ranging from 0 to 100 years. Rice straw was rapidly decomposed during the first 30 days, after which 73% of the added straw C, on average, was retained in the soil and 46% of the straw C remained in the soil after one year. Throughouttheentireincubation period, 0.2–0.9% of the added straw C was incorporated into DOM, and 2–5% was recovered in MB. The paddy cultivation age strongly affected the straw contribution to the organic C pools. In barren land (0 year), 32–60% of the DOM was derived from straw C, while 13–30% of the DOM was derived from straw C in 5–100-year paddy soils. On average, straw C contributed to 88% of the MB in barren land, 50% in 5-year soil, and 13% in 100-year soil. Consequently, over the duration of paddy cultivation, the contribution of rice straw C to the MB decreased, while the contribution of SOM increased. Our study has indicated that DOM in paddy soils mainly originates from SOM rather than from added plant residues but that plant residues are an important C source for microorganisms.

26346. 题目: Intertidal zonation affects diversity and functional potentials of bacteria in surface sediments: A case study of the Golden Bay mangrove, China
文章编号: N18062596
期刊: Applied Soil Ecology
作者: Ping Zhu, Yaping Wang, Tiantian Shi, Xiaoli Zhang, Guoqiang Huang, Jun Gong
更新时间: 2018-06-25
摘要: The combined effects of intertidal zonation and mangrove vegetation on benthic bacterial communities and ecological functions were studied. MiSeq sequencing of the 16S rRNA gene and PICRUSt predictive functional profiles were used to investigate the diversity, community structure and potential metabolic functions of benthic bacteria in surface sediments of a mangrove ecosystem. Compared with the lower intertidal zone, bacterial alpha diversity and richness were significantly higher in the upper intertidal zone and highly associated with sediment organic matter. The upper zone was occupied by higher proportions of heterotrophic bacteria involved in the degradation of organic compounds. These included Desulfobacterales, Anaerolineae and Acidobacteria, while the proportion of Rhodobacterales and Xenococcaceae was greatly increased in the lower zone. No significant difference of either alpha diversity or community composition was found between rhizosphere and bulk sediments, except that higher relative proportions of Rhizobiales and Actinobacteria occurred in rhizosphere sediments. The shift in bacterial community structure was mainly driven by changes in sediment Pb and NH4 + concentrations. Among the major carbon, nitrogen and sulfur cycling processes examined, higher potentials of cellulose and hemicellulose degradation, dissimilatory sulfate reduction, and nitrate or nitrite reduction occurred in the upper intertidal zone. Assimilatory sulfate reduction and sulfur oxidation potentials were higher in the root-associated sediments than in the bulk sediments. This study indicated that intertidal zonation was more important than root effects in modulating benthic bacterial diversity and functional potentials in a mangrove ecosystem.

26347. 题目: Organic fertilization shapes the biodiversity of fungal communities associated with potato dry rot
文章编号: N18062595
期刊: Applied Soil Ecology
作者: Katarzyna Gleń-Karolczyk, El?bieta Bolig?owa, Jacek Antonkiewicz
更新时间: 2018-06-25
摘要: Intensive farming based on synthetic pesticides and mineral fertilizers has led to a loss of soil biodiversity, which contributes to the suppression of plant pathogens. The key role in the restoration of biodiversity and soil aggregate stability is fulfilled by organic fertilization. Potato reacts well to this type of fertilization. On the other hand, its tubers, during both the vegetative and storage periods, are exposed to a series of infections caused by soil fungi. Of particular economic importance is dry rot, a storage disease with a complex etiology. This study presents an evaluation of the impact of different organic fertilization forms (manure, white mustard intercrop, barley stubble, barley straw and a combination of barley straw and white mustard intercrop) on losses caused by dry rot. For the first time, their role in the formation of: counts, species composition and belonging to frequency and trophic groups of fungi communities colonizing dry-rotting tubers has been specified. Furthermore, a pioneering element of this research is its evaluation of fungi community biodiversity and its influence on the development of dry rot. The main discoveries are as follows: (i) 24 fungi species (14 pathogenic, 6 saprotrophic, 4 antagonistic), which are the cause of dry rot; (ii) dry rot development is mainly determined by the share of saprotrophic fungi, where their increase reduces the percentage of infected tubers; (iii) manure and white mustard favors tuber colonization by saprotrophic and antagonistic fungi and increases biodiversity of the fungi, which results in improved healthiness; (iv) straw and a lack of fertilization increase the frequency of pathogens and reduce biodiversity, resulting in a stronger development of dry rot. In sustainable agriculture management systems, disease risk can be minimized through introduction of organic matter to soil.

26348. 题目: Plant cover and management practices as drivers of soil quality
文章编号: N18062594
期刊: Applied Soil Ecology
作者: S.C. Panico, V. Memoli, F. Esposito, G. Maisto, A. De Marco
更新时间: 2018-06-25
摘要: Human activities intensively modify soil properties and quality according to land-use and management practices. In Mediterranean areas, pollution and fires may directly alter some soil abiotic properties as well as the steady-state condition of soil microbiota. The aim of this study was to evaluate if the chemical and biological characteristics of two kinds of soil, Arenosols and Andosols, of a natural reserve and an urban park respectively, were affected by the same or different plant covers (trees and grasses). At each site, five sub-samples of surface soils (0–10 cm) were collected under maquis (trees) and gap of grasses. The soils were analyzed for physico-chemical parameters (organic matter and water contents, pH, C, N, Cr, Cu, Ni and Pb concentrations) and biological parameters (microbial and fungal biomass, respiration, metabolic quotient and coefficient of endogenous mineralization). The soil quality was evaluated through an integrated index, calculated taken into account all the investigated parameters. The results highlighted that soils under trees inside the urban park, with the highest amount of organic matter, showed higher microbial biomass and activity as compared to soils under grasses. The high concentration of Cu and Pb in these latter soils inhibited the microbial biomass and activity that were not exclusively affected by litter quality. Soil quality would seem to be strongly affected by the pedogenetic derivation and the management practices more than plant covers.

26349. 题目: Reduced efficiency of tropical flies (Diptera) in the decomposition of snail cadavers following molluscicide poisoning
文章编号: N18062593
期刊: Applied Soil Ecology
作者: Finbarr G. Horgan, Carmencita C. Bernal, Socrates Letana, Alberto I. Naredo, Daniel Ramp, Maria Liberty P. Almazan
更新时间: 2018-06-25
摘要: Decomposition is a key ecosystem service that reduces non-living organic matter, returning nutrients to the soil. In this study, we examine the responses by fly (Diptera) communities to molluscicide-poisoned apple snail (Pomacea canaliculata) cadavers in a tropical rice production landscape. Fewer molluscicide-poisoned cadavers were colonised by decomposer flies (niclosamide = 61% of cadavers with fly larvae; methaldehyde = 53%; Camellia sp. seed extract [saponin] = 50%) compared to control (freezer-killed) cadavers (81%). Metaldehyde, niclosamide and saponin reduced the abundance (average 51% reduction), biomass-density (average 63% reduction) and species richness (average 38% reduction) of flies emerging from the snail cadavers. The decay of control cadavers was generally faster (57% more tissue removed over 3 days) than molluscicide-treated cadavers. We suggest that poisoned carcasses potentially affect ecological communities across a range of trophic levels.

26350. 题目: The effect of earthworm and arbuscular mycorrhizal fungi on availability and chemical distribution of Zn, Fe and Mn in a calcareous soil
文章编号: N18062592
期刊: Applied Soil Ecology
作者: H. Dehghanian, A. Halajnia, A. Lakzian, A.R. Astaraei
更新时间: 2018-06-25
摘要: Micronutrient deficiencies most frequently occur in calcareous soils. In sustainable soil management enhanced soil biological activity has been proposed as a method for improving soil fertility. Therefore, the objective of this study was to evaluate the effect of earthworm and arbuscular mycorrhizal fungi (AMF) on fractionation and availability of Zn, Fe and Mn in a calcareous soil under maize cultivation. For this purpose a greenhouse experiment was conducted with four treatments including control, earthworm addition (E), AMF inoculation (AMF) and both earthworms addition and AMF inoculation (E + AMF). The results showed that the biological treatments (E, AMF and E + AMF) significantly increased Zn, Fe and Mn uptake by maize. Although the presence of earthworms in E + AMF treatment had no significant effect on mycorrhizal colonization but decreased the concentration of Zn and Mn in shoot compared to AMF treatment. Dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased in all biological treatments. The highest amount of DOC and MBC were found in treatments containing earthworms (E and E + AMF) and E + AMF treatment respectively. The biological treatments significantly decreased bound to Fe-MnO fraction of studied elements compared to control. Due to the slight changes in other fractions, it seems that biological treatments increased the uptake of Zn, Mn and Fe by maize probably with impact on bound to Fe-MnO fractions.

26351. 题目: Soil organic carbon stock in grasslands: Effects of inorganic fertilizers, liming and grazing in different climate settings
文章编号: N18062591
期刊: Journal of Environmental Management
作者: Samuel Eze, Sheila M. Palmer, Pippa J. Chapman
更新时间: 2018-06-25
摘要: Grasslands store about 34% of the global terrestrial carbon (C) and are vital for the provision of various ecosystem services such as forage and climate regulation. About 89% of this grassland C is stored in the soil and is affected by management activities but the effects of these management activities on C storage under different climate settings are not known. In this study, we synthesized the effects of fertilizer (nitrogen and phosphorus) application, liming and grazing regime on the stock of SOC in global grasslands, under different site specific climatic settings using a meta-analysis of 341 datasets. We found an overall significant reduction ( 8.5%) in the stock of SOC in global managed grasslands, mainly attributable to grazing ( 15.0%), and only partially attenuated by fertilizer addition (+6.7%) and liming (+5.8%), indicating that management to improve biomass production does not contribute sufficient organic matter to replace that lost by direct removal by animals. Management activities had the greatest effect in the tropics ( 22.4%) due primarily to heavy grazing, and the least effect in the temperate zone ( 4.5%). The negative management effect reduced significantly with increasing mean annual temperature and mean annual precipitation in the temperate zone, suggesting that temperate grassland soils are potential C sinks in the face of climate change. For a sustainable management of grasslands that will provide adequate forage for livestock and mitigate climate change through C sequestration, we recommend that future tropical grassland management policies should focus on reducing the intensity of grazing. Also, to verify our findings for temperate grasslands and to better inform land management policy, future research should focus on the impacts of the projected climate change on net greenhouse gas exchange and potential climate feedbacks.

26352. 题目: The impact of environmental policy on soil quality: Organic carbon and phosphorus levels in croplands and grasslands of the European Natura 2000 network
文章编号: N18062590
期刊: Journal of Environmental Management
作者: Andrea Hagyó, Gergely Tóth
更新时间: 2018-06-25
摘要: In this study, the Natura 2000 nature protection network of the European Union is assessed in the context of soil quality management. We explore the hypothesis that the soil quality of croplands and grasslands — as indicated by soil organic carbon and phosphorus levels — is better in terms of environmental parameters within the Natura 2000 network than outside it. The soil organic carbon and phosphorus content of 479 cropland and 450 grassland sites within Natura 2000 were compared with their nearest neighbours outside the network. The comparisons were repeated for pairs of both cropland and grassland sites by soil texture groups. The study revealed that organic carbon content was significantly higher in Natura 2000 sites than in non-protected areas for both croplands and grasslands. For croplands, this was true only for those with signs of ploughing, whereas for croplands without signs of ploughing there were no significant differences between Natura 2000 and non-protected areas. Areas with sand and loamy sand soils had significantly higher soil organic carbon content within the Natura 2000 network than outside it, for both croplands and grasslands. This was the only texture class that showed a significant difference in the case of croplands, whereas three further texture groups had higher soil organic carbon content in Natura 2000 grassland sites than on grassland sites outside this network. There was no significant difference in soil phosphorus content between areas within the Natura 2000 network and non-protected areas, except for grasslands with light textured soils, where soil phosphorus levels were significantly lower within Natura 2000 sites than outside them. The results suggest that the management of croplands and grasslands of Natura 2000 sites tends to perform better than that of adjacent areas with similar land cover in terms of soil carbon conservation. The difference is more evident for sites with certain soil characteristics. On the other hand, the nutrient input - as determined by phosphorus levels - of Natura 2000 croplands and grasslands generally does not appear to be less intensive than that of surrounding areas outside the network.

26353. 题目: Evaluation of water treatment capacity, nutrient cycling, and biomass production in a marine aquaponic system
文章编号: N18062589
期刊: Ecological Engineering
作者: Suzanne E. Boxman, Michael Nystrom, Sarina J. Ergas, Kevan L. Main, Maya A. Trotz
更新时间: 2018-06-25
摘要: The need to expand marine fish production and improve the economic viability and sustainability of recirculating aquaculture systems led to the development of a zero-discharge, marine aquaponic system. In this study, water treatment capacity, nutrient cycling, and biomass production were evaluated in a prototype, commercial-scale marine aquaponic system that included a moving bed bioreactor (MBBR) for nitrification, a sand filter for solids removal and denitrification, and hydroponic plant beds. Red drum (Sciaenops ocellatus), two species of edible halophytes sea purslane (Sesuvium portulacastrum) and saltwort (Batis maritima), and organic solids, were successfully produced over a 9-month period. Extensive analysis of solids, organic matter, and nutrients (nitrogen and phosphorous) in water and plant biomass was used to develop detailed mass balances on the system. Simultaneous operation of the moving bed bioreactor (MBBR) and plant beds resulted in high ammonia removal rates, allowing the system to support a high fish biomass density (38.8 kg/m3). Passive denitrification was the main nitrate removal mechanism, contributing to approximately 59% of aqueous nitrogen removal. Conversion of a sand filter to a side-stream denitrification reactor resulted in removal of 17% of the daily aqueous nitrogen load and prevented nitrate accumulation in the system. In addition to fish and edible halophyte production, 34 kg of organic solids were harvested from the sand filter and provided to a commercial nursery that used the solids as a fertilizer. This study demonstrates that marine aquaponics is an effective way to simultaneously produce marine fish, edible halophytes, and fertilizer. Addition of biological MBBR and a denitrifying sand filter was shown to be beneficial in situations where there are space limitations for plant growth, unexpected plant losses, or to support high densities of fish.

26354. 题目: Performance of ornamental plants in monoculture and polyculture horizontal subsurface flow constructed wetlands for treating wastewater
文章编号: N18062588
期刊: Ecological Engineering
作者: Ana María Leiva, Romina Nú?ez, Gloria Gómez, Daniela López, Gladys Vidal
更新时间: 2018-06-25
摘要: The aim of this study was to evaluate the effect of two ornamental plants in monoculture and polyculture horizontal subsurface flow (HSSF) constructed wetlands for treating wastewater. Two pilot-scale HSSF systems each with a surface area of 4.5 m2 were operated over two years (2015 and 2016); a) one was planted with a mixture of Cyperus papyrus and Zantedeschia aethiopica (HSSF-Cyp/Zant), and b) the other was planted only with Cyperus papyrus (HSSF-Cyp). To compare the performance between monoculture and polyculture systems, in situ parameters and organic matter (chemical oxygen demand (COD) and biological oxygen demand (BOD5)), total suspended solids (TSS), nutrients (total nitrogen (TN) and total phosphorus (TP)) and pathogens (fecal coliform (FC) and total coliform (TC)) removal efficiencies were evaluated. Moreover, growth characteristics, biomass production and nutrients uptake of different plants used in HSSF systems were also compared. The removal efficiencies of organic matter, suspended solids, nutrients and pathogens during the operational years were above 60%, 90%, 10% and 1.8 Log most probable number (MPN)/100 mL, respectively, without significant differences between HSSF-Cyp/Zant and HSSF-Cyp. The biomass production and the density of both HSSF systems fluctuated between 19.7 and 21.5 kg dry weight (DW)/m2 and 454–684 individuals/m2. Regarding the nutrient content of different plants used, Zantedeschia aethiopica, which was planted in the polyculture system, had the highest TN and TP content in all plants tissues (59.6 g N/kg·DW and 8.28 g P/kg·DW, respectively). However, TN and TP mass balances determined that the effect of monoculture and polyculture systems was not significant. Despite these results, polyculture CWs represent a good alternative of treatment system because they provide social benefits to the community such the improving of the system landscape and a better habitat quality. Moreover, some authors reported that polyculture system enhance the resistance to environmental stress and disease and the system landscape.

26355. 题目: Relationship between groundwater levels and oxygen availability in fen peat soils
文章编号: N18062587
期刊: Ecological Engineering
作者: Jan Dickopp, Andreas Lengerer, Marian Kazda
更新时间: 2018-06-25
摘要: Groundwater levels (GWL) are a major controlling factor for aeration and organic matter turnover in wetland soils but little is known about this relationship under field conditions. This study tested how the O2 availability in fen peat soils is related to groundwater levels. The study encompassed five sites over a wide range of land use intensity. Ground water levels and soil oxygen saturation in 5 cm and 20 cm depth were measured biweekly in three replicates per site over periods of 2–3 years. The O2 levels were not linearly proportional to the GWL, but changed sharply from anoxic to nearly atmospheric levels depending on the positions of water table. Binary logistic regression analyses (LRA) were calculated for the individual sites in order to predict the threshold GWL for defined probabilities of hypoxic or oxic conditions in 5 cm depth. The GWLs for 95% probability of oxic conditions were markedly lower for the managed grasslands ( 116 cm and 89 cm to surface level, respectively) than for the unmanaged pasture and the sedge fen ( 60 cm and 38 cm). Hypoxic conditions required GWLs close to the surface (7 cm and 2 cm for the pasture and the restored site, respectively) while in 5 cm soil depth managed grasslands remained hypoxic even at GWLs of 8 cm and 28 cm. In 20 cm soil depth, full oxygen saturation never occurred even at GWL as low as 80 cm. Threshold GWL required for 95% probability of oxic conditions was higher with increasing porosity and rooting density. The offset between GWL and oxic conditions can be used for hydrological wetland management, especially for restoration efforts.

26356. 题目: Vermistabilization of paper mill sludge by an epigeic earthworm Perionyx excavatus: Mitigation strategies for sustainable environmental management
文章编号: N18062586
期刊: Ecological Engineering
作者: Ananthanarayanan Yuvaraj, Natchimuthu Karmegam, Ramasundaram Thangaraj
更新时间: 2018-06-25
摘要: The present study demonstrates the vermistabilization of paper mill wastewater sludge (PMS) spiked with cow dung (CD) employing indigenous epigeic earthworm Perionyx excavatus Perrier. A total of six treatments were prepared along with a positive control (PC) and negative control (NC). Twenty earthworms were released into each treatment including PC and NC without earthworms. The different proportions viz., T1 (CD – 100%), T2 (PMS:CD – 1:3), T3 (PMS:CD – 1:2), T4 (PMS:CD – 1:1), T5 (PMS:CD – 3:1), T6 (PMS:CD – 2:1), PC (PMS – 100%) and NC (PMS – 100%) and changes in chemical parameters and microbial properties were recorded during the course of 60 days. Vermistabilization caused a significant decrease in the level of heavy metals: Cd (2.9–27.8%), Cu (0.22–42.3%), Pb (1.3–56.3%) and Cr (0.8–46.2%). The bioconcentration factor (BCFs) was also calculated and great amount of heavy metals accumulated in their body (mg kg 1) that ranged from 0.31 ± 0.003–0.45 ± 0.007 for Cd, 0.12 ± 0.005–0.24 ± 0.003 for Cu, 0.15 ± 0.005–0.31 ± 0.006 for Pb and 0.29 ± 0.007–0.56 ± 0.001 mg kg 1 for Cr, accumulation of heavy metals are in the order: Cr > Cd > Pb > Cu. The physicochemical parameters of earthworm treated substrate such as electrical conductivity, total nitrogen, total phosphorus and total potassium were significantly increased; whereas, pH, total organic carbon, C:N ratio (carbon: nitrogen) and C:P ratio (carbon: phosphorus) were reduced after 60 days of vermistabilization. The vermistabilized materials also had a higher population of bacteria (98.90 ± 0.30 CFU × 106 g 1), fungi (43.75 ± 0.55 CFU × 103 g 1) and actinomycetes (67.65 ± 0.45 CFU × 105 g 1) than initial mixtures. Moreover, several histopathological changes were observed in earthworm tissues viz., disintegration of cells, irregular surface of epidermis, cellular debris, irregular cellular compartmentation, and oval-shaped nucleus. Higher level of histopathological abnormalities was recorded in PC (PMS-100%) while none were detected in lower concentrations of PMS. Furthermore, the study concludes that the paper mill sludge in a mixture of cow dung (1:1 ratio) can be a useful proposition for utilizing this hazardous waste through the adoption of vermitechnology.

26357. 题目: Changes in soil enzymes, soil properties, and maize crop productivity under wheat straw mulching in Guanzhong, China
文章编号: N18062585
期刊: Soil and Tillage Research
作者: Kashif Akhtar, Weiyu Wang, Guangxin Ren, Ahmad Khan, Yongzhong Feng, Gaihe Yang
更新时间: 2018-06-25
摘要: Addition of organic material, such as crop straw mulch in most soils is considered a strategy for sustainable agricultural production. We conducted a two-year experiment in 2015 and 2016 to determine changes in soil biochemical properties and maize yield in response to treatment with wheat-straw mulch. The treatments consisted of the addition of different levels of wheat-straw mulch (S1: 0, S2: 2500, S3: 5000 kg ha 1). Soil samples from four depths (0.1, 0.2, 0.3, and 0.4 m) were collected and analyzed. Soil enzymes, such as invertase, phosphatase, urease, and catalase, were significantly higher in the S3 treatment than in the S1 treatment. Values were greater for the samples collected at 0.1 m soil depth than those collected from deeper soil layers. Regarding soil properties, soil organic carbon (SOC), available nitrogen (AN), available phosphorus (AP), total nitrogen (TN), total phosphorus (TP), and soil water content (SWC) were significantly higher in S3 at 0–0.1 m soil depth than in other treatments. Compared with the (S1), an average increase in SOC, AN, AP, TN, TP, and SWC in 0–0.4 m soil depth with full straw mulch (S3), were 32.4, 31.9, 32.0, 11.8, 16.7, and 18.5%, higher, respectively. On average, urease, phosphatase, invertase, and catalase increased by 15.1, 11.0, 88.4, and 24.0%, respectively in the S3 treatment compared with that in the S1 treatment at 0–0.1 m depth, and decreased with increasing soil depth. The S3 treatment had increased grain yield (7%), biomass yield (28%), and water use efficiency (8%), compared with the S1 treatment. Overall, our results suggested that the S3 straw mulch treatment (5000 kg ha 1) could be used to sustain maize productivity and promote a better relationship between soil enzymes and soil properties in the semi-arid conditions of the Guanzhong area.

26358. 题目: Characterization of the heavy, hydrolysable and non-hydrolysable fractions of soil organic carbon in conventional and no-tillage soils
文章编号: N18062584
期刊: Soil and Tillage Research
作者: Ravindra Ramnarine, Robert P. Voroney, Kari E. Dunfield, Claudia Wagner-Riddle
更新时间: 2018-06-25
摘要: Quantification of soil organic carbon (SOC) pool fractions under different tillage systems is important in understanding SOC dynamics and storage. Two major pools of SOC that can be isolated are the light (LF) and heavy fractions (HF). Few studies have quantified the effect of tillage systems on the hydrolysable (HYF) and non-hydrolysable fractions (NHF) which comprise the HF. The objective of this study was to evaluate if there were significant changes in the quantity and δ13C of the HF, HYF, and NHF fractions of SOC after six years of no-tillage (NT), on arable soils that were previously under conventional tillage (CT). Our study used 13C natural abundance (rotation of C3 and C4crops) on a calcareous Typic Hapludalf soil in southern Ontario, Canada. The HF (>1.7 g cm 3) was isolated using density fractionation and separated into its HYF and NHF using acid hydrolysis (6 M HCl) for three soil depths: 0–10, 10–20, and 20–30 cm. The HF pool (90–93% of SOC) was significantly greater (P < 0.05) in the NT (28.9) than the CT system (25.5 Mg C ha 1) only for the 0–10 cm depth. The dominant SOC fraction from the HF pool was the NHF (62–65% of SOC) for both tillage systems. However, the HYF (25–30% of SOC) was significantly greater in the NT (9.3) than the CT system (7.0 Mg C ha 1) only for the 0–10 cm depth. Additionally, there was a significantly higher proportion of C4-derived C in the HF only at the 0–10 cm depth of NT soils. Differences in the δ13C of the whole soil and SOC fractions show a preservation of newly derived C in the HF, HYF and NHF of NT soils. We conclude that the adoption of NT systems on arable soils increases the quantity of HF and HYF in the 0–10 cm depth only, but there is no difference in carbon sequestration potential when treatments are compared over the 0–30 cm depth in the short-term.

26359. 题目: Consolidation and surface sealing of nine harrowed Swedish soils
文章编号: N18062583
期刊: Soil and Tillage Research
作者: Maria Sandin, Nicholas Jarvis, Mats Larsbo
更新时间: 2018-06-25
摘要: The structure of agricultural topsoils varies considerably throughout the year due to interactions between climatic and biological factors and agricultural management practices. Tillage generally decreases soil density and increases macroporosity, but the resulting arrangement of clods and aggregates is unstable and the soil eventually reverts back to its denser pre-tillage condition. Accounting for post-tillage changes in soil structure and related hydraulic properties could greatly improve model predictions of hydrological and transport processes. Model testing, development and parameterization is, however, currently hampered by a lack of direct measurements of the changes occurring in the structural pore system. We subjected repacked samples of soil collected from the harrowed layer of nine different fine- and medium-textured Swedish mineral soils to subsequent wetting and drying cycles in the laboratory. Initial wetting and equilibration at 30 cm pressure potential was followed by three cycles of simulated rainfall (5 mm h 1 for 4 h) and equilibration. X-ray tomography was used to quantify changes in surface and total porosity, pore size distribution (PSD) and connectivity of structural pores. Total porosity decreased (by 2–24%) in all soils except for two clay soils where in one case the porosity increased slightly (3%) and remained unchanged in the other. In six of the soils, the PSD shifted significantly towards smaller pore sizes, and in four of these soils the connectivity of the pore network decreased. Soil surface porosity decreased most markedly in two silt loam soils (by 73% and 75%). For the nine soils changes were strongly correlated with silt content. Only weak correlations were found between the changes in total porosity and soil texture and organic carbon content. Changes in the PSD appeared to be mainly controlled by the initial structure of the sample created at the time of tillage and sample preparation.

26360. 题目: Crop yield, weed infestation and soil fertility responses to contrasted ploughing intensity and manure additions in a Mediterranean organic crop rotation
文章编号: N18062582
期刊: Soil and Tillage Research
作者: Paola Baldivieso-Freitas, José M. Blanco-Moreno, Laura Armengot, Lourdes Chamorro, Joan Romanyà, Francisco Xavier Sans
更新时间: 2018-06-25
摘要: Conservation agriculture and organic farming are two alternative strategies that aim to improve soil quality and fertility in arable cropping systems through reducing tillage intensity, maintaining soil cover and increasing nutrient recycling, using farmyard and green manures. However, these practices can increase weed infestation or decrease nutrient availability. The objectives of this study were to evaluate the effects of tillage type (mouldboard vs. chisel ploughing), fertilization and green manure on soil parameters (SOC, N, bulk density, carbon stocks, and soil microbial biomass Cmic and Nmic), weed abundance and crop yields in a four-year rotation of spelt, chickpea, winter wheat and lentil in the Mediterranean region (Catalonia, Spain). Tillage and green manure did not affect crop yields or weed biomass, although during the last year of the experiment, plots with mouldboard ploughing had less weed biomass and higher lentil biomass. Fertilization was the most important factor, increasing the cereal yields, SOC, N and soil microbial biomass (Cmic and Nmic) content of the soil. However, fertilization did not favour chickpea and lentil crops because weed competition limited legume crop growth. Overall, there was a loss of SOC and a reduction of carbon stocks over the four years of the trial in the soil because of the deep soil tillage (25 cm) and low crop productivity irrespective of tillage type. In contrast, N content increased in all of the plots and was enhanced by fertilization. The use of chisel plough stratified the distribution of SOC and N in the surface layers (0–10 cm). Both Cmic and Cmic/SOC ratio increased in fertilized treatments, suggesting an increased lability of SOC. The application of more stabilized organic matter may be a better practice to build up soil organic matter and to maintain crop yields in organic farming systems.