粪肥施用土壤抗生素抗性基因来源、转移及影响因素

随着新型抗生素开发速度的不断下降以及抗性基因(Antibiotic resistant genes,ARGs)的快速出现和传播,细菌抗药性和ARGs对公共健康存在威胁,被公认为当前全球亟待解决的难题。虽然土壤本底存在ARGs,但畜禽粪便施用等人类活动加速了ARGs在土壤环境中的扩散和传播。粪肥施入土壤后,其对土壤微生物的抗性选择压力及基因水平转移导致的ARGs扩散转移将持续存在。畜禽粪便中的抗性细菌所携带的ARGs、土壤中抗生素累积导致微生物产生的ARGs和粪肥刺激含有ARGs微生物的繁殖等均为土壤中ARGs的主要来源。土壤中ARGs可以向水体和农作物传移,并随着食物链向动物及人类传播。自然因素(温度、降水、时间和土壤类型)和人为因素(抗生素的含量和种类、粪便种类和处理方式、重金属含量及生物质炭添加)均会影响土壤中ARGs的持久和扩散。目前,粪肥施用土壤中ARGs污染对环境质量及健康的潜在影响并不完全清楚,建议加强模型建立、溯源、生物地理分布、从污染源向环境介质的转移规律、削减措施和机制等方面研究,以有效遏制ARGs在环境中的污染,真正做到畜禽粪便资源化、无害化利用。     

磺胺嘧啶对土壤氮矿化及相关微生物参数的影响

兽用抗生素进入土壤,已经带来了新的土壤污染生态学问题,并已引起广泛关注。本文研究了不同浓度磺胺嘧啶残留对土壤氮矿化量及相关微生物参数的影响。结果表明,磺胺嘧啶对土壤氮矿化产生抑制作用,且抑制作用在低浓度比高浓度更为敏感。通过主成分分析和多元回归分析可知,在各相关微生物参数中,土壤微生物群落功能多样性可作为预测磺胺嘧啶残留时土壤氮矿化强度变化的指标。     

基于文献计量的近30年国内外土壤微生物研究分析

为了解国内外土壤微生物的最新研究热点和发展趋势,借助Web of Science中SCI-EXPANDED数据库,利用VOSviewer、CiteSpace可视化分析软件等工具,对1990—2018年间发表的关于土壤微生物研究文献的国家、研究机构、期刊来源、主要研究内容及关注热点进行计量分析。结果表明,该领域的中国发文量呈快速增长趋势,但总被引频次较低;美国的发文量、总被引频次均位于首位。中国科学院是重要的研究机构,其发文量、总被引频次均位于第一,但篇均被引频次较低。主要的期刊来源有Applied and Environmental Microbiology、Soil Biology&Biochemistry等。国内关键词共现网络形成较晚,但发展速度较快,表现出同国外研究热点趋同的发展趋势。国内外研究热点主要集中于土壤微生物参与土壤有机质分解、碳氮养分循环、对污染土壤的微生物降解和修复作用、环境条件变化对土壤微生物群落结构多样性的影响、植物-微生物相互作用机理等。本文对了解土壤微生物研究领域的发展态势具有一定参考价值。     

畜禽粪便厌氧发酵过程抗生素抗性基因归趋及驱动因子分析

针对畜禽养殖业抗生素抗性基因(antibiotic resistance genes, ARGs)污染问题,该文选取厌氧发酵技术,对比不同厌氧发酵体系内ARGs消长与潜在宿主菌,挖掘不同因子与ARGs的相互关系。结果表明,厌氧发酵体系内微生物群落变化是ARGs消长的主要驱动因子,确定ARGs的潜在宿主菌是目前研究的难点;抗生素和重金属也是ARGs消长的重要驱动因子,控制抗生素污染和重金属污染可有效减缓ARGs污染;可移动遗传元件在ARGs水平传播过程中起着重要作用。综合而言,厌氧发酵体系内各个因子直接或间接影响ARGs消长,其中工艺参数是控制整个厌氧发酵体系的先决因素,在特定工艺参数下,微生物群落与体系物化指标相互影响与制约;微生物通过分子内部可移动遗传元件实现ARGs在不同微生物之间的水平传播。综上所述,通过综合协调各类因子实现厌氧发酵体系内ARGs消控是今后研究重点。     

我国畜禽粪肥还田对农田土壤抗性基因积累的影响综述

畜禽养殖粪肥还田导致抗生素及抗性基因(ARGs)在农田土壤中的残留与传播,农作物及土壤动物亦受到影响。论文以长期施用粪肥的农田为主要研究对象,在充分的文献阅读基础上,阐述了我国畜禽养殖粪肥所导致的农田生态系统中ARGs的残留情况,重点分析了我国农田土壤中ARGs的污染扩散程度以及粪源ARGs的传播路径,概述了粪肥种类和预处理技术等粪肥条件对还田土壤中ARGs水平的影响,并对后续研究提出了建议和展望。     

基于文献计量分析的土壤微生物入侵研究现状及发展趋势

随着农业经济发展,人类及其他动植物等的活动为外源微生物在食物链、环境介质中传播创造了条件,造成外源微生物频繁流动并对土壤生态系统产生扰动,进而引发微生物入侵。为了解国内外微生物入侵相关研究进展,本文利用CiteSpace、VOSviewer及HistCite对Web of Science核心合集数据库中微生物入侵领域的主要研究热点及其变化趋势等进行计量分析。结果表明：微生物入侵相关研究文献数量逐年上升,受到的关注度越来越高;美国、中国、德国、印度、澳大利亚等国家在该领域发文量居前列,且具有较紧密的国际学术合作网络;高通量测序与宏基因组为核心的微生物测定分析技术的快速发展,使得微生物入侵成为研究热点,当前的研究文献集中于根际促生菌作用机制、根际微生物群与植物健康等方面。研究指出有益微生物入侵可有效防治植物病害、促进植物生长以及修复污染土壤等,但病原微生物入侵土壤可造成作物减产、质量下降,甚至可经食物链传播而威胁人类及其他动物的健康,因此微生物入侵的影响与入侵菌株性质紧密相关。未来研究趋势主要集中于入侵微生物与特异性土著微生物的相互作用关系、植物病原微生物的防控机制与技术应用等方面,以期为土壤健康与绿色农业生产提供理论依据。     

基于文献计量分析的地下水中氨氮污染去除研究

为研究三十年来地下水中氨氮污染去除的研究热点与发展趋势，本文利用CiteSpace和VOSviewer文献可视化软件，分析了Web of Science数据库和CNKI数据库中已发表地下水中氨氮去除相关文献的发文数量、发文国家及机构、发文作者、载文期刊、关键词和共被引情况。结果表明：2000年之后，地下水氨氮污染去除研究的发文数量不断增长，中美两国在该领域的发文更多、联系更为紧密，近年来在相关政策的推动下，我国在该领域的研究成果明显增多；中国地质大学是发文量最多的机构。目前研究热点集中在材料吸附、厌氧氨氧化、硝化作用等去除方式，研究对象较多关注浅层含水层、潜流带的地下水，未来应更加强新型吸附材料筛选及微生物脱氮等技术的研发，同时注重评估修复技术的绿色可持续。     

土壤磷素形态及其分级方法研究进展

基于对土壤磷素相关文献的全面梳理与系统总结,明确国内外土壤磷素研究的现状、热点与未来发展趋势。以Web of Science核心数据库中1990 ~ 2021年间8444篇与土壤磷素相关的研究论文为数据源,利用CiteSpace软件对发文国家、机构、关键词及其聚类等进行可视化分析。结果表明：土壤磷素研究的发文数量从2017年开始快速增长。美国、中国和澳大利亚发文数量位列前三,其中美国和澳大利亚中介中心性较高。研究机构合作网络显示中介中心性较高的机构为中国农业科学院、阿德莱德大学和拉筹伯大学,其分别以农田磷素可持续管理、植物-微生物介导磷素利用效率、土壤磷组分和磷循环为研究重点。文献共被引分析表明,磷素的资源短缺、遗留效应、径流迁移特征和限制机制是该领域研究的重点内容。关键词共现网络、聚类和突现性分析表明,土壤氮磷互作、磷素-植物效应、磷素有效性、动态变化等是该研究领域的热点。研究趋势集中于微生物（群落）、养分限制（化学计量比）和气候变化等方面对土壤磷有效性和磷周转的影响。未来充分挖掘微生物资源、缓解土壤养分限制将为土壤磷素的可持续利用提供科学措施。     

基于文献计量法的土壤退化研究现状及热点分析

为揭示土壤退化领域研究现状、热点和趋势,采用文献计量法和CiteSpace软件,利用Web of Science数据库Science Citation Index子库检索1988—2018年的土壤退化领域相关文献,从关键词、作者、机构、国家等方面进行系统分析,得到结论:1988—2002年发文量8 357篇,2003—2018年发文量达到31 496篇,增长速度快;研究热点集中在土壤污染物、土壤微生物和化学农药等方面;该领域核心作者较多,有341位,在研究中起到了重要作用;美国的发文量最多、影响力最大,并且与其他多个国家存在合作关系,中国发文量仅次于美国,但合作国家数量较少,影响力有待提升;中国科学院、美国农业部、西班牙高等科学研究理事会发文量位居前三,但是中国科学院论文的质量和影响力有待提升。     

基于WoS引文数据库对2008—2021年土壤团聚体研究文献的计量分析

[目的]为深入了解国内外土壤团聚体研究进展和未来发展趋势,明确当前的热点问题,为土壤团聚体领域的科研工作者与决策者提供参考。[方法]基于Web of Science引文数据库,借助VOSviewer, CiteSpace科学图谱绘制软件和R语言的BiblioShiny程序分析工具,对土壤团聚体研究的发文量、期刊、国家(地区)、机构、关键词和主题演变进行计量分析。[结果]土壤团聚体领域发文量总体呈现上升的趋势;从国家研究实力上来看排在前三位的有中国、美国和德国,其中中国的发文量远超其他国家,比例为25.4%;研究机构中有中国科学院、中国科学院大学、西北农林科技大学占据主要地位;主要发文期刊有Geoderma,Soil&Tillage Research,Catena和Science of the Total Environment等;从战略坐标图和关键词分析可知土壤有机质(碳)为该领域研究的核心主题,“黄土高原”“保护性农业”“生态系统服务”“土壤健康”“微生物群落”等主题词是该领域近5 a来研究的热点内容。[结论]在气候变化背景下,土壤团聚体与有机质、微生物量研究是当前土壤团聚体...     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Variation in quality parameters between and within 14 Nordic tree fruit and berry species

Abstract

A 3-year study was carried out to investigate quality parameters in 14 tree fruit and berry species grown in southern Norway. The species were blueberry, apple, aronia, sour cherry, sweet cherry, red raspberry, strawberry, blackcurrant, gooseberry, red currant and elderberry, harvested along with wild bilberry, cloudberry and lingonberry. Significant differences between species were identified for all quality parameters. The coefficient of variation between species was lowest for pH (12.5%), dry matter (18.9%) and soluble solids (25.3%), followed by titratable acids (59.3%), total phenolics (83.8%), antioxidant capacity FRAP (85.7%) and antiradical power by the DPPH-assay (97.8%), total monomeric anthocyanins (132%) and ascorbic acid (137%). Average coefficient of variation within species were lower and ranged from 4 (pH) to 62% (ascorbic acid). Only the FRAP values were significantly affected by harvesting year with lower levels in 2004 than in 2005 and 2006. There were significant interactions between species and harvesting year for dry matter, soluble solids, pH, ascorbic acid and FRAP. The results indicate generic ranges in composition within species independent upon growing location and climate, and the composition of the tree fruits and berries is not likely to deviate from these ranges. It is concluded that desirable composition of tree fruits and berries and their products should primarily be achieved by selection among species rather than searching fors broadened variation within individual species.     

Potassium Fixation and Release Characteristics in Rhizosphere and Nonrhizosphere Soils for a Rapeseed–Rice Cropping Sequence

Potassium (K) fixation and release in soil are important factors in the long-term sustainability of a cropping system. Changes in K concentration and characteristics of K fixation and release in rhizosphere and nonrhizosphere soils in the rapeseed (Brassica napus L.)–rice (Oryza sativa L.) rotation were investigated using a rhizobox system. The concentrations of different forms of K in both rhizosphere and nonrhizosphere soils decreased with plants compared to without plants, regardless of K fertilizer application. Potassium uptake by crops mainly came from the rhizosphere soil. In the treatment without K fertilizer (–K), the main form of K supplied by the soil to the crops was 1.0 mol L^?1 nitric acid (HNO₃) nonextractable K, followed by nonexchangeable K, and then exchangeable K. In the treatment with K fertilizer (+K), the main K forms supplied by the soil to the crops were exchangeable K and nonexchangeable K. The amount and rate of K fixation after one cycle of the rapeseed–rice rotation was greater in rhizosphere soil than in nonrhizosphere soil. The amount and rate of K fixation of soil in the +K treatment were significantly less than in the –K treatment. The cumulative amounts of K released with 1.0 mol L^?1 ammonium acetate (NH₄OAc) and 1.0 mol L^?1 HNO₃ extraction increased with the increasing numbers of extractions, but the K-releasing power of soil by successive extraction decreased gradually and finally became almost constant. The release of K was less in rhizosphere soil than in nonrhizosphere soil. The release of K in the +K treatment was similar to that in the –K treatment in rhizosphere soil, but the K release in nonrhizosphere soil was greater with the +K than the –K treatment. Overall, the information obtained in this study will be helpful in formulating more precise K fertilizer recommendations for certain soils.