微塑料输入与秸秆添加对潮土和黄棕壤氮淋溶的影响

为探究微塑料输入与秸秆添加对农田土壤氮淋溶的影响,以潮土和黄棕壤为研究对象,每种土壤各设置8个处理,包括对照（CK）、低量微塑料（PE1）、中量微塑料（PE2）、高量微塑料（PE3）、秸秆（S）、秸秆+低量微塑料（S+PE1）、秸秆+中量微塑料（S+PE2）、秸秆+高量微塑料（S+PE3）,研究了添加秸秆与不添加秸秆条件下,不同微塑料输入量对土壤氮淋溶的影响。结果表明,仅添加微塑料条件下,与对照（CK）相比,潮土PE1、PE2、PE3处理总氮（TN）淋溶量均无显著差异,黄棕壤仅PE1处理显著增加了TN淋溶量。在添加秸秆（S）处理中,与对照（CK）相比,潮土添加秸秆后显著降低了硝态氮（NO₃^--N）、铵态氮（NH₄⁺-N）、TN淋溶量,分别降低了31.15%、13.45%、15.26%,黄棕壤添加秸秆后显著增加了TN淋溶量,增加了22.56%。添加秸秆处理相较于不添加秸秆处理,潮土各浓度微塑料输入下NO₃^--N、NH₄⁺-N、TN的累计淋溶量呈降低趋势,而黄棕壤低量微塑料输入降低了TN淋溶量,高量微塑料输入增加了TN淋溶量。偏最小二乘路径模型（PLS-PM）分析表明,在潮土中添加秸秆主要通过影响淋溶液pH和NO₃^--N淋溶量影响氮素淋溶,微塑料添加量对氮淋溶无显著影响;在黄棕壤中添加秸秆主要通过影响淋溶液NO₃^--N、NH₄⁺-N淋溶量影响氮淋溶,微塑料添加量主要通过影响淋溶液NH₄⁺-N淋溶量影响氮淋溶。研究结果可为农田土壤微塑料污染风险的管控及减少土壤氮素的淋失提供依据。     

Effects of organic amendment and herbicide treatment on soil microbial biomass

 The interactive effects of vermi-compost from sewage sludge and either the sulfonylurea herbicide, rimsulfuron, or the imidazolinone herbicide, imazethapyr, on some soil biochemical and microbiological properties were investigated. The herbicides were applied at field and 10-fold field rates. Both herbicides exerted a detrimental effect on soil microbial biomass and its biochemical properties. Even though the effect of both herbicides on soil microbial biomass was not detectable at the field rate, some significant influences on acid and alkaline phosphatase were observed. The higher rate of herbicide application impaired the observed microbial parameters to a greater degree. The detrimental effects seemed to be reduced by organic amendments. Among the studied microbial characteristics, the specific respiration quotient was particularly reliable and sensitive in determining the influence of herbicides on the soil microbial biomass. In this paper a new synthetic index, specific hydrolytic activity (qFDA), for assessing microbial activity in reply to xenobiotic treatments is proposed. Received: 31 May 1999     

秸秆深层覆盖对水分入渗及蒸发的影响

 为探讨秸秆还田对土壤水分入渗和蒸发造成的影响,通过在土表下20 cm处铺设3cm厚秸秆隔层的土柱试验表明:在灌溉水分入渗时,秸秆隔层阻碍了土壤重力水入渗,降低了土壤重力水由土壤上层向下层入渗的速率;在土壤水分蒸发过程中,秸秆层隔断了土壤的毛细管,使秸秆层以下土壤水很难通过土壤毛细管作用而向地表运移并蒸发。秸秆深层覆盖可以使深层土壤水分的蒸散量减少2%～3%,对深层土壤的蓄水保墒有积极的作用。     

小分子有机物对土壤酶活性及微生物多样性的影响

目前对小分子有机物的研究主要集中在叶面肥方面,较少在土壤肥料的应用方面,而对土壤酶活性以及微生物功能多样性的研究就更少。以分别添加葡萄糖、甘油以及甘氨酸的土壤(25℃培养)为试材,采用酶活性(每15 d取样)测定方法与Biolog-Eco板技术(取培养45 d的土样),研究小分子有机物对土壤微生物及酶活性的影响。结果表明,3种小分子有机物处理土壤的4种酶活性在15～75 d内,变化规律基本一致;在45 d时葡萄糖处理土壤的过氧化氢酶活性显著高于清水对照(CK)、甘油以及甘氨酸,而碱性磷酸酶活性显著低于其它处理。与CK、葡萄糖以及甘氨酸相比,甘油处理土壤微生物平均吸光度值和功能多样性指标(除指数D外)显著提高,而CK、葡萄糖以及甘氨酸处理之间没有显著性差异。葡萄糖、甘油以及甘氨酸处理改变了土壤的微生物功能多样性以及碳源利用比分,其中甘氨酸和葡萄糖处理土壤胺类利用百分比(AM)几乎为零。土壤微生物多样性与酶活性冗余分析表明,碱性磷酸酶与微生物功能多样性指数S、U、H′、碳水化合物利用百分比以及AM呈显著正相关,相关系数分别为0.588、0.669、0.616、0.678及0.603,与指数D及蔗糖酶活性呈显著负相关,相关系数分别为-0.737和-0.741。由此可知,不同种类小分子有机添加物对土壤酶活性以及微生物功能多样性影响不一,其中甘油显著提高了土壤微生物代谢活性以及多样性指数(除指数D外),而土壤酶活性与微生物功能多样性的主成分分析表明甘氨酸与另外两种小分子有机物存在明显差别。     

长期施钾和秸秆还田对河北潮土区作物产量和土壤钾素状况的影响

以河北冲积平原典型潮土区小麦-玉米轮作长期定位试验（19922009年）为基础,分析了长期施用钾肥和秸秆还田对作物产量、 土壤钾含量及钾素平衡的影响。研究结果表明,不同处理下小麦、 玉米17年平均产量均表现为NPKStNPKNPStNP,其中,小麦、 玉米NPKSt处理比NP处理分别增产9.37%和19.23%,NPK处理比NP处理分别增产6.32%和18.25%; NPSt处理比NP处理分别增产2.76%和9.60%; 长期定位施肥下,各处理耕层土壤（020 cm）各施钾肥的处理其速效钾、 缓效钾含量均与NP处理差异极显著,且表现为NPKStNPKNPStNP; 各处理下层土壤（2040 cm）的速效钾、 缓效钾含量差异均不显著,从钾素平衡看,NP处理钾素表观年盈亏量为-170.0 kg/hm2,土壤钾严重亏缺; NPSt处理实际平衡盈亏率-58.4%,表观年盈亏量为-150.6 kg/hm2; NPK处理钾素表观年盈亏量-3.1 kg/hm2,盈亏率-1.0%,基本接近平衡; NPKSt处理实际平衡盈亏率36.8%,表观年盈亏量为111.4 kg/hm2。试验结果说明,在潮土区,在施氮、 磷肥的基础上,配施钾肥或秸秆还田不仅能持续提高小麦、 玉米的高产、 稳产生产能力, 而且对保持农田土壤钾素平衡、 有效改善耕层土壤钾素状况、 提高土壤肥力有重要的作用。     

不同筛分方式对土壤团聚体及土壤微生物群落的影响

探究土壤团聚体组成、稳定性、有机碳含量及微生物数量在不同土壤筛分方式下的变化,对团聚体筛分方式进行优化。以黑土为研究对象,设置不同筛分方式处理,比较干土干筛、干土湿筛、润土干筛、润土湿筛4种筛分方式的优缺点。结果表明,润土干筛比干土湿筛处理≥2 mm粒径的土壤团聚体高出约85.97%,而在2～0.25、≤0.25 mm粒级中团聚体所占比例最高的干土湿筛比最低的润土干筛分别高出约80.90%、91.82%。>0.25 mm水稳性团聚体含量(R_0.25)在润土干筛下达到最高,为99.35%,该指标与土壤团聚体稳定性成正相关,其值越高则表示土壤抗蚀能力越强。干土湿筛处理下各粒级团聚体土壤有机碳分布平均。干土湿筛处理下,土壤细菌和放线菌的数量最高。而润土干筛处理下土壤真菌数量较高,与润土湿筛、干土干筛、干土湿筛3个处理方式相比有显著性差异。综上发现,干土湿筛处理下土壤团聚体稳定性更好,土壤微生物数量较高,在一定程度上对土壤结构、土壤质量起到优化的作用。     

Effects of soil moisture and plant interactions on the soil microbial community structure

A greenhouse pot experiment was conducted to investigate the influence of soil moisture content and plant species on soil microbial community structure using cultivation-independent methods. White clover and ryegrass were grown individually or in a mixture. Plants were subjected to soil moisture content corresponding to 60% field capacity (FC) and 80% FC. Total plant biomass of white clover and ryegrass increased with increasing soil moisture contents. At a given soil moisture content, total biomass of white clover was lower in the ryegrass–clover (RC) mixture compared with those grown individually, while total biomass of ryegrass was higher. Microbial community structure assessed by phospholipid fatty acid analysis (PLFA) was more affected by plant species than soil moisture. Community level physiological profiles (CLPP), in terms of diversity of substrate utilization and average well colour development (AWCD) were affected by plant species and soil moisture. Soil moisture effects were more pronounced in clover than in ryegrass. AWCD and diversity of substrate utilization in the ryegrass–clover mix were similar to those of sole clover while they differed from that of ryegrass suggesting a dominant effect of clover in the mix.     

长期秸秆还田对潮土土壤团聚体碳氮和作物产量的影响

为探究潮土区长期秸秆还田对土壤团聚体碳、氮含量和作物产量的影响,以河北省低平原潮土区小麦-玉米轮作系统为研究对象,利用38年化肥与秸秆配施长期定位试验,研究了不施肥(CK)和等量氮、磷肥用量下0 kg/hm²(S0)、2250 kg/hm²(S2250)、4500 kg/hm²(S4500)和9000 kg/hm²(S9000)秸秆还田量下,土壤团聚体碳、氮含量和作物产量。结果表明:与不施肥CK相比,长期施肥与秸秆还田可以增加各粒径团聚体中有机碳和全氮含量,其中,秸秆还田对提高0～10 cm表层土壤水稳性团聚体有机碳含量效果较好,且随秸秆还田量的增加,水稳性团聚体有机碳提升效果越明显。长期秸秆还田对各粒径团聚体中碳氮比无较大影响。>0.25 mm团聚体中有机碳和全氮富集系数较高,且0～10 cm土层,S2250、S4500和S9000处理均表现为随着团聚体粒径减小团聚体中有机碳富集系数逐渐降低。长期秸秆还田可以提高作物产量,且高秸秆还田量对小麦产量的提高效果更明显。>0.25 mm团聚体中有机碳含量与小麦产量之间的关系最密切,当该粒径团聚体中有机碳含量增加1 g/kg时,小麦产量可以增加329.62 kg/hm²;而0.25～0.053和<0.053 mm团聚体中有机碳含量与小麦产量相关性较差。综上,秸秆还田可以增加土壤团聚体中有机碳含量,提升土壤肥力,促进作物增产。     

免耕对潮土不同粒级团聚体有机碳含量及微生物碳代谢活性的影响

利用中国科学院封丘农业生态国家实验站玉米-小麦轮作免耕定位试验平台,研究不同耕作方式对潮土不同粒级团聚体的分布、有机碳含量及微生物群落碳代谢活性的影响。结果表明,与传统翻耕处理相比,免耕潮土中大于250μm粒级团聚体显著增加(p0.05),50～2μm粒级团聚体显著减少(p0.05),250～50μm和小于2μm两个粒级团聚体没有明显变化;大于250μm和250～50μm两个粒级团聚体有机碳含量显著升高(p0.05),50～2μm和小于2μm两个粒级团聚体有机碳含量没有明显变化,250～50μm粒级取代50～2μm粒级成为对土壤有机碳总量贡献最大的团聚体。BIOLOG测试结果表明,免耕和翻耕两种措施下不同粒级团聚体微生物群落碳代谢特征存在明显差异,且免耕处理250～50μm和小于2μm两个粒级团聚体微生物群落碳代谢活性显著低于翻耕处理(p0.05)。结果显示,免耕有利于小粒级团聚体向大粒级团聚体方向聚合,大于50μm粒级团聚体固持的有机碳增多,其中持碳最多的250～50μm粒级团聚体的微生物碳代谢活性下降,故土壤有机碳稳定性升高。     

长期秸秆还田对华北潮土肥力、 氮库组分及作物产量的影响

【目的】近年,华北小麦-玉米轮作系统秸秆全量还田已逐步普及,但秸秆还田下土壤氮库组成的变化并不清楚。本文利用肥料定位试验,研究了长期秸秆还田(32年)对华北潮土肥力、 氮库组分和作物产量的影响。【方法】研究选用河北省衡水旱作试验站长期定位试验的不施肥(对照CK)和等量氮、 磷肥用量下的0kg/hm2(S0)、 2250 kg/hm2(S1)、 4500 kg/hm2(S2)和9000 kg/hm2(S3)秸秆还田处理。于2012年小麦收获后采集各处理020 cm土样,利用新鲜土样测定微生物量氮、 NH+4-N和NO-3-N;风干土壤用常规方法测定氮磷钾全养分、 有机质和pH,用Bremner法测定有机氮(酸解氨基酸态氮、 酸解氨态氮、 氨基糖氮和酸解未知态氮),用Silver-Bremner法测定固定态铵。同时结合长期试验数据, 分析长期秸秆还田下有机质和作物产量的变化。【结果】与试验开始前(1981年)相比,长期施用化肥处理的土壤全磷和有机质显著增加,全氮没有明显变化,而全钾出现降低趋势(-3.2%);秸秆用量的增加提高了全氮、 全磷和有机质,降低了pH值,但对全钾没有影响。酸解氨基酸态氮、 酸解氨态氮和未知态氮为潮土有机氮的主要组分;与CK相比,长期施肥提高了土壤有机氮含量,酸解氨基酸态氮、 酸解氨态氮和氨基糖氮均随秸秆用量的增加而增加,而不同施肥处理对酸解未知态氮和非酸解氮没有明显影响。长期化肥施用提高了微生物量氮和晶格固定态铵,秸秆用量的增加进一步提高了微生物量氮,但降低了固定碳铵。施肥没有明显影响NH+4-N含量,但长期施用化肥提高了NO-3-N含量,且高量秸秆还田对NO-3-N含量的提高具有促进作用。施肥显著提高了作物产量,在施用化肥基础上增施秸秆进一步提高了小麦和玉米产量,且玉米产量随秸秆用量的增加而增加,而高量秸秆还田对小麦产量并没有显著影响。【结论】长期化肥(氮、 磷肥)和秸秆结合施用提高了土壤肥力(主要为氮、 磷), 增加了土壤碳固持,但仅玉米秸秆还田导致了土壤钾消耗,增加钾肥投入维持土壤钾平衡是必要的。长期秸秆还田对酸解氨基酸态氮的贡献高于酸解氨态氮;高量秸秆还田提高了微生物量氮和NO-3-N含量,但降低了固定态铵含量。长期秸秆还田提高了作物产量,而为保证秸秆还田后茬的作物高产,与之配套的还田方法和田间管理是很必要的。     

Effects of biochar on copper immobilization and soil microbial communities in a metal-contaminated soil

Purpose

Copper (Cu) contamination has been increasing in land ecosystems. Biochars (BCs) and arbuscular mycorrhizal fungi (AMF) are known to bind metals, and metallophyte can remove metals from soils. Will BC in combination with AMF contain the Cu uptake by a metallophyte growing in a metal-contaminated soil? The objective of this study was to investigate the effects of BCs on the Cu immobilization and over soil microbial communities in a metal-contaminated soil in the presence of AMF and metallophyte.

Materials and methods

Two BCs were produced from chicken manure (CMB) and oat hull (OHB). A Cu-contaminated sandy soil (338 mg kg^?1) was incubated with CMB and OHB (0, 1, and 5 % w/w) for 2 weeks. Metallophyte Oenothera picensis was grown in pots (500 mL) containing the incubated soils in a controlled greenhouse for 6 months. A number of analyses were conducted after the harvest. These include plant biomass weight, microbial basal respiration, and dehydrogenase activity (DHA), AMF root colonization, spore number, and glomalin production; changes in fungal and bacterial communities, Cu fractions in soil phases, and Cu uptake in plant tissues.

Results and discussion

The BCs increased the soil pH, decreased easily exchangeable fraction of Cu, and increased organic matter and residual fraction of Cu. The BCs provided favorable habitat for microorganisms, thereby increasing basal respiration. The CMB increased DHA by ～62 and ～574 %, respectively, for the low and high doses. Similarly, the OHB increased soil microbial activity by ～68 and ～72 %, respectively, for the low and high doses. AMF root colonization, spore number, and total glomalin-related soil protein (GRSP) production increased by ～3, ～2, and ～3 times, respectively, in soils treated with 1 % OHB. Despite being a metalophyte, O. picensis could not uptake Cu efficiently. Root and shoot Cu concentrations decreased or changed insignificantly in most BC treatments.

Conclusions

The results show that the BCs decreased bioavailable Cu, decreased Cu uptake by O. picensis, improved habitat for microorganisms, and enhanced plant growth in Cu-contaminated soil. This suggests that biochars may be utilized to remediate Cu-contaminated soils.

     

秸秆生物炭配施氮肥对潮土土壤碳氮含量及作物产量的影响

【目的】探讨玉米秸秆生物炭配施氮肥对华北潮土区土壤理化特性和作物产量的影响,阐明土壤和植株对生物炭和氮肥施用的响应,旨在为该区域秸秆资源高效利用、培肥土壤及作物增产提供科学依据。【方法】以华北冬小麦–夏玉米轮作区为研究对象,研究玉米秸秆生物炭 (缺氧条件下 450℃ 热裂解 1 小时获得) 配施氮肥对土壤养分含量、微生物量以及作物产量的影响。试验采用裂区设计,以秸秆生物炭施用量为主区,施氮量为副区。秸秆生物炭用量设 0、7.5 和 22.5 t/hm2 3 个水平 (以 BC₀、BC_7.5、BC_22.5 表示);氮肥用量设 0、150、225 和 300 kg/hm2 4 个水平 (以 N₀、N₁₅₀、N₂₂₅、N₃₀₀ 表示)。小麦在 2014 年 10 月 9 日播种,次年 6 月 8 日收获;玉米在 2015 年 6 月 10 日播种,当年 9 月 28 日收获。在作物成熟期进行产量测定,并采集 0—20 cm 土壤样品以及采用常规方法进行土壤有机碳 (SOC)、全氮 (TN)、可溶性有机碳 (DOC)、铵态氮 (NH₄+-N)、硝态氮 (NO₃–-N)、土壤微生物量碳 (MBC) 和微生物量氮 (MBN) 的测定。【结果】生物炭对土壤养分含量、微生物量碳氮及作物产量有极显著影响。生物炭用量增加,土壤 SOC、TN、DOC、NO₃–-N 含量以及土壤 SOC/TN 比值均显著增加,较 BC₀ 最大增加幅度分别为 165.0%、74.1%、39.1%、75.1% 和 44.0%。MBC、MBN 含量和作物产量均以 BC_7.5 处理达最大值,较 BC₀ 最大增加幅度分别为 49.2%、57.6% 和 46.1%,BC_22.5 较 BC_7.5 处理平均降低 12.1%、7.3% 和 9.7%;施用生物炭降低 NH₄+-N 含量,BC_7.5 和 BC_22.5 处理较 BC₀ 分别下降 18.4% 和 23.7%。随着氮肥施用量的增加,SOC、DOC、NH₄+-N、MBC、MBN 含量均先增后减,在施氮水平为 150 kg/hm2 时,其含量均达最大值,较 N₀ 最大增加幅度分别为 29.7%、22.9%、44.8%、79.4% 和 115.3%。所有施氮的处理作物产量较 N₀ 均显著增加,而三个施氮处理间其产量差异不显著 (P>0.05)。【结论】在维持作物产量不降低的情况下,短期内 N₁₅₀BC_7.5 处理对提升土壤肥力的效果最佳,是较为理想的施肥方式,但其有效机制及长期效果还需进一步试验研究。     

长期平衡施肥对潮土微生物活性和玉米养分吸收的影响

利用中国科学院封丘农业生态实验站农田生态系统养分平衡长期定位试验地,研究氮磷钾平衡施肥(NPK)与缺素施肥(NK、PK、NP)对土壤微生物生物量、酶活性、呼吸强度以及玉米养分吸收的影响。结果发现,与不施肥对照(CK)相比,NPK处理玉米根系与茎叶生物量、籽粒产量以及植株氮磷钾吸收量均大幅提高,NP处理次之,PK与NK处理则无显著影响;同一处理玉米茎叶与根系养分含量接近,而籽粒的全氮和全磷含量较高、全钾含量偏低;与NPK处理相比,缺施氮、磷或钾肥均直接导致玉米植株相应养分的明显亏缺或其他养分的过量富集,但在根系、茎叶和籽粒部位的累积情况存在一定差异。与CK相比,所有施加磷肥的处理(NPK、NP、PK)土壤微生物生物量(碳、氮、磷)、脱氢酶、转化酶、脲酶与碱性磷酸酶活性以及土壤微生物代谢活性和土壤基础呼吸强度均显著升高(p<0.05),土壤微生物代谢熵则显著下降(p<0.05),而缺施磷肥的NK处理除显著提高脲酶活性外(p<0.05),对其他指标均无显著影响。结果表明,氮磷钾平衡施肥在促进土壤微生物繁育和保育微生物代谢活性以及促进作物生长和保证养分吸收等方面显得非常重要,而缺素施肥中以缺施磷肥的不利影响最为突出。     

Effects of sulfamethoxazole on soil microbial communities after adding substrate

The effect of the antibiotic sulfamethoxazole (SMX) on soil bacteria was studied using two methods (leucine incorporation and Biolog plates) of estimating pollution-induced community tolerance (PICT). SMX was added to an agricultural soil in a microcosm setup. The addition of different substrates (manure and alfalfa), and a non-amended soil, were also studied over 5 weeks. PICT measurements were validated by comparison with other measurements. Community structure was assessed using phospholipid fatty acid (PLFA) analysis and community-level physiological profiling (CLPP), and bacterial growth was estimated using leucine incorporation. Increased PICT was found at SMX concentrations of 20 and 500 mg SMX kg⁻¹ soil in samples containing manure and alfalfa, and at 500 mg SMX kg⁻¹ soil in non-amended soil (only concentration tested) using leucine incorporation. No effect was seen at 1 mg SMX kg⁻¹ soil. It was not necessary to add any substrate to increase the microbial activity in order to detect the effects of a bacteriostatic toxicant such as SMX when using measures based on bacterial growth. Direct inhibition of bacterial growth 2 days after SMX addition was correlated to PICT. No major changes in PICT due to SMX addition were found when using Biolog plates. However, there was a tendency towards increased PICT at the higher SMX concentrations in the manure-amended soil. Thus, different methods of detecting PICT have different sensitivities in detecting the toxic effects of SMX. The effects of substrate amendment were reflected by changes in the microbial community, estimated using both PLFA and CLPP. SMX was found to have a clear effect at the two highest levels of SMX in the manure- and alfalfa-amended soils, with an increase in fungal and a decrease in bacterial PLFAs. Little difference in the PLFA composition was found in the non-amended soil. CLPP was only affected at the highest SMX concentration. Although different variables showed different sensitivities to the effects of SMX, the results were consistent with an initial decrease in bacterial growth rates of sensitive species, which eventually transformed into more tolerant species, altering the community composition.     

Effects of genetically modified plants on microbial communities and processes in soil

The development and use of genetically modified plants (GMPs) has been a topic of considerable public debate in recent years. GMPs hold great promise for improving agricultural output, but the potential for unwanted effects of GMP use is still not fully understood. The majority of studies addressing potential risks of GMP cultivation have addressed only aboveground effects. However, recent methodological advances in soil microbial ecology have allowed research focus to move underground to try to gain knowledge of GMP-driven effects on the microbial communities and processes in soil that are essential to key terrestrial ecosystem functions. This review gives an overview of the research performed to date on this timely topic, highlighting a number of case studies. Although such research has advanced our understanding of this topic, a number of knowledge gaps still prevent full interpretation of results, as highlighted by the failure of most studies to assign a definitively negative, positive or neutral effect to GMP introduction. Based upon our accumulating, yet incomplete, understanding of soil microbes and processes, we propose a synthesis for the case-by-case study of GMP effects, incorporating assessment of the potential plant/ecosystem interactions, accessible and relevant indicators, and tests for unforeseen effects.     

Effect of biochar amendment on soil carbon balance and soil microbial activity

We investigated the behavior of biochars in arable and forest soil in a greenhouse experiment in order to prove that these amendments can increase carbon storage in soils. Two qualities of biochar were produced by hydrothermal pyrolysis from ¹³C labeled glucose (0% N) and yeast (5% N), respectively. We quantified respiratory losses of soil and biochar carbon and calculated mean residence times of the biochars using the isotopic label. Extraction of phospholipid fatty acids from soil at the beginning and after 4 months of incubation was used to quantify changes in microbial biomass and to identify microbial groups utilizing the biochars. Mean residence times varied between 4 and 29 years, depending on soil type and quality of biochar. Yeast-derived biochar promoted fungi in the soil, while glucose-derived biochar was utilized by Gram-negative bacteria. Our results suggest that residence times of biochar in soils can be manipulated with the aim to “design” the best possible biochar for a given soil type.     

施肥及秸秆还田对砂姜黑土细菌群落的影响

利用Illumina平台Miseq高通量测序技术对小麦分蘖期砂姜黑土耕层土壤细菌进行高通量测序,结合相关生物信息学分析,探讨了不施化肥秸秆不还田(CK)、施化肥秸秆不还田(F)以及不施化肥秸秆还田(W)3种处理土壤细菌群落组成、多样性和结构的变化。结果显示,测序共获得14 873个OTUs,计173 323条读数,平均读长439 bp。砂姜黑土细菌优势门(相对丰度10%)为变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)、放线菌门(Actinobacteria)和拟杆菌门(Bacteroidetes);优势纲(相对丰度10%)为α-变形菌纲(Alphaproteobacteria)、β-变形菌纲(Betaproteobacteria)、酸杆菌纲(Acidobacteria)、鞘脂杆菌纲(Sphingobacteriia)和γ-变形菌纲(Gammaproteobacteria);优势属(相对丰度1%)共47个,3个处理中均有分布的优势属21个,F处理的细菌优势属的种类最多,为39个。相对丰度最大的门、纲和属分别是变形菌门(38.7%~43.1%)、α-变形菌纲(14.5%~18.1%)和鞘氨醇单胞菌属(Sphingomonas)(4.6%~7.7%)。F处理细菌丰富度指数(Chao1指数和ACE指数)显著低于CK及W处理,W处理和CK处理土壤细菌丰富度指数无显著差异,与CK处理相比,F处理ACE指数降低22.8%。W处理土壤细菌Shannon多样性指数显著大于CK及F处理,W处理Shannon指数较CK处理提高4.1%,而F处理土壤细菌Shannon指数与CK处理无显著差异。F处理Simpson指数显著高于CK及W处理;F处理Simpson指数较CK处理提高38.1%,而W处理细菌Simpson指数最小,显著低于CK处理,较CK降低23.8%。分层聚类图显示在属的水平上,W处理和CK处理土壤细菌群落结构相似性较高,F处理与CK处理及W处理细菌群落结构差异较大。施化肥对土壤细菌优势类群组成、相对丰度及群落结构的影响大于秸秆还田,施化肥显著降低了土壤细菌丰富度,秸秆还田显著提高了土壤细菌的多样性。     

Degradation and humification of maize straw in soil microcosms inoculated with simple and complex microbial communities

Microbial communities are responsible for soil organic matter cycling and thus for maintaining soil fertility. A typical Orthic Luvisol was freed from organic carbon by thermal destruction at 600°C. Then the degradation and humification of ¹⁴C‐labelled maize straw by defined microbial communities was analysed. To study the role of microbial diversity on the humification of plant material, microcosms containing sterilized soil were inoculated with a natural microbial community or with microbial consortia consisting of bacterial and fungal soil isolates. Within 6 weeks, 41 ± 4% of applied ¹⁴C‐labelled maize straw was mineralized in the soil microcosms containing complex communities derived from a soil suspension, whilst the most efficient communities composed of soil isolates mineralized less than 35%. The humification products were analysed by solution state ¹³C‐NMR‐spectroscopy and gel permeation chromatography (GPC). The analyses of humic acids extracts by solution state ¹³C‐NMR‐spectroscopy revealed no difference in the development of typical chemical functional groups for humic substances during incubation. However, the increase in specific molecular size fractions of the extracted humic acids occurred only after inoculation with complex communities, but not with defined isolates. While it seems to be true that redundancy in soil microbial communities contributes to the resilience of soils, specific soil functions may no longer be performed if a microbial community is harshly affected in its diversity or growth conditions.     

不同秸秆还田方式对和田风沙土土壤微生物 多样性的影响

秸秆还田是有效利用秸秆资源的重要途径,能够提高土壤养分含量、调节土壤微生物的群落结构和多样性,但目前还缺乏不同秸秆还田方式对新疆沙化土壤肥力和微生物多样性影响的系统报道。为探索新疆沙化土壤肥力可持续提升模式,于2010—2012年在和田风沙土土壤上设置秸秆直接还田(NPKS)、过腹还田(NPKM,15.0 t×hm~(-2))和炭化还田(NPKB1,2.5 t×hm~(-2);NPKB2,15.0 t×hm~(-2))定位试验,研究不同秸秆还田处理对和田风沙土土壤养分、微生物数量、土壤酶活性和Biolog碳源利用的影响。结果表明:1)与单施化肥(NPK)相比,不同秸秆还田方式均能显著提高风沙土土壤养分含量,其中NPKM处理效果最好,其次是NPKB2处理,NPKS和NPKB1处理分别为第3和第4。2)不同秸秆还田方式对土壤微生物数量影响差异显著,均增加了土壤中细菌、放线菌和生理菌群的数量,与NPK处理相比,细菌数量NPKB2处理最高,放线菌数量NPKM处理最高,分别显著提高了413.16%和574.19%。但NPKB1和NPKB2处理对生理菌群数量的提升效果好于NPKS处理和NPKM处理。土壤酶活性,不同秸秆还田方式总体好于NPK处理,NPKM处理的提升效果最好。3)Biolog碳源利用分析表明不同秸秆还田方式均能提高风沙土土壤微生物活性和丰富度指数。主成分分析表明,不同秸秆还田方式土壤微生物群落明显不同,起分异作用的碳源主要为羧酸类和糖类。聚类分析显示NPKB2和NPKM处理之间、NPKB1和NPKS处理之间土壤微生物功能相似。由此可以看出,不同秸秆还田方式均能显著提高和田沙化土壤微生物活性和功能多样性,但不同方式的增效不同。从3年定位试验结果看,秸秆过腹还田和炭化还田的效果较好,秸秆直接粉碎还田有增加土传病害的风险。该结果将为南疆沙化土壤肥力可持续提升提供一定的理论指导。     

秸秆还田对黑土亚表层微生物群落结构的影响特征及原因分析

为明确切碎秸秆与秸秆颗粒对黑土亚表层土壤微生物群落结构的影响效应,从而评价不同秸秆还田方式对亚表层的培肥效果,该研究于2016—2018年在东北黑土区进行一次性玉米秸秆深埋还田试验,设置切碎秸秆低量(QS1)、切碎秸秆高量(QS5)、秸秆颗粒低量(KL1)与秸秆颗粒高量(KL5)4种秸秆还田处理,并与秸秆不还田(CK)进行对比,于每年玉米收获季对土壤理化指标及微生物菌群结构进行监测。结果表明,1)秸秆还田第1年,切碎秸秆处理显著提高土壤总磷脂脂肪酸含量及真菌摩尔百分数,其高量处理较CK最高增加71.0%和120.5%,而秸秆颗粒处理对细菌、革兰氏阳性菌和革兰氏阴性菌的摩尔百分数增幅更显著,其高量处理最高增加41.6%、29.7%和26.3%;还田第2年高量处理显著提高各菌群磷脂脂肪酸含量,且切碎高量处理的真菌摩尔百分数含量显著高于颗粒高量处理21.0%;还田第3年仅高量处理下的菌群结构有显著分异。2)还田初期切碎秸秆处理显著提高真菌:细菌比值,而低量还田则对革兰氏阳性菌和革兰氏阴性菌比有提高,随还田时间的增加,高量还田比值提高更显著,利于长期维持生态系统稳定性。3)秸秆高量还田可显著改...