不同施肥处理对西藏山南地区麦田土壤微生物变化的影响

本文对不同施肥措施下麦田土壤微生物数量及种类的变化进行了测定和分析。结果表明 :有机肥与N、P、K肥的合理配施 ,肥效持久 ,能促进微生物生长繁殖 ,细菌、放线菌、真菌、固氮菌、纤维素分解菌数量均能相对长期保持较高水平 ;可显著增强纤维素分解强度 ,促进土壤有机质的分解 ,有利于培肥土壤。微生物种类鉴定表明 :细菌的数量以芽孢杆菌为主 ,球菌较少 ;放线菌主要为链霉菌属的灰褐色类群 ;真菌主要为腐霉属、木霉属、葡萄孢属 ;固氮菌为圆褐固氮菌 ;纤维素分解菌以食纤维细菌、链霉菌属的白孢类群和葡萄穗霉属、腐霉属等真菌最常见     

不同施肥处理对西藏山南地区麦田土壤微生物变化的影响

本文对不同施肥措施下麦田土壤微生物数量及种类的变化进行了测定和分析。结果表明：有机肥与N、P、K肥的合理配施，肥效持久，能促进微生物生长繁殖，细菌、放线菌、真菌、固氮菌、纤维素分解菌数量均能相对长期保持较高水平；可显著增强纤维素分解强度，促进土壤有机质的分解，有利于培肥土壤。微生物种类鉴定表明：细菌的数量以芽孢杆菌为主，球菌较少；放线菌主要为链霉菌属的灰褐色类群；真菌主要为腐霉属、木霉属、葡萄孢属；固氮菌为圆褐固氮菌；纤维素分解菌以食纤维细菌、链霉菌属的白孢类群和葡萄穗霉属、腐霉属等真菌最常见。     

木醋液及炭醋肥对设施土壤微生物数量及相关性的影响

本文通过田间小区试验,研究连续施用木醋液和炭醋肥对设施菜地土壤微生物数量的影响,为设施土壤改良提供科学依据。采用微生物培养法研究木醋液及炭醋肥施入设施土壤中对5茬蔬菜生长期间土壤细菌、真菌、放线菌、自生固氮菌、纤维分解菌和无机磷细菌数量的影响,并对不同类群微生物数量进行相关性分析。结果表明:设施土壤中施入木醋液和炭醋肥能够显著或极显著地增加土壤细菌、放线菌、自生固氮菌、纤维分解菌和无机磷细菌数量,减少真菌数量。二者的施用还能增强设施土壤不同类群微生物数量间的相关性;自生固氮菌和纤维分解菌呈极显著的正相关,无机磷细菌与其他类群之间的相关性存在处理间差异。相比对照,炭醋肥增加了土壤细菌、放线菌、自生固氮菌、纤维分解菌和无机磷细菌数量分别为23.9%、22.5%、72.5%、4.3%和46.9%;木醋液分别增加了11.3%、11.2%、66.7%、2.6%和24.9%;炭醋肥和木醋液施用后真菌数量分别减少了40.9%和54.9%。因此炭醋肥的施用效果优于木醋液,但是二者的连用超过3茬则无显著影响。     

川西亚高山林线过渡带土壤特性研究

初步研究了川西亚高山林线过渡带残积母质土壤(0-15 cm,15-30 cm和15-47 cm)物理、化学及生物学特性.结果表明,随土层深度加深.林线过渡带土壤石砾和物理性砂粒含量分别达35%～86%和67%～82%,粘粒和物理性粘粒为2%～9%和16%～24%,土壤团聚度和结构水稳性分别为9%～25%和20%～29%,容重为0.82～1.58.表明整个土壤砂粒、粉粒和粘粒比例失调.其物理结构较差.表层(0-15 cm)土壤有机质、阳离子交换量(CEC)、全N和P、有效N和P含量,细菌、真菌、放线菌、细菌生理类群数量以及微生物量碳和氮含量,脲酶、蔗糖酶、酸性磷酸酶、中性磷酸酶、碱性磷酸酶、多酚氧化酶和过氧化氢酶等酶活性均显著高于下层土壤.整个土壤微生物以细菌为主要类群,占85%～95%,其次是真菌和放线菌,细菌生理类群数量排序为氨化细菌>好氧固氮菌>有机磷分解菌>无机磷分解菌>反硝化菌>硝化细菌>好气纤维索分解菌>嫌气纤维素分解菌,且表层显著高于下层.林线过渡带土壤较低的有效养分含量可能是影响其植物生长的关键因子之一.     

山药田土壤微生物群落分布特征及间作豆科植物的改良效果

为解析山药田连作后的土壤微生态环境变化,探寻连作障碍产生的微生物学机理,采用田间小区试验和室内检测分析相结合的方法,以粮田土壤为对照,在分析山药田土壤微生物群落分布特征的基础上,探究间作苜蓿、三叶草和大豆3种豆科植物对土壤微生态环境的改良效果。结果表明:在0～100 cm土层中,山药田和粮田土壤细菌、真菌和放线菌三大微生物种群的数量基本表现为随土层加深而降低的趋势。与粮田相比,山药苗期0～100 cm土层土壤细菌和真菌数量均表现为山药田土壤高于粮田土壤,特别是真菌数量,高于粮田土壤1.86～4.48倍。而固氮菌和放线菌数量则表现为粮田土壤高于山药田土壤的趋势,特别是0～20 cm土层,分别比山药田土壤提高了1.51和0.75倍。山药收获期,0～20和20～40 cm土层山药田土壤细菌、固氮菌和放线菌数量均呈现出低于粮田土壤,而真菌数量高于粮田土壤的趋势,且0～100 cm土层土壤细菌与真菌数量的比值均降低。间作苜蓿、三叶草和大豆后可显著提高0～40 cm土层土壤中的固氮菌、解磷细菌及放线菌的数量。说明山药连作会明显影响土壤三大微生物群落的组成结构,而间作豆科植物对土壤微生物群落分布有一定的改良效果。     

玉米秸秆造夹层处理对盐碱地土壤微生物数量的影响

为探讨农作物秸秆对盐碱化土壤的改良效果,对山西省太谷县团场村盐碱土进行玉米秸秆造夹层处理,在每个内夹层以上取样,测定土壤三大类群微生物(细菌、放线菌、真菌)和两种生理功能群微生物(亚硝酸细菌、好气性纤维素分解菌)的数量,试验结果表明:玉米秸秆造夹层土层内,细菌、真菌、放线菌的数量显著高于对照区(未加玉米秸秆造夹层),粉碎玉米秸秆用量为4000 kg/667 m~2、填埋深度为10 cm的小区均相应高于其他处理的小区;玉米秸秆造夹层处理的土壤,生理功能群微生物好气性纤维素分解菌、亚硝酸细菌的数量均显著高于对照区,用量4000 kg/667 m~2、填埋深度为10 cm的小区均相应高于其他处理的小区。本研究表明农作物秸秆夹层能够很好地增加盐碱地土壤的微生物数量,对盐碱地具有较好的改良效果。     

光合细菌和有机肥对土壤主要微生物类群的影响

将光合细菌菌液和发酵有机肥施入农田土壤，研究表层土壤中微生物区系变化。结果表明，光合细菌和有机肥显著增加土壤中放线菌、异养细菌、固氮菌、氨化细菌和硝化细菌数量，减少反硝化细菌数量，改善土壤微生物区系，光合细菌作用比有机肥更稳定和持久。光合细菌还能明显降低真菌数量，提高放线菌／真菌比值，促进土壤健康。     

白浆土微生物学特性和生物学活性的研究

本研究报道了白浆土垦植前后不同肥力耕层土壤细菌、放线菌和真菌数量;芽孢杆菌、真菌和好气纤维素细菌的优势组成;土壤接触酶、转化酶和脲酶活性,以及纤维素分解率和呼吸活性,并检测了固氮菌的拮抗生物活性。研究表明,耕作层(黑土层)下亚表层土壤的不良农化和生物学性状,通过不变动土壤层次,以大量有机能源物质并配合无机肥料一次富集于该土层中,可迅速强化该层土壤生物学活性,并达到改善其土体构型的目的。     

高寒草地不同退化程度下土壤微生物及土壤酶活性变化特征

为探讨不同退化程度对高寒草地土壤微生物及土壤酶活性的影响,以青藏高原东北缘祁连山3种不同退化程度(轻度退化、中度退化、重度退化)高寒草地为研究对象,测定和分析土壤3大类微生物(细菌、真菌、放线菌)和氮素生理群(氨化细菌、好气性固氮菌、嫌气固氮菌、硝化细菌、反硝化细菌)数量、微生物量(碳、氮)及土壤酶活性(蔗糖酶、脲酶、磷酸酶、过氧化氢酶)变化特征。结果表明:(1)相同土层不同退化程度,土壤3大类微生物数量、氮素生理群、微生物量以及土壤酶活性随退化程度的加重总体呈减小的趋势,重度退化程度下各指标含量最小,中等退化程度可增加10—20cm土壤放线菌、氨化细菌及反硝化细菌数量和20—30cm土壤细菌、真菌、放线菌、好气性固氮菌、反硝化细菌数量;(2)不同土层相同退化程度,土壤3大类微生物数量、氮素生理群、微生物量以及土壤酶活性随土层深度的加深均逐渐减小。研究结果对评价草地退化程度提供了新思路,同时为高寒草地的恢复和重建提供了重要的理论依据。     

连续5年施菜籽饼肥和稻草覆盖对茶园土壤生态系统的影响

在长沙县百里茶廊连续进行5年的定位试验,研究施菜籽饼肥结合稻草覆盖对丘陵茶园土壤生态系统的影响。结果表明,施菜籽饼肥加稻草覆盖处理(TI)茶园土壤pH、有机质含量、全氮含量、有效磷含量均显著高于纯施化肥处理(T3),0～40cm土层土壤容重显著低于T3处理,0～60cm土层土壤水分含量、0～20cm土层蚯蚓数量和生物量、氨基化细菌、好气性自生固氮菌、嫌气性自生固氮菌、放线菌、真菌和细菌等微生物数量均显著高于T3处理。施菜籽饼肥结合稻草覆盖可显著改善丘陵茶园土壤生态功能,菜籽饼化肥配施结合稻草覆盖(T2)也一定程度改善了土壤生态系统,长期不施肥使茶园土壤养分贮存量全面下降。     

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。     

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.     

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.     

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,     

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.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.