长期施用生物有机肥对土壤肥力及微生物生物量碳的影响

为了研究施用生物有机肥(EM堆肥,即有效微生物制剂 堆肥)对土壤肥力及微生物生物量碳的影响,进行了7年的施用15t/hm2.a有机肥、施用7.5t/hm2.a有机肥(包括EM堆肥、EM鸡粪肥和传统有机肥)、施用化肥和对照处理的田间试验。结果表明:长期施用生物有机肥的土壤肥力明显提高。随着生物有机肥用量的提高,碱性土壤的pH值逐渐降低,土壤有机质、全N、碱解氮、有效磷、速效钾、微生物生物量碳含量增加,与有机肥施用量呈显著正相关。施用化肥可一定程度提高土壤有机质、全N和有效养分含量,但作用不明显。施肥对土壤肥力和微生物量碳的影响趋势是:EM堆肥>传统堆肥>化肥>对照。土壤微生物量碳与土壤有机质、全N、碱解氮、有效磷、速效钾含量呈显著正相关,可以作为施肥过程中土壤质量变化的生物学指标。     

宁南山区土壤酶活性特征及其与肥力因子的关系

分析了黄土丘陵区土壤酶活性与土壤肥力因子之间的关系。相关分析结果表明,土壤有机质与全N、速效磷、速效钾等密切相关,同时与土壤几种酶活性有较好的相关性。土壤酶活性依赖于有机质,当有机质含量增加时,酶积极参与其转化分解过程,活性提高。脲酶、蔗糖酶活性与土壤N、P、K含量关系最大,土壤速效钾与蔗糖酶活性关系最大。通径分析结果表明:土壤肥力因子对脲酶活性的直接作用顺序为有机质>速效钾>速效氮>阳离子交换量>全N>速效磷>物理性黏粒>土壤pH。有机质是影响土壤脲酶活性、碱性磷酸酶活性的主要因素,速效钾是影响蔗糖酶活性的最主要因素。     

有机无机肥配施对麦-稻轮作系统土壤微生物学特性的影响

采用盆栽试验研究了不同比例有机无机肥配施对连续4茬麦-稻轮作后土壤微生物学特性的影响。结果表明,与对照相比,单施化肥处理促进了土壤微生物生物量碳、氮和微生物熵的增加,提高了土壤蔗糖酶、蛋白酶、脲酶活性,降低了过氧化氢酶活性,提高了放线菌的数量,但对土壤细菌、真菌数量的影响不明显;有机无机肥配施处理的土壤微生物生物量碳、微生物生物量氮、微生物熵、土壤酶活性及3大类土壤微生物数量显著高于单施化肥及对照处理;土壤微生物生物量碳、微生物生物量氮、微生物熵和3大类微生物数量随着有机肥配施比例的提高而增加,以配施30%有机肥处理的最高;土壤酶活性综合指数以配施20%有机肥处理的最高。可见,化肥配施有机肥特别是配施中高量有机肥更有利于改善土壤微生物学特性,提高土壤生产能力。     

蚯蚓堆肥与益生菌配施对西瓜地土壤肥力及微生物特性的影响

基于等量养分条件,本试验研究了蚯蚓堆肥与解淀粉芽孢杆菌(X)和荧光假单胞菌(Y)两株不同功能益生菌配施对西瓜地土壤肥力和微生物特性的影响。结果表明,不论添加益生菌与否,蚯蚓堆肥较单施化肥或常规堆肥均提高了土壤速效养分含量,显著增加了土壤微生物生物量和土壤酶活性,其中土壤 NO3–-N 含量较常规堆肥提高了14.7%。益生菌的添加活化了土壤养分,增加了土壤细菌、放线菌、解淀粉芽孢杆菌和荧光假单胞菌数量,降低了土壤真菌数量,同时显著提高了土壤酶活性。各处理比较而言,蚯蚓堆肥配施益生菌在土壤速效养分含量、土壤微生物生物量及土壤酶活性上提升作用最为明显,其中蚯蚓堆肥配施混合益生菌处理(VCXY)的土壤细菌数量和蔗糖酶活性相较于常规堆肥配施混合益生菌处理(CDXY)分别提高了32.0%和14.4%。方差分析结果表明,蚯蚓堆肥和常规堆肥与益生菌在土壤速效磷、速效钾、微生物生物量碳、细菌数量、真菌数量、脲酶及蔗糖酶活性上存在显著交互作用。综上所述,蚯蚓堆肥与益生菌配施可显著促进土壤肥力和微生物活性的改善,可替代部分化肥用于设施蔬菜的绿色生产和土壤培肥。     

沼液配施化肥对土壤质量及作物生长的影响

研究沼液配施化肥对土壤微生物特性、土壤养分及玉米生长的影响。结果表明:沼液配施化肥及单施沼液均能降低土壤真菌数量和增加细菌、放线菌数量,其中45%沼液配施55%化肥处理真菌数量较常规施肥显著降低66%,细菌、放线菌数量分别显著增加160.3%、312.5%。沼液配施化肥可显著增加土壤脲酶、磷酸酶及蔗糖酶活性,但过氧化氢酶含量变化不明显。施用沼液可有效促进土壤有机质、全氮、全磷、碱解氮、有效磷和速效钾含量的增加,且差异显著。沼液配施化肥有效提高土壤微生物生物量(SMB)和有机碳(SOC)含量,其中45%沼液配施55%化肥处理土壤微生物生物量碳(SMBC),微生物生物量氮(SMBN)、微生物生物量磷(SMBP)和有机碳(SOC)含量较常规施肥分别显著增加70.0%、195.6%、91.6%和71.6%。施用沼液降低了SMBC/SMBN值,而土壤微生物熵(qMB)和土壤SMBN/TN值均增加,且随着沼液用量的增加先增加后降低。相关性分析表明,土壤SMB与土壤有机质、全磷、碱解氮、有效磷、速效钾间均呈显著或极显著正相关关系,脲酶、磷酸酶、蔗糖酶均与土壤养分呈显著或极显著正相关关系,过氧化氢酶与土壤养分的相关性不显著。沼液配施化肥对玉米生长及光合作用有显著促进作用,以45%沼液配施55%化肥处理最佳,随着沼液配施比例的增加,玉米产量先增加后降低,45%沼液配施55%化肥处理最高,较常规施肥显著增加40.9%。综合分析,45%沼液配施55%化肥可有效改善土壤结构,显著提高土壤肥力,从而促进作物生长,增加产量,可作为沼液配施化肥的最佳比例。     

蚯蚓堆肥与益生菌配施对土壤肥力及微生物特性的影响

基于等量养分条件,本试验研究了蚯蚓堆肥与解淀粉芽孢杆菌(X)和荧光假单胞菌(Y)两株不同功能益生菌配施对西瓜地土壤肥力和微生物特性的影响。结果表明,不论添加益生菌与否,蚯蚓堆肥较单施化肥或常规堆肥均提高了土壤速效养分含量,显著增加了土壤微生物生物量和土壤酶活性,其中土壤NO_3~–-N含量较常规堆肥提高了14.7%。益生菌的添加活化了土壤养分,增加了土壤细菌、放线菌、解淀粉芽孢杆菌和荧光假单胞菌数量,降低了土壤真菌数量,同时显著提高了土壤酶活性。各处理比较而言,蚯蚓堆肥配施益生菌在土壤速效养分含量、土壤微生物生物量及土壤酶活性上提升作用最为明显,其中蚯蚓堆肥配施混合益生菌处理(VCXY)的土壤细菌数量和蔗糖酶活性相较于常规堆肥配施混合益生菌处理(CDXY)分别提高了32.0%和14.4%。方差分析结果表明,蚯蚓堆肥和常规堆肥与益生菌在土壤速效磷、速效钾、微生物生物量碳、细菌数量、真菌数量、脲酶及蔗糖酶活性上存在显著交互作用。综上所述,蚯蚓堆肥与益生菌配施可显著促进土壤肥力和微生物活性的改善,可替代部分化肥用于设施蔬菜的绿色生产和土壤培肥。     

碱渣处理的秸秆堆肥对红壤生物功能和花生产量品质的影响

通过大田小区试验,研究碱渣处理秸秆堆肥对红壤养分含量、微生物学性质和花生产量及品质的影响。设置不施肥对照(CK)、单施化肥(NPK)、5%碱渣花生秸秆堆肥配施化肥(NPK+PC)和5%碱渣水稻秸秆堆肥配施化肥(NPK+RC)等4个处理,于花生收获期测定土壤养分含量、酶活性、微生物生物量、BIOLOG功能多样性变化,并同时测定花生产量、秸秆生物量和农艺性状指标的变化。结果表明,碱渣处理的秸秆堆肥配施化肥有效缓解了红壤的酸化程度,增强了土壤的保水能力,提高了土壤速效养分的含量;碱渣处理的花生秸秆堆肥配施化肥对微生物生物量氮(MBN)的提高效果较好,而水稻秸秆堆肥配施化肥对转化酶和微生物生物量碳(MBC)的效果较好;BIOLOG分析结果显示,水稻秸秆堆肥配施化肥改善了微生物碳源利用能力和功能多样性,花生秸秆堆肥配施化肥次之;花生秸秆堆肥配施化肥通过增加百果重,从而使花生增产,同时提高了花生荚果全氮、全磷含量,增加了荚果养分累积量。由此可见,碱渣处理的秸秆堆肥配施化肥不仅可以提高土壤肥力和生物功能,还可以促进花生高产、高质,具有一定的应用价值。     

长期有机无机肥配施对褐土微生物生物量碳、氮量及酶活性的影响

通过对山西省寿阳长期定位试验田0―20 cm和20―40 cm的土壤测定和分析,探讨了长期有机无机肥配施下褐土微生物生物量碳、氮和酶活性的变化以及相关性。结果表明,褐土微生物生物量C、N变化基本一致。褐土微生物生物量碳、氮从0―20 cm到20―40 cm土层均呈减少趋势;长期单施高量有机肥、有机无机肥合理配施都能提高褐土微生物生物量碳、氮;不同用量的长期单施化肥处理不能使微生物生物量C、N显著增加。脲酶和碱性磷酸酶活性从0―20 cm到20―40 cm土层呈减少趋势;长期单施高量有机肥和有机无机肥合理配施可使褐土脲酶及碱性磷酸酶活性增加。脲酶活性随单施化肥量的增加有变大趋势,而碱性磷酸酶活性则呈变小趋势。土壤微生物量碳氮、土壤酶活性及土壤养分之间的显著相关性表明,微生物生物量C、N和土壤酶活性可以判断褐土土壤有机质和N素状况,可作为评价褐土土壤肥力水平和土壤培肥效果的生物学指标,同时也可为提高褐土土壤肥力水平和土壤培肥效果提供依据。     

有机肥和化肥长期施用对土壤活性有机氮组分及酶活性的影响

本文以中国农业科学院山东禹城长期定位施肥试验为平台,研究了长期施用有机肥和化肥26年后对土壤活性氮库不同组分［颗粒有机氮（POM-N）、 可溶性有机氮（DON）、 微生物量氮（SMBN）及轻组有机氮（LFOM-N）］及土壤酶活性的影响。结果表明,与不施肥相比,长期施肥显著提高了土壤全氮、 颗粒有机氮、 可溶性有机氮、 微生物量氮以及轻组有机氮的含量,长期施有机肥效果好于化肥,施用高量有机肥效果好于施用常量有机肥。常量施用量下,50%有机肥和50%化肥配施处理其土壤全氮和活性有机氮库各组分含量与高量化肥处理的相当。长期施化肥处理土壤全氮及活性有机氮库各组分含量随施肥量的增加而显著增高。POM-N对土壤全氮的贡献率最高,且明显受施肥方式的影响,LFOM-N对土壤全氮的贡献率不随施肥方式的改变而变化。长期施肥处理土壤脲酶、 碱性磷酸酶和蔗糖酶活性显著增加,它们之间及与土壤全氮、 速效磷及有机碳含量间呈现显著或极显著相关性,脲酶活性与土壤各活性氮组分间也存在显著或极显著相关性; 但长期施肥后土壤过氧化氢酶的活性低于不施肥     

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。     

Chemical and Microbiological Soil Characteristics under Conventional and Organic Coffee Production Systems

The objective of this study was to evaluate the effect of Conilon coffee (Coffea canephora) cultivated under conventional and organic management systems on the chemical and microbiological characteristics of the soil, as compared to an Atlantic forest. Chemical soil properties, microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial activity (MA), and metabolic quotient (qCO2) were determined at depths of 0–10 cm and 10–20 cm in two seasons (summer and winter). Although microbiological attributes varied according to the season and soil depth, MBC provided 54.15% of relative contribution to distinguish the treatments, followed by MBN and MA. Results indicate that the cultivation of coffee under organic management is more sustainable than under conventional system. Carbon from microbial biomass was the most important soil microbiological attribute in the clustering of the different management methods. Atlantic forest soil followed by organic coffee cultivation soil showed the best soil-quality indices.     

不同施氮水平下土壤的生化性质对干湿交替的响应

以中国科学院封丘农业生态试验站水氮耦合长期试验地为研究平台,采集五个施氮水平(施氮0、150、190、230、270 kg hm-2)下表层0 ～ 20 cm土壤并测定其土壤肥力参数(土壤pH、全氮、全磷、全钾、碱解氮、速效磷、速效钾、有机碳).结果表明:施氮降低了土壤pH、速效磷、全钾,增加了全氮、碱解氮、有机碳,除有机碳随施氮水平的增加而增加外,其他肥力参数并未随施氮水平的增加而发生规律性变化.土壤经过0、3、6、10次干湿交替,培养60 d后测定其生物和化学性质(土壤铵态氮、硝态氮、溶解性有机碳、脲酶活性、脱氢酶活性、微生物生物量碳、土壤基本呼吸).双因素方差分析显示干湿交替次数对铵态氮、硝态氮、无机氮、溶解性有机碳、脱氢酶活性、微生物生物量碳和土壤基本呼吸均有极显著作用,而干湿交替次数和施氮水平对除脱氢酶活性以外的其他土壤性质均无交互作用.五个施氮水平下土壤硝态氮、无机氮、溶解性有机碳、脲酶活性、脱氢酶活性和微生物生物量碳均随干湿交替次数增加而增加,土壤基本呼吸随干湿交替次数增加而降低.高施氮水平(施氮超过190 kg hm-2)下土壤性质的变异系数更小并能更好地发生聚类.研究表明当土壤遭遇干湿交替时,高施氮水平下土壤更能维持其生化性质的稳定.     

长期有机培肥提高红壤性水稻土生物学特性及水稻产量的微生物学机制

  【目的】  依托位于江西红壤研究所的有机肥长期定位试验，探究长期施用紫云英、猪粪和秸秆还田对土壤微生物量、酶活性和产量的影响，阐明土壤微生物学特性对土壤肥力的生物指示功能，揭示影响作物产量和微生物学特性的关键环境因子。  【方法】  长期定位试验始于1981年，选取的6个处理分别为:CK (不施肥)、NPK (单施化肥)、M1 (早稻施绿肥)、M2 (早稻加倍施绿肥)、M3 (早稻施绿肥+晚稻施猪粪) 和M4 (早稻施绿肥+晚稻秸秆还田)，此外，有机处理 (M1、M2、M3和M4) 在施用有机物料的基础上，每季还补充一定量化肥（N 69 kg/hm2、P₂O₅ 30 kg/hm2、K₂O 67.5 kg/hm2）。于每季收获后测定水稻产量。2018 年早稻收获后，采集耕层 (0—20 cm)土壤，测定土壤化学指标、微生物量碳氮、脲酶及其他参与土壤碳、氮、磷和硫循环的胞外酶活性。  【结果】  1) 2009—2018年间，长期施肥处理明显提高了水稻产量，其中M3处理的产量最高，其次为M2处理，二者均明显高于NPK处理；2) 土壤微生物量及酶活性均以有机处理 (M1、M2、M3和M4) 较高，其中M3处理土壤微生物量碳含量及各类土壤酶活性最高，M2处理土壤微生物量氮含量最高。有机处理较CK和NPK处理提高了土壤微生物熵。此外，微生物量碳氮和土壤酶活性与有机碳、全氮间存在显著或极显著相关关系；3) 有机碳与土壤微生物量 (0.895)、碳循环相关酶活性 (0.903)、氮循环相关酶活性 (0.854) 及水稻产量 (0.827) 呈显著正影响 (P < 0.05)；土壤pH与土壤碳循环相关酶活性 (0.378) 和氮循环相关酶活性 (0.365) 呈显著正影响 (P < 0.05)，对水稻产量 (0.211) 也表现为正影响，但不显著 (P > 0.05)。相较于pH，土壤有机碳含量在提高水稻产量、改善土壤微生物学特性上发挥了更为重要的作用。  【结论】  土壤微生物量碳氮和参与土壤碳、氮、磷和硫循环的胞外酶活性均可作为土壤微生物学指标表征土壤肥力的变化。土壤有机碳含量是提高作物产量、调控土壤微生物量和酶活性的关键因子。在供试条件下，长期实行早稻施绿肥+晚稻施猪粪的有机培肥，是提高土壤微生物量及酶活性并提高水稻产量的最佳选择。     

复合微生物肥对碱土生物学性状与土壤肥力的影响

为探讨复合微生物肥对碱土的改良效果,对内蒙古农业大学海流图科技园区碱土试验地开展了施用复合微生物肥的田间试验,探讨了其对土壤生物学性状和土壤肥力的影响。结果表明:施用复合微生物肥处理较不施肥处理显著降低了耕层土壤pH和EC值,分别降低0.32~0.88个单位和0.17~0.39 mS/cm;显著提高了土壤酶活性、微生物碳氮、有机质和速效养分含量,过氧化氢酶、脲酶、磷酸活性酶和蔗糖酶活性分别提高62.90%~158.06%、57.66%~74.82%、38.89%~69.44%和41.37%~53.25%;土壤微生物碳、氮、碳氮比和微生物熵分别提高71.41%~82.36%、29.13%~31.84%、30.16%~37.13%和33.33%~37.68%;土壤有机质、碱解氮、有效磷和速效钾含量分别提高22.48%~35.19%、22.40%~33.33%、104.04%~132.97%和34.28%~37.82%。施用复合微生物肥处理较习惯施肥处理降低了耕层土壤pH和EC值,分别降低0.16~0.72个单位和0.06~0.28 mS/cm;显著提高了土壤酶活性、微生物碳氮、有机质和速效钾含量,土壤脲酶、磷酸活性酶和蔗糖酶活性分别提高15.82%~28.42%、21.95%~48.78%和29.32%~40.19%;土壤微生物碳、氮、碳氮比和微生物熵分别提高37.07%~45.82%、15.79%~18.22%、26.27%~33.03%和21.05%~25%;土壤有机质和速效钾含量分别提高10.40%~21.85%和23.66%~41.19%。以上结果表明,施用复合微生物肥能明显改善碱土的生物学性状,提高土壤肥力,不同施肥量梯度中,1500 kg/hm²处理的综合效应最好。     

Pruned tea bushes secrete more root exudates to influence microbiological properties in soil

Pruning is adopted at 3–4 years interval as an agronomic practice during tea cultivation. It was hypothesized that biomass loss during pruning will imply stress on tea bushes. The aim of this study was to quantify changes in different parameters (labile organic carbon fractions, phosphatase activity, microbial biomass and microbial respiration) in tea rhizosphere due to pruning by collecting soil samples from the rhizosphere of ten of each pruned and un-pruned tea bushes. Hot-water extractable and dissolved organic C contents in rhizosphere soil of pruned tea were significantly (P ≤ 0.05) higher than those in the soil of un-pruned tea bushes. Analysis of phospholipid fatty acids (PLFA) revealed that the rhizosphere of pruned tea plants had higher population of Gram (+) and Gram (-) bacteria, fungi, actinomycetes and lower denitrifying bacterial population as compared to un-pruned tea plants. Activity of acid phosphatase enzyme in soil was also increased due to pruning. A separate study revealed that de-centering may induce production of up to 50% more labile organic carbon compounds by young tea as compared to un-pruned plants. Therefore, it could be concluded that pruned tea bushes secrete more root exudates to influence microbiological and biochemical properties in rhizosphere.     

Microbial processes controlling P availability in forest spodosols as affected by soil depth and soil properties

Because carbon dioxide (CO₂) concentration is rising, increases in plant biomass and productivity of terrestrial ecosystems are expected. However, phosphorus (P) unavailability may disable any potential enhanced growth of plants in forest ecosystems. In response to P scarcity under elevated CO₂, trees may mine deeper the soil to take up more nutrients. In this scope, the ability of deep horizons of forest soils to supply available P to the trees has to be evaluated. The main objective of the present study was to quantify the relative contribution of topsoil horizons and deep horizons to P availability through processes governed by the activity of soil micro-organisms. Since soil properties vary with soil depth, one can therefore assume that the role of microbial processes governing P availability differs between soil layers. More specifically, our initial hypothesis was that deeper soil horizons could substantially contribute to total plant available P in forested ecosystems and that such contribution of deep horizons differs among sites (due to contrasting soil properties). To test this hypothesis, we quantified microbial P and mineralization of P in ‘dead’ soil organic matter to a depth of 120 cm in forest soils contrasting in soil organic matter, soil moisture and aluminum (Al) and iron (Fe) oxides. We also quantified microbiological activity and acid phosphomonoesterase activity. Results showed that the role of microbial processes generally decreases with increasing soil depth. However, the relative contribution of surface (litter and 0–30 cm) and deep (30–120 cm) soil layers to the stocks of available P through microbial processes (51–62 kg P ha^?1) are affected by several soil properties, and the contribution of deep soil layers to these stocks vary between sites (from 29 to 59%). This shows that subsoils should be taken into account when studying the microbial processes governing P availability in forest ecosystems. For the studied soils, microbial P and mineralization of P in ‘dead’ soil organic matter particularly depended on soil organic matter content, soil moisture and, to a minor extent, Al oxides. High Al oxide contents in some sites or in deep soil layers probably result in the stabilization of soil organic compounds thus reducing microbiological activity and mineralization rates. The mineralization process in the litter also appeared to be P-limited and depended on the C:P ratio of soil organic matter. Thus, this study highlighted the effects of soil depth and soil properties on the microbial processes governing P availability in the forest spodosols.     

稻—油轮作下有机替代对土壤胞外酶活性及多功能性的影响

通过田间定位试验,研究有机肥替代部分化肥对稻—油轮作体系下土壤胞外酶活性及多功能性的影响,为稻—油轮作体系土壤培肥和合理施肥提供理论依据。试验基于总养分替代原则,以不施肥为对照(CK),设置全量化肥(CF)、有机肥替代20%化肥(CFM1)及有机肥替代40%化肥(CFM2)处理,测定土壤化学性质、微生物学性质和土壤胞外酶活性,应用多元回归分析探讨土壤性质对土壤胞外酶活性及多功能性的影响。结果表明:与CF处理相比,CFM1、CFM2处理的微生物量碳、氮和土壤呼吸在油菜季平均增加275.27%,41.90%和64.29%;而在水稻季平均增加115.06%,338.32%,60.87%。有机肥替代部分化肥也显著提高土壤有机质、全氮、全磷和速效养分含量,增幅为13.25%~95.48%。相比单施化肥,有机肥替代部分化肥显著增加油菜季土壤β—葡糖苷酶、纤维素酶、木聚糖酶、亮氨酸氨基肽酶、N—乙酰—β—D—氨基葡糖苷酶和酸性磷酸酶等碳氮磷循环相关胞外酶活性,增幅为20.33%~140.31%;而在水稻季,只有木聚糖酶活性显著增加,增幅为133.63%~159.86%。油菜季土壤胞外酶活性变化的关键因子为土壤微生物量碳,而水稻季的则为土壤速效磷。相比不施肥和单施化肥,有机肥替代处理显著增加土壤多功能性,油菜季土壤多功能性的主要预测因子和调控因子主要是速效钾和速效氮含量,而水稻季的则为速效磷和微生物量氮。总之,有机肥替代部分化肥有利于土壤养分、土壤胞外酶活性和多功能性提高,是维持作物稳产和保持土壤生物健康的重要措施。     

Microbial biomass activities in urban soils in two consecutive years

Ecological soil functions are protected in Germany. Thus, for the sustainable use of urban soil resources data on the function of soils to serve as a habitat are required. Soil microbial biomass and activities were studied in two surface horizons in two consecutive years at nine sites in Stuttgart, Germany, differing in land use. Microbial biomass (chloroform‐fumigation extraction, substrate‐induced respiration) and microbial activities (potential N mineralization, potential ammonium oxidation, and enzyme activities of dehydrogenase, urease, arylsulfatase, and phosphatase) were determined in 2001 and 2002. DIN/ISO standard methods were applied as far as they were available. Furthermore, soil chemical properties were determined in the 2001‐samples. Large differences in chemical and microbiological properties among surface horizons were found. Concentrations of microbial biomass and microbial activities were, however, often comparable to agricultural or forest surface soils. The lowest microbial biomass and activities were observed at a highly disturbed railway area where vegetation was missing and total organic C (TOC) had been altered by anthropogenic organic particles. In contrast, microorganisms were promoted at vegetated sites and where organic impurities were negligible. As TOC was altered by obscure organic matter, total N (TN) and not TOC closely correlated with soil microbiological properties. Biomass and activity generally decreased with depth, but mixing of organic matter resulted in more uniform depth distribution of microbial properties in one garden soil. In 2002, microbial biomass and activity were often lower compared to 2001, but interpretation of this difference hampered as the number of samples taken was probably not sufficient to address the spatial variability in soil properties. Additional studies are needed to develop simple and cost‐effective procedures for the evaluation of ecological quality of urban soils by combined efforts of city planners and soil scientists.