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1.
K. Gajananda 《European Journal of Soil Science》2007,58(3):704-713
Schirmacher oasis (SO) (70°46′04′′S to 70°44′24′′S; 11°49′54′′[± 48]E to 11°26′03′′[± 02]E), one of the smallest oases in Antarctica, is situated on Dronning Maud Land, which is about 70 km south of the Princess Astrid Coast of east Antarctica. This oasis is a small rocky moraine, surrounded by the vast polar ice cap and Antarctic ice shelf. It represents cold desert conditions, devoid of any higher plant and animal life, except for a few patches of microbiotic crusts in some suitable niches. Melted water from glaciers, ice and snow produces about 30 fresh water lakes and many streams, which supply essential nutrients to the autotrophs (algae, mosses and lichens). Between 30 December 1999 and 29 January 2000, soil samples were collected from 14 sparsely vegetated sites to study the soils and ecology over this oasis. Bio‐physicochemical parameters, organic carbon and microbial activities (dehydrogenase) of the soils were determined. The average surface air temperature and wind velocities during the sampling period were −0.87°C and 4.3 m s−1. The average pH, plant biomass (standing crops) and moisture content were 7.5, 22.5 g m−2 and 375.4%. Total organic carbon (TOC) contents of the soil samples ranged from 1.16 to 2.58% and the mean value was 1.58%. Dehydrogenase activity (DHA) was low and the average was 0.008 mg Triphenyl formazan (TPF) g soil−1 day−1. The low DHA in SO suggests that anaerobic oxidation of organic C is poor. TOC and DHA are negatively correlated with plant biomass (r=−0.14, P= 0.62 and r=−0.21, P= 0.48). The organic C and microbial activities are dependent on the amount of the autotrophic productivity and abundances. TOC correlated significantly with DHA (r= 0.85, P < 0.001), which indicates that organic C is an important factor in controlling the development of DHA in the SO. The averaged bio‐physicochemical data in the oasis do not deviate much from the respective mean values and the TOC is expected to remain in the range of 1–2%; however, a small change in human activity is likely to cause long‐term impacts in this pristine ecosystem. 相似文献
2.
Harvester ants (Messor spp.) function as an essential link between aboveground resources and below-ground biota such as the microbial community.
We examined changes in soil microbial biomass and functional diversity resulting from harvester ant (Messor spp.) activity in the Negev Desert, Israel. Abiotic and biotic soil parameters were recorded during two seasons—wet and dry—also
representing food availability periods for the ants (low and high seed availability, respectively). Soil samples were collected
monthly from the 0- to 10- and 10- to 20-cm soil layers: (1) near the nest entrance, (2) under chaff piles, and (3) at a 2-m
radius from the nest entrance (control). Harvester ant activity increased the percentage of organic matter, total soluble
nitrogen, and microbial activity in nest-modified soils in comparison to the control soils. Higher CO2 evolution was recorded in the low-seed season in ant nest soils than in the control soils. During the high-seed season, higher
carbon dioxide evolution was recorded only at the nest entrance locations. There were no differences in microbial biomass
between the low- and high-seed seasons, but highest microbial biomass was found under chaff in low-seed season and in nest
soils in high-seed season. Microbial functional diversity was higher in nest-modified soils than in the control soils. This
study suggests that the effect of harvester ant nests on soil fertility is due to increased microbial biomass and microbial
activity in ant nest-modified soils. 相似文献
3.
Differences in soil microbial communities between ex-arable and undisturbed soils are often assumed to reflect long-term legacies of agricultural practices. Ex-arable soils, however, are commonly dominated by different plant species than undisturbed soils making it difficult to separate the importance of land-use and plant-growth legacies. In a system where non-native plants dominate ex-arable soils, we decoupled land-use (ex-arable, undisturbed) and plant-growth (native, non-native) effects on soil microbial communities using a factorial sampling design. Soils were removed from 14 sites that formed a 52-year chronosequence of agricultural abandonment. Microbial abundance and composition were measured using whole-soil phospholipid fatty acid analyses and microbial activity was measured in a subset of samples using sole-carbon-source utilization analyses. We found that both non-native-cultivated and ex-arable soils were independently associated with lower microbial abundance and diversity than native and undisturbed soils. We also found a correlation between microbial abundance and age-since-agricultural abandonment in ex-arable/non-native-cultivated soils suggesting that non-native plant effects accumulate over time. Microbial activity was consistent with microbial abundance; microbial communities in non-native-cultivated, ex-arable soils were slow to respire most carbon sources. Our data suggests that agricultural practices create soil conditions that favor non-native plant growth and non-native plants maintain these conditions. Potential mechanisms explaining how non-natives create soils with small microbial communities and how small microbial communities may benefit non-natives are discussed. 相似文献
4.
Evaluating the efficacy of cyanobacterial formulations and biofilmed inoculants for leguminous crops
Radha Prasanna Sodimalla Triveni Ngangom Bidyarani Santosh Babu Kuldeep Yadav Anurup Adak 《Archives of Agronomy and Soil Science》2013,59(3):349-366
Our investigation was aimed towards evaluating the agronomic potential of biofilmed preparations (developed using Anabaena/Trichoderma as matrices with different agriculturally useful bacteria/fungi as partners) and selected cyanobacterial strains (Anabaena laxa (T7) RP8/Calothrix sp.). The formulations were prepared using paddy straw compost:vermiculite (1:1) as carrier and tested as inoculants in mungbean and soybean. The effects of the formulations were evaluated in terms of microbiological, nutrient availability, and plant biometric parameters. The Trichoderma viride–Bradyrhizobium biofilm exhibited 20–45% enhancement in fresh/dry weight of plants over other microbial treatments, while the T. viride–Azotobacter biofilm exhibited highest dehydrogenase activity in the soil and nitrogen fixation. T7 RP8 recorded statistically at par yield values with the T. viride–Bradyrhizobium (T5) biofilm treatment in mungbean. In soybean, among all the treatments, the T5 biofilm recorded the highest fresh weight of plants and available N in soil at harvest. The Anabaena–T. viride biofilmed formulations proved to be the most promising for soybean, recording 12–25% enhanced yield and microbial activity (measured as dehydrogenase activity). This study highlights the promise of cyanobacterial inoculants and biofilmed biofertilizers as promising inputs for integrated nutrient management strategies in agriculture. 相似文献
5.
Invertebrate control of soil organic matter stability 总被引：17，自引：0，他引：17
V. Wolters 《Biology and Fertility of Soils》2000,31(1):1-19
The control of soil organic matter (SOM) stability by soil invertebrates is evaluated in terms of their impact on the inherent
recalcitrance, accessibility to microorganisms, and interaction with stabilizing substances of organic compounds. Present
knowledge on internal (ingestion and associated transformations) and external (defecation, constructions) control mechanisms
of soil invertebrates is also reviewed. Soil animals contribute to the stabilization and destabilization of SOM by simultaneously
affecting chemical, physical, and microbial processes over several orders of magnitude. A very important aspect of this is
that invertebrates at higher trophic levels create feedback mechanisms that modify the spatio-temporal framework in which
the micro-food web affects SOM stability. Quantification of non-trophic and indirect effects is thus essential in order to
understand the long-term effects of soil biota on SOM turnover. It is hypothesized that the activities of invertebrates which
lead to an increase in SOM stability partly evolved as an adaptation to the need for increasing the suitability of their soil
habitat. Several gaps in knowledge are identified: food selection and associated changes in C pools, differential effects
on SOM turnover, specific associations with microorganisms, effects on dissolution and desorption reactions, humus-forming
and humus-degrading processes in gut and faeces, and the modification of invertebrate effects by environmental variables.
Future studies must not be confined merely to a mechanistic analysis of invertebrate control of SOM stability, but also pay
considerable attention to the functional and evolutionary aspects of animal diversity in soil. This alone will allow an integration
of biological expertise in order to develop new strategies of soil management which can be applied under a variety of environmental
conditions.
Received: 6 April 1999 相似文献
6.
Microbial biomass is an important source of soil organic matter, which plays crucial roles in the maintenance of soil fertility and food security. However, the mineralization and transformation of microbial biomass by the dominant soil macrofauna earthworms are still unclear. We performed feeding trials with the geophagous earthworm Metaphire guillelmi using 14C-labelled bacteria (Escherichia coli and Bacillus megaterium) cells, fungal (Penicillium chrysogenum) cells, protein, peptidoglycan, and chitin. The mineralization rate of the microbial cells and cell components was significantly 1.2–4.0-fold higher in soil with the presence of M. guillelmi for seven days than in earthworm-free soil and 1–11-fold higher than in fresh earthworm cast material. When the earthworms were removed from the soil, the mineralization of the residual carbon of the microbial biomass was significantly lower than that in the earthworm-free soil, indicating that M. guillelmi affects the mineralization of the biomass in soil in two aspects: first stimulation and then reduction, which were attributed to the passage of the microbial biomass through the earthworm gut, and that the microorganisms in the cast could play only minor roles in the stimulated mineralization and residual stabilization of microbial biomass. Large amounts (8–29%) of radiolabel of the tested microbial biomass were assimilated in the earthworm tissue. Accumulation of fungal cells (11%) and cell wall component chitin (29%) in the tissue was significantly higher than that of bacterial cells (8%) and cell wall component peptidoglycan (15%). Feeding trails with 14C-lablled microbial cells and cell components provided direct evidence that microbial biomass is a food source for geophagous earthworm and fungal biomass is likely a more important food source for earthworms than bacterial biomass. Findings of this study have important implications for the roles of geophagous earthworms in the fate of microbial biomass in soil. 相似文献
7.
针对土壤自由生活线虫的环境适应性及其生态功能研究一直是土壤动物学和生态学的核心内容之一。前期研究表明南极土壤自由生活线虫能够在极端干旱的土壤中生存，尤其是线虫的优势种群之一——Plectus murrayi, 在生理生态水平上均表现出独特的适应性。土壤自由生活线虫Plectus murrayi是仅在南极麦克默多山谷（McMurdo Dry Valleys, MDV）发现的主要陆生生物之一，目前已在多领域成为研究极端环境下生态学以及生物学的模式生物。本文旨在综述其系统发育、分布、生命周期和实验室发育的最新研究，以及其在遗传水平上的耐冷冻和耐干燥性，结合南极沙漠土壤的特殊生态系统，阐述其对于探索生命极限的意义。基于P. murrayi在南极麦克默多山谷土壤的生境分布，与其他南极自由生活线虫相比，P. murrayi喜欢相对较高的湿度和较低的盐度土壤生境。由于全球气候变暖，南极麦克默多山谷的温度和湿度不断增加，P. murrayi极可能成为南极沙漠中的主要陆生动物。通过对P. murrayi的研究，能够探索其适应和功能基因之间的新联系，这些基因在理解细胞对极端微环境的抗逆性有着至关重要的作用，具有长远的农业以及医学利用价值。未来对南极麦克默多山谷土壤环境压力的短期和长期响应的研究，有助于揭示细胞对环境干旱、寒冷的耐受和修复作用，探明生物进化与生态系统复杂性之间的关系，以及不同微环境在塑造更复杂系统重的群落中的作用。 相似文献
8.
Relative to volcanic sites in Iceland and Hawaii the Hg distribution ratio soil: air around Mt. Erebus (Ross Island, U.S. Antarctica) is anomously low. Air values for all three areas are similar. Differences are a reflection of extremely low soil levels at Antarctic sample sites. This condition appears to arise from the paucity of vegetation and lower degree of bio-concentration among Antarctic biota. 相似文献
9.
[目的] 研究藻菌混合结皮对土壤水肥保持及玉米幼苗生长的影响,为土壤治理与改良策略提供理论依据。[方法] 使用来自内蒙古翁牛特沙漠的2种产胞外多糖的细菌（Sphingomonas sp.D3-1和Massilia armeniaca sp.ZMN-3）和2种藻类（Cladophora aegagrophila D3-a和Nostoc sphaeroides0 D3-25）制备成藻菌混合剂后,喷洒至土壤表面,形成土壤结皮。研究藻菌混合结皮与土壤水肥保持、微生物数量及酶活性的关系,及其对玉米幼苗的影响。[结果] 与对照相比,藻菌混合结皮明显延缓了土壤水分的流失速度,并使氮、磷和钾的平均淋失效率分别减少了76.9%,64.4%和47.8%,土壤中的细菌、真菌和放线菌数量分别增加了8.3,1.8和3.1倍,芽孢杆菌的数量下降了12.4%。另外,在玉米盆栽中,藻菌混合结皮使玉米幼苗的地上部鲜/干重、根部鲜/干重和地上/下部长度分别提升30.0%/55.6%,55.4%/38.5%和16.5%/18.0%,叶绿素含量增加15.0%。[结论] 藻类与产胞外多糖的细菌共同形成的藻菌混合结皮,明显改善了土壤的水肥保持效果,可作为治理土壤的新途径加以推广。 相似文献
10.
Mazur A Telega G Kotowicz A Małek H Jarochowicz S Gierczak B Mazurkiewicz M Pop T Zajkiewicz K Dobrucki M Mazur D 《Public health nutrition》2008,11(9):978-981
AIM: The aim of the present study was to determine the impact of food advertising in primary and secondary schools on the food purchasing habits of children. METHODS: All forty-four primary and secondary schools in Rzeszow, Poland were included in the investigation; 15000 children attend primary and secondary schools in the region. Schools were visited by members of the research team, who filled in a questionnaire regarding the type of food products displayed or advertised in the school shop window and recorded the presence of direct corporate advertising in the proximity of the school shop. Shop owners were asked to fill in a form describing food purchases by students within the week preceding the visit. The school principal (or one of teachers) completed a form describing the school's policy regarding food advertising and the sponsorship of school activities by food companies. RESULTS: Recommended foods like milk, yogurts and fruit were offered by only 40.9 % of shops. There was a correlation between foods offered in the shop and foods purchased by students. In schools, 40.9% (95% CI 25.8, 56.0%) of shop windows displayed or advertised 'healthy' foods while 9.1% (95% CI 0.0, 17.9%) of shops displayed advertisements of food companies. The difference between display of 'healthy' food in shop windows and display of food on company advertisements was significant (likelihood ratio chi2 test, P < 0.04). Type of school (primary v. secondary) was not significant factor in advertising or purchasing pattern. CONCLUSIONS: Educational programmes should be introduced in schools with the aim of improving the understanding of nutritional principles among pupils, teachers and parents. 相似文献
11.
Distribution and abundance of soil fungi in Antarctica at sites on the Peninsula, Ross Sea Region and McMurdo Dry Valleys 总被引：1，自引：0，他引：1
Fungal abundance and diversity were studied from 245 soil samples collected in 18 distinct ice-free locations in Antarctica including areas in the McMurdo Dry Valleys, Ross Sea Region, and the Antarctic Peninsula. Cultivable fungal abundance in soil was found to be most positively correlated with percent carbon and nitrogen based on a Spearman’s rank correlation test of six soil parameters. Soil moisture and C/N ratio were also positively correlated with fungal abundance while pH and conductivity were negatively correlated. These results suggest that nutrient limitations in these highly oligotrophic environments are a primary factor in determining the distribution and abundance of indigenous fungi. Other effects of the extreme Antarctic environment likely affect fungi indirectly by limiting the distribution and abundance of plant-derived sources of carbon. 相似文献
12.
13.
Different concentrations of sorghum diastatic malt (SDM) were added to pregelatinized pastes from regular maize flour with the aim of hydrolyzing the starch to produce liquefied foods with 15% solids. Viscosities of the blends decreased as the concentration of SDM increased. Addition of 6.66% SDM based on total amount of solids reduced viscosity by ≈50% when compared with a food that did not contain any SDM. Addition of 33.3 or 46.6% SDM reduced viscosity by ≈70 or 75%, respectively. Most of the reduction in viscosity occurred within 1–3 min of incubation with warm water. Weanling rats were fed a combination 33.3% SDM and 66.6% of either quality protein maize (QPM), regular maize (RMZ) or decorticated pearl millet (DPM) to estimate protein efficiency ratios (PER), protein digestibility, biological value (BV), and net protein utilization (NPU). Rat growth was positively correlated with dietary lysine content and essential amino acid (EAA) scores; therefore, animals fed QPM weanling food had significantly higher (P < 0.05) protein digestibility corrected EAA scores, PER, BV, and NPU than counterparts fed diets based on RMZ or DPM. This demonstrates that it is feasible to produce nutritious liquefied weaning foods blending 33.3% SDM with 66.6% QPM using simple processing techniques. 相似文献
14.
南极半岛海洋气候区的土壤I.风化作用 总被引：2，自引：0，他引：2
南极海洋性气候区是南极风化与成土作用相对较强的地区。本在对本区气候特点进行分析的基础上，明确了冻胀风化是本区最主要的物理风化形式，强烈的现代地貌过程对本区风化与成土过程具有显影响。阐述了本区内化学风化的主要过程、机制与产物，同时指出生物因素在本区的岩石风化与原始土壤形成过程具有重要意义。 相似文献
15.
本文采用饲料类芽孢杆菌(Paenibacillus pabuli,P)、深红紫链霉菌(Streptomyces violaceorubidus,S)和黄绿木霉(Trichoderma aureoviride,T),组合构建了3种单菌剂(P、S和T)、3种两菌种复合菌剂(PT、PS和ST)及1种3菌种复合菌剂(PST),并将之添加到红壤中,监测各菌剂添加后土壤总磷脂脂肪酸(PLFAs)量、特征微生物PLFAs百分含量、土壤呼吸速率及总代谢熵的变化,旨在探明外源腐解微生物的物种组合对土壤微生物群落结构和代谢活性的影响,进而为优化有机物分解菌剂种群配置提供参考。结果显示,添加单菌剂的P、S和T处理及添加两菌种复合菌剂的PT和PS处理,土壤微生物生物量显著增加,增幅17.2%~121.6%(P0.05)。添加外源腐解微生物后,各处理的土壤微生物群落的细菌百分含量基本稳定在79.6%~83.1%,真菌百分含量显著增加8.8%~50.6%;而放线菌百分含量除P和ST处理外,其他处理显著降低9.4%~69.8%。PLFAs数据的主成分分析表明,各外源菌剂处理与CK处理间的群落结构变异由小到大依次为:接种单菌剂的P、S和T处理,接种两菌种复合菌剂的PT、PS和ST处理,接种3菌种复合菌剂的PST处理。添加单菌剂的P、T处理以及添加两菌种复合菌剂的ST处理,在短期内影响了土壤微生物的对数生长,使土壤呼吸速率的峰值分别提高48.7%、53.7%和78.7%;且外源腐解微生物组合的物种数量越多,土壤微生物进入潜伏期所需的时间越长。从外源腐解微生物对土壤肥力的长期影响来看,两菌种复合菌剂ST的添加使土壤微生物代谢活性提高28.9%,因此该处理的土壤碳矿化量增加11.1%;添加单菌剂的S处理使土壤微生物代谢活性显著降低32.4%,因此该处理的土壤碳矿化量仅降低7.3%;而添加两菌种复合菌剂的PS处理和3菌种复合菌剂的PST处理,在保持代谢活性不变的情况下,其土壤碳矿化量也降低5.8%~8.7%,其原因有待进一步研究。综上所述,外源腐解微生物的添加会改变土壤微生物的群落结构及其生长轨迹,且随外源腐解微生物组合的物种数量增多这一干扰程度越大,而土壤微生物代谢活性与外源腐解微生物组合的物种数量无显著相关性。 相似文献
16.
南极半岛海洋气候区的土壤Ⅵ.空间可变性与土壤景观 总被引：1，自引：0，他引：1
本文通过对南极海洋气候区自然环境和地表特征分析,指出本区土被发育与分布具有明显的不连续性特征;同时,在分析研究本区成土因素的空间变化格局及其对土壤发生、发育与演化影响的基础上,论述了南极海洋气候区土壤属性上的强烈空间可变性和类型上的高度分异性;最后,对本区有代表性的土壤景观系列进行了分析,指出成土因素空间变异的微域性特点造成了本区土壤景观的多样性与复杂性,本区自然环境的快速变化可能最终导致土壤景观的演变与重塑。 相似文献
17.
Kerri L. Steenwerth Louise E. JacksonFrancisco J. Calderón Mark R. StrombergKate M. Scow 《Soil biology & biochemistry》2003,35(3):489-500
Phospholipid ester-linked fatty acid (PLFA) profiles were used to evaluate soil microbial community composition for 9 land use types in two coastal valleys in California. These included irrigated and non-irrigated agricultural sites, non-native annual grasslands and relict, never-tilled or old field perennial grasslands. All 42 sites were on loams or sandy loams of similar soil taxa derived from granitic and alluvial material. We hypothesized that land use history and its associated management inputs and practices may produce a unique soil environment, for which microbes with specific environmental requirements may be selected and supported. We investigated the relationship between soil physical and chemical characteristics, management factors, and vegetation type with microbial community composition. Higher values of total soil C, N, and microbial biomass (total PLFA) and lower values of soil pH occurred in the grassland than cultivated soils. The correspondence analysis (CA) of the PLFA profiles and the canonical correspondence analysis (CCA) of PLFA profiles, soil characteristics, and site and management factors showed distinct groupings for land use types. A given land use type could thus be identified by soil microbial community composition as well as similar soil characteristics and management factors. Differences in soil microbial community composition were highly associated with total PLFA, a measure of soil microbial biomass, suggesting that labile soil organic matter affects microbial composition. Management inputs, such as fertilizer, herbicide, and irrigation, also were associated with the distinctive microbial community composition of the different cultivated land use types. 相似文献
18.
Subantarctic islands have depauperate floras and faunas. When combined with recent changes in climate, these factors increase the likelihood of alien species establishing in the subantarctic. Cargo, food and expeditioners in transit to the subantarctic as part of the Australian Antarctic Program (AAP) were inspected to determine their potential as vectors for alien species.All cargo items were found to have the potential to act as vectors for alien species introductions. Cargo containers were found to harbour plant material, seeds and spider webs. A major potential source of contamination is transport used on resupply expeditions for ship to shore transfers. The presence of large numbers of littoral organisms on the bottom of a barge highlighted the real risk of a potential pathway for the introduction of marine taxa. Insect infestation, scale, fungal infection and the presence of soil were all problems associated with the provision of fresh food to subantarctic stations.Equipment identified as high risk vectors included equipment cases, day packs and the cuffs and Velcro® closures of outer clothing. Many expeditioners had travelled overseas in the six months prior to embarkation and had recently visited alpine or high latitude environments. A total of 981 propagules and five moss shoots were collected from clothing and equipment of 64 expeditioners. Ninety species from 15 families were identified, most of which were grass caryopses. Asteraceae and Poaceae contained the greatest diversity of propagules. In germination trials a total of 163 plants (24 species) were identified. A risk assessment was prepared to determine issues posing a threat to subantarctic quarantine and assess possible logistic and management changes to minimise these threats. Many changes suggested have since been implemented resulting in a reduction in the number of alien species recorded in subsequent inspections. 相似文献
19.
Amanda J. Bennett Sally Hilton Gary D. Bending David Chandler Peter Mills 《Biology and Fertility of Soils》2014,50(8):1267-1279
Glasshouse bioassays were conducted to assess the impact of different inputs of oilseed rape plant material on soil and rhizosphere microbial diversity associated with subsequently grown oilseed rape (Brassica napus) plants. The first bioassay focussed on the effect of oilseed rape rhizodeposits and fresh detached root material on microbial communities, in a rapid-cycling experiment in which oilseed rape plants were grown successively in pots of field soil for 4 weeks at a time, with six cycles of repeated vegetative planting in the same pot. Molecular analyses of the microbial communities after each cycle showed that the obligate parasite Olpidium brassicae infected the roots of oilseed rape within 4 weeks after the first planting (irrespective of the influence of rhizodeposits alone or in the presence of fresh detached root material), and consistently dominated the rhizosphere fungal community, ranging in relative abundance from 43 to 88 % when oilseed rape was grown more than once in the same soil. Fresh detached root material also led to a reduction in diversity within the soil fungal community, due to the increased relative abundance of O. brassicae. In addition, rhizosphere bacterial communities were found to have a reduced diversity over time when fresh root material was retained in the soil. In the second glasshouse experiment, the effect of incorporating mature, field-derived oilseed rape crop residues (shoots and root material) on microbial communities associated with subsequently grown oilseed rape was investigated. As before, molecular analyses revealed that O. brassicae dominated the rhizosphere fungal community, despite not being prevalent in either the residue material or soil fungal communities. 相似文献
20.
干土效应对土壤生物组成及矿化与硝化作用的影响 总被引：25，自引：3，他引：25
将经过风干、过筛后的2种旱地红壤加水培养,并和新鲜土培养条件相比较,研究干土效应对土壤生物组成及矿化与硝化作用的影响.试验共4个处理(1)农田旱地风干土加水培养(RU);(2)农田旱地新鲜土培养(FU);(3)苗圃旱地风干土加水培养(RN);(4)苗圃旱地新鲜土培养(FN).结果表明红壤风干土加水预培养5 d后,细菌、放线菌、真菌数量比新鲜土显著增加(p＜0.01),细菌数量增加最为明显,农田旱地和苗圃旱地风干土处理分别是新鲜土的6.26倍和6.84倍,红壤风干土加水培养处理的微生物量碳、氮也随之增加.培养28 d后土壤中微生物数量趋于稳定,与预培养5 d时的数量相当或稍有下降,但风干后加水培养处理的微生物数量仍保持大于新鲜土的趋势(农田旱地的放线菌除外),微生物量碳、氮也存在同样的趋势.风干土加水培养后微生物数量的迅速增加,使得氮素矿化速度加快,由此导致NH+4-N量显著增加(p＜0.01),培养28 d后,NH+4-N量较预培养5 d时有所增加,且明显高于新鲜土培养处理;NO-3-N含量也增加,但新鲜土处理显著高于风干土处理.土壤风干处理对土壤自由生活线虫的影响比较大,农田旱地和苗圃旱地风干土加水培养28 d后,其自由生活线虫数量仅为新鲜土的16.0%和30.1%,显示风干土加水培养难以恢复土壤微型动物的数量.28 d的矿化和硝化培养试验结果显示,风干土加水培养处理的净矿化量和矿化率均高于新鲜土处理,苗圃旱地风干土处理的增量达到了显著水平(p＜0.05),但是硝化作用却刚好相反,农田旱地和苗圃旱地的净硝化量及硝化率均是新鲜土处理显著高于风干土处理(p＜0.05),其原因是对硝化作用起重要作用的硝化菌(氨氧化细菌和亚硝酸氧化细菌)数量在经历了风干过程后很难恢复到新鲜土水平. 相似文献