Soil Alkaline Phosphatase Activity Research Articles

Effects of inoculation with organic-phosphorus-mineralizing bacteria on soybean (Glycine max) growth and indigenous bacterial community diversity.

Three different organic-phosphorus-mineralizing bacteria (OPMB) strains were inoculated to soil planted with soybean (Glycine max), and their effects on soybean growth and indigenous bacterial community diversity were investigated. Inoculation with Pseudomonas fluorescens Z4-1 and Brevibacillus agri L7-1 increased organic phosphorus degradation by 22% and 30%, respectively, compared with the control at the mature stage. Strains P. fluorescens Z4-1 and B. agri L7-1 significantly improved the soil alkaline phosphatase activity, average well color development, and the soybean root activity. Terminal restriction fragment length polymorphism analysis demonstrated that P. fluorescens Z4-1 and B. agri L7-1 could persist in the soil at relative abundances of 2.0%-6.4% throughout soybean growth. Thus, P. fluorescens Z4-1 and B. agri L7-1 could potentially be used in organic-phosphorus-mineralizing biofertilizers. OPMB inoculation altered the genetic structure of the soil bacterial communities but had no apparent influence on the carbon source utilization profiles of the soil bacterial communities. Principal components analysis showed that the changes in the carbon source utilization profiles of bacterial community depended mainly on the plant growth stages rather than inoculation with OPMB. The results help to understand the evolution of the soil bacterial community after OPMB inoculation.

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.

Effect of Vermicompost on Chemical and Biological Properties of an Alkaline Soil with High Lime Content during Celery (<i>Apium graveolens</i> L. var. dulce Mill.) Production

The aim of this study was to investigate impact of vermicompost on chemical and biological properties of an alkaline soil with high lime content in the presence of plant under the open field conditions in semiarid Mediterranean region of Turkey. The study also included farmyard manure and chemical fertilizers for comparison and was conducted in two consecutive growth seasons in the same plots to observe any cumulative effect. Plots were amended with fertilizers in different rates and celery (Apium graveolens L. var. dulce Mill.) was grown as the test plant. In general, vermicompost appeared to be more effective to increase organic matter, N, P, and Ca compared to farmyard manure. Soil alkaline phosphatase and β-glucosidase activities, especially in the second growth season, were significantly elevated by the vermicompost application. Urease activity, however, appeared not to be influenced by the type of organic fertilizer. A slight but statistically significant difference was detected between organic amendments in terms of number of aerobic mesophilic bacteria with vermicompost giving the lower values. Results showed that, in general, vermicompost significantly alters chemical and biological properties of the alkaline soil with high lime content during celery production under field conditions compared to farmyard manure and that it has a high potential to be used as an alternative to conventional organic fertilizers in agricultural production in the Mediterranean region of Turkey.

The Combined Effect of Cu, Zn and Pb on Enzyme Activities in Soil from the Vicinity of a Wellhead Protection Area

ABSTRACTHeavy metals are known to have adverse effects on soil ecosystems, while soil enzyme activities are sensitive to soil pollution. This study investigated the combined effects of Cu, Zn and Pb on the activities of invertase (IN), urease (U) and alkaline phosphatase (ALP) in soil obtained from the vicinity of a wellhead protection area via an orthogonal array (OA) design method. The experimental results showed the following: (1) Cu showed higher inhibition on the activities of all three enzymes than Zn and Pb when three metals were all present in the soil sample. IN activity, U activity and ALP activity decreased as the levels of Cu increased, and ranged from 15.9% to 55.7%, 3.57% to 78.6%, and 3.23% to 75.3%, respectively. Their lowest values were found in samples at 35 days with 400 mg/kg Cu. (2) Zn and Pb had different influences on the activities of the three enzymes. The lowest IN activity (the highest reduction 58.0%) and U activity (76.8%) were observed when Zn was at the concentration of 100 mg/kg after 35 days, whereas the highest inhibitory function of Zn on ALP activity (75.3%) was at 300 mg/kg after 7 days. When the concentration of Pb increased from 35 to 350 mg/kg, the activities of IN (62.5%) and U (69.6%) were most inhibited at 35 days and 14 days, respectively. However, when Pb was at the concentration of 500 mg/kg after 14 days, ALP activity (72.0%) showed the lowest value. (3) With respect to the three hydrolases in this study, ALP was the most sensitive to the two-variable interactive effects of Cu, Zn and Pb, especially Cu × Pb. It is concluded that the soil ALP activity may be a sensitive tool for assessing additive toxic effect on soil biochemical parameters. To provide more information about the potential ecological risk of chemicals on soil ecosystems, much more should be done to clearly determine the mechanisms of the combined effects of heavy metals in soil.

Phosphate-solubility and phosphatase activity in Gangetic alluvial soil as influenced by organophosphate insecticide residues

An experiment was conducted under laboratory conditions to investigate the effect of four organophosphate insecticides, viz. monocrotophos, profenophos, quinalphos and triazophos at their field application rates (0.75, 1.0, 0.5 and 0.6kga.i.ha−1, respectively), on the growth and activities of phosphate solubilizing microorganisms in relation to availability of insoluble phosphates in the Gangetic alluvial soil of West Bengal, India. The proliferation of phosphate solubilizing microorganisms was highly induced with profenophos (38.3%), while monocrotophos exerted maximum stimulation (20.8%) towards the solubility of insoluble phosphates in soil. The phosphatase activities of the soil (both acid phosphatase and alkaline phosphatase) were significantly increased due to the incorporation of the insecticides in general, and the augmentation was more pronounced with quinalphos (43.1%) followed by profenophos (27.6%) for acid phosphatase, and with monocrotophos (25.2%) followed by profenophos (16.1%) for alkaline phosphatase activity in soil. The total phosphorus was highly retained by triazophos (19.9%) followed by monocrotophos (16.5%), while incorporation of triazophos and quinalphos manifested greater availability of water soluble phosphorus in soil.

Inoculation with selected microbial consortia not only enhances growth and yield of French bean but also reduces fertilizer application under field condition

French bean is an important vegetable crop. An earlier pot culture study brought out that Paenibacillus polymyxa (Pp) and Pantoea agglomerans (Pa) to be the best PGPR (both being equally good) and Funneliformis mosseae (Fm) to be the best arbuscular mycorrhizal (AM) fungus for inoculating French bean. In the present investigation, a pot culture experiment was conducted in a polyethylene house to study the effect of soil inoculation with Pp, Pa and Fmsingly and in combination on the growth of French bean. Plant growth, nutrition, yield, mycorrhizal root colonization and alkaline phosphatase activity in the root zone soil were found to be higher when Fmwas co-inoculated with both the PGPR Pp+Pacompared to inoculation with individual organisms and the uninoculated treatment. The percent increase in fruit yield over control was 108% when inoculated with all the three organisms. It was concluded that the inoculated organisms interact synergistically and a microbial consortia consisting of all the three organisms is the best for inoculating French bean. This pot culture trial was followed by a field experiment to validate the results of the pot culture trial and to find out the possibility of reducing the amount of chemical fertilizer application through the application of the selected microbial consortia. The six treatments for the field experiment were (i) control (ii) microbial consortia (MC) consisting of Fm+Pp+Pa(iii) MC+100NPK (100% recommended NPK fertilizer by the University of Agricultural Sciences in the region) (iv) MC+75NPK (75% recommended fertilizer) (v) MC+50NPK (50% recommended fertilizer) and (vi) 100NPK. The result brought out that plant height, stem girth, shoot dry biomass and fruit yield are higher in the treatment MC+75NPK and is statistically on par with the treatment 100NPK, suggesting that application of chemical fertilizers for French bean cultivation can be reduced by 25% through treatment with microbial consortia. The increase in fruit yield was 41% and 32.5% in MC+75NPK and 100NPK treatments respectively over control, thus 7% more in MC+75NPK treatment compared to the treatment with recommended chemical fertilizer.

Effects of living mulches on the soil nutrient contents, enzyme activities, and bacterial community diversities of apple orchard soils

Living mulches are used widely for soil management in apple orchards on the Loess Plateau of China. However, little information is available on the impact of living mulches on the soil enzyme activities and the soil micro-ecological environment. We compared three commonly used living mulch treatments: living mulch with white clover (Trifolium repens L.), living mulch with crown vetch (Coronilla varia L.), living mulch with perennial ryegrass (Lolium perenne L.) and a no mulch treatment, and analyzed their effects on the soil nutrient contents, enzyme activities, and bacterial community function, structure and diversity. Total organic carbon (TOC) in the soil under the living mulch treatments was 16–44% greater than with no mulch, while total nitrogen (TN) under white clover and crown vetch was 50% greater than with no mulch. TN under perennial ryegrass was not significantly different from the no mulch treatment. The white clover and crown vetch significantly improved the soil invertase, urease, and alkaline phosphatase activity levels, whereas the perennial ryegrass only improved the soil alkaline phosphatase activity. All living mulches significantly increased the soil bacterial carbon metabolic activity and the bacterial community diversity. Principal component analysis (PCA) of the Biolog and terminal restriction fragment length polymorphism (T-RFLP) showed that living mulch significantly altered the soil bacterial community structure and function, and different types of living mulch have various impacts on that. Our results indicate that the living mulch application benefits the development of soil micro-ecology and soil quality, and the long-term influences of living mulch on soil biological status should be considered when selecting the types of living mulch to be used. According to this study, living mulch with crown vetch is recommended in apple orchards on the Loess plateau.

Arbuscular mycorrhizal fungal diversity, root colonization, and soil alkaline phosphatase activity in response to maize-wheat rotation and no-tillage in North China.

Monitoring the effects of no-tillage (NT) in comparison with conventional tillage (CT) on soil microbes could improve our understanding of soil biochemical processes and thus help us to develop sound management strategies. The objective of this study was to compare the species composition and ecological function of soil arbuscular mycorrhizal (AM) fungi during the growth and rotation of crops under NT and CT. From late June 2009 to early June 2010, 32 topsoil (0-15 cm) samples from four individual plots per treatment (CT and NT) were collected at both the jointing and maturation stages of maize (Zea mays L.) and wheat (Triticum aestivum L.) from a long-term experimental field that was established in an Aquic Inceptisol in North China in June 2006. The AM fungal spores were isolated and identified and then used to calculate species diversity indices, including the Shannon- Wiener index (H'), Evenness (E), and Simpson's index (D). The root mycorrhizal colonization and soil alkaline phosphatase activity were also determined. A total of 34 species of AM fungi within nine genera were recorded. Compared with NT, CT negatively affected the soil AM fungal community at the maize sowing stage, leading to decreases in the average diversity indices (from 2.12, 0.79, and 0.82 to 1.79, 0.72, and 0.74 for H', E, and D, respectively), root mycorrhizal colonization (from 28% to 20%), soil alkaline phosphatase activity (from 0.24 to 0.19 mg/g/24 h) and available phosphorus concentration (from 17.4 to 10.5 mg/kg) at the maize jointing stage. However, reductions in diversity indices of H', E, and D were restored to 2.20, 0.81, and 0.84, respectively, at the maize maturation stage. CT should affect the community again at the wheat sowing stage; however, a similar restoration in the species diversity of AM fungi was completed before the wheat jointing stage, and the highest Jaccard index (0.800) for similarity in the species composition of soil AM fungi between CT and NT was recorded at the wheat maturation stage. Our results also demonstrated that NT resulted in the positive protection of the community structure of AM fungi and played an important role in maintaining their functionality especially for maize seedlings.

Arbuscular mycorrhizal fungal species composition, propagule density, and soil alkaline phosphatase activity in response to continuous and alternate no-tillage in Northern China

PurposeArbuscular mycorrhizal (AM) fungi provide a direct link between soil and roots, and are renowned for their ability to increase nutrient phytoavailability, notably phosphorus (P). The objective of this study was to evaluate influences of continuous and alternate no-tillage on soil AM fungal species composition and soil P-supply parameters. Materials and methodsIn June 2006, a long-term field experiment was established in a sandy loam soil under the rotation of summer maize (Zea mays L.) and winter wheat (Triticum aestivum L.) in Northern China, including conventional tillage (CT), no-tillage (NT) and alternate tillage (AT — tillage in the wheat season and no-tillage in the maize season). Top soil samples (0–15cm) from four individual plots per treatment were collected before maize harvest on 18 September 2010. Soil AM fungal spores were isolated and identified, and the external mycelium length, soil alkaline phosphatase (ALP) activity and soil P content were also determined. Results and discussionThirty species of AM fungi within seven genera, Acaulospora, Claroideoglomus, Funneliformis, Glomus, Racocetra, Rhizophagus, and Scutellospora, were recovered. Some species sporulated differentially across the three treatments, and the lowest Jaccard index (J) of similarity in species composition was recorded between NT and CT (J=0.767), but there were no significant differences in soil total P and available P contents, as well as in AM fungal spore density (SD), species richness (SR) and diversity indices, including Shannon–Wiener index (H′), Evenness (E) and Simpson's index (D). Compared with CT, NT rather than AT significantly increased (P<0.05) the external mycelium length, soil ALP activity, and soil organic C content. ConclusionsOur results demonstrated the vital role of NT in maintaining external hyphae growth and soil ALP activity rather than in promoting AM fungal species diversity and spore density, and suggested that 4-year continuous NT will not cause degradation in either AM fungal community or soil P-supply efficiency.

Rhizosphere interactions between earthworms (Eisenia fetida) and arbuscular mycorrhizal fungus (Funneliformis mosseae) promote utilization efficiency of phytate phosphorus in maize

Rhizosphere interactions between earthworms (Eisenia fetida) and arbuscular mycorrhizal fungus (AMF, Funneliformis mosseae), suggested to promote phytate mineralization and maize phosphorus (P) content were studied in the Organization for Economic Co-operation and Development (OECD) (non-phosphorus active soil). Maize was planted and amended with AMF and/or earthworms (E) as well as insoluble phytate-P (C6H18O24P6), in comparison to not amended maize (control). The maize shoot and root biomass, shoot and root P uptake, soil alkaline phosphatase activity, soil microbial biomass P, available P, and the Shannon–Wiener index (H) for the bacterial communities from T-RFLP profiles were measured at harvest. The results indicated that both AM and AM+E treatments significantly increased the utilization efficiency of phytate-P in maize. Our results suggest there are significantly positive interactions between earthworms and AMF in terms of promoting the utilization efficiency of phytate-P in maize and enhancing soil microbial biomass P and alkaline phosphatase activity. The positive interaction enhanced soil microbial biomass P and alkaline phosphatase activity by regulating the bacterial diversity in the soil. The bacterial diversity was significantly correlated with alkaline phosphatase activity, shoot and root P content, biomass and the utilization efficiency of phytate-P. Additionally, alkaline phosphatase activity was positively correlated with microbial biomass P. Flavobacteriaceae and Xanthomonadales, which were the dominant bacteria under all conditions. A significant correlation was observed between Flavobacteriaceae and alkaline phosphatase activity as well as shoot P content, and there was also a significant correlation between Betaproteobacteria and the root and shoot P content. Earthworm and AMF interaction could enhance the phytate-P mineralization in the belowground and improve linking between the aboveground and belowground for phytate-P utilization.

Soil bacterial phoD gene abundance and expression in response to applied phosphorus and long-term management

Bacterial transformation of phosphorus (P) compounds in soil is largely dependent on soil microbial community function, and is therefore sensitive to anthropogenic disturbances such as fertilization or cropping systems. However, the effect of soil management on the transcription of bacterial genes that encode phosphatases, such as phoD, is largely unknown. This greenhouse study examined the effect of long-term management and P amendment on potential alkaline phosphatase (ALP) activity and phoD gene (DNA) and transcript (RNA) abundance. Soil samples (0–15 cm) were collected from the Glenlea Long-term Rotation near Winnipeg, Manitoba, to compare organic, conventional and prairie management systems. In the greenhouse, pots of soil from each management system were amended with P as either soluble mineral fertilizer or cattle manure and then planted with Italian ryegrass (Lolium multiforum). Soils from each pot were sampled for analysis immediately and after 30 and 106 days. Significant differences among the soil/P treatments were detected for inorganic P, but not the organic P in NaHCO3-extracts. At day 0, ALP activity was similar among the soil/P treatments, but was higher after 30 days for all P amendments in soil from organically managed plots. In contrast, ALP activity in soils under conventional and prairie management responded to increasing rates of manure only, with significant effects from medium and high manure application rates at 30 and 106 days. Differences in ALP activity at 30 days corresponded to the abundance of bacterial phoD genes, which were also significantly higher in soils under organic management. However, this correlation was not significant for transcript abundance. Next-generation sequencing allowed the identification of 199 unique phoD operational taxonomic units (OTUs) from the metagenome (soil DNA) and 35 unique OTUs from the metatranscriptome (soil RNA), indicating that a subset of phoD genes was being transcribed in all soils.

Impacts of farmland conversion to apple (Malus domestica) orchard on soil organic carbon stocks and enzyme activities in a semiarid loess region

AbstractLand‐use change often affects the sizes of soil organic carbon (SOC) stocks and the activities of soil enzymes. Responses of relevant soil quality indices caused by farmland conversion to orchard are largely unknown in the semiarid loess regions. This study was conducted at orchard sites, which have been under very intensive cultivation, to evaluate the impacts of farmland conversion to apple (Malus domestica) orchard on SOC stocks and soil enzyme activities in the semiarid loess region of Weibei, Shaanxi province, China. The spatial and temporal changes in a variety of soil quality indices were measured for the 0–100 cm soil profile in apple orchards of three age groups (&lt; 10 y, juvenile; 10–15 y, mature; &gt; 15 y, over‐mature) and adjacent farmlands (control). After farmland conversion, total SOC (TOC) content and density and soil alkaline phosphatase activity significantly decreased, while soil catalase activity increased for the 0–100 cm soil profile. The labile SOC (LOC) content, its proportion to TOC content, and carbon management index (CMI, changes in the total content and lability of SOC) significantly increased in the 0–40 cm soil layer, whereas soil urease and invertase activities only increased in the 0–20 cm layer (P &lt; 0.05). With increasing age of apple orchards, SOC stocks significantly increased after 10 y, being more than 10% larger in mature and over mature orchards than in adjacent farmlands. The LOC content and CMI value also had an increasing trend, while soil enzyme activities showed different response patterns. There were significant correlations between soil enzyme activities, SOC fractions, and CMI value (P &lt; 0.05). We concluded that farmland conversion to apple orchard affected soil quality by reducing SOC stocks in the soil profile and changing SOC content as well as soil enzyme activities at various depth intervals. Long‐term apple cultivation was effective to restore SOC stocks, although it took over a decade to rebuild a new increasing trend after farmland conversion.

Effect of Rhizosphere Enzymes on Phytoremediation in PAH-Contaminated Soil Using Five Plant Species

A pot experiment was performed to study the effectiveness of remediation using different plant species and the enzyme response involved in remediating PAH-contaminated soil. The study indicated that species Echinacea purpurea, Festuca arundinacea Schred, Fire Phoenix (a combined F. arundinacea), and Medicago sativa L. possess the potential for remediation in PAH-contaminated soils. The study also determined that enzymatic reactions of polyphenol oxidase (except Fire Phoenix), dehydrogenase (except Fire Phoenix), and urease (except Medicago sativa L.) were more prominent over cultivation periods of 60d and 120d than 150d. Urease activity of the tested species exhibited prominently linear negative correlations with alkali-hydrolyzable nitrogen content after the tested plants were cultivated for 150d (R2 = 0.9592). The experiment also indicated that alkaline phosphatase activity in four of the five tested species (Echinacea purpurea, Callistephus chinensis, Festuca arundinacea Schred and Fire Phoenix) was inhibited during the cultivation process (at 60d and 120d). At the same time, the study determined that the linear relationship between alkaline phosphatase activity and effective phosphorus content in plant rhizosphere soil exhibited a negative correlation after a growing period of 120d (R2 = 0.665). Phytoremediation of organic contaminants in the soil was closely related to specific characteristics of particular plant species, and the catalyzed reactions were the result of the action of multiple enzymes in the plant rhizosphere soil.

Changes in nitrogen and phosphorus limitation during secondary succession in a karst region in southwest China

Nitrogen (N) and/or phosphorus (P) limitation to primary productivity and other biological processes can change in a variety of ways as ecosystems develop. How N limitation and P limitation change from the early to the late stages of a secondary succession following farmland abandonment remains unclear in karst ecosystems in southwest China. We used community foliar N:P ratio, soil alkaline phosphatase activity (APA) and other indicators of nutrient status (soil organic carbon [SOC], total soil N [TN], and total soil P [TP], Alkali-hydrolyzable N [AN], and available soil phosphorus [AP] concentrations) to examine changes in N and P status during secondary vegetation succession. Four types of plant communities (grasslands, shrublands, secondary forest, and primary forest) represented the early, middle, late, and very late successional stages, respectively. Community foliar N:P ratio, APA, and APA per unit SOC increased as succession proceeded from the grassland to the secondary and primary forest communities. Moreover, community foliar N:P ratios in the grassland were positively correlated with soil TN, while community foliar N:P ratios in the secondary forest and primary forest were negatively correlated with soil TP, but were not correlated with soil TN. Community foliar N:P ratios in the shrubland were not correlated with either soil TN or TP. Our results suggest that the grassland in the karst region of southwest China is N limited, that the secondary and primary forests are P limited, and that the shrubland is constrained by N and P together or by other nutrients.

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.

黄土丘陵区小流域侵蚀环境对土壤微生物量及酶活性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 黄土丘陵区小流域侵蚀环境对土壤微生物量及酶活性的影响 DOI: 10.5846/stxb201310302611 作者: 作者单位: 西北农林科技大学资源环境学院,西北农林科技大学 资源环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金重点基金(41030532); 国家自然科学基金面上项目(41171226); 教育部新世纪优秀人才支持计划(NCET-12-0479) Effect of erosion on soil microbial biomass and enzyme activity in the Loess Hills Author: Affiliation: College of Resources and Environment, Northwest A＆F University,College of Resources and Environment, Northwest A＆F University 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:土壤侵蚀环境直接影响土壤的特性,对土壤微生物的形成和稳定具有重要的影响。土壤微生物量推动着土壤的物质循环和能量流动,对土壤中各种环境的变化有很强的敏感性。土壤酶活性能表示土壤微生物功能的多样性,与土壤微生物量有着紧密的联系。为了探究不同侵蚀环境对土壤微生物量和酶活性的影响,以黄土丘陵区陈家坬小流域为研究区,选择5种不同侵蚀环境下0-10cm和10-20cm土层的土壤为研究对象,对土壤微生物量及其土壤蔗糖酶、脲酶和碱性磷酸酶活性进行了研究。结果表明:(1)土壤微生物量碳、氮、磷含量均表现为0-10cm大于10-20cm土层;土壤微生物量碳和磷在阴沟坡最大,在阳梁峁坡和峁顶较小,且阴沟坡和峁顶差异显著;土壤微生物量氮在阳沟坡最大,阴阳梁峁坡最小,差异性显著(P < 0.01)。(2)土壤脲酶、蔗糖酶和碱性磷酸酶活性均表现为0-10cm大于10-20cm土层,且在不同侵蚀环境下均表现为阴梁峁坡最大,阳梁峁坡最小。(3)相关性分析表明,土壤微生物量碳、氮、磷与土壤脲酶、蔗糖酶、碱性磷酸酶活性之间均有极显著的正相关。 Abstract:Erosion directly affects soil characteristics and has a significant effect on the formation and stability of the soil microbial community. Soil microbial biomass not only plays a significant role in energy flow and nutrient cycling, but it also shows great sensitivity to changes in soil environment. Soil enzyme activities are indicative of the functional diversity of the soil microbial community, as they are closely associated with soil microbial biomass. To reveal the effect of different erosion environments on soil microbial biomass and soil enzyme activities, soil samples were collected from the Chengjiawa watershed, located in the Yanhe watershed of the hill and gully region of Ansai County, Yan'an, Shaanxi Province, China. Soil samples were collected from five erosion environments in the valley, at depths of 0-10 cm and 10-20 cm. We studied the characteristics of soil microbial biomass including carbon, nitrogen, and phosphorus, soil enzyme activities including soil urease, invertase, and alkaline phosphatase, and correlations between soil microbial biomass and enzyme activities. The results showed that: (1) Soil microbial biomass carbon, nitrogen, and phosphorus were significantly different between the 0-10 cm and 10-20 cm soil layers; soil microbial biomass carbon and phosphorus in the shaded lower slopes were higher than in the other tested environments, whereas in the sunny middle slope and the hill top they were lower than in the other tested soil environments. The difference between the shaded lower slopes and sunny hill top were significant. Soil microbial biomass nitrogen in the sunny lower slope was significantly higher than in the other tested soil environments. Overall, soil microbial biomass of the ditch slope was higher than in the other tested environments. This suggested that the erosion affects the soil microbial properties, and that soil nutrient accumulation and mineralization ability of soils on the downhill slope were higher than in other tested locations. (2) Soil urease, sucrase, and alkaline phosphatase activities were higher in the 0-10 cm layer than in the 10-20 cm layer. In different erosion environments, soil enzyme activities were higher in the shaded middle slope than in any other tested environments, while they were the lowest in the sunny middle slopes. Soil alkaline phosphatase activity did not significantly differ between different soil environments. Soil invertase activity in the shaded middle slopes was significantly different from the other four types of erosion environments. The difference in soil urease activity between the shaded lower slope and other tested environments was significant. Comparisons showed that the environment exposed to erosion affected the properties of soil enzyme activities; the responses of soil invertase and urease were more sensitive to changes in the soil environment. (3) Pearson correlation analysis showed that soil microbial biomass carbon, nitrogen, and phosphorus were significantly positively correlated with each other, as were the soil urease, sucrase, and alkaline phosphatase activities. There was a significant positive correlation between soil microbial biomass and soil enzyme activities, which suggested that these two properties were closely linked and inseparable components of the soil microbial community. Different environments exposed to erosion have diverse levels of soil organic matter content, different physicochemical properties of the soil, diverse forms of soil microbes, and differ in the amount of soil microbial biomass and soil enzyme activities. These differences were reflected in the soil quality, vegetation types, and resistance to soil erosion. 参考文献 相似文献 引证文献

Arbuscular mychorrizal fungus enhances maize (Zea Mays L.) growth and organic carbon sequestration in wheat (Triticum aestivum L.) straw-amended soils

A pot experiment was conducted to investigate the effects of wheat (Triticum aestivum L.) straws and arbuscular mycorrhizal (AM) fungi on maize (Zea mays L.) growth and organic carbon (C) sequestration in a sterilized sandy loam soil. The experiment included three treatments: control, amendment with wheat straws (S), and amendment with wheat straws plus inoculation with AM fungus Glomus caledonium (S+M). Compared with the control, the amendment of wheat straws significantly (P<0.05) increased soil alkaline phosphatase (ALP) activity in maize seedling period (30 d) and plant phosphorus (P)-uptake and shoot biomass at harvest time (110 d), and also tended to increase soil organic C content as well as produced low but demiurgic crop yield at harvest time. In wheat straw-amended soils, G. caledonium inoculation significantly (P<0.05) decreased soil pH and significantly (P<0.05) increased plant P-uptake as well as soil ALP activity in seedling period, and tended to increase shoot biomass and grain yield in seedling and harvest periods, respectively. Furthermore, G. caledonium inoculation tended to increase soil organic C content at harvest time, which was significantly (P<0.05) higher than that of the control, suggesting potential application of AM fungi in facilitating crop production and C sequestration

The influence of grazing exclosure on soil C stocks and dynamics, and ecological indicators in upland arid and semi-arid rangelands

Soil carbon (C) storage and quality in rangeland ecosystems may change as a result of long-term heavy grazing, especially in upland arid and semi-arid rangelands characterized by low soil organic C contents. The impact of grazing exclosure on soil C stock and mineralization, microbial biomass C and the activities of invertase and alkaline phosphatase involved in C and P cycling as soil ecological indicators were studied in woody and non-woody rangeland ecosystems of two sites (viz., Sabzkouh with woody cover and Boroujen with non-woody cover) located in Zagros Mountains, Central Iran. At each site, soil samples were taken from 0 to 15cm depth of the two rangelands including heavy grazing (HG) and ungrazed (UG) regimes, and analyzed for their chemical and microbial properties. Results demonstrate that soil organic C and total N contents, and C/N ratios were not affected by grazing regime at Boroujen, while ungrazed rangelands had higher C (17%) and N (19%) contents compared with heavily grazed rangelands at Sabzkouh. Grazing exclosure increased soil C mineralization (44.7–73.6%) and turnover (24–64%) at both study sites, and increased the amount of soil microbial biomass C (5.4-fold) and decreased the metabolic quotient (90%) only at Sabzkouh. Soil invertase activity was significantly higher (1.3–2.1 times) in ungrazed than heavily grazed rangelands at both sites, whereas ungrazed rangelands had significantly greater soil alkaline phosphatase activity (19%) compared with heavily grazed rangelands only at Sabzkouh. The variations in the effect of grazing exclosure on soil organic matter (SOM) dynamics and C sequestration in these upland arid and semi-arid rangelands were due to differences between rangelands in initial SOM contents, and probably could be due to differences in plant productivity and composition, and the amount of rainfall between the study sites. Non-woody rangelands contained less soil C and N contents, and C mineralization but greater microbial biomass C than woody rangelands, reflecting a clear difference in substrate quality and soil C availability. Soil biochemical and microbial indices as ecological indicators can reflect grazing exclosure effects on soil restoration only in woody rangelands.

Tillage effects on phosphorus composition and phosphatase activities in soil aggregates

Phosphorus (P) and phosphatase activities in soil aggregates affected by tillage under cold monsoon climate remain poorly understood. Based on the hypothesis that the distribution of P composition and phosphatase activities in soil aggregates should be affected by different tillage practices, a field experiment was conducted to study the effects of moldboard plow (MP), ridge tillage (RT), and no-tillage (NT) on the distribution of soil P composition determined by 31P nuclear magnetic resonance (NMR) and phosphatase activities in different size fractions of soil aggregates (>2, 1–2, 0.25–1, and <0.25mm) at the 0 to 20cm depth in northeastern China. NT treatment had significantly higher organic P proportion in total P and larger proportions of monoesters and diesters in extracted total P than the MP treatment, whereas the MP treatment showed higher concentrations of total P, organic P, plant available P, NaOH-EDTA extracted total P, orthophosphate and monoesters. Soil alkaline phosphatase (AlP) and phosphodiesterase (PD) activities under NT were significantly higher than those under MP, and the responses of AlP in 0.25–1mm size fraction and PD in <0.25mm size fraction were more sensitive to tillage treatments. Overall, although NT facilitated more P stored in the organic P form and increased phosphatase activities, soil with NT had lower total and plant available P compared to traditional MP treatment and therefore, MP may be the right practice to conserve soil P under cold monsoon climate.

Alkaline phosphatase activity and its relationship to soil properties in a saline–sodic soil reclaimed by cropping wolfberry (Lycium barbarum L.) with drip irrigation

In order to ascertain the alkaline phosphatase (ALP) activity and its relationship with soil properties in saline–sodic soils during reclamation, a study was conducted in a saline–sodic soil reclaimed by cropping wolfberry (Lycium barbarum L.) with drip irrigation, in Ningxia Plain, Northwest China. The soil ECe, pH and SAR in 0–30 cm were 12.3 dS m−1, 9.4 and 44.1 (mmol/L)0.5, respectively. Soil transects with different planting years were intensively sampled, which had a wide gradient of salinity and sodicity. Ranging from 1.1 to 42.4 μg g−1 h−1, soil ALP activities increased with the increasing planting years, and showed a large spatial variability within transect. The higher ALP activities were always found beneath the drip emitters. More soil physicochemical properties became related significantly to the ALP activities as the planting years increased, indicating that the ALP activities could be better predicted by other properties after reclamation. Path analyses showed that the negative direct effects of soil pH on ALP activities became clearly dominant as the planting years increased. The positive effects of organic matter on ALP activities exerted indirectly, mainly through pH, total N, and available P. Soil ALP activities decreased exponentially with pH, which varied from 7.38 to 10.00. Our findings demonstrated that soil pH was the limiting factor for improving soil ALP activities in this saline–sodic soil, and after three planting years, soil biological activities and fertility level increased significantly.