不同施肥处理对黄泥土微生物生物量碳氮和酶活性的影响

通过室内培育实验,研究了不同施肥处理对黄泥土微生物生物量C、N和脲酶、酸性磷酸酶、蔗糖酶活性的影响。培养过程中,单施化肥处理土壤微生物生物量C、N均呈下降趋势,施用有机肥处理的土壤微生物量C前期升高至一定水平后或保持稳定、或呈下降趋势,而微生物生物量N总体均呈下降趋势;不同施肥处理的脲酶活性呈前期上升后期下降趋势,而酸性磷酸酶和蔗糖酶则单施化肥处理呈上升趋势、配施有机肥处理呈下降趋势。与对照处理相比,单施化肥处理显著降低土壤微生物生物量C、N,高量施用化肥处理还显著降低土壤脲酶活性,但对酸性磷酸酶和蔗糖酶活性的影响并不明显。秸秆施用可显著提高土壤微生物生物量C、N和酶活性,特别是高量施用秸秆的效果更明显。施用猪粪由于同时带入了大量的活性养分,对土壤微生物生物量C、 N和酶活性的影响尚难评价。在高度集约农业利用下,继续保持较高的化肥施用量并不利于土壤生物质量的维护和提高,而秸秆直接还田才是保持土壤健康状态的有效措施。     

EFFECTS OF GREEN MANURE CONTINUOUS APPLICATION ON SOIL MICROBIAL BIOMASS AND ENZYME ACTIVITY

A three-year field experiment was carried out to study the effects of green manure application on the soil microbial biomass carbon, nitrogen and soil enzyme activities in order to provide a theoretical basis on low-carbon agriculture, environment-friendly agriculture and promote the sustainable development of tobacco production. Six treatments were set and were: check (CK) (contrast, no application of green manure), T1 (application of ryegrass only 1 year), T2 (application of ryegrass 2 years), T3 (application of oats 2 years), T4 (application of ryegrass 3 years), and T5 (application of oats 3 years), which was based on continuous planting oats and ryegrass (Lolium multiflorum L.) in our experiment. The results showed that soil microbial biomass carbon, nitrogen, and the activity of soil urease, acid phosphatase (ACP), sucrase, and catalase increased with each year and with the application of green manure. Compared with the control, after the application of green manure the content of soil microbial biomass carbon and nitrogen increased 1.94%–93.07% and 2.30%–145.07%, respectively, and the activity of soil urease, ACP, sucrase, and catalase increased 1.45%–56.52%, 2.34%–33.17%, 0.96%–172.66%, and 3.33%–85.71%, respectively. Correlation analysis indicated that soil microbial biomass carbon and soil enzymes activity had certain relevance that showed the dynamic process of soil microbial biomass and enzyme activity were coordinate with the decomposition process of green manure and the absorption of mine nutritional to tobacco plant. The results demonstrate that continuous application of green manure could increase soil biological fertility level.     

Gross nitrogen mineralization and nitrification rates and their relationships to enzyme activities and the soil microbial biomass in soils treated with dairy shed effluent and ammonium fertilizer at different water potentials

 Gross N mineralization and nitrification rates and their relationships to microbial biomass C and N and enzyme (protease, deaminase and urease) activities were determined in soils treated with dairy shed effluent (DSE) or NH₄ ⁺ fertilizer (NH₄Cl) at a rate equivalent to 200 kg N ha^–1 at three water potentials (0, –10 and –80 kPa) at 20  °C using a closed incubation technique. After 8, 16, 30, 45, 60 and 90 days of incubation, sub-samples of soil were removed to determine gross N mineralization and nitrification rates, enzyme activities, microbial biomass C and N, and NH₄ ⁺ and NO₃ ^– concentrations. The addition of DSE to the soil resulted in significantly higher gross N mineralization rates (7.0–1.7 μg N g^–1 soil day^–1) than in the control (3.8–1.2 μg N g^–1 soil day^–1), particularly during the first 16 days of incubation. This increase in gross mineralization rate occurred because of the presence of readily mineralizable organic substrates with low C : N ratios, and stimulated soil microbial and enzymatic activities by the organic C and nutrients in the DSE. The addition of NH₄Cl did not increase the gross N mineralization rate, probably because of the lack of readily available organic C and/or a possible adverse effect of the high NH₄ ⁺ concentration on microbial activity. However, nitrification rates were highest in the NH₄Cl-treated soil, followed by DSE-treated soil and then the control. Soil microbial biomass, protease, deaminase and urease activities were significantly increased immediately after the addition of DSE and then declined gradually with time. The increased soil microbial biomass was probably due to the increased available C substrate and nutrients stimulating soil microbial growth, and this in turn resulted in higher enzyme activities. NH₄Cl had a minimal impact on the soil microbial biomass and enzyme activities, possibly because of the lack of readily available C substrates. The optimum soil water potential for gross N mineralization and nitrification rates, microbial and enzyme activities was –10 kPa compared with –80 kPa and 0 kPa. Gross N mineralization rates were positively correlated with soil microbial biomass N and protease and urease activities in the DSE-treated soil, but no such correlations were found in the NH₄Cl-treated soil. The enzyme activities were also positively correlated with each other and with soil microbial biomass C and N. The forms of N and the different water potentials had a significant effect on the correlation coefficients. Stepwise regression analysis showed that protease was the variable that most frequently accounted for the variations of gross N mineralization rate when included in the equation, and has the potential to be used as one of the predictors for N mineralization. Received: 10 March 1998     

A field study of gross rates of N mineralization and nitrification and their relationships to microbial biomass and enzyme activities in soils treated with dairy effluent and ammonium fertilizer

Abstract. Gross N mineralization and nitrification rates were measured in soils treated with dairy shed effluent (DSE) (i.e. effluent from the dairy milking shed, comprising dung, urine and water) or ammonium fertilizer (NH₄Cl) under field conditions, by injecting ¹⁵N-solution into intact soil cores. The relationships between gross mineralization rate, microbial biomass C and N and extracellular enzyme activities (protease, deaminase and urease) as affected by the application of DSE and NH₄Cl were also determined. During the first 16 days, gross mineralization rate in the DSE treated soil (4.3–6.1 μg N g^?1 soil day^?1) were significantly (P 14;< 14;0.05) higher than those in the NH₄Cl treated soil (2.6–3.4 μg N g^?1 soil day^?1). The higher mineralization rate was probably due to the presence of readily mineralizable organic substrates in the DSE, accompanied by stimulated microbial and extracellular enzyme activities. The stable organic N compounds in the DSE were slow to mineralize and contributed little to the mineral N pool during the period of the experiment. Nitrification rates during the first 16 days were higher in the NH₄Cl treated soil (1.7–1.2 μg N g^?1 soil day^?1) compared to the DSE treated soil (0.97–1.5 μg N g^?1 soil day^?1). Soil microbial biomass C and N and extracellular enzyme activities (protease, deaminase and urease) increased after the application of the DSE due to the organic substrates and nutrients applied, but declined with time, probably because of the exhaustion of the readily available substrates. The NH₄Cl application did not result in any significant increases in microbial biomass C, protease or urease activities due to the lack of carbonaceous materials in the ammonium fertilizer. However, it did increase microbial biomass N and deaminase activity. Significant positive correlations were found between gross N mineralization rate and soil microbial biomass, protease, deaminase and urease activities. Nitrification rate was significantly correlated to biomass N but not to the microbial biomass C or the enzyme activities. Stepwise regression analysis showed that the variations of gross N mineralization rate was best described by the microbial biomass C and N.     

新型肥料对全球三大粮食作物产量和土壤生物学活性影响的Meta分析

  【目的】  随着近年来农业发展方式从资源消耗型向绿色生态型的转变,发展绿色新型肥料成为一大热门。已有研究大多关注新型肥料对三大粮食作物 (小麦、玉米和水稻) 产量、氮吸收和氮利用效率的影响,但关于新型肥料对土壤生物学活性影响的系统研究相对较少。本研究旨在整合已有的研究结果,定量分析新型肥料对三大作物产量和土壤生物学活性的影响,进而为加快新型肥料的研发与推广提供科学依据。  【方法】  本研究数据来源于“中国知网 (CNKI) ”及“Web of Science”数据库,以“小麦”、“玉米”、“水稻”、“产量”、“微生物量”、“酶活性”、“新型肥料”为主要关键词检索相关的田间试验文献,共筛选出文献29篇,包含32个独立试验,共545组数据。以施用传统化学肥料为对照组,施用新型肥料为试验组,采用Meta分析的方法,整合分析施用新型肥料对作物产量、土壤微生物量及酶活性的影响。  【结果】  与施用传统化学肥料相比,施用新型肥料显著提高三大作物产量、地上部吸氮量和氮肥利用效率,分别提高8.4%、9.9%和36.8%。施用新型肥料显著增加土壤微生物量氮 (14.6%),但对土壤微生物量碳无显著影响。施用新型肥料显著提高了土壤磷代谢酶活性 (8.6%) 和氧化相关酶活性 (5.7%),但对土壤碳代谢酶活性和氮代谢酶活性无显著影响。  【结论】  施用新型肥料提高了三大作物产量、地上部吸氮量和氮肥利用效率,同时增加了土壤微生物量氮、土壤磷代谢酶活性和氧化相关酶活性,提高了农田生态系统土壤生物学活性。     

Tebuconazole application decreases soil microbial biomass and activity

A short-term mesocosm experiment was conducted to ascertain the impact of tebuconazole on soil microbial communities. Tebuconazole was applied to soil samples with no previous pesticide history at three rates: 5, 50 and 500 mg kg⁻¹ DW soil. Soil sampling was carried out after 0, 7, 30, 60 and 90 days of incubation to determine tebuconazole concentration and microbial properties with potential as bioindicators of soil health [i.e., basal respiration, substrate-induced respiration, microbial biomass C, enzyme activities (urease, arylsulfatase, β-glucosidase, alkaline phosphatase, dehydrogenase), nitrification rate, and functional community profiling]. Tebuconazole degradation was accurately described by a bi-exponential model (degradation half-lives varied from 9 to 263 days depending on the concentration tested). Basal respiration, substrate-induced respiration, microbial biomass C and enzyme activities were inhibited by tebuconazole. Nitrification rate was also inhibited but only during the first 30 days. Different functional community profiles were observed depending on the tebuconazole concentration used. It was concluded that tebuconazole application decreases soil microbial biomass and activity.     

铅对两个红壤中酶活性的影响

Enzyme activities have the potential to indicate biological functioning of soils. In this study, soil urease, dehydrogenase, acid phosphatase and invertase activities and fluorescein diacetate（FDA） hydrolysis were measured in two red soils spiked with Pb^2＋ ranging from 0 to 2 400 mg kg^-1 to relate the enzyme activity values to both plant growth and the levels of available and total Pb^2＋ concentrations in soils, and to examine the potential use of soil enzymes to assess the degrees of Pb contamination. Soil samples were taken for enzyme activities assaying during 3 month’s incubation and then after planting of celery（Apium graveolens L.） and Chinese cabbage（Brassica chinensis L.）. Enzyme activities in the red soil derived from arenaceous rock（RAR） were generally lower than those in the red soil developed on Quaternary red earths（REQ）. At high Pb^2＋ loadings, in both incubation and greenhouse studies, urease activity and FDA hydrolysis were significantly inhibited. But there were no significant relationships between soil dehydrogenase, acid phosphatase or invertase activity and soil Pb^2＋ loadings in both RAR and REQ soils. The growth of celery and Chinese cabbage increased soil urease activity and FDA hydrolysis, but had minimal effect on dehydrogenase and invertase activities. There were positive correlations between celery biomass and soil urease activity and FDA hydrolysis. These results demonstrate that urease activity and FDA hydrolysis are more sensitive to Pb^2＋ than acid phosphatase, dehydrogenase and invertase activities in the RAR and REQ soils.     

连年翻压绿肥对植烟土壤微生物量及酶活性的影响

通过3年田间定位试验,研究连年翻压绿肥对植烟土壤微生物量碳、氮及酶活性的影响。结果表明,连年翻压绿肥能提高土壤微生物量碳、氮及土壤脲酶、酸性磷酸酶、蔗糖酶、过氧化氢酶的活性,且随翻压年限的增加而增加。整个生育期,翻压3年绿肥的处理与对照相比微生物量碳、氮分别提高31.0%~67.1%、23.0%~145.1%;土壤脲酶、酸性磷酸酶、蔗糖酶、过氧化氢酶活性分别提高34.4%~51.9%、11.0%~18.6%、58.0%~172.7%、24.0%~50.0%,表明翻压绿肥后土壤生物过程活跃,利于有机物质的转化和烤烟正常生长所需的营养供应。动态变化特征表明,翻压绿肥1、2、3年的各处理微生物量碳、氮均在团棵期出现峰值,土壤脲酶、酸性磷酸酶、过氧化氢酶均在旺长期出现峰值。在出现峰值时翻压3年的处理与对照相比微生物量碳、氮分别提高67.1%、60.7%;土壤脲酶、酸性磷酸酶、过氧化氢酶活性分别提高51.9%、14.2%、30.6%。此时正值生育旺期,利于烟株生长发育,说明连年翻压绿肥后培肥土壤效果显著。土壤微生物量C、N和酶活性能灵敏反映土壤肥力的变化,可作为评价土壤质量的生物学指标。     

Effects of a cadmium-contaminated sewage sludge compost on dynamics of organic matter and microbial activity in an arid soil

 An incubation experiment lasting 120 days was carried out to ascertain the effect on the soil microbial activity and organic matter mineralization of adding a sewage sludge compost contaminated with two different levels of Cd to an arid soil. Two composts, with a low (2 mg kg^–1) and high (815 mg kg^–1) Cd content, respectively, were used in this experiment. Both composts increased the total organic C, humic substance and water-soluble C contents, the beneficial effects still being noticeable after 120 days of incubation. The most labile C fraction (water-soluble C) was the most sensitive to the high Cd content. The high Cd concentration decreased soil microbial biomass C and stimulated the metabolic activity of the microbial biomass, the metabolic quotient (qCO₂) revealing itself to be a very sensitive index of the stress that the incorporation of a Cd-contaminated sewage sludge compost causes in a soil. The effect of Cd contamination on enzyme activities (urease, protease that hydrolyse N-α-benzoil-l-arginamide, phosphatase, and β-glucosidase) depended on the enzyme studied. Received: 10 September 1997     

三江平原湿地不同土地利用方式对土壤养分及酶活性的影响

以中国科学院三江平原湿地生态试验站为对象,研究了不同利用方式（湿地草甸、旱田系统、退耕成草、退耕成林）对土壤酶活性分布特征及相关因子的影响。结果表明:土壤利用方式不同,土壤酶活性（转化酶、脲酶、磷酸酶和过氧化氢酶）、有机碳含量和土壤养分含量有较大差异。土壤有机碳、全氮、全钾、速效磷、碱解氮、微生物量碳和氮均呈现出一致的变化规律,依次表现为湿地草甸 > 退耕草地 > 退耕林地 > 旱田系统,也即由湿地草甸退化过程中,土壤养分含量逐渐降低,其中不同土地利用方式下土壤全磷含量差异不显著（p>0.05）,在湿地的退化过程中,土壤全磷并没有发生显著的变化。与湿地草甸相比,土壤蔗糖酶、脱氢酶、脲酶和酸性磷酸酶活性均显著降低,其活性分别降低了32.69%,36.71%,50.00%,44.28%,由旱田系统恢复为湿地草甸系统后,土壤各种酶活性均显著增加,其中土壤蔗糖酶、脱氢酶、脲酶和酸性磷酸酶活性分别比旱田系统增加了26.68%,31.51%,48.19%,43.84%;表明由湿地草甸开垦为耕地和由耕地恢复为湿地草甸和林地,发生着两种不同的生物学过程,前者为微生物降解过程,而后者则为微生物累积过程。相关性分析表明SOC,TN和SMBC对土壤蔗糖酶、脱氢酶、脲酶和酸性磷酸酶活性的贡献为正,对土壤酶活性起到主导作用。主成分分析表明影响土壤酶活性最主要的因子为SOC,TN和SMBC。     

Enzymatic activities and microbial biomass in soil as influenced by metalaxyl residues

A laboratory experiment was conducted to study the impact of metalaxyl application at different concentration levels on microbial biomass and the biochemical activities in soil. A dissipation study of metalaxyl highlighted 52.5-56.8% loss of metalaxyl due to the presence of microbial activity. However, a small but significant decline in microbial biomass was observed on 60 d of incubation period. Metalaxyl showed a highly significant effect in decreasing total N and organic C content in soil from 0 to 30 d of incubation. Dehydrogenase, phosphatase, urease, arylsulphatase and β-glucosidase activities were monitored in metalaxyl treated soils. Except urease, all the enzymatic activities initially increased and then decreased. Urease activity showed a continuous gradual decrease throughout the experimental period. Thus, metalaxyl might influence the growth and development of crop-plants, since it has direct impact on nutrient recycling and energy flow in soil.     

Influence of soil properties on microbial populations, activity and biomass in humid subtropical mountainous ecosystems of India

 Microbial populations, biomass, soil respiration and enzyme activities were determined in slightly acid organic soils of major mountainous humid subtropical terrestrial ecosystems, along a soil fertility gradient, in order to evaluate the influence of soil properties on microbial populations, activity and biomass and to understand the dynamics of the microbial biomass in degraded ecosystems and mature forest. Although the population of fungi was highest in the undisturbed forest (Sacred Grove), soil respiration was lowest in the 7-year-old regrowth and in natural grassland (approximately 373 μg g^–1 h^–1). Dehydrogenase and urease activities were high in "jhum" fallow, and among the forest stands they were highest in the 7-year-old regrowth. Microbial biomass C (MBC) depended mainly on the organic C status of the soil. The MBC values were generally higher in mature forest than in natural grassland, 1-year-old jhum fallow and the 4-year-old alder plantation. The MBC values obtained by the chloroform-fumigation-incubation technique (330–1656 μg g^–1) did not vary significantly from those obtained by the chloroform-fumigation-extraction technique (408–1684 μg g^–1), however, the values correlated positively (P<0.001). The enzyme activities, soil respiration, bacterial and fungal populations and microbial biomass was greatly influenced by several soil properties, particularly the levels of nutrients. The soil nutrient status, microbial populations, soil respiration and dehydrogenase activity were greater in Sacred Grove, while urease activity was greater in grassland. Received: 14 October 1998     

Distribution and fate of 13C-labeled root and straw residues from ryegrass and crimson clover in soil under western Oregon field conditions

Annual ryegrass (Lolium multiflorum Lam.) and crimson clover (Trifolium incarnatum L.) were pulse-labeled with ¹³C-CO₂ in the field between the initiation of late winter growth (mid-February) and through flowering and seed formation (late May). Straw was harvested after seed maturation (July), and soil containing ¹³C-labeled roots and root-derived C was left in the field until September. ¹³C-enriched and ¹³C-unenriched straw residues of each species were mixed in factorial combinations with soil containing either ¹³C-enriched or ¹³C-unenriched root-derived C and incubated in the field for 10 months. The contributions of C derived from straw, roots, and soil were measured in soil microbial biomass C, respired C, and soil C on five occasions after residue incorporation (September, October, November, April, and June). At straw incorporation (September), 25–30% of soil microbial biomass C was derived from root C in both ryegrass and clover treatments, and this value was sustained in the ryegrass treatment from September to April but declined in the clover treatment. By October, between 20 and 30% of soil microbial biomass C was derived from straw, with the percentage contribution from clover straw generally exceeding that from ryegrass straw throughout the incubation. By June, ryegrass root-derived C contributed 5.5% of the soil C pool, which was significantly greater than the contributions from any of the three other residue types (about 1.5%). This work has provided a framework for more studies of finer scale that should focus on the interactions between residue quality, soil organic matter C, and specific members of the soil microbial community.     

不同修复方式对铅锌尾矿砂微生态环境的改良作用

采用盆栽试验方法研究黑麦草、黑麦草联合改良剂等不同修复方式对铅锌尾矿砂的理化性质和微生物性状的改良作用。结果表明,不同处理使铅锌尾矿砂中有机质、碱解氮、速效磷含量显著提高,其中黑麦草联合10%菜园土和1%赤泥处理(CN1)对铅锌尾矿砂中有机质、碱解氮、速效磷含量明显提高,分别比对照提高了51.82%,300.00%和901.29%。添加改良剂显著增加了黑麦草的生物量,减少了黑麦草根部重金属的含量。不同处理使铅锌尾矿砂中微生物数量,微生物C、N含量显著增加,其中CN1处理使细菌、真菌、放线菌数量和微生物C、N含量增加效果最好,分别比对照增加了33.78,5.99,21.82,6.34,6.35倍。各处理显著提高了尾矿砂中脲酶、磷酸酶、蔗糖酶、纤维素酶活性,其中CN1处理使脲酶、磷酸酶、蔗糖酶、纤维素酶活性分别比对照提高了18.43,12.58,5.00,9.15倍。黑麦草联合10%菜园土和1%赤泥较其他处理有利于提高铅锌尾矿砂的肥力,改良尾矿砂的微生态环境,促进植物生长。     

Effect of cattle slurry in grassland on microbial biomass and on activities of various enzymes

We examined the long-term effects of cattle slurry, applied at high rates, on microbial biomass, respiration, the microbial quotient (qCO₂) and various soil enzyme activities. In March, June, July, and October 1991, slurry-amended grassland soils (0–10 cm) contained significantly higher levels of microbial biomass, N mineralization and enzyme activities involved in N, P, and C cycling. With microbial biomass as the relative value, the results revealed that the slurry treatment influenced enzyme production by the microbial biomass. High levels of urease activity were the result not only of a larger microbial biomass, but also of higher levels of enzmye production by this microbial biomass. The ratio of alkaline phosphatase and xylanase to microbial biomass was nearly constant in the different treatments. The metabolic quotient (qCO₂) declined with increased levels of slurry application. Therefore it appears that microorganisms in slurry-amended soils require less C and energy if there is no competition for nutrients. The results of this study suggest that urease activity, nitrification, and respiration (metabolic quotient) can be used as indicators of environmental stress, produced by heavy applications of cattle slurry.     

Criteria for measurement of microbial growth and activity in soil

Changes in CO₂ evolution, phosphatase and urease activity and ATP contents were related to bacterial and fungal biomass determined microscopically during glucose mineralization at different concentrations of mineral nutrients. Similar results were obtained in a sandy loam and a clay soil except that in the clay the increase in microbial and enzyme activities were delayed. Higher initial rates of CO₂ evolution were noted after the addition of P to a glucose and N amended soil at C:P ratios greater than 30:1. Increases in phosphatase activity coincided with increases in bacterial and fungal populations only in treatments without inorganic P. Peak rates of CO₂ evolution preceded biomass production by 18–24 h, therefore, CO₂ evolution rates did not show a correlation on normal regression analysis with biomass. Soil ATP content was influenced by P concentrations and soil type. ATP was therefore not a specific indicator of biomass in the detailed studies where P concentrations and sequential growth of bacteria and fungi were major factors. Soil urease increased with bacterial and fungal populations. It did not respond to P other than through microbial biomass and was highly correlated with microbial biomass. The results show that no one measurement of microbial biomass or activity is sufficient to interpret microbial growth in the soil system. Each of the criteria measured were sensitive to specific conditions affecting biomass and activity.     

黑麦草与施肥对石油-铅-镉复合污染土壤微生物活性的影响

随着工业和农业生产的发展,重金属、有毒有机物及其复合污染土壤日益增多,其修复问题在世界范围内是一项具有挑战性的任务。以砂质壤土为试验对象,模拟石油-铅-镉复合污染,共设置4个处理:(1)对照处理,复合污染土壤(CK);(2)不施肥处理,复合污染土壤+黑麦草(NF);(3)施氮肥处理,复合污染土壤+黑麦草+氮肥(F1);(4)施氮肥和磷肥处理,复合污染土壤+黑麦草+氮肥+磷肥(F2),研究种植黑麦草与施肥处理对石油-铅-镉复合污染土壤微生物活性的影响,以期为污染土壤修复及环境影响评价提供初步的理论基础。结果表明:黑麦草与施肥对复合污染土壤基础呼吸、微生物量碳均有促进作用,处理NF、F1和F2的土壤基础呼吸强度比对照处理CK最高分别增加约20.94%,24.41%,42.69%,其中施加氮、磷肥(F2)对土壤基础呼吸影响最显著;第10天时,处理NF、F1和F2土壤微生物量碳含量与对照相比分别增加约26.92%,127.43%,181.89%,施肥处理土壤微生物量碳含量显著高于不施肥处理;不同种类的酶活性对黑麦草与施肥的响应不尽相同,其中种植黑麦草与施肥均会抑制石油-铅-镉复合污染土壤中FDA水解酶活性,施加氮肥在一定时间内能较好地维持石油-铅-镉复合污染土壤内的脱氢酶活性,施肥能有效地提高并维持复合污染土壤中脲酶活性,而过氧化氢酶活性受黑麦草与施肥影响不显著。研究表明种植黑麦草配施氮、磷肥对土壤微生物基础呼吸、土壤微生物量碳及相关土壤酶活性均有增强作用,进而有利于促进土壤污染物的去除及土壤质量的改善。     

Differences in soil enzyme activities,microbial community structure and short-term nitrogen mineralisation resulting from farm management history and organic matter amendments

Changes in soil microbial biomass, enzyme activities, microbial community structure and nitrogen (N) dynamics resulting from organic matter amendments were determined in soils with different management histories to gain better understanding of the effects of long- and short-term management practices on soil microbial properties and key soil processes. Two soils that had been under either long-term organic or conventional management and that varied in microbial biomass and enzyme activity levels but had similar fertility levels were amended with organic material (dried lupin residue, Lupinus angustifolius L.) at amounts equivalent to 0, 4 and 8 t dry matter lupin ha^?1. Microbial biomass C and N, arginine deaminase activity, fluorescein diacetate hydrolysis, dehydrogenase enzyme activity and gross N mineralisation were measured in intervals over an 81-day period. The community structure of eubacteria and actinomycetes was examined using PCR–DGGE of 16S rDNA fragments. Results suggested that no direct relationships existed between microbial community structure, enzyme activities and N mineralisation. Microbial biomass and activity changed as a result of lupin amendment whereas the microbial community structure was more strongly influenced by farm management history. The addition of 4 t ha^?1 of lupin was sufficient to stimulate the microbial community in both soils, resulting in microbial biomass growth and increased enzyme activities and N mineralisation regardless of past management. Amendment with 8 t lupin ha^?1 did not result in an increase proportional to the extra amount added; levels of soil microbial properties were only 1.1–1.7 times higher than in the 4 t ha^?1 treatment. Microbial community structure differed significantly between the two soils, while no changes were detected in response to lupin amendment at either level during the short-term incubation. Correlation analyses for each treatment separately, however, revealed differences that were inconsistent with results obtained for soil biological properties suggesting that differences might exist in the structure or physiological properties of a microbial component that was not assessed in this study.     

The combined effects of earthworms and arbuscular mycorrhizal fungi on microbial biomass and enzyme activities in a calcareous soil spiked with cadmium

Earthworms and arbuscular mycorrhizal fungi (AMF) are known to independently affect soil microbial and biochemical properties, in particular soil microbial biomass (SMB) and enzymes. However, less information is available about their interactive effects, particularly in soils contaminated with heavy metals such as cadmium (Cd). The amount of soil microbial biomass C (MBC), the rate of soil respiration (SRR) and the activities of urease and alkaline phosphatase (ALP) were measured in a calcareous soil artificially spiked with Cd (10 and 20 mg Cd kg⁻¹), inoculated with earthworm (Lumbricus rubellus L.), and AMF (Glomus intraradices and Glomus mosseae species) under maize (Zea mays L.) crop for 60 days. Results showed that the quantity of MBC, SRR and enzyme activities decreased with increasing Cd levels as a result of the elevated exchangeable Cd concentration. Earthworm addition increased soil exchangeable Cd levels, while AMF and their interaction with earthworms had no influence on this fraction of Cd. Earthworm activity resulted in no change in soil MBC, while inoculation with both AMF species significantly enhanced soil MBC contents. However, the presence of earthworms lowered soil MBC when inoculated with G. mosseae fungi, showing an interaction between the two organisms. Soil enzyme activities and SRR values tended to increase considerably with the inoculation of both earthworms and AMF. Nevertheless, earthworm activity did not affect ALP activity when inoculated with G. mosseae fungi, while the presence of earthworm enhanced urease activity only with G. intraradices species. The increases in enzyme activities and SRR were better ascribed to changes in soil organic carbon (OC), MBC and dissolved organic carbon (DOC) contents. In summary, results demonstrated that the influence of earthworms alone on Cd availability is more important than that of AMF in Cd-polluted soils; and that the interaction effects between these organisms on soil microorganism are much more important than on Cd availability. Thus, the presence of both earthworms and AMF could alleviate Cd effects on soil microbial life.     

Soil microbial biomass and enzyme activity in subarctic agricultural and forest soils

Summary Microbial biomass, activities of dehydrogenase, phosphatase, and urease, and numbers of ammonium oxidizers were determined at monthly intervals on soil samples obtained from an on-going tillage residue-management study during the summers of 1985 and 1986. The site was cleared of black spruce (Picea mariana, Mill.) in 1979 and has been planted to spring barley (Hordeum vulgare) since 1982. Tillage treatments were no-tillage or disked twice, and residuemanagement treatments were removal of stubble and loose straw or leaving all straw on the plots. Microbial biomass and enzyme activities were moderate to high in the Ap horizon but very low in the B horizon. There was no difference in any parameter measured due to tillage or residue management. In 1986, comparisons were made between the Ap horizon and the agricultural soil and the A horizon of the soil beneath an adjacent black-spruce forest. Total microbial biomass and enzyme activities were generally greater in the forest soil than in the agricultural soil. However, specific activity of the biomass was generally greater in the agricultural soil. Soil microbial biomass and urease activities of both agricultural and forest soils were similar to those reported for warmer climates, but dehydrogenase activity was higher and phosphatase was lower.