Soil Acid Phosphatase Activity Research Articles

Effects of intensive management on soil C and N pools and soil enzyme activities in Moso bamboo plantations.

In order to elucidate the effects of intensive management on soil carbon pool, nitrogen pool, enzyme activities in Moso bamboo (Phyllostachys pubescens) plantations, we collected soil samples from the soil surface (0-20 cm) and subsurface (20-40 cm) layers in the adjacent Moso bamboo plantations with extensive and intensive managements in Sankou Township, Lin'an City, Zhejiang Province. We determined different forms of C, N and soil invertase, urease, catalase and acid phosphatase activities. The results showed that long-term intensive management of Moso bamboo plantations significantly decreased the content and storage of soil organic carbon (SOC), with the SOC storage in the soil surface and subsurface layers decreased by 13.2% and 18.0%, respectively. After 15 years' intensive management of Masoo bamboo plantations, the contents of soil water soluble carbon (WSOC), hot water soluble carbon (HWSOC), microbial carbon (MBC) and readily oxidizable carbon (ROC) were significantly decreased in the soil surface and subsurface layers. The soil N storage in the soil surface and subsurface layers in intensively managed Moso bamboo plantations increased by 50.8% and 36.6%, respectively. Intensive management significantly increased the contents of nitrate-N (NO3--N) and ammonium-N (NH4+-N), but decreased the contents of water-soluble nitrogen (WSON) and microbial biomass nitrogen (MBN). After 15 years' intensive management of Masoo bamboo plantations, the soil invertase, urease, catalase and acid phosphatase activities in the soil surface layer were significantly decreased, the soil acid phosphatase activity in the soil subsurface layer were significantly decreased, and other enzyme activities in the soil subsurface layer did not change. In conclusion, long-term intensive management led to a significant decline of soil organic carbon storage, soil labile carbon and microbial activity in Moso bamboo plantations. Therefore, we should consider the use of organic fertilizer in the intensive mana-gement process for the sustainable management of Moso bamboo plantations in the future.

Increase phosphorus availability from the use of alfalfa (Medicago sativa L) green manure in rice (Oryza sativa L.) agroecosystem.

Alfalfa is a good green manure source, but its effect on rice growth has not been fully elucidated. Two green manure species, alfalfa and broad bean (Vicia faba L.), and two N fertilizer levels, alone or combination, were applied to a rice field. The results indicated that alfalfa had more pronounced effects on increasing soil labile phosphorus (P) fractions (including NaHCO3-Pi, NaOH-Pi), P uptake and soil enzyme activities (dehydrogenase, urease, acid phosphatase and β-glucosidase) than broad bean and N fertilizer. The transformation of NaHCO3-Po to labile P regulated by alfalfa played a significant direct and indirect effect on grain yield. Although a much lower N input from alfalfa addition, a similar grain yield with N fertilizer treatment was achieved, and the integration of alfalfa with N fertilizer produced the highest grain yield and P availability, which was associated with the highest urease, acid phosphatase and β-glucosidase activity in soil. These results indicate that alfalfa green manure had a great ability of increasing grain yield through enhancing P availability in rice paddy, which could give us a way to reduce N fertilizer application by enhancing P availability.

Phosphorus Supplying Capacity of Value Added Compost Prepared from Low-Grade Indian Rock Phosphates and Crop Residue

In this study, value added compost was prepared from low-grade Indian rock phosphates (RPs) and isabgol straw as an alternative sources of phosphorus. Three different sources of low-grade RP namely Udaipur, Jhabua and Purulia were evaluated for alternative source of P. Total carbon (C) decreased while total nitrogen (N) increased, leading to a decrease in the C/N ratio at the end of composting. Notable increases in total and available P was found in the composts charged with RPs. The rate of P released from the composts was studied through leaching experiment in the laboratory. An incubation study was carried out to evaluate the effect of different compost on soil P availability. Data revealed that the sharp increase in water soluble P from all the compost at 14 days of leaching then a gradual decrease. Significantly higher water soluble P released from the value added (RP charged) compost as compared to ordinary compost throughout the leaching period. Application of value added compost in soil increased water soluble, available P, microbial biomass C and P as well as acid and alkaline phosphatase activity in soil. Initially, the value added compost showed lower available P as compared to DAP however, improved significantly at a later stage of incubation. The increase in different labile pools of P in soil amended with value added compost also indicates substantial amount of P mobilized from the compost during incubation. Thus, the value added compost could be an effective alternative of chemical fertilizer and promising technology to utilize low-grade RP as P source.

Rhizobial Inoculation Increases Soil Microbial Functioning and Gum Arabic Production of 13-Year-Old Senegalia senegal (L.) Britton, Trees in the North Part of Senegal.

Rhizobial inoculation has been widely used in controlled conditions as a substitute for chemical fertilizers to increase plants growth and productivity. However, very little is known about such effects on mature trees in natural habitats. In this study, we investigated the effect of rhizobial inoculation on soil total microbial biomass, mineral nitrogen content, potential CO2 respiration, fluorescein diacetate (FDA), acid phosphatase activities, and gum arabic production by 13-year-old Senegalia senegal (synonym: Acacia senegal) under natural conditions in the north part of Senegal during two consecutive years. Rhizobial inoculation was performed at the beginning of the rainy season (July) for both years with a cocktail of four strains (CIRADF 300, CIRADF 301, CIRADF 302, and CIRADF 303). Rhizospheric soils were collected in both dry and rainy seasons to a depth of 0–25 cm under uninoculated and inoculated trees. Trees were tapped in November (beginning of dry season) using traditional tools. Gum arabic was harvested every 15 days from December to March. The results obtained from both years demonstrated that rhizobial inoculation increased significantly the percentage of trees producing gum arabic, gum arabic production per tree, soil microbial biomass, FDA, and acid phosphatase activities. However, there was no significant effect on C mineralization and mineral nitrogen (N) content. Gum arabic production was positively correlated to rainfall, soil microbial biomass, and mineral nitrogen content. Our results showed a positive effect of rhizobial inoculation on soil microbial functioning and gum arabic production by mature S. senegal trees. These important findings deserve to be conducted in several contrasting sites in order to improve gum arabic production and contribute to increase rural population incomes.

Long-term fertilization increases soil nutrient accumulations but decreases biological activity in navel orange orchards of subtropical China

With its high economic benefits, navel orange (Citrus sinensis) has been widely planted and fertilizer has been increasingly applied in the subtropical China in the last 30 years. Comprehensive assessments are needed to explore the long-term fertilization impacts on soil chemical and biological properties in the navel orange orchards. Through a large number of soil and leaf samples from the young, middle-aged, and mature navel orange orchards, this study examined the impacts of stand age (corresponding to the fertilization year using compound chemical fertilizer) on seasonal variations in major soil properties and leaf nutrients in the subtropical China. Soil total nitrogen (N) and mineral N were significantly higher in the middle-aged and mature orchards than in the young orchard. Total phosphorus (P), available P, labile P, slow P, occluded P, weathered mineral P, total exactable P, and residual P generally increased with fertilization years (P < 0.05), and the increasing percentages for soil P fractions were much higher than those for N variables. The total N and P use efficiencies (plant uptake/soil input) were 20–34 and 10–15 %, respectively. Soil microbial biomass, invertase, urease, and acid phosphatase activities showed significant seasonal variations and decreased with fertilization years. Leaf N concentration significantly decreased with fertilization years, but no difference was found for P. Soil self-fertilization was impeded, and less fertilizer amount should be applied especially in the older navel orange orchards since N and P accumulations do not increase leaf nutrients but worsen soil biological quality.

Mycorrhizal (Rhizophagus Intraradices) Symbiosis and Fe and Zn Availability in Calcareous Soil

ABSTRACTGreenhouse experiment was conducted to assess the iron (Fe) and zinc (Zn) fractionation patterns in soils of arbuscular mycorrhizal (AM) fungus-inoculated and uninoculated maize plants fertilized with varying levels of Fe and Zn. Soil samples were collected for Fe and Zn fractions and available Fe, Zn and phosphorus (P) contents besides organic and biomass carbon (BMC), soil enzymes and glomalin. Major portion of Fe and Zn fractionations was found to occur in the residual form. Mycorrhizal symbiosis increased the organically bound forms of Fe and Zn while reducing the crystalline oxide, residual Fe and Zn fractions, indicating the transformation of unavailable forms into available forms. Soil enzymes, viz. dehydrogenase and acid phosphatase activities in M+ soils, were significantly higher than M− soil consistently. Overall, the data suggest that mycorrhizal symbiosis enhanced the availability of Fe and Zn as a result of preferential fractionation and biochemical changes that may alleviate micronutrient deficiencies in calcareous soil.Abbreviations: AM: arbuscular mycorrhiza; Fe: Iron; Zn: Zinc; P: Phosphorous; Amox-Zn: amorphous oxide bound zinc; Cryox-Zn: crystalline oxide bound zinc; DAS: days after sowing; DTPA: diethylene Triamine Penta Acetic Acid; MnO2-Zn: manganese oxide bound zinc; OC-Zn: organically bound zinc; WSEX: water soluble plus exchangeable zinc; MnO2 Fe: manganese oxide bound iron; OC-Fe: Organically bound iron; WSEX Fe: water soluble plus exchangeable iron.

The Influence of Phosphorus Sources on the Growth and Rhizosphere Soil Characteristics of Two Genotypes of Wheat (Triticum aestivum L.)

ABSTRACTA rhizobox experiment was conducted to investigate the effects of phosphorus (P) sources on the rhizosphere soil characteristics of two wheat genotypes Xiaoyan54 (P-efficient) and Jing411 (P-inefficient), which were colonized with an arbuscular mycorrhizal fungus and grown in Cumulic Haplustoll. The four P sources included a control (no added P), OP [organic P: sodium (Na)-phytate], IP [inorganic P: monopotassium phosphate (KH2PO4)], and OPIP (Na-phytate plus KH2PO4). The results showed that when no exogenous P was added the shoot biomass of Xiaoyan54 was 28% significantly higher than Jing 411. The acid phosphatase activity (APA) in the rhizosphere soil was significantly depressed when inorganic P was added; the APA for Xiaoyan54 was higher than that of Jing411 in most of the layers regardless of the P source. Inorganic and organic P fertilizer conditions did not significantly impact the soil pH relative to the control, and the pH did not significantly differ between the two genotypes. In conclusion, when no exogenous P was added, shoot biomass of Xiaoyan54 was greater than Jing411. This increase was promoted by greater soil APA but not soil acidification. The rhizosphere soil pH was not altered across different wheat genotypes or P sources, but APA was increased in the soil of control and OP-treated plants compared with IP- and OPIP-treated plants. The APA of Xiaoyan54 was higher than Jing411 for all of the P sources. The response mechanism of rhizosphere soil acidification is different from acid phosphatase exudation in plants receiving different P sources under arbuscular mycorrhizal fungus inoculation.

Impact of litter contaminated with glyphosate-based herbicide on the performance of Pontoscolex corethrurus, soil phosphatase activities and soil pH

The bioavailability of glyphosate from plant residues may be high in the soil matrix. In order to determine the impact of litter contaminated with glyphosate (GLY) on the growth and cocoon production of the earthworm Pontoscolex corethrurus as well as on acid and basic phosphatase activities and soil pH, a commercial glyphosate-based herbicide was applied to three types of litter mixed with soil. Earthworms from a GLY-free coffee plantation were grown for 132days in microcosms in a two-factorial design. The first factor was glyphosate (GLY; 21.6g of glyphosate per kg of litter, with two levels (−GLY, +GLY), and the second factor was type of litter (Coffea arabica, Musa cavendishii, Inga vera). All studied factors (except days*litter*glyphosate interaction) had significant effects on earthworm biomass (P<0.05). Treatments with Coffea and Musa litter -GLY had significantly higher biomass (P<0.05), whereas treatments with Inga litter -GLY and +GLY had the lowest biomass. A decline in earthworm biomass was detected in all treatments with glyphosate (+GLY) after 72days. No significant effect on cocoon production was detected for the main factors or their interaction. Litter type showed a marginal effect (P=0.06); the average (±SE) number of cocoons decreased from Musa (5.8±2.9) to Coffea (1.3±0.56) and Inga (0.17±0.17). Soil pH significantly (P=0.006) decreased at the end of the experiment from 4.4±0.17 in -GLY to 3.9±0.06 in +GLY. Acid phosphatase activity increased in treatments with Musa and Inga +GLY (P<0.05), while alkaline phosphatase activity in the same substrates was higher in treatments with -GLY (P<0.05). We conclude that repeated application of litter contaminated with glyphosate negatively affects earthworm vitality and increases soil acidity and acid phosphatase activity.

Phosphorus resorption by young beech trees and soil phosphatase activity as dependent on phosphorus availability.

Motivated by decreasing foliar phosphorus (P) concentrations in Fagus sylvatica L. forests, we studied P recycling depending on P fertilization in mesocosms with juvenile trees and soils of two contrasting F. sylvatica L. forests in a greenhouse. We hypothesized that forests with low soil P availability are better adapted to recycle P than forests with high soil P availability. The P resorption efficiency from senesced leaves was significantly higher at the P-poor site (70%) than at the P-rich site (48%). P fertilization decreased the resorption efficiency significantly at the P-poor site to 41%, while it had no effect at the P-rich site. Both acid and alkaline phosphatase activity were higher in the rhizosphere of the P-poor than of the P-rich site by 53 and 27%, respectively, while the activities did not differ in the bulk soil. Fertilization decreased acid phosphatase activity significantly at the P-poor site in the rhizosphere, but had no effect on the alkaline, i.e., microbial, phosphatase activity at any site. Acid phosphatase activity in the P-poor soil was highest in the rhizosphere, while in the P-rich soil, it was highest in the bulk soil. We conclude that F. sylvatica resorbed P more efficiently from senescent leaves at low soil P availability than at high P availability and that acid phosphatase activity in the rhizosphere but not in the bulk soil was increased at low P availability. Moreover, we conclude that in the P-rich soil, microbial phosphatases contributed more strongly to total phosphatase activity than plant phosphatases.

青藏高原东缘不同树种人工林对土壤酶活性及养分的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 青藏高原东缘不同树种人工林对土壤酶活性及养分的影响 DOI: 10.5846/stxb201409221877 作者: 作者单位: 西南林业大学,中科院成都生物所,西南林业大学,西南林业大学,中国科学院成都生物所,中科院成都生物所 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目(31270492);国家"十二五"科技支撑计划子课题(2011BAC09B04-02);中国科学院战略性先导科技专项子课题(XDA05070306) Effects of afforestation with different tree species on soil enzyme activities and nutrient content in eastern Qinghai-Tibetan Plateau, China Author: Affiliation: Southwest Forestry University,,,,,Chengdu Institute of Sciences Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为评价不同树种人工林对土壤酶及养分的影响,选择立地条件和营林方式相同的4种人工林(连香树[CJ]、油松[PT]、落叶松[LK]和华山松[PA])为研究对象,以落叶灌丛(QC)为对照,比较不同树种人工林地土壤酶活性和土壤养分的变化。结果显示:(1)造林降低了土壤酸性磷酸酶、脱氢酶、β-葡萄糖苷酶和过氧化氢酶活性,但人工造林后土壤脲酶活性增加;(2)造林也明显影响了土壤养分,与对照林地相比,除CJ人工林土壤中磷(P)略高外,造林地土壤有机碳(TOC)、氮(N)、水可提取有机碳(WEOC)和氮(WEON)、铵态氮(NH4+-N)和硝态氮(NO3--N)均降低;(3)不同的人工林树种之间土壤养分及酶活性也存在一定的差异性,CJ和LK人工林土壤C、N、P及相关酶活性明显不同于PT和PA人工林;(4)土壤酶与养分变化有一定的相关性,除转化酶和多酚氧化酶反应较迟钝外,其它酶对环境反应较敏感。综合分析表明,在川西地区选择高密度单一树种造林并没有改善土壤养分和酶活性,在该地区选择落叶或阔叶树种造林可使土壤肥力恢复。 Abstract:Afforestation is known to be the main source of restoration of degraded soil fertility and a driving force of soil processes. Plant species affect quantity and quality of carbon resources in the rhizosphere, which influence the composition and diversity of microbial community in these environments. Different plant species promote proliferation of different microbial communities by releasing different amounts and types of root exudates. Moreover, plants may directly or indirectly affect soil nutrient availability by altering soil enzyme activities through releasing extracellular enzymes and/or altering microbial community that is known to be major contributors of enzyme activities in soil. However, few studies have been conducted to elucidate the effects of afforestation with different tree species on enzyme activities and nutrients in soil. To evaluate the changes in enzyme activities and nutrients in soil after 26 years(1987-2013) of afforestation with different tree species, four plantations stands with dominant tree species(e.g., Cercidiphyllum japonicum[CJ], Pinus tabulaeformis[PT], Larix kaempferi[LK], and Pinus armandii[PA]) were selected, and a native broad-leaf forest(QC) was used as control. Four plantations were cultivated under similar site conditions and same planting patterns. Seven soil enzymes including soil urease, acid phosphatase, invertase, β-glucosidase, dehydrogenase, catalase, and polyphenol oxidase, their activities, and soil nutrients were determined. Our results showed that:(1) Afforestation significantly influenced soil enzyme activities. For example, compared with QC, afforestation with CJ, PT, LK, and PA decreased soil acid phosphatase, β-glucosidase, dehydrogenases, and catalase activities, whereas activity of soil urease was significantly higher in CJ and LK plantations than in other stands;(2) Afforestation also significantly affected soil nutrient content. Except for total phosphates, soil total organic carbon, total nitrogen, water extractable carbon and nitrogen, NH4+-N, and NO3--N were significantly lower in the four plantations than in the QC stand;(3) Enzyme activity and nutrient availability was higher in LK and CJ plantations, than in PT and PA plantations;(4) Soil enzyme activities were correlated to soil nutrients depending on specific enzymes. Except for invertase and catalase, activities of other five soil enzymes examined in this study were sensitive to changes in soil environment, especially to the nutrient content. Our results suggested that high-density afforestation with monoculture decreased soil nutrients and soil enzyme activities. Additionally, deciduous or broad-leaved tree species(e.g., LK or CJ) can be appropriate for restoration of soil fertility by afforestation and structure modification of monoculture plantation. We concluded that soil enzymes are a good indicator of change in soil fertility induced by afforestation with different tree species or land use change. 参考文献 相似文献 引证文献

Response of Soil Microbial Properties to Long-Term Application of Organic and Inorganic Amendments in a Tropical Soil (Saria, Burkina Faso)

Soil microbial biomass carbon (MBC), β-glucosidase, acid phosphatase and fluorescein diacetate (FDA) activities and bacterial community structure were assessed in a long-term (26 years) experiment, at physiological stages of sorghum growth, comparing different management methods for organic (manure, straw residues) and inorganic (urea) amendments at the INERA field station in Saria (Burkina Faso). Annual application of manure led to the highest soil microbial biomass and enzyme activities. Investigations indicated that only microbial biomass and β-glucosidase activities were affected during the cropping season. Phosphatase and FDA enzyme activities did not depend on the crop development stages. The application of N fertilizer modified phosphatase and FDA enzyme activities, the activities being higher in soils amended with N fertilizer. The bacterial community structure was analyzed by PCR-denaturing gradient gel electrophoresis (PCR-DGGE) targeting the eubacterial 16S rRNA gene. Cluster analysis of PCR-DGGE patterns showed two major clusters, the first containing the mineral fertilization and straw treatments and the second, the straw + urea, manure and manure + urea treatments. Sorghum grain yields were the highest for manure treatments. In this long-term experiment, applying straw did not produce a better grain yield than that obtained in the un-amended plot.

Soil Enzyme Activities, Organic Carbon and Microbial Population as Influenced by Integrated Nitrogen Management for Banana

Soil enzyme activities, organic carbon (OC) and microbial population were assessed periodically in banana plantation imposed by integrated nitrogen (N) management treatments on Inceptisol during 2005–06. The treatment comprising substitution of N through farmyard manure (FYM), neem cake and vermicompost in 25, 50 and 33% proportion along with recommended dose of fertilizers (RDF). The OC content of soil was increased significantly by the application of inorganic fertilizers and organic manures viz., FYM, neem cake and vermicompost except the treatment received only RDF. The magnitude of increase in OC was significantly higher in the treatment receiving FYM, neem cake and vermicompost. The population of soil actinomycetes, bacteria and fungi were increased consistently up to 240 days after planting of banana. Higher population of actinomycetes (118×105 g−1 soil), fungal (141×104 g−1 soil) and bacteria (159×106 g−1 soil) were recorded with the application of organics. Soil urease and dehydrogenase activity was increased consistently up to 120 days after planting, whereas acid phosphatase activity increased up to 165 days after planting of banana. Significantly highest urease activity (44.8 mg NH4-N 100g−1 soil h−1) was obtained in soils receiving 50% N through FYM and 50% N through RDF followed by 100% N through FYM, vermicompost and neem cake (42.8 mg NH4-N 100g−1 soil h−1) at 120 days after planting, whereas significantly higher soil acid phosphatase activity (6.01 μMP g−1 soil h−1) and dehydrogenase activity (85.0 μg TPF g−1 soil 24h−1) were recorded with application of 100% N in equal proportion through FYM, neem cake and vermicompost. However, application of inorganic fertilizers as per soil test to banana resulted in lower magnitude of urease, acid phosphatase and dehydrogenase activity.

Impact of Microbial Inoculants on Microbial Quantity, Enzyme Activity and Available Nutrient Content in Paddy Soil

The experiment was conducted to study the impact of application of microbial inoculants, compared with no microbial fertilizer, on enzyme activity, microbial biomass and available nutrient contents in paddy soil in Heilongjiang Province. The application of soil phosphorus activator was able to increase the quantity of bacteria and fungi in soil, but its effect on actinomycetes in soil was not significant. The application of microbial inoculants increased the urease and sucrase activities in soil over the growing season, but only at the maturing stage soil acid phosphatase activity was enhanced with the applying soil phosphorus activator. The application of soil phosphorus activator increased alkali-hydrolyzable nitrogen and available phosphorus contents in soil, but did not increase available potassium content in soil. The optimal microbial inoculant application rate as applied as soil phosphorus activator was 7.5 kg·hm−2.

Effects of Common Mycorrhizal Network on Plant Carbohydrates and Soil Properties in Trifoliate Orange-White Clover Association.

Common mycorrhizal network (CMN) allows nutrients and signals to pass between two or more plants. In this study, trifoliate orange (Poncirus trifoliata) and white clover (Trifolium repens) were planted in a two-compartmented rootbox, separated by a 37–μm nylon mesh and then inoculated with an arbuscular mycorrhizal fungus (AMF), Diversispora spurca. Inoculation with D. spurca resulted in formation of a CMN between trifoliate orange and white clover, whilst the best AM colonization occurred in the donor trifoliate orange–receptor white clover association. In the trifoliate orange–white clover association, the mycorrhizal colonization of receptor plant by extraradical hyphae originated from the donor plant significantly increased shoot and root fresh weight and chlorophyll concentration of the receptor plant. Enzymatic activity of soil β-glucoside hydrolase, protease, acid and neutral phosphatase, water-stable aggregate percentage at 2–4 and 0.5–1 mm size, and mean weight diameter in the rhizosphere of the receptor plant also increased. The hyphae of CMN released more easily-extractable glomalin-related soil protein and total glomalin-related soil protein into the receptor rhizosphere, which represented a significantly positive correlation with aggregate stability. AMF inoculation exhibited diverse changes in leaf and root sucrose concentration in the donor plant, and AM colonization by CMN conferred a significant increase of root glucose in the receptor plant. These results suggested that CMN formed in the trifoliate orange–white clover association, and root AM colonization by CMN promoted plant growth, root glucose accumulation, and rhizospheric soil properties in the receptor plant.

Responses of soil acid phosphatase and beta-glucosidase to nitrogen and phosphorus addition in two subtropical forests in southern China

Elevated nitrogen (N) deposition has dramatically altered soil phosphorus (P) and carbon (C) cycles in forests and altered extracellular enzyme activity. However, the effects of N addition and the interactive effects of combined N and P additions on soil enzyme (e.g. phosphatase and glucosidase) activity in different types of forests (young vs. old-growth) remain unclear. To better understand this, a long-term N–P fertilization experiment was initiated in January 2007 in two subtropical forests (an old-growth monsoon evergreen broadleaf forest (MEBF) and a young Masson pine forest (MPF)) in southern China. Four treatments were established, including control (no nutrient addition), N addition (150 kg Nha−1yr−1), P addition (150 kg Pha−1yr−1) and NP addition (150 kg Nha−1yr−1 plus 150 kg Pha−1yr−1). Soil physicochemical properties, acid phosphatase (APA-s) and β-glucosidase (BGA-s) activity per soil were measured in July 2012 and July 2013. Both APA-s and BGA-s were higher in MEBF than in MPF. N addition significantly stimulated APA-s in MEBF and BGA-s in MPF. P addition significantly suppressed APA-s in both forests and BGA-s in MEBF. Moreover, P addition decreased the stimulating effect of N addition on APA-s in MEBF and on BGA-s in MPF. Our results suggest that (1) N addition may exacerbate soil P limitation in old-growth forests and result in the deficiency of easily available C in young forests and (2) P addition may mitigate these negative effects of N addition in both forest types. Our findings suggest that P fertilization may be an effective practice to improve soil P availability in old-growth forests and soil C availability in young forests under N deposition condition.

Penicillium menonorum: A Novel Fungus to Promote Growth and Nutrient Management in Cucumber Plants

The present study is the first report on the isolation of Penicillium menonorum from rhizosphere soil in Korea and its identification based on morphological characteristics and internal transcribed spacer gene sequence. The fungal isolate was named KNU-3 and was found to exhibit plant growth-promoting (PGP) activity through indole acetic acid (IAA) and siderophore production, as well as P solubilization. KNU-3 produced 9.7 mg/L IAA and solubilized 408 mg of Ca3PO4/L, and inoculation with the isolate significantly (p < 0.05) increased the dry biomass of cucumber roots (57%) and shoots (52%). Chlorophyll, starch, protein, and P contents were increased by 16%, 45%, 22%, and 14%, respectively, compared to plants grown in uninoculated soil. The fungus also increased soil dehydrogenase (30%) and acid phosphatase (19%) activities. These results demonstrate that the isolate KNU-3 has potential PGP attributes, and therefore it can be considered as a new fungus to enhance soil fertility and promote plant growth. Moreover, the discovery of PGP ability and traits of this fungus will open new aspects of research and investigations. In this study, plant growth promotion by P. menonorum KNU-3 is reported for the first time in Korea after its original description.

Spatial dynamics of dark septate endophytes and soil factors in the rhizosphere of Ammopiptanthus mongolicus in Inner Mongolia, China

Improved understanding of the spatial patterns of desert soil resources and the role of dark septate endophytes (DSE) is required to measure plant growth in desert areas. Spatial dynamics of DSE and soil factors were investigated in Wuhai, Urad Back Banner and Alxa Left Banner, located in Inner Mongolia, China. Soil samples in the rhizosphere of Ammopiptanthus mongolicus were collected. Sampling sites and soil depth had a significant influence on the morphology, distribution and infection of DSE. Hyphae, microsclerotia and total root infection of DSE reached their maxima in the 0–20 cm soil layer. Microsclerotial infection at Wuhai and Alxa Left Banner was higher than that at Urad Back Banner. Hyphal infection was significantly positively correlated with amounts of organic matter and available nitrogen, and activities of soil alkaline phosphatase, acid phosphatase and urease. Microsclerotial infection was significantly positively correlated with amounts of soil organic matter and available nitrogen. Root infection had no significant correlation with soil factors. We concluded that the dynamics of DSE have a highly spatial pattern, and were influenced by nutrient availability and enzymatic activity. This study suggests that the morphology and infection of DSE are useful indicators for evaluating soil quality and function of desert ecosystems.

Enhancement of arbuscular mycorrhizal fungus (Glomus versiforme) on the growth and Cd uptake by Cd-hyperaccumulator Solanum nigrum

Arbuscular mycorrhizal fungus (AMF) can enhance plant growth and resistance to toxicity produced by heavy metals (HMs), affect the bioavailability of HMs in soil and the uptake of HMs by plants, and thus has been emerged as the most prominent symbiotic fungus for contribution to phytoremediation. A greenhouse pot experiment was conducted to assess the effect of Glomus versiforme BGC GD01C (Gv) on the growth and Cd accumulation of Cd-hyperaccumulator Solanum nigrum in different Cd-added soils (0, 25, 50, 100mgCdkg−1 soil). Mycorrhizal colonization rates were generally high (from 71% to 82%) in Gv-inoculated treatments at all Cd levels. Gv colonization enhanced soil acid phosphatase activity, and hence elevated P acquisition and growth of S. nigrum at all Cd levels. Moreover, the presence of Gv significantly increased DTPA-extractable (phytoavailable) Cd concentrations in 25 and 50mgCdkg−1 soils, but did not affect phytoavailable Cd in 100mgCdkg−1 soil. Similarly, inoculation with Gv significantly increased Cd concentrations of S. nigrum in 25 and 50mgCdkg−1 soils, but decreased Cd concentrations of the plants in 100mgCdkg−1 soil. Overall, inoculation with Gv greatly improved the total Cd uptakes in all plant tissues at all Cd levels. The present results indicated that S. nigrum associated with Gv effectively improved the Cd uptake by plant and would be a new strategy in microbe-assisted phytoremediation for Cd-contaminated soils.

Effects of dual inoculation with arbuscular mycorrhizal fungi and rhizobia on Acacia senegal (L.) Willd. seedling growth and soil enzyme activities in senegal

Acacia senegal (L.) Willd. is a multipurpose legume that is economically and ecologically important in Sahelian areas, especially in Senegal. It has long been used for arabic gum production. However, drought and overexploitation lead to decreased soil fertility and tree productivity. An experiment was conducted to examine the response of A. senegal seedlings to inoculation with mixed arbuscular mycorrhizal fungi (Glomus fasciculatum, Rhizophagus irregularis and Glomus verriculosum) and rhizobial strains (ORS 3574, ORS 3593, ORS 3607 and ORS 3628) in glasshouse conditions. After 6 months of culture under non-sterilized field soil from Dahra (northern part of Senegal), plant height, arbuscular mycorrhizal root colonization rate and soil acid phosphatase activity were significantly enhanced by the combined inoculation of arbuscular mycorrhizal fungi (AMF) and rhizobia. However, plant biomass, soil spore density and hyphal length were significantly improved by the single inoculation with mycorrhizal or rhizobial strains. The number of nodules was higher for rhizobial inoculated plants. No significant increase in shoot nutrient contents was observed after inoculation. The microbial inoculation enhances the soil acid phosphatase activity whereas no positive effect was noticed on soil total microbial activity. These results indicate that the single inoculation with AMF or rhizobia improves A. senegal seedling growth under this non-sterilized field soil better than the dual inoculation. It is suggested that, for the success of a dual inoculation, a careful selection of effective combinations of microsymbionts is necessary to enhance plant growth and soil bio-functioning and for restoration of soil fertility in a given environment.

Effects of Tetracycline Son Soil Enzyme Activities in an Alluvial Soil

Aims: To study the effect of various doses of tetracycline (TC), oxytetracycline (OTC) and chlortetracycline (CTC) on the enzymatic (DHA, acid phosphatase, alkaline phosphatase, urease and catalase) activity in sewage amended and un-amended alluvial soil. Methodology: A laboratory incubation study was conducted during 2012-2013 on an Aligarh farm alluvial soil. The enzymatic activity was studied in presence of various doses of three tetracycline antibiotics in soil; soil amended with sewage sludge; and mixture of sewage sludge and tetracyclines at different time intervals [(0 (4h), 7, 14, 21, 35, 56, 70,91d]. Results: Activity of all the studied enzymes was significantly inhibited for up to 14-21 days of incubation (14 d for DHA and acid phosphatase, 21 d for alkaline phosphatase, urease and catalase) and thereafter inhibition got weaker. The activity of all the studied enzymes decreased with increase in the doses of tetracyclines. Higher enzymatic activity was observed in sewage sludge amended soil than in the un-amended soil. Tetracyclines in presence of sewage sludge were found to have no appreciable effect on enzymatic activities. Conclusions: Dehydrogenase, acid and alkaline phosphatase, urease and catalase activity in tetracycline free soil was superior to soil containing antibiotics in the period of 2-3 weeks of incubation. The inhibition of soil enzyme activity was directly proportional to tetracycline concentration. In presence of sewage sludge, the studied enzymes activity initially increased up to Original Research Article Bansal; BJMMR, 5(8): 1007-1016, 2015; Article no.BJMMR.2015.111 1008 3 weeks and decreased thereafter. In presence of sewage sludge and antibiotics, the activity of enzymes remains almost unchanged. The activity of studied enzymes in soil was positively correlated to soil organic content.