土壤变暖对土壤微生物活性的影响

讨论了土壤变暖对土壤微生物活性的影响及其后果。许多研究表明，土壤呼吸与土壤温度呈正相关关系。描述这种关系所用的模式有线性回归分析、A10关系式、幂关系式、Arrhenius关系式及其它关系式，但这些模式通常不能准确地估计呼吸率。尽管如此，几乎所有的研究都显示土 壤温度强烈地影响土壤微生物活性及呼吸。在一定温度范围内，土壤变暖提高土壤微生物活性及呼吸率。解释这种现象的一种机制是微生物群体组成随温度升高而改变。文章最后指出，为了得出更加的结论及更加准确地预测全球变暖对土壤的影响，应进一步加强土壤变暖对土微生物活性的影响的研究。     

甲胺磷对土壤微生物活性的影响

研究了有机磷杀虫剂甲胺磷在５种没的浓度下对土壤微生物性所产生的影响,结果表明,甲胺磷地细菌、放线菌和固氮菌群的生长具有不同程度的抑制作用,而对真菌却有一定的刺激效应;土壤的呼吸作用、氨化作用增强,自生固氮能力、硝化作用以及铁离子价数转换作用减弱,甲胺磷对土壤微生物活性的影响,随着处理浓度的提高,作用强度、作用时间有所加剧和延长。     

腐殖酸生物活性肥料对冬小麦生长及土壤微生物活性的影响

施用腐殖酸生物活性肥料对冬小麦生长和土壤微生物活性的试验结果表明,于等量无机养分水平下,施用腐殖酸生物活性肥料冬小麦群体发育平稳,改善植株性状明显,增强抗逆性能。与施用无机复混肥和习惯施肥处理相比,施用腐殖酸生物活性肥料,冬小麦穗长分别增加0.4和0.5cm,旗叶面积分别增加0.7和1.1cm2,次生根条数分别增加1.3和2.2条。产量构成因素中有效穗数,穗粒数和千粒重施用生物活性肥处理也明显高于无机复混肥和习惯施肥,其产量分别增加9.0％和15.2％,差异达显著水平。同时腐殖酸生物活性肥料能够促进土壤有益微生物繁衍,使土壤微生物数量明显增加,提高土壤脲酶、蔗糖酶、磷酸酶和过氧化氢酶活性,对提高肥效,增强土壤肥力,改善作物营养环境有一定作用。     

不同施肥措施对棉田土壤微生物量及其活性的影响

通过测定不同施肥措施下棉田土壤微生物量及微生物活性的动态变化,探讨了不同施肥措施对棉田土壤的培肥效应,结果表明,有机肥合理配施N、P、K化肥,可以促进土壤微生物量显著增长,土壤呼吸强度、纤维素分解强度等微生物活性指标明显提高,增强了土壤养分容量及供应强度,有利于培肥土壤。     

夜间增温与农田铜污染对小麦吸持铜的影响

当前部分农业土壤铜(Cu)富集与非对称气候变暖潜在地影响我国小麦生产,理解夜间增温与土壤Cu污染对小麦吸持利用Cu的影响有助于确保小麦的安全优质生产。本研究利用田间被动式夜间增温系统,设置土壤Cu污染与对照对比盆栽试验,研究小麦地上部物质积累、不同组织Cu含量与积累量、Cu迁移系数对增温的响应。结果表明,夜间增温显著增加小麦茎叶(增幅为25.1%)、穗(增幅为221.3%)、地上部(增幅为22.7%)和全株(增幅为22.3%)的生物量,能缓解土壤Cu污染对小麦生长的抑制。夜间增温使对照处理小麦茎叶、穗、地上部与全株的Cu积累量显著增加14.7%～56.5%;使Cu污染下小麦根、穗和全株的Cu积累量显著增加12.1%～22.8%,却使Cu污染下小麦茎叶Cu含量显著降低13.9%。夜间增温和Cu污染胁迫影响Cu在不同小麦组织间的迁移和利用,夜间增温显著增加了对照处理下Cu由根向茎的迁移系数,但由茎向叶、茎向穗的迁移系数显著降低;Cu污染胁迫下,夜间增温显著降低了由根向茎的转运,且未显著影响Cu由茎向叶的转运,却增加了茎向穗的转运利用。Cu污染胁迫改变了小麦吸收利用Cu对夜间增温的响应规律。夜间增温有利于小麦生物产量、缓解Cu胁迫生长危害,但增加了Cu胁迫农田粮食遭受Cu污染的潜在风险。     

长白山苔原生态系统土壤酶活性及微生物生物量对增温的响应

采用开顶箱(open-top chamber,OTC)增温方法 (+1.1~1.9℃),研究了长白山苔原生态系统土壤酶活性、土壤微生物生物量、土壤微生物群落结构及土壤微生物呼吸对温度升高的响应。结果表明,连续三个生长季(6-9月)增温,没有明显地改变土壤蔗糖酶(58.1和45.9 mg g-124 h-1)和纤维素酶(0.34和0.26 mg g-172 h-1)的活性,但土壤脲酶活性升高80.1%(0.82和0.46 mg g-124 h-1),过氧化氢酶活性也升高10.1%(1.18和1.07 ml KMnO4g-1h-1)。增温与对照条件下土壤微生物生物量碳含量(0.85和0.75 mg g-1)、氮(0.07和0.06 mg g-1)、磷(0.013和0.011 mg g-1)和土壤微生物呼吸(6.1和6.3μmol m-2s-1)无明显差异。相关分析表明,土壤微生物生物量月际间明显的变化与土壤含水量及土壤有机质的相对变化有关。增温改变了土壤微生物的群落结构。增温并未引起与碳循环相关的酶活性、土壤微生物生物量和土壤微生物呼吸发生明显变化,可能是短期增温及增温幅度不足以使土壤微生物活性产生明显的改变。     

川西平原土壤微生物生物量碳氮磷含量特征及其影响因素分析

本文通过区域调查采样和统计分析,探讨了川西平原土壤微生物生物量碳（MBC）、土壤微生物生物量氮（MBN）和土壤微生物生物量磷（MBP）含量特征及其对气候、海拔、母质和土地利用等因素的响应,揭示了其关键影响因素,以期为川西平原地区土壤质量管理提供参考。结果表明,不同土壤类型的MBC、MBN和MBP含量表现为冲积土显著高于水稻土、潮土和黄壤（P<0.05）,潮土MBC/MBN显著高于水稻土。气候和海拔的影响为：MBC、MBN和MBP含量随着≥ 0℃积温、≥ 10℃积温、年均温和年均降水量的增加呈指数减少,而随干燥度和海拔增加呈线性增加。不同成土母质中,MBC、MBN和MBP含量均为灰色冲积物显著高于老冲积物。不同土地利用方式下,三者含量为草地显著高于水田和旱地,水田、旱地和林地差异不显著。皮尔森相关分析和冗余分析表明,MBC和MBN均与≥ 0℃积温、年均温呈极显著负相关（P<0.01）,与海拔呈极显著正相关关系,MBP与母质呈现极显著负相关关系。逐步回归分析表明,MBC主要受年均温、干燥度、年均降水量和母质的影响;MBN主要受海拔、干燥度和年均降水量的综合影响;MBP主要受母质、年均温、≥ 10℃积温和年均降水量的调控。因此,川西平原土壤MBC、MBN、MBP能灵敏地反映不同采样点气候的变化,可为该区气候变化下土壤碳、氮、磷的响应预测提供参考。     

玉米秸秆覆盖冬小麦免耕播种对土壤微生物量碳的影响

土壤微生物量碳(SMBC)是土壤有机碳的一部分,在养分循环中起着重要作用.本研究目的在于揭示我国华北平原玉米秸秆覆盖冬小麦免耕对土壤微生物量碳的影响.4～5年的试验结果表明,不同耕作方式对农田SMBC含量的时空变异具有显著的影响.玉米秸秆覆盖免耕播种处理上层(0～10cm)的含量比下层(10～20cm)增加47.4%,而清茬翻耕和还田翻耕处理的含量在土壤中的分层不显著.不同的耕作方式的SMBC含量均随气温降低而减少.全年平均来看,在0～10咖土层,不同耕作方式的SMBC含量大小表现为覆免>还翻>清翻,在10～20cm土层则表现为还翻>覆免=清翻.整个耕层(0～20cm)表现为还翻>覆免>清翻.在气温较低时,覆盖免耕的SMBC含量比清茬翻耕和还田翻耕低.在土壤表层,不同耕作方式SMBC含量的稳定性大小表现为还翻>覆免>清翻;在下层,不同耕作方式之间差异不显著.     

秸秆还田方式对关中盆地土壤微生物量碳氮和冬小麦产量的影响

为了探究秸秆还田方式对土壤碳氮过程、水热过程和作物产量的影响,对比分析了关中平原无秸秆还田(T0)、秸秆覆盖还田(T1)、秸秆翻压还田(T2)和氨化秸秆翻压还田(T3)4种还田方式对冬小麦生育期土壤微生物量碳(MBC)、微生物量氮(MBN)、有机碳(SOC)、全氮(TN)、温度、水分利用效率(WUE)和产量的影响。结果表明:MBC和MBN在整个生育期大致呈现先增加再降低的趋势,在拔节期达到最大值,不同秸秆还田处理在生育期均能有效增加土壤MBC和MBN含量;不同秸秆还田方式均能增加耕作层SOC和TN含量,且对表层(0—10cm)的影响最为明显,大于下表层(10—20cm);T1、T2和T3在前期可提升土壤温度,T2日均温最大,越冬期后降低日平均地温;T3、T1和T2分别增加地上部生物量19.41%,5.63%和11.19%,增加籽粒产量23.48%,20.17%和13.17%,其中T3增产效果达到显著水平,明显优于其他秸秆还田方式;同对照相比,T3、T2和T1可显著提高WUE 28.73%,15.36%和18.83%。T3提高冬小麦籽粒产量和地上部生物量的效果优于其他秸秆还田方式,建议氨化秸秆翻压还田最为优化,对于关中地区旱作农业秸秆还田技术的完善和实践具有一定的指导作用。     

土壤微生物量碳周转分析方法及其影响因素

简述了目前国内外常用的3种测定土壤微生物生物量C周转分析方法及其影响因素、改进的土壤微生物生物量C周转动力学测定方法及其应用前景,并分析了国内外不同生态环境、土壤质地和耕作管理制度等的土壤微生物生物量C周转的研究结果。     

分根装置中接种AM真菌对玉米秸秆降解及土壤微生物量碳、氮和酶活性的影响

本试验通过两室分根装置种植玉米,利用网袋法研究接种Glomus mosseae和Glomus etunicatum两种AM真菌对玉米秸秆降解的影响。试验分别在玉米移栽后第20 d、30 d、40 d、50 d和60 d时取样,通过测定接种AM真菌后玉米秸秆中碳、氮释放,土壤中3种常见酶活性、微生物量碳、微生物量氮及土壤呼吸的动态变化,探讨AM真菌降解玉米秸秆可能的作用机制。研究结果表明:经60 d的培养后,与未接种根室相比,接种G.mosseae和G.etunicatum真菌的菌根室玉米秸秆降解量提高了20.75%和20.97%;另外,接种G.mosseae和G.etunicatum加快了玉米秸秆碳素释放,降低了氮素释放,致使碳氮比降低25.45%和26.17%,有利于秸秆进一步降解。在本试验条件下,接种AF真菌的菌根室中土壤酸性磷素酶、蛋白酶和过氧化氢酶活性均有显著提高,并增加了微生物量碳、氮和土壤呼吸作用,形成了明显有别于根际的微生物区系。这一系列影响都反映出AM真菌能够直接或间接作用于玉米秸秆的降解过程,是导致玉米秸秆降解加快的重要原因。     

小麦–玉米轮作体系长期施肥对塿土微生物量碳、氮及酶活性的影响

以20年塿土小麦玉米轮作体系长期肥料定位试验为平台,探讨不同施肥模式下土壤化学肥力要素、微生物量碳氮及酶活性的响应。试验包括不施肥（CK）、单施氮肥（N）、氮磷（NP）、磷钾（PK）、氮磷钾（NPK）、NPK+秸秆（SNPK）以及不同量有机肥+NPK（M1NPK、M2NPK）等8种施肥模式。结果表明,与CK相比,长期施用NP提高土壤有机碳含量达34.0%、全氮34.0%、全磷58.5%、速效磷608.9%、微生物量碳23.3%、微生物量氮54.0%、蔗糖酶53.9%、脲酶132.6%、碱性磷酸酶29.9%以及脱氢酶40.9%。长期施用NPK与NP效果相似,钾素效果甚微。作物秸秆还田配合氮磷钾化肥与氮磷钾相比没有明显影响土壤有机碳、氮和磷水平,但是显著提高微生物量碳的含量（29.5%）、碱性磷酸酶（23.0%）和脱氢酶（26.9%）的活性。有机肥配合氮磷钾与其它施肥处理相比,显著提升土壤化学肥力要素、微生物量碳氮和酶活性,特别是引起了磷素的大量富集（速效磷含量大于150 mg/kg）。因此,塿土不施有机物情况下,氮磷配合可以提高土壤化学和生物肥力,作物秸秆还田配合氮磷钾化肥的培肥效果优于氮磷钾化肥配合,而合理的有机无机肥配合是塿土提升化学肥力和保证生物健康的最佳施肥模式。     

A meta-analysis of the effects of experimental warming on soil carbon and nitrogen dynamics on the Tibetan Plateau

Alpine ecosystems at high altitudes and latitudes are notably sensitive to climatic warming and the Tibetan Plateau is a widely distributed alpine ecosystem. The magnitude of climatic warming on the Tibetan Plateau is expected to be considerably greater than the global average. However, a synthesis of the experimental warming soil carbon and nitrogen data is still lacking and whether forest soils are more sensitive to warming than grassland soils remains unclear. In this study, we used a meta-analysis approach to synthesise 196 observations from 25 published studies on the Tibetan Plateau. Warming significantly increased microbial biomass carbon (MBC) by 14.3% (95% CI: 2.9–24.6%), microbial biomass nitrogen (MBN) by 20.1% (95% CI: 2.0–45.1%), net nitrogen mineralization by 49.2% (95% CI: 38.1–62.3%) and net nitrification by 56.0% (95% CI: 51.4–66.1%), but did not significantly affect soil carbon (95% CI: −13.9 to 2.7%) or nitrogen (95% CI: −12.4 to 2.6%). The mean annual air temperature was negatively correlated with the warming effects on MBC and MBN. Grasslands exhibited significant MBC and MBN responses to warming. Specifically, soil microbial biomass was more responsive to warming in colder environments. Moreover, forest soils are not always more sensitive to warming than grassland soils as previous studies have suggested. These findings indicate that clarifying the effect of warming on alpine soils need consider ecosystem types and their local climate.     

Interactive effects of warming, soil humidity and plant diversity on litter decomposition and microbial activity

Human activity has induced a multitude of global changes that are likely to affect the functioning of ecosystems. Although these changes act in concert, studies on interactive effects are scarce. Here, we conducted a laboratory microcosm experiment to explore the impacts of temperature (9, 12 and 15 °C), changes in soil humidity (moist, dry) and plant diversity (1, 4, 16 species) on soil microbial activity and litter decomposition.We found that changes in litter decomposition did not mirror impacts on microbial measures indicating that the duration of the experiment (22 weeks) may not have been sufficient to determine the full magnitude of global change effects. However and notably, changes in temperature, humidity and plant litter diversity/composition affected in a non-additive way the microbial parameters investigated. For instance, microbial metabolic efficiency increased with plant diversity in the high moisture treatment but remained unaffected in low moisture treatment suggesting that climate changes may mask beneficial effects of biodiversity on ecosystem functioning. Moreover, litter decomposition was unaffected by plant litter diversity/composition but increased with increasing temperature in the high moisture treatment, and decreased with increasing temperature in the low moisture treatment.We conclude that it is inevitable to perform complex experiments considering multiple global change agents in order to realistically predict future changes in ecosystem functioning. Non-additive interactions highlight the context-dependency of impacts of single global change agents.     

Effects of past and current crop management on soil microbial biomass and activity

Because soil biota is influenced by a number of factors, including land use and management techniques, changing management practices could have significant effects on the soil microbial properties and processes. An experiment was conducted to investigate differences in soil microbiological properties caused by long- and short-term management practices. Intact monolith lysimeters (0.2 m² surface area) were taken from two sites of the same soil type that had been under long-term organic or conventional crop management and were then subjected to the same 2.5-year crop rotation [winter barley (Hordeum vulgare L.), maize (Zea mais L.), lupin (Lupinus angustifolius L.), and rape (Brassica napus L. ssp. oleifera)] and two fertilizer regimes (following common organic and conventional practices). Soil samples were taken after crop harvest and analyzed for microbial biomass C and N, microbial activity (fluorescein diacetate hydrolysis, arginine deaminase activity, and dehydrogenase activity), and total C and N. The incorporation of the green manure stimulated growth and activity of the microbial communities in soils of both management histories. Soil microbial properties did not show any differences between organically and conventionally fertilized soils, indicating that crop rotation and plant type had a larger influence on the microbial biomass and enzyme activities than fertilization. Initial differences in microbial biomass declined, while the effects of farm management history were still evident in enzyme activities and total C and N. Links between enzyme activities and microbial biomass C varied depending on treatment, indicating differences in microbial community composition.     

Substrate inputs and pH as factors controlling microbial biomass, activity and community structure in an arable soil

Our aim was to determine whether the smaller biomasses generally found in low pH compared to high pH arable soils under similar management are due principally to the decreased inputs of substrate or whether some factor(s) associated with pH are also important. This was tested in a soil incubation experiment using wheat straw as substrate and soils of different pHs (8.09, 6.61, 4.65 and 4.17). Microbial biomass ninhydrin-N, and microbial community structure evaluated by phospholipid fatty acids (PLFAs), were measured at 0 (control soil only), 5, 25 and 50 days and CO₂ evolution up to 100 days. Straw addition increased biomass ninhydrin-N, CO₂ evolution and total PLFA concentrations at all soil pH values. The positive effect of straw addition on biomass ninhydrin-N was less in soils of pH 4.17 and 4.65. Similarly total PLFA concentrations were smallest at the lowest pH. This indicated that there is a direct pH effect as well as effects related to different substrate availabilities on microbial biomass and community structure. In the control soils, the fatty acids 16:1ω5, 16:1ω7c, 18:1ω7c&9t and i17:0 had significant and positive linear relationships with soil pH. In contrast, the fatty acids i15:0, a15:0, i16:0 and br17:0, 16:02OH, 18:2ω6,9, 17:0, 19:0, 17:0c9,10 and 19:0c9,10 were greatest in control soils at the lowest pHs. In soils given straw, the fatty acids 16:1ω5, 16:1ω7c, 15:0 and 18:0 had significant and positive linear relationships with pH, but the concentration of the monounsaturated 18:1ω9 PLFA decreased at the highest pHs. The PLFA profiles indicative of Gram-positive bacteria were more abundant than Gram-negative ones at the lowest pH in control soils, but in soils given straw these trends were reversed. In contrast, straw addition changed the microbial community structures least at pH 6.61. The ratio: [fungal PLFA 18:2w6,9]/[total PLFAs indicative of bacteria] indicated that fungal PLFAs were more dominant in the microbial communities of the lowest pH soil. In summary, this work shows that soil pH has marked effects on microbial biomass, community structure, and response to substrate addition.     

聚丙烯酸盐类土壤改良剂对燕麦土壤微生物量氮及酶活性的影响

以燕麦田土壤为研究对象,探讨了聚丙烯酸盐类土壤改良剂及其复配(聚丙烯酸钾、聚丙烯酰胺、腐植酸钾、聚丙烯酸钾+腐植酸钾、聚丙烯酰胺+腐植酸钾)对燕麦田土壤微生物量氮及土壤酶活性的影响。结果表明,不同土壤改良剂均能提高土壤有机质、碱解氮、速效磷和速效钾的含量,各指标分别比对照增加了8.24%～30.22%、7.60%～19.29%、5.15%～29.45%和27.86%～68.86%;土壤改良剂能促使燕麦全生育期内0～10、10～20和20～40 cm各土层的土壤微生物量氮含量显著提高,聚丙烯酸钾+腐植酸钾和聚丙烯酰胺+腐植酸钾复配处理较其各单施效果显著,随土壤深度的增加土壤微生物量氮逐层递减;与对照相比,土壤改良剂能显著提高燕麦全生育期各土层过氧化氢酶活性,在抽穗期活性最高,且以聚丙烯酸钾+腐植酸钾较高;但对于脲酶,聚丙烯酸钾+腐植酸钾、聚丙烯酰胺+腐植酸钾和腐植酸钾3个处理在苗期显著低于对照,在抽穗期和成熟期高于对照,两种酶活性均随土壤深度的增加逐渐降低。     

Seasonal variations of soil microbial biomass and activity in warm- and cool-season turfgrass systems

Plant growth can be an important factor regulating seasonal variations of soil microbial biomass and activity. We investigated soil microbial biomass, microbial respiration, net N mineralization, and soil enzyme activity in turfgrass systems of three cool-season species (tall fescue, Festuca arundinacea Schreb., Kentucky bluegrass, Poa pratensis L., and creeping bentgrass, Agrostis palustris L.) and three warm-season species (centipedegrass, Eremochloa ophiuroides (Munro.) Hack, zoysiagrass, Zoysia japonica Steud, and bermudagrass, Cynodon dactylon (L.) Pers.). Microbial biomass and respiration were higher in warm- than the cool-season turfgrass systems, but net N mineralization was generally lower in warm-season turfgrass systems. Soil microbial biomass C and N varied seasonally, being lower in September and higher in May and December, independent of turfgrass physiological types. Seasonal variations in microbial respiration, net N mineralization, and cellulase activity were also similar between warm- and cool-season turfgrass systems. The lower microbial biomass and activity in September were associated with lower soil available N, possibly caused by turfgrass competition for this resource. Microbial biomass and activity (i.e., microbial respiration and net N mineralization determined in a laboratory incubation experiment) increased in soil samples collected during late fall and winter when turfgrasses grew slowly and their competition for soil N was weak. These results suggest that N availability rather than climate is the primary determinant of seasonal dynamics of soil microbial biomass and activity in turfgrass systems, located in the humid and warm region.     

Experimental warming effects on the microbial community of a temperate mountain forest soil

Soil microbial communities mediate the decomposition of soil organic matter (SOM). The amount of carbon (C) that is respired leaves the soil as CO₂ (soil respiration) and causes one of the greatest fluxes in the global carbon cycle. How soil microbial communities will respond to global warming, however, is not well understood. To elucidate the effect of warming on the microbial community we analyzed soil from the soil warming experiment Achenkirch, Austria. Soil of a mature spruce forest was warmed by 4 °C during snow-free seasons since 2004. Repeated soil sampling from control and warmed plots took place from 2008 until 2010. We monitored microbial biomass C and nitrogen (N). Microbial community composition was assessed by phospholipid fatty acid analysis (PLFA) and by quantitative real time polymerase chain reaction (qPCR) of ribosomal RNA genes. Microbial metabolic activity was estimated by soil respiration to biomass ratios and RNA to DNA ratios. Soil warming did not affect microbial biomass, nor did warming affect the abundances of most microbial groups. Warming significantly enhanced microbial metabolic activity in terms of soil respiration per amount of microbial biomass C. Microbial stress biomarkers were elevated in warmed plots. In summary, the 4 °C increase in soil temperature during the snow-free season had no influence on microbial community composition and biomass but strongly increased microbial metabolic activity and hence reduced carbon use efficiency.