植物功能群多样性对人工湿地微生物生物量和营养滞留的影响

为了检验植物功能群多样性是否影响人工湿地植物生物量、微生物生物量和填料营养滞留,本研究在垂直流人工湿地中设置了5个植物功能群丰富度处理（未栽培处理以及分别栽培1、2、3和4个功能群处理）,分别分析了不同处理下的植物生物量、微生物生物量碳和氮、填料中有机碳、NH+4N、NO-3N和有效磷含量。单因素方差分析表明:植物生物量、微生物生物量碳和氮均随着植物功能群丰富度显著提高 (P 0.05),而填料中的NH+4N和NO-3N含量仅依赖于植物栽培与否。相关分析揭示出植物功能群丰富度与植物生物量、微生物生物量碳和氮以及填料中的NO-3N含量均呈正相关关系,而微生物生物量碳分别与填料中的NH+4N和NO-3N含量呈正相关。本研究突出了植物功能群多样性在改善人工湿地中的植物生物量、微生物生物量碳和氮方面的重要性。     

种植利用紫云英对稻田土壤微生物及酶活性的影响

为研究种植利用紫云英对稻田土壤的培肥作用,设不种紫云英不施化肥(对照)、种植紫云英不施化肥(紫云英)、不种紫云英施化肥(单施化肥)、种植紫云英同时施化肥(紫云英+化肥)4个处理,分析了各处理在紫云英苗期、紫云英盛花期、早稻收获期、晚稻收获期的土壤养分、酶活性、微生物数量。结果表明,与对照相比,施化肥及种植翻压紫云英均能改善土壤养分状况,紫云英与化肥配施效果最好,能够明显提高土壤速效磷、速效钾、全氮含量。施用化肥或种植翻压紫云英均能促进微生物生长,4个处理中以紫云英+化肥处理对土壤微生物生长有较好的促进作用,其次为单施化肥处理。     

Effect of nitrogen fertilization and irrigation on soil microbial activities and population dynamics — a field study

In a field experiment, net nitrogen (N) mineralization and immobilization were studied in relation to: 1) population dynamics and activities of N-metabolizing soil microbial communities, 2) changes in substrate-induced respiration (SIR) and 3) potential urease acitvity. Nitrogen fertilization (80 kg NO₃-N ha^-1) without irrigation induced additional N mineralization up to 280 kg N ha^-1. Net N-mineralization was weakly correlated to cell numbers of ammonifying and NH₄⁺-oxidizing microorganisms. Potential urease activity, respiration activity, and substrate-induced respiration activity were not correlated with the amount of mineralized nitrogen. Irrigation significantly increased potential urease activity of the soil microflora. Substrate induced respiration activity and basal respiration activity of the soil microflora were highest in the unfertilized and non irrigated treatment. But greatest differences were detected between the two sampling dates. NO₂^--oxidizing and ammonifying microbial populations increased, while populations of NH₄⁺-oxidizing and denitrifying microorganisms decreased with time. The results of this study demonstrate the interaction of nitrogen fertilizer application and irrigation on population dynamics of N-transforming soil microorganisms and microbial activities under field conditions. Detailed microbiological investigations of this type improve our understanding of nitrogen transformations in soil and suggest possible reasons of nitrogen losses, so that N fertilizer can be used more effectively and N losses be reduced.     

沙漠系统中豆类作物根际附近区域土壤微生物群落研究

The aim of the current study was to gain a better understanding of the changes in soil microbial biomass and basal respiration dynamics in the vicinity of the bean caper （Zygophyllura duraosura） perennial desert shrub and the inter-shrub sites. Microbial biomasses as well as basal respiration were found to be significantly greater in the soil samples taken beneath the Z. duraosura shrubs than from the inter-shrub sampling sites, with no differences between the two sampling layers （0-10 and 10-20 cm） throughout the study period. However, seasonal changes were observed due to autumn dew formation, which significantly affected microbial biomass and basal respiration in the upper-layer inter-shrub locations. The calculated metabolic coefficient （qCO2） revealed significant differences between the two sampling sites as well as between the two soil layers, elucidating the abiotic effect between the sites throughout the study period. The substrate availability index was found to significantly demonstrate the differences between the two sites, elucidating the significant contribution of Z. duraosura in food source availability and in moderating harsh abiotic components. The importance of basal microbial parameters and the derived indices as tools demonstrated the importance and need for basic knowledge in understanding plant-soil interactions determined by an unpredictable and harsh desert environment.     

湿地土壤质量退化的模糊综合评价

Due to frequent soil Cd contamination and wide use of butachlor in China,there is a need to assess their combined toxicity to soil microorganisms.The combined effects of cadmium (Cd,10 mg kg^-1 soil) and herbicide butachlor (10,50,and 100 mg kg^-1 soil) on enzyme activities and microbial community structure in a paddy soil were assessed using the traditional enzyme assays and random amplified polymorphic DNA (RAPD) analysis.The results showed that urease and phosphatase activities were significantly reduced by high butachlor concentration (100 mg kg^-1 soil).When the concentrations of Cd and butachlor added were at a ratio of 1:10,urease and phosphatase activities were significantly decreased whereas enzyme activities were greatly improved at the ratio of 1:5,which indicated that the combined effects of Cd and butachlor on soil urease and phosphatase activities depended largely on their addition concentration ratios.Random amplified polymorphic DNA (RAPD) analysis showed loss of original bands and appearance of new bands when compared with the control soil.Random amplified polymorphic DNA fingerprints suggested substantial differences between the control and treated soil samples,with apparent changes in the number and size of amplified DNA fragments.The addition of high concentration butachlor and the combined impacts of Cd and butachlor significantly affected the diversity of the microbial community.RAPD analysis in conjunction with other biomarkers such as soil enzyme parameters would prove a powerful ecotoxicological tool.Further investigations should be carried out to understand the clear link between RAPD patterns and enzyme activity.     

一次性根区穴施尿素提高夏玉米产量和养分吸收利用效率

为了明确氮肥一次施用对作物产量和肥料利用率的影响,探寻夏玉米全生育期一次性施氮技术,该文通过2a(2015-2016)在安徽省太和县砂姜黑土和东至县红黄壤的田间试验,研究了农民习惯分次施氮(SSB)、一次性根区穴施尿素(RZF)和一次性条施尿素(BDP)对夏玉米产量、氮磷钾养分吸收和利用的影响。结果表明,各处理玉米产量的顺序为RZFSSB≈BDPCK,RZF比SSB和BDP分别显著增产8.8%和9.8%。RZF的氮磷钾素积累均为各处理最高,氮肥表观利用率为50.1%~58.9%,比SSB和BDP分别提高8.3和12.4个百分点,并且氮肥农学利用率和偏生产力均最高。RZF的磷肥表观利用率为17.5%,比SSB和BDP分别显著提高18.1%和27.2%。同一施氮水平下,太和点的产量、生物量和氮素积累量比东至点分别高31.5%、25.2%和46.3%。一次性根区穴施尿素提高了氮肥在耕层土壤的集中度,降低了氮素释放速度,达到缓控释肥的效果,能够显著增加玉米产量、提高氮肥利用率。可见,一次根区施肥能够替代当前习惯的分次施肥,实现作物高产稳产,对于化学氮肥减量施用、提高肥料利用率具有很大的潜力和空间,值得进一步研发施肥机械和推广应用。     

Effect of soil application of nickel on growth,micronutrient concentration and uptake in barley (Hordeum vulgare L.) grown in Inceptisols of Varanasi

A pot experiment was conducted in a glass house on low nickel containing alluvial soil in the Department of Soil Science and Agricultural Chemistry, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, during 2012–13 and 2013–14, to study the response of barley to soil application of nickel (Ni). There were ten treatments of Ni (0, 2.5, 5, 10, 15, 20, 30, 40, 50 and 60 mg kg^?1) studied with recommended dose of fertilizers nitrogen, phosphorus, potassium and sulfur (N:P:K:S :: 40:30:30:20 mg kg^?1).The results showed a significant increase in plant height, number of tillers, chlorophyll content, straw and grain yield, and 1,000 grains weight with application of 10 mg Ni kg^?1 soil during both years of study. The micronutrient concentration and uptake in straw and grain increased with application of <15 mg Ni kg^?1 soil and beyond that declined significantly. Diethylenetriaminepentaacetic acid-extractable micronutrient iron, manganese, copper, zinc and nickel (Fe, Mn, Cu, Zn and Ni) content in soil increased with increasing level of Ni. The maximum urease activity in post-harvest soil was noticed with application of 40 mg Ni kg^?1 soil. The microbial population viz. bacteria, fungi and actinomycetes were higher with 5, 30 and 10 mg Ni kg^?1 soil, respectively.     

复合重金属污染对典型湿润富铁土中氮的矿化势、脲酶及磷酸酶活性的影响

Individual and combined effects of Cu,Pb,Zn and Cd on N mineralization,urease and phosphatase were examined in a Typic Udic Ferrisol in laboratory by employing and uniform design and a single factor design,Soil pollution caused by heavy metals inhibited N mineralization (N0 value)and urease and phosphatase activities.The combined pollution of metals alleviated their toxicity to N mineralization to some extent whereas aggravated the toxicity to urease and phosphatase.Phosphorous application could mitigat the toxic effect of heavy metals on phosphatase activities,while alleviating effect of N application on the toxicity of heavy metals to urease was inconsistent.However,the mitigating effect of the fertilizers was limited in heavily polluted soils.     

Root growth and N‐uptake activity of oilseed rape (Brassica napus L.) cultivars differing in nitrogen efficiency

Nitrate‐N uptake from soil depends on root growth and uptake activity. However, under field conditions N‐uptake activity is difficult to estimate from soil‐N depletion due to different loss pathways. We modified the current mesh‐bag method to estimate nitrate‐N‐uptake activity and root growth of two oilseed‐rape cultivars differing in N‐uptake efficiency. N‐efficient cultivar (cv.) ‘Apex' and N‐inefficient cv. ‘Capitol' were grown in a field experiment on a silty clayey gleyic fluvisol near Göttingen, northern Germany, and fertilized with 0 (N₀) and 227 (N₂₂₇) kg N ha^–1. In February 2002, PVC tubes with a diameter of 50 mm were installed between plant rows at 0–0.3 and 0–0.6 m soil depth with an angle of 45°. At the beginning of shooting, beginning of flowering, and at seed filling, the PVC tubes were substituted by PVC tubes (compartments) of the same diameter, but with an open window at the upper side either at a soil depth of 0–0.3 or 0.3–0.6 m allowing roots to grow into the tubes. Anion‐exchange resin at the bottom of the compartment allowed estimation of nitrate leaching. The compartments were then filled with root‐free soil which was amended with or without 90 mg N (kg soil)^–1. The newly developed roots and nitrate‐N depletion were estimated in the compartments after the installing period (21 d at shooting stage and 16 d both at flowering and grain‐filling stages). Nitrate‐N depletion was estimated from the difference between NO ‐N contents of compartments containing roots and control compartments (windows closed with a membrane) containing no roots. The amount of nitrate leached from the compartments was quantified from the resin and has been taken into consideration in the calculation of the N depletion. The amount of N depleted from the compartments significantly correlated with root‐length density. Suboptimal N application to the crop reduced total biomass and seed‐yield formation substantially (24% and 38% for ‘Apex’ and ‘Capitol’, respectively). At the shooting stage, there were no differences in root production and N depletion from the compartments by the two cultivars between N₀ and N₂₂₇. But at flowering and seed‐filling stages, higher root production and accordingly higher N depletion was observed at N₀ compared to N₂₂₇. Towards later growth stages, the newly developed roots were characterized by a reduction of root diameter and a shift towards the deeper soil layer (0.3–0.6m). At low but not at high N supply, the N‐efficient cv. ‘Apex’ exhibited higher root growth and accordingly depleted nitrate‐N more effectively than the N‐inefficient cv. ‘Capitol’, especially during the reproductive growth phase. The calculated nitrate‐N‐uptake rate per unit root length was maximal at flowering (for the low N supply) but showed no difference between the two cultivars. This indicated that the higher N‐uptake efficiency of cv. ‘Apex’ was due to higher root growth rather than higher uptake per unit of root length.     

Influence of leguminous cover crops on microbial and selected enzyme activities in soils of a plantation

A study dealing with ecological sustainability of plantation based land use initiated in 1991 in a 19 yr old coconut plantation consists of growing certain leguminous crops like Atylosia, Pueraria, Centrosema and Calopogonium as soil cover in separate plots with lemon grass as live bounds. These cover crops are grown during the rainy season and incorporated into the soil towards the end of the monsoon every year. The effect of such cover crops on soil microbial counts (total counts, fungi, actinomycetes and bacteria), biomass C, organic C, total N and on the activity of enzymes like urease, amidase, L-glutaminase, aryl sulphatase and dehydrogenase was determined in soils (Ap horizon) collected from these plots after 5 years. Soils with cover crops registered significantly higher microbial biomass, biomass C, organic C and total N compared to control. Consequently, all the enzymes were activated to different degrees in soils with cover crops. Significant and positive relationships of enzyme activities with organic C, mineral N and total N suggested that growing cover crops, increased C turnover and N availability and therefore, provided a conducive environment for microbial proliferation, enzyme synthesis and accumulation in the soil matrix.     

模拟人工湿地中硫酸盐氯霉素处理对细菌数量、湿地酶活性和生化作用的影响

【目的】细菌被认为是人工湿地中最重要的微生物成分,因为湿地中的一些生化过程均与细菌群落有关。然而,这一结论都是通过将细菌群落动态与湿地具体生化过程和废水净化效率进行比较得出的,因而是间接的,直接证据尚缺乏。本研究试图通过国际上通用的选择性抑制手段,再结合细菌数量、酶活性和生化过程分析,进一步认识细菌在人工湿地中的重要性。【方法】本研究依托垂直流模拟人工湿地进行。湿地从上至下,顺序地填充细砂（直径1~2 mm）、粗砂（直径6~12 mm）和石块（直径50~120 mm）3种填料。植物为香附子 （Cyperu srotundus L.）。废水为来自养猪场的排出液,废水灌溉采用间歇方式进行。废水的滞留时间为7 d,排空时间为0.5 d。共设置6个浓度的硫酸链霉素处理（0、 1.0、 1.5、 2.0、 2.5和3.0 mg/kg沙子）,调查了硫酸链霉素处理浓度与湿地填料中细菌数量、 酶活性和生化作用之间的关系。细菌数量用平板计数法测定,纤维素酶、 -葡糖糖苷酶、 蔗糖酶、 蛋白酶、 脲酶、 硝酸还原酶和酸性磷酸酶活性采用常规的酶学方法分析;纤维素降解作用、 氨化作用、 硝化作用、 反硝化作用、 有机磷降解作用和无机磷转化作用用室内培养分光光度法测定。【结果】随着硫酸链霉素处理浓度的增加,CMC纤维素酶、 -葡糖糖苷酶和蛋白酶活性未发生明显改变（P0.05）,而细菌数量、 脲酶、 硝酸还原酶和酸性磷酸酶活性却显著下降（P0.05）。在6种生化作用中,除了纤维素降解作用和无机磷转化作用没有发生显著变化外（P0.05）,其余4种生化作用（氨化作用、 硝化作用、 反硝化作用和有机磷降解作用）均随着硫酸链霉素浓度的增加而显著下降（P0.05）。主成分分析表明, 生化作用的总体变化清楚地区分了链霉素的不同浓度 (P 0.05),而酶活性的总体变化则未能区分。【结论】本研究突出了细菌在人工湿地氮和有机磷转化方面的重要性,因为细菌的逐渐抑制导致了与氮和磷循环有关的酶以及生化作用的显著降低。另一方面,还发现土壤生化作用的总体变化对链霉素的浓度梯度比酶活性敏感,这一规律是否具有普遍性还需进一步验证。     

Changes in growth,microbial and enzyme activities in oil palm nursery in response to bioinoculants and chemical fertilizers

ABSTRACT

A study was conducted to assess the influence of bioinoculants and chemical fertilizers on survival and enzymes activity of microbes in rhizosphere and growth of oil palm seedlings. Bioinoculants namely Azotobacter chroococcum, Azospirillum brasilense, Bacillus megaterium, Frateuria aurantia and Glomus aggregatum were applied individually, combindly and integrated with chemical fertilizers. Most convincing and highly significant results for growth parameters, phosphatases, dehydrogenase and trehalase activity were observed in potting mixture with application of bioinoculants + 25% recommended dose of chemical fertilizers (RDF). Extreme levels of esterase in potting mixture were noticed under the treatment with bioinoculants + 50% RDF followed by bioinoculants + 25% RDF. The highest population of Azotobacter, Azospirillum, Bacillus and Frateuria in potting mixture was enumerated with consortium of bioinoculants + 25% RDF. Glomalin content and root infection recorded in Glomus aggregatum was ostensibly superior to rest of the treatments except consortium of bioinoculants + 25% RDF. Correlation analysis revealed significant and positive interaction between microbial population and enzyme activities. The study suggests that integrated use of bioinoculants along with 25% RDF play a significant role in enhancing oil palm seedling growth through increased microbial population and enzyme activity in rhizosphere.     

不同耕作方式对土壤有机碳、微生物量及酶活性的影响

【目的】依托8年长期(2005~2012)固定道定位试验,研究不同耕作方式对土壤有机碳、土壤微生物量、土壤酶活性在0—90 cm土层的分布特征,为优化中国西北干旱区的耕作方式提供理论依据。【方法】试验包括固定道垄作(PRB)、固定道平作(PFT)与传统耕作(CT)三种耕作模式下的土壤有机碳土壤总有机碳(TOC)、颗粒有机碳(POC)、土壤微生物量碳(MBC)、土壤微生物量氮(MBN)、土壤微生物量磷(MBP)、蔗糖酶、过氧化氢酶、脲酶及小麦产量进行了测定和分析。【结果】在0—90 cm土层,不同耕作方式下的TOC、POC、MBC、MBN、MBP、蔗糖酶活性、脲酶活性均随着土层的增加呈下降趋势,过氧化氢酶活性呈先下降后增大的分布特征;在0—60 cm,固定道保护性耕作能够显著增加心土层作物生长带土壤有机碳储量,有机碳储量大小为PRBPFTCT;PRB、PFT较CT可以显著增加0—10 cm作物生长带TOC、POC、MBC、MBN、MBP含量、蔗糖酶、脲酶活性,其大小为PRBPFTCT;耕作方式对过氧化氢酶活性影响不显著;TOC、POC、MBC、MBN、MBP、蔗糖酶活性、脲酶活性、过氧化氢酶活性之间均达到了显著或极显著相关。【结论】PRB较PFT、CT能够提高耕作层(0—10 cm)土壤有机碳含量、土壤微生物量、土壤酶活性, 增加作物产量, 增大0—60 cm土层有机碳储量,耕作方式(PRB、PFT及CT)对10 cm以下土层土壤环境改善作用不明显。     

Effect of pruned material,extracts, and polyphenols of tea on enzyme activities and microbial community structure in soil

Pruning is a regular management practice performed in tea fields, but its effects on soil properties and microbial community structures have not been well explored. Effects of tea pruned material, tea extracts, and tea polyphenols application on soil properties and microbial characteristics, including pH, soil enzyme activities, culturable microbial population, and bacterial community, were investigated in a pot-incubation experiment lasting for 10 weeks. Results indicated that returning of tea pruned material or its extracts significantly increased the soil pH as compared to control. The soil invertase and urease activities, as well as the culturable microbial population treated with pruned material were much higher than those in control, while polyphenol oxidase activity was similar among different treatments. Denaturing gradient gel electrophoresis analysis of bacterial community indicated that the Shannon’s diversity index (H) of all nine treatments receiving additives slightly decreased as compared to control. Pruning returning specifically induced several beneficial bacterial species, including Brevibacterium sp. and Burkholderia sp. In conclusion, pruning returning alleviated soil acidification, induced soil enzyme activities, stimulated culturable microbial population, and reshaped the microbial community. This research suggests that this management could be applied as an alternative agricultural practice in tea cultivation.     

Conservation tillage and optimal water supply enhance microbial enzyme (glucosidase,urease and phosphatase) activities in fields under wheat cultivation during various nitrogen management practices

Field experiments were conducted on sandy clay loam soil at New Delhi, during the winter season of 2007 and 2008 to investigate the effect of tillage, irrigation regimes, i.e. sub-optimal, optimal and supra-optimal water supply, and integrated nutrient management practices (INM) on soil enzymatic activities after cultivation of wheat (Triticum aestivum). Soil glucosidase (54.5%), urease (88.8%), acid phosphatase (97.4%) and alkaline phosphatase (85.3%) activities increased significantly under conservation tillage compared with conventional tillage fields. An optimal water supply (i.e. three irrigations) led to a significant increase in soil enzymatic activity over sub-optimal (i.e. two) and supra-optimal (five) irrigation. Urease activity was slightly lower in the sub-optimal irrigations, but higher in supra-optimal irrigations by 15.5% than in optimal irrigation in conventional tillage. This study suggests that inorganic and organic nutrient combinations with conservation tillage and optimal water supply significantly improved soil enzymatic activities.     

Ramifications of crop residue loading for soil microbial community composition,activity and nutrient supply

Variable results have been reported on the effects of crop residue loads on soil microbial properties. We investigated changes in soil bacterial composition, β-glucosidase enzyme activity and nutrient bioavailability in response to wheat residue loading. The treatments included three levels of above-ground wheat residues (removed, retained or supplemented), with or without fertilizer N. Bacteroidetes, Firmicutes and Verrucomicrobia (the first two are copiotrophs) were less abundant where residues were removed than where residues were retained or supplemented, but the reverse was true for Actinobacteria, Cyanobacteria, Chloroflexi and Nitrospirae (all oligotrophs, although some Actinobacteria can be copiotrophic). Actinobacteria were also less abundant where fertilizer N was applied, and the abundances of their genera (including Arthrobacter and Mycobacterium) increased where residues were removed, confirming that they were oligotrophic in this study. β-diversity showed similar differences in the bacterial community structures because of residue management, but α-diversity was not affected by residue management or N fertilizer. β-glucosidase enzyme activities increased as C inputs increased with residue manipulation and N fertilizer. The enzyme activities increased with increasing residue loading in the 0–15 cm soil depth, but decreased with soil depth. Soil K supply increased with increasing residue loading, but nitrate-N supply was highest with residue retention. These results demonstrate remarkable resilience of soil microbial functioning under a wide range of crop residue inputs, without adverse effects on enzyme activity attributable to inorganic N fertilizer. The increasing β-glucosidase activity with increasing residue loading probably explains why crop residue return does not always increase soil C stocks.     

不同干扰强度下农业生态系统土壤微生物生物量和活性的分异

Different management practices in six agroecosystems located near Goldsboro, NC, USA were conducted including a successional field (SU), a plantation woodlot (WO), an integrated cropping system with animals (IN), an organic farming system (OR), and two cash-grain cropping systems employing; either tillage (CT) or no-tillage (NT) to examine if and how microbial biomass and activity differ in response to alterations in disturbance intensity from six land management strategies. Results showed that soil microbial biomass and activity differed, with microbial activity in intermediately disturbed ecosystems (NT, OR, IN) being significantly higher (P < 0.01) than systems with either high or low disturbance intensities. There was also a significant and a highly significant ecosystem effect from the treatments on microbial biomass C (MBC) (P < 0.05) and on microbial activity (respiration) (P < 0.01), respectively. Multiple comparisons of mean respiration rates distinctly separated the six ecosystem types into three groups: CT < NT, SU and WO < OR and IN. Thus, for detecting microbial response to disturbance changes these results indicated that the active component of the soil microbial community was a better indicator than total biomass.     

Nitrogen forms affect root growth,photosynthesis, and yield of tomato under alternate partial root‐zone irrigation

To increase efficiency of water and nitrogen (N) fertilizer use, this study was conducted with a split‐root pot experiment to investigate the effects of different forms of N fertilizer on root growth, photosynthesis, instantaneous water use efficiency (IWUE), and yield of tomato (Lycopersicon esculentum L.) under alternate partial root‐zone irrigation (APRI). Three irrigation modes comprised conventional irrigation (CI) and two kinds of APRI, i.e., APRI with water content in the drying soil compartment controlled at ≥ 60% or 40% of the water‐holding capacity (APRI‐60, APRI‐40). Two N forms included ammonium‐N and nitrate‐N supplied as calcium nitrate or ammonium sulfate, respectively. The results show that APRI‐60 enhanced root growth and increased leaf IWUE with a slight yield reduction compared with CI regardless of the N form supplied. In contrast, APRI‐40 significantly decreased root growth and inhibited photosynthesis, thereby resulting in a significant yield loss. In addition, at the flowering stage tomato plants grew better with ammonium‐N than nitrate‐N supply; however, at the fruit expansion stage and maturity stage, the tomato plants had a higher biomass accumulation and yield with nitrate‐N than ammonium‐N supply. Therefore, the application of APRI should consider the soil water condition coupled with an appropriate N form. In the present study, APRI controlled at ≥ 60% of the water‐holding capacity (WHC) for the drying soil side with nitrate‐N supply was the best water‐fertilizer supply for tomato cultivation.     

鸡粪与化肥不同配比对杨树苗根际土壤酶和微生物量碳、氮变化的影响

为比较鸡粪有机肥与化肥以不同比例配施对杨树苗根际土壤环境的作用效果,通过盆栽试验,研究了N100（尿素提供100%的氮）、 M10N90（鸡粪和尿素分别提供10%和90%的氮)、 M30N70（鸡粪和尿素分别提供30%和70%的氮）和M50N50（鸡粪和尿素各提供50%的氮）等处理对一年生杨树苗根际土壤酶活性、 微生物量碳（SMBC）和微生物量氮（SMBN）的影响。结果表明, 同N100处理相比,M30N70处理的杨树苗根际土壤脲酶、 碱性磷酸酶、 过氧化氢酶和蔗糖酶活性分别提高14.41%~26.49%、 13.87%~27.93%、 12.07%~27.08%和29.17%~46.43%; 根际SMBC、 SMBN含量分别提高63.00%~76.62%、 40.01%~90.38%。在杨树苗的年生长过程中,根际土壤脲酶、 碱性磷酸酶、 过氧化氢酶和蔗糖酶活性均在施肥后120 d 最高; 而根际SMBC和SMBN含量分别在施肥后90 d和30 d达到最大值。随着杨树苗的生长发育,SMBN含量逐渐降低,而在落叶期有一定的回升。与M30N70处理相比,M10N90和M50N50处理对杨树苗根际土壤酶和微生物量碳、 氮的影响较小。综合分析认为,鸡粪有机肥与化肥以3∶7比例配施对杨树苗根际区域生态环境的改善效果最佳。     

Effects of pasture improvement and intensive cultivation on microbial biomass,enzyme activities,and composition and size of earthworm populations

We investigated the quantity and distribution of organic C, microbial biomass C, protease, arylsulphatase and arylphosphatase activity, and earthworm numbers and biomass in the soil from a 37-year-old grazed pasture supplied with superphosphate at rates of 0, 188, and 376 kg ha^-1 annually. The results were compared with a non-irrigated wilderness site which had not been used for agriculture and an arable site that had been intensively cultivated for 11 consecutive years. In the 0- to 5-cm layer, organic C followed the trend arableAporrectodea caliginosa (77–89% of total numbers) although Lumbricus rubellus made an increasing contribution to the population with increasing superphosphate rates. In the unirrigated wilderness site the population consisted of 56% A. caliginosa and 44% L. rubellus. While Octolasion cyaneum and A. rosea made up a small proportion of the population in the improved pasture sites, they were not present in the wilderness or arable sites. A. caliginosa was the only species present in the arable site. The mean fresh weight of individuals followed the order arable相似文献