4种农药对枇杷园土壤磷酸酶活性及微生物呼吸的影响

应用室内培养方法研究了甲基托布津、代森锰锌、杀灭菊酯、阿维菌素4种农药对枇杷园土壤磷酸酶活性及微生物呼吸的影响,并对4种农药进行了安全性评价。结果表明,经杀菌剂甲基托布津和代森锰锌处理的土壤,磷酸酶活性受到明显抑制,且抑制效果未见恢复。经杀灭菊酯和阿维菌素处理的土壤,磷酸酶活性变化呈现"抑制-恢复-激活"趋势;抑制作用随农药浓度的升高而增强;但7d后磷酸酶活性受到了一定程度的激活,35d达到最高值;高浓度杀灭菊酯和低浓度阿维菌素显示出较强的激活作用。农药对土壤微生物呼吸作用的影响初期表现为轻微激活,5d后出现抑制作用,12d后基本恢复正常,接近对照水平。通过安全性评价可知,供试4种农药对土壤微生物的危害较小,为无毒害或无实际危害的农药。     

苯磺隆对土壤酶活性的影响

通过盆栽小麦试验,研究了苯磺隆污染对土壤尿酶、碱性磷酸酶和蛋白酶活性的动态影响。结果表明,苯磺隆处理前期(14d前)对土壤脲酶活性具有抑制作用(除第1天0.1、0.5mg/kg处理),且抑制作用随着苯磺隆浓度的增大而增强,第7天脲酶活性最小,最大抑制率为74.8%;处理后期(14d后)对脲酶活性具有一定的激活作用,最高激活率达183.0%。而低浓度苯磺隆对土壤碱性磷酸酶和蛋白酶具有一定的激活效应,高浓度苯磺隆对土壤碱性磷酸酶和蛋白酶具有抑制-激活效应,对碱性磷酸酶的抑制作用表现在处理的最初7d,对蛋白酶的抑制作用表现在处理前期(14d前)。结果表明苯磺隆对土壤酶活性的影响不仅与苯磺隆处理的浓度和培养时间有关,同时还与土壤酶的种类有关,土壤尿酶活性对表征苯磺隆污染具有一定的指示作用。     

施用木质素对土壤中尿素转化及释放的影响

通过室内培养试验,研究木质素不同用量对土壤NH4+-N含量、NO3--N含量、脲酶活性的影响。结果表明,木质素能抑制土壤脲酶活性,并且随木质素施入量的增加抑制强度增强。木质素对土壤脲酶活性的抑制时间主要在尿素施入土壤后1～14 d,在培养第8 d前后木质素对脲酶抑制率出现最大值,21 d后木质素对脲酶活性不再具有明显的抑制作用。木质素通过抑制土壤脲酶活性而延缓尿素的水解,降低铵态氮释放速度。在加入等量尿素态氮的情况下,木质素用量为0.3～0.6 g/kg,尿素水解时间延缓3 d;当木质素用量增加至2.7～6.7 g/kg时抑制时间延长到7 d。木质素同时抑制了土壤中铵态氮向硝态氮转化,降低土壤硝态氮含量,使施入的尿素较长时间以铵态氮的形式保存在土壤中。     

尿素与多效唑配施对苯磺隆胁迫下土壤酶活性的影响

通过盆栽试验,采用三因素完全随机设计,研究尿素、多效唑配施对苯磺隆胁迫下土壤脲酶、碱性磷酸酶、蛋白酶活性的影响。结果表明:不同浓度苯磺隆对土壤脲酶活性表现为抑制—激活作用,抑制和激活作用均随着苯磺隆浓度的增大而增强,第60 d激活率是对照的2.83倍;低浓度苯磺隆对碱性磷酸酶表现为激活—抑制—激活作用,高浓度苯磺隆表现为抑制—激活作用,第60 d极显著地高于对照,是对照的2.49倍;低浓度苯磺隆对蛋白酶活性表现为激活—抑制作用,高浓度苯磺隆表现为抑制—激活作用;尿素、多效唑(除B1N1处理对蛋白酶的影响外)配施可减弱苯磺隆对土壤脲酶、碱性磷酸酶和蛋白酶活性的抑制作用,大多数处理表现为抑制—激活作用,在处理结束时(第60 d),脲酶和碱性磷酸酶仍极显著地高于对照。     

生化抑制剂组合对黄泥田土壤尿素态氮转化的影响

采用室内恒温、恒湿培养方法,通过不同剂量和配比试验,研究脲酶抑制剂(N-丁基硫代磷酰三胺,NBPT)、硝化抑制剂(2-氯-6(三氯甲基)吡啶,NP)及其两者组合对尿素态氮在黄泥田土壤中的转化作用效果。结果表明:尿素在黄泥田土壤中,有效作用时间≤3d;不同剂量NBPT处理可以缓释尿素3~9d,有效抑制脲酶活性,减缓尿素分解(效果表现为1.0%0.5%0.25%),对土壤中NO3-生成量及表观硝化率的影响基本与尿素一致;不同剂量NP处理可以有效抑制NH4+-N向NO3--N转化,其有效调控时间长达72d以上(效果表现为0.6%0.3%0.15%)。第72d,不同剂量NBPT和NP处理土壤中表观硝化率分别为64%和43%左右,NP对硝化作用抑制效果显著(P0.05)。与仅添加NBPT和NP处理相比,在黄泥田土壤中两者组合表现出对氮素转化明显的协同抑制效果,既能缓释尿素施入3~9d,有效抑制脲酶活性,减缓尿素水解,又能保持土壤中较高NH4+-N含量的时间超过72d。其中,NBPT 0.5%+NP 0.3%组合抑制效果最佳。总体认为,在黄泥田土壤中施用生化抑制剂时,NBPT和NP选用范围分别为≤0.5%和≤0.3%。     

外源青霉素对菜田土壤酶活性与油菜品质的影响

通过向土壤中添加青霉素溶液的方法研究了油菜种植条件下不同浓度的外源青霉素对土壤脲酶、转化酶和蛋白酶等3种重要水解酶活性和油菜品质的影响.结果表明:青霉素加入土壤后.与不施加青霉素的对照相比,各浓度(0.15,0.3,0.45 mg/kg)的青霉索对土壤转化酶、蛋白酶活性的抑制率最高分别为45.67%,63.87%,69.43%和57.96%,63.68%,67.51%,培养14 d以后,各浓度青霉素对转化酶的抑制作用逐渐减弱;16 d以后,对蛋白酶活性的抑制作用才开始减弱.且酶活性的抑制程度及持续时间与处理浓度成正相关(r=0.95**).外源青霉素对土壤脲酶活性的影响在5 d前表现为激活作用,且激活作用随青霉素浓度的升高而增强,与对照相比.其最高激活率分别为1.03%,18.37%,20.23%;在6.7 d后表现为抑制作用,最高抑制率为62.84%～77.53%.脲酶、转化酶和蛋白酶的抑制时间分别为:28 d.28～49 d,42～56 d.收获期时.油菜叶片中可溶性糖与蛋白质含量分别下降78%～86.2%和5.2%～34.2%,且可溶性糖与蛋白质含量的降低程度与处理浓度成负相关(r=0.95**).     

包膜脲酶抑制剂增效尿素对小麦生长的影响及其机理研究

为有效提高尿素氮利用率,促进新型缓/控释氮肥的研发。在盆栽试验条件下,研究了脲酶抑制剂氢醌(HQ)部分或全部包膜与尿素掺混施用对小麦生长及土壤不同形态氮素含量和脲酶活性的影响。试验共设5个处理:对照(CK)、普通尿素(U)、U+普通HQ(SRU1)、U+包膜HQ(SRU2)和U+30%普通HQ+70%包膜HQ(SRU3)。结果表明:与SRU1相比,包膜HQ能够促进小麦生长,改善小麦产量构成,增加小麦产量,并提高氮素利用率,其中SRU2、SRU3分别增加了小麦产量的34.71%,56.54%;与SRU2相比,SRU3处理中普通HQ与包膜HQ配合施用前期能够有效抑制尿素水解,维持土壤中NH_4~+—N的适宜浓度,后期能增加土壤NH_4~+—N含量,保证土壤有效氮的持续供应,减少氮素损失,使小麦整个生育期内土壤脲酶活性维持在较低水平。综上,HQ部分包膜与尿素掺混施用的SRU3处理土壤氮的供应能力最强,氮素利用率最高,对小麦生长的促进作用最显著。     

土霉素及镉污染对土壤呼吸及酶活性的影响

随着饲料工业以及畜禽养殖业的规模化发展,抗生素和重金属在土壤环境中同时存在的几率不断增大。为了分析抗生素和重金属对土壤微生物生态系统的影响,以土霉素(OTC)与镉(Cd)为污染物,采用室内培养法,研究了土霉素(OTC)与镉(Cd)单一处理及复合污染对土壤呼吸和酶活性的影响。结果表明,10mg/kg重金属镉单独污染对土壤微生物呼吸表现为先抑制后激活作用,且显著抑制了土壤蔗糖酶、脲酶、磷酸酶活性,对3种酶活性平均抑制率从大到小依次为:蔗糖酶磷酸酶脲酶;1mg/kg土霉素显著激活土壤微生物呼吸,50和200mg/kg土霉素对土壤微生物呼吸的影响呈现出先抑制后激活的规律。各处理浓度下的土霉素对蔗糖酶和脲酶活性均主要表现为抑制作用,对磷酸酶活性的影响呈现出一定的波动性;当土霉素的浓度为1和200mg/kg时,其与10mg/kg镉的复合污染对土壤微生物呼吸及3种酶活性的影响主要为拮抗作用,但当土霉素的浓度为50mg/kg时,与10mg/kg镉的复合污染对土壤微生物呼吸及3种酶活性的影响则主要为协同作用。微生物呼吸对土霉素与镉胁迫更为敏感,最高抑制率和激活率分别可达98.98%和300.82%,土壤酶活性受土霉素和镉污染的影响要弱于它们对土壤微生物呼吸的影响。     

醋酸棉酚对土壤脲酶活性的抑制作用

采用实验室模拟培养、测定剩余尿素量的方法,对醋酸棉酚作为一种新型脲酶抑制剂进行初步研究,并探讨醋酸棉酚对红壤脲酶活性抑制作用的影响因素。结果表明,醋酸棉酚与尿素混合施用,培养2d,1%醋酸棉酚(相对于尿素质量)的脲酶抑制率为53.57%。土壤持水量对脲酶活性有较大影响,且在脲酶活性高时,醋酸棉酚的脲酶抑制作用更强。随着温度的升高,醋酸棉酚对土壤脲酶的抑制作用越来越明显,且表现出混合性抑制的特征。醋酸棉酚提前施用7d,尿素回收率从混合施用的73.64%增加到99.00%,说明改进施用方式可大幅度提高醋酸棉酚的脲酶抑制效果。     

脲酶/硝化抑制剂对土壤脲酶活性、有效态氮及春小麦产量的影响

通过田间随机区组试验,就缓释尿素对土壤脲酶活性,土壤有效态氮及小麦产量的影响进行了研究。本试验设置4个处理,1)普通尿素(U);2)U+脲酶抑制剂LNS(SRU1);3)SRU1+硝化抑制剂双氰胺(DCD)(SRU2);4)SRU1+硝化抑制剂3,5-二甲基吡唑(DMP)(SRU3)。结果表明,在整个春小麦(TriticumaestivumL.)生育期内,SRU1、SRU2和SRU3处理的土壤脲酶活性低于U处理,且SRU2、SRU3处理的土壤NH4+-N含量在较长时间内维持在较高水平;小麦成熟期,SRU1、SUR2和SRU3处理土壤有效态N含量显著高于U处理(p<0.05);SRU1、SRU2、SRU3处理小麦的生物学性状和产量略高于U处理,但是处理间没有显著差异。     

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,     

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.     

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.     

Electron donor and pH relationships for biologically enhanced dissolution of chlorinated solvent DNAPL in groundwater

Biologically enhanced dissolution offers a method to speed removal of chlorinated solvent dense non-aqueous-phase liquid (DNAPL) sources such as tetrachloroethene (PCE) and trichoroethene (TCE) from aquifers. Bioremediation is accomplished by adding an electron donor to the source zone where fermentation to intermediates leading to acetic acid and hydrogen results. The hydrogen and possibly acetic acid are used by dehalogenating bacteria to convert PCE and TCE to ethene and hydrochloric acid. Reductive dehalogenation is thus an acid forming process, and sufficient alkalinity must be present to maintain a near neutral pH. The bicarbonate alkalinity required to maintain pH above 6.5 is a function of the electron donor: 800 mg/L of bicarbonate alkalinity is sufficient to achieve about 1.2 mM TCE dechlorination with glucose, 1.7 mM with lactate, and a much higher 3.3 mM with formate. Laboratory studies indicate that in mixed culture, formate can be used as an electron donor for complete conversion to ethene, contrary to pure cultures studies indicating it cannot. Various strategies can be used to add electron donor to an aquifer for DNAPL dehalogenation while minimizing pH problems and excessive electron donor usage, including use of injection-extraction wells, dual recirculation wells, and nested injection-extraction wells.     

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.     

Increase in auxiliary photoprotective photosynthetic pigments in wheat seedlings induced by Azospirillum brasilense

Inoculation of wheat seedlings with the plant growth-promoting bacterium Azospirillum brasilense Cd was immobilized in alginate microbeads and, without applying any stress, significantly increased the quantity of several photosynthetic pigments, such as chlorophyll a, chlorophyll b, and the auxiliary photoprotective pigments violaxanthin, zeaxanthin, antheroxanthin, lutein, neoxanthin, and β-carotene. This resulted in greener plants with no apparent visible stress. After monitoring the quantity of photosynthetic pigments for 4 weeks, we observed that inoculated plants had higher quantities of pigments in shoot and stem. The greatest difference in the quantity of all pigments between inoculated and noninoculated plants occurred in the first week of growth. Regardless of treatment, the quantity of pigments in stems was three to four times less than the quantity of these pigments in shoots. Application of Azospirillum, either as liquid inoculant or as alginate microbeads, did not alter the positive effect of the bacteria on pigment production or the positive response of the plants towards A. brasilense Cd inoculation.     

In-situ enrichment and analysis of atrazine-degrading microbial communities using atrazine-containing porous beads

We examined the community composition of microbes that colonized atrazine-containing beads buried in agricultural soils that differed in atrazine treatment history. Bacterial abundance was 5-40-fold greater in atrazine-fortified beads. In beads containing 20 mg atrazine kg⁻¹ buried in soil with a history of atrazine application (conditioned soil), the abundance of Actinobacteria increased approximately 80-fold whereas in control soil, Actinobacteria were enriched only 10-fold and the gamma-Proteobacteria and Planctomycetes increased by 60- and 25-fold, respectively. The gamma-Proteobacteria were enriched by 120- and 230-fold in beads containing 200 mg atrazine kg⁻¹ in conditioned and control soil, respectively. The results demonstrate that BioSep^® beads are a suitable matrix for recruiting a diverse subset of the bacterial community involved in atrazine degradation.