生物质炭对土壤N2O消耗的影响及其微生物影响机理*

贺超卉, 董文旭, 胡春胜**, 李佳珍,3

生物质炭对土壤N2O消耗的影响及其微生物影响机理*

贺超卉1,2,3, 董文旭2, 胡春胜2**, 李佳珍2,3

(1. 中国科学院大学中丹学院 北京 100049; 2. 中国科学院遗传与发育生物学研究所农业资源研究中心/河北省土壤生态学重点实验室/中国科学院农业水资源重点实验室 石家庄 050022; 3. 中国科学院大学 北京 100049)

生物质炭在温室气体减排方面具有很大的发展前景, 它不仅能实现固碳, 对于在大气中停留时间长且增温潜势大的N2O也能发挥积极作用。本研究采用室内厌氧培养试验, 按照生物质炭与土壤质量比(0、1%和5%)加入一定量生物质炭, 土壤重量含水率控制在20%。利用Robotized Incubation平台实时检测N2O和N2浓度变化, 通过测定土壤中反硝化功能基因丰度(、、)分析生物质炭对N2O消耗的影响及其微生物方面的影响机理。结果表明: 经过20 h厌氧培养后, 0生物质炭处理的反硝化功能基因丰度(基因拷贝数∙g-1)分别为6.80×107()、5.59×108()和1.22×108()。与0生物质炭处理相比, 1%生物质炭处理的基因丰度由最初的2.65×108基因拷贝数∙g-1升至7.43×108基因拷贝数∙g-1,基因丰度则提高了一个数量级, 由4.82×107基因拷贝数∙g-1升至1.50×108基因拷贝数∙g-1, 然而基因丰度并无明显变化; 5%生物质炭处理的反硝化功能基因丰度并未发生显著变化。试验结束时, 添加生物质炭处理的N2/(N2O+N2)比值也明显高于0生物质炭处理。相关性分析结果表明,基因丰度和基因丰度均与N2O浓度在0.01水平上显著相关。试验末期基因丰度和基因丰度均随着N2O浓度的降低而升高。因此在本试验中, 添加1%生物质炭可显著提高和基因型反硝化细菌的丰度, 增大N2/(N2O+N2)比值, 促进N2O彻底还原成N2。生物质炭对于N2O主要影响机理是增大了可以还原氧化亚氮的细菌活性, 促进完全反硝化。

生物质炭; 温室气体减排; 土壤微生物; N2O消耗; 反硝化; 基因丰度

全球温室气体中约有8%是由N2O组成的[1], 由于广泛使用合成氮肥, 农业成为全球N2O排放的主要来源, 农业源温室气体排放量占全球温室气体排放总量的11%, 已超过2020年的排放目标[2-3]。N2O是一种强效温室气体, 在大气中的停留时间长达114年之久, 以100年计, 单位质量的N2O增温潜势相当于CO2的298倍[4-5]。并且, 排放过多的N2O到大气中会造成臭氧层破坏, 当其浓度高到一定程度时还会引发酸雨, 进而影响人类活动。目前大气N2O浓度已经大幅上升, 从前工业化时代的270 mol·L-1增加到现在的324 mol·L-1[6]。虽然曾有研究表明N2O可以通过非生物氧化还原过程产生[7-8], 但其产生途径主要是由微生物利用土壤中的氮, 经过一系列反应产生的, 包含以下3个反应过程: 硝化、反硝化作用和硝酸盐异化还原[9]。土壤中超过2/3的N2O均来自于硝化与反硝化过程[10], 每个过程排放的相对贡献不仅取决于土壤特征(土壤结构、可用碳源、pH、微生物活性), 还与外部环境条件密切相关(温度、降雨量等)。N2O产生途径的复杂性以及空间和时间的不定性给减少土壤N2O排放带来了巨大的挑战[11]。

关于生物质炭的研究早在19世纪就已经开展, 最初是亚马逊河流域的印第安人在“Terra Preta”上种植农作物, 发现这种土壤可以提高粮食产量。经后面研究证实, 这种黑色土壤富含稳定的生物质炭, 是增加土壤肥力和粮食作物增产的主要原因[12-14]。随着人们对生物质炭的认识不断深入, 它也逐渐被应用在各个领域的研究当中。生物质炭是生物质在厌氧或无氧的密闭环境中高温热解(<700 ℃)生成的孔隙丰富、性质稳定、富含碳素并具有不同程度芳香化的固态物质[15-16]。生物质炭能将植物光合作用所固定的有机碳转化为稳定的惰性碳, 使其不被微生物迅速矿化, 从而实现固碳减排。因此, 生物质炭对缓解全球变暖意义重大。

向土壤中添加生物质炭是目前控制土壤N2O排放的重要措施, 首次关于生物质炭可减少土壤N2O排放的报道是温室试验, 研究发现, 向种有黄豆()的土壤使用生物质炭后, N2O排放可减少50%, 而对于腐殖生臂形草()草地, 减排效率则高达80%[17]。此后, 利用生物质炭减少土壤N2O排放成为研究的热点, 并且众多研究者们也根据试验结果提出了不同的假设来解释这一现象。比如, 生物质炭可加强土壤的通气性, 增大土壤pH, 有利于土壤固氮, 可与土壤中的有机碳和氮反应, 改良酶活性等。然而, 各种机理都存在一定的争议性。迄今为止, 关于生物质炭抑制农田N2O排放的报道及相关研究日渐增加, 由于试验环境、土壤特性和生物质炭的制作条件不尽相同, 因此得出的结论也存在很大的差异。并且众多研究中的关注点都是N2O排放, 少有针对N2O从土壤排放后的消耗进行深入研究。所以本研究探究了添加不同量生物质炭对N2O排放的影响, 同时通过检测不同处理中土壤反硝化功能基因、和的丰度以分析生物质炭的微生物作用机理。旨在研究生物质炭影响土壤N2O排放的基础上进一步探讨排放之后的N2O气体在生物质炭改良后的土壤中的微生物消耗机理, 以此从机理层面验证生物质炭对N2O减排的积极作用及其环境效益。

1 材料与方法

1.1 供试土壤与生物质炭

选用表层0~10 cm的潮褐土(中国科学院栾城农业生态系统试验站, 37°53′N, 114°41′E), 自然风干后挑选出土壤中的植物残渣和石头等杂物, 过2 mm筛后避光保存以备用。试验所用生物质炭购买自陕西亿鑫生物能源科技开发有限公司, 最高热解温度(HTT)为520 ℃, 粒径≤2 mm, 以便与土壤充分混匀。

土壤pH用电位法测定。称取10 g风干土样于50 mL高型烧杯中, 加入25 mL蒸馏水, 用玻璃棒搅拌1~2 min, 静置30 min, 然后用便携式pH计(METTLER TOLEDO)测定上层清液的pH。土壤总碳和总氮含量采用元素分析仪(vario MACRO cube; Elementar, Germany)测定。土壤有机质的测定采用重铬酸钾容量法-稀释热法。土壤容重采用环刀法测定。土壤孔隙度(t)计算如下[18]:

t=1-b/d(1)

式中:b为土壤容重,d为土壤比重。

根据上述方法, 本试验用土pH 为7.61, 土壤有机碳含量为9.3 g∙kg-1, 全碳和全氮分别为14.9 g∙kg-1和1.0 g∙kg-1, 碳氮比是9.30。土壤容重为1.30 g∙cm-3, 孔隙度为50.94%。

1.2 试验设计

本试验为室内厌氧培养(含氧量为0), 试验采用120 mL培养瓶, 所加土壤质量为10 g, 按照生物质炭与土壤质量比加入一定量生物质炭[不添加生物质炭(0BC)、添加1%生物质炭(1%BC)和添加5%生物质炭(5%BC)], 并将土壤含水率调节为20%, 每个处理设置3个重复。为防止小瓶漏气, 准备工作结束后盖上橡胶盖, 并用铝盖压紧密封。随后用真空抽气泵系统将每个小瓶中的空气置换为氦气, 制造厌氧环境。将小瓶内部气压与大气压平衡后, 使用注射器向培养瓶内注入1 mL的纯N2O气体(99.8%), 利用Robotized Incubation平台实时测定培养瓶内的N2O和N2浓度变化。为了比较灭菌与不灭菌之间的效果差异, 另外设置了两组灭菌试验, 灭菌温度为130 ℃, 时长为1 h, 其生物质炭添加量为0和5%, 其他条件和步骤均与不灭菌处理保持一致。试验共进行20 h, 试验结束后取各重复的土壤样品, 用于后续的测定。

1.3 土壤NH4+-N和NO3–-N测定

试验结束后, 准确称取每个重复的10.00 g土样, 加入50 mL 2 mol∙L-1KCl溶液浸提, 在震荡机上振荡1 h, 取出静置并过滤。浸提液中的NO3–-N使用紫外分光光度计(UV-2450, Shimadzu, Japan)测定, NH4+-N使用全自动化学分析仪(SmartChem 140, AMS Alliace, France)测定。

1.4 土壤微生物总DNA提取

为了探究生物质炭对土壤N2O消耗的影响及其微生物方面的影响机制, 分别提取了培养前的干土和培养后各处理的土壤样品的DNA, 提取方法按照FastDNA Spin Kit for Soil (MP biomedicals, USA)试剂盒的操作手册进行。提取后用微量紫外-可见光分光光度计(NanoDrop ND-2000c Technologies, Wilmington, DE)测定其浓度, 初步判断土壤微生物总DNA提取效果。随后将提取成功的土壤DNA保存至-20 ℃条件下, 待定量PCR扩增时再取出依次将浓度稀释至20 ng∙µL-1左右。

1.5 实时荧光定量PCR

本试验主要分析的基因是土壤中亚硝酸盐还原酶编码基因()和N2O还原酶编码基因(), 基因丰度以每种基因的拷贝数∙g-1(干土)表示。反硝化功能基因荧光定量PCR反应体系为20 µL, 包含10 µL 2 × TB Green Premix Ex Taq (Takara Biotech, Dalian, China)、各0.5 µL的上游引物和下游引物(10 µmol∙L-1)、8 µL超纯水和1 µL稀释的DNA模板。每种基因对应的引物分别是F1aCu:R3Cu ()[19], cd3aF:R3cd ()[20-21], nosZ- F:nosZ-1622R ()[20,22]。分别以含有亚硝酸盐还原酶基因()和一氧化二氮还原酶基因()的重组pGEM®-T裁体作为标准质粒, 然后计算出标准质粒的拷贝数, 按照10倍浓度梯度进行稀释, 并以108~102浓度梯度的标准质粒作为模板, 同时设置3个阴性对照, 和DNA模板同时在荧光定量PCR仪(CFX Connect™, Bio-Rad, USA)进行定量PCR扩增。扩增程序为: 95 ℃预变性2 min, 95 ℃变性30 s, 57 ℃()、56.8 ℃()、59 ℃()退火40 s, 72 ℃延伸30 s, 40个循环。

1.6 数据处理与分析

所有数据均使用EXCEL 2016和IBM SPSS Statistics 19.0 (SPSS Inc., USA)进行处理与分析, 在SPSS中采用单因素方差分析, 处理间差异用Duncan法进行多重比较, 相关性分析使用Pearson法。绘图所用软件为EXCEL 2016和OriginPro 9.0。

2 结果与分析

2.1 N2O和N2浓度变化

在厌氧条件下经过20 h培养后, 灭菌处理后的土壤中N2O浓度基本保持不变, 显著高于未经灭菌的土壤(图1), 表明微生物在N2O和N2的转换过程充当重要角色。添加生物质炭时, N2O浓度的下降速率和N2的生成速率大于0BC处理, 而且在室内培养20 h后, 添加1%和5%生物质炭处理的N2O浓度由最初的近200 µmol∙L-1基本降为零, 表明生物质炭可以促进土壤N2O消耗过程。在试验末1%和5%生物质炭处理的N2浓度稍高于0BC处理, 不过3个处理间的差异不大。由图1c可知, N2/(N2O+N2)及N2O/ (N2O+N2)变化趋势基本一致, 意味着在本厌氧试验中, 注入的N2O主要是被微生物通过反硝化过程转化为N2。并且随着培养时间的延长, 不同处理之间的差异也逐渐变大。虽然灭菌处理后N2浓度仍有小幅度上升, 这可能是土壤及土壤与生物质炭的混合物中存在某些化学还原过程, 将少量的N2O还原成了N2。

图1 厌氧条件下添加生物质炭对土壤N2O(a)、N2(b)浓度及其所占比例(c)的影响[图c中, 实线为N2/(N2O+N2)的比值, 虚线为N2O/(N2O+N2)的比值]

0BC: 0生物质炭处理; 1%BC: 1%生物质炭处理; 5%BC: 5%生物质炭处理; 0BCS: 0生物质炭+高压蒸汽灭菌处理; 5%BCS: 5%生物质炭+高压蒸汽灭菌处理。0BC: 0 biochar application; 1%BC: 1% biochar application; 5%BC: 5% biochar application; 0BCS: 0 biochar application and autoclaving; 5%BCS: 5% biochar application and autoclaving.

2.2 土壤NH4+-N和NO3–-N含量变化

与试验初始含量相比, 所有处理的土壤NH4+-N含量都显著升高, 由最初的8.12 mg·kg-1左右升至19.69 mg·kg-1(0BC)、18.72 mg·kg-1(1%BC)和13.97 mg·kg-1(5%BC), 而NO3–-N含量则由6.11 mg·kg-1降至0.1 mg·kg-1左右(表1)。很明显, 此时占主导地位的是反硝化过程, 试验末反硝化过程的底物NO3–-N基本被完全消耗了。随着生物质炭添加量的增加, 试验末NH4+-N含量呈现由高到低的趋势, NO3–-N含量大幅度下降, 这可能是在厌氧条件下, 反硝化作用强于硝化过程, 但是生物质炭本身经过高温裂解后可能含有某些有毒有机物, 会抑制微生物生长繁殖, 从而减弱反硝化作用, 使得最后1%和5%生物质炭处理的NO3–-N含量稍高于0BC处理。此外, 土壤矿化作用及硝酸盐异化还原成铵(DNRA)的过程也会分别增加NH4+-N和减少NO3–-N含量。

表1 厌氧条件下添加生物质炭对试验前和试验末土壤NH4+-N和NO3–-N含量的影响

Table 1 Impact of biochar on initial and final soil NH4+-N and NO3–-N contents under anaerobic condition mg∙kg-1

0BC: 0生物质炭处理; 1%BC: 1%生物质炭处理; 5%BC: 5%生物质炭处理。数据为3次重复的平均值加减标准误。同一行内不同字母表示在0.05水平下差异显著。0BC: 0 biochar application; 1%BC: 1% biochar application; 5%BC: 5% biochar application. Values are means ± S.E. (= 3). Different letters within a row indicate significant differences at0.05.

2.3 反硝化功能基因丰度

培养前后每克干土中反硝化功能基因的拷贝数变化如图2所示。培养试验开始前, 3种反硝化功能基因丰度(基因拷贝数∙g-1)分别为5.59×107()、2.65×108()和4.82×107()。试验开始时基因丰度比及大一个数量级, 试验前后土壤中的基因丰度变化也最为显著。经过20 h厌氧培养后, 0、1%和5%生物质炭处理的基因丰度变化不大, 与0BC处理相比, 1%BC和5%BC处理的基因丰度稍有下降, 但是统计学上变化并不显著。而试验前后及基因丰度均显著提高一倍以上, 其中以添加1%生物质炭时基因丰度变化最明显。在1%BC处理中,基因丰度由最初的5.59×107基因拷贝数∙g-1提高至6.24×107基因拷贝数∙g-1,基因丰度则由2.65×108基因拷贝数∙g-1升至7.43×108拷贝数∙g-1,基因丰度提高了一个数量级, 由4.82×107基因拷贝数∙g-1升至1.50×108基因拷贝数∙g-1。

图2 厌氧条件下添加生物质炭对土壤反硝化功能基因丰度的影响

dry soil: 培养前土壤; 0BC: 0生物质炭处理; 1%BC: 1%生物质炭处理; 5%BC: 5%生物质炭处理。不同字母表示在<0.05水平下差异显著。dry soil: soil before the experiment; 0BC: 0 biochar application; 1%BC: 1% biochar application; 5%BC: 5% biochar application. Different letters indicate significant differences at0.05.

为进一步了解试验前后反硝化细菌与N2O浓度之间的关系, 对所有处理中的基因丰度与N2O浓度数据汇总并进行了相关性分析, 汇总结果如图3所示。字母“b”表示试验前, 字母“a”表示试验后。试验初期由于注入了1 mL 99.8%的N2O气体, 培养瓶内N2O浓度较大, 在试验结束时, 3个生物质炭处理的N2O浓度都明显下降, 具体趋势如图1a所示。而随着N2O浓度的下降各种反硝化菌基因丰度也出现不同程度的上升, 其中基因丰度变化最为明显。相关性分析显示,基因丰度和基因丰度均与N2O浓度在0.01水平上显著相关, 但是与基因丰度之间无显著相关性。

3 讨论

亚硝酸盐还原酶(Nir)和氧化亚氮还原酶(Nos)是反硝化过程的关键酶, 其中亚硝酸盐还原酶共有两种类型: 一种是由基因编码的[23], 还有一种则是由基因编码的[24],和也是反硝化功能基因中被研究最多的基因[25]。由基因编码的氧化亚氮还原酶是反硝化作用的最后一步, 将N2O催化还原为N2。因为在土壤pH≤6.1时, 微生物很难产生氧化亚氮还原酶[26], 且对O2十分敏感[27-28]。故本试验所用土壤pH为7.61, 培养环境为厌氧(充满氦气), 排除pH和O2对生物质炭作用的影响。

图3 厌氧条件下土壤反硝化N2O浓度和反硝化功能基因丰度关系图

空心符号表示试验前(a)的基因丰度, 实心符号表示试验后(b)的基因丰度。Hollow symbols indicate gene abundance before the trail (a), filled symbols indicate gene abundance after the trial (b).

本试验结果显示向土壤中施加少量生物质炭可促进N2O向N2的转化过程, 增大和反硝化基因丰度。经过20 h厌氧培养后, 3种不同生物质炭处理的及基因拷贝数均显著提高一倍以上, 然而基因丰度稍有上升, 但是统计学上变化并不显著。在添加1%生物质炭处理中,基因丰度变化不明显,基因丰度则提高了一个数量级。与0BC处理相比, 添加生物质炭处理可抑制N2O浓度, 并且反硝化功能基因丰度(和)均高于0BC处理。除此之外, 生物质炭对N2O的抑制作用在很多学术报道中都有所体现[18,29-32]。Anderson等[33]研究表明, 向土壤中施加松木生物质炭后可增大反硝化菌(如)的数量; Chen等[34]发现在水稻()田里施加生物质炭同样可以促进的生长; 但是也有研究者提出添加生物质炭并不会影响基因丰度[35-36]。不过, 生物质炭对N2O的具体影响还取决于试验所处的环境及供试土壤和生物质炭类型, 试验条件有利于硝化过程的进行或者使用粪肥生产的生物质炭则对N2O排放无抑制作用。在本厌氧培养试验中, 向土壤中添加生物质炭可促进N2O转化为N2, 显著提高和基因型反硝化细菌的丰度, 但是却降低了基因丰度, 虽然影响并不显著。这说明生物质炭主要是通过提高基因丰度促进完全反硝化过程, 通过微生物消耗途径使得注入培养瓶内的N2O被还原成N2。有研究表明, 在堆肥过程中添加生物质炭可显著增大和基因拷贝数, 降低基因丰度从而抑制N2O排放, 且在控制N2O排放中起关键作用的是和基因[37], 这与本试验相关性分析得出的结果相吻合,基因丰度和基因丰度均与N2O浓度在0.01水平上显著相关。在试验后期, 随着N2O浓度的降低,基因丰度和基因丰度显著升高, 以基因丰度变化最为明显。此外, 在砂土(Tenosol)[38]和粉黏壤土[39]中施加生物质炭也可提高基因丰度。Castaldi等[40]和Xu等[41]通过定量研究反硝化酶活性(DEA), 指出生物质炭可大幅度提升DEA速率。Cayuela等[42]通过研究15种农田土壤发现与本试验相近的结果, 即添加生物质炭后每种土壤的N2O/(N2O+N2)比值都有所下降; 作者提出生物质炭在增大基因丰度的同时, 还可以作为传递电子的介质, 有利于电子与反硝化微生物之间的传递, 促进N2O还原为N2。不过, 生物质炭对N2O的抑制机理和整个微生物过程还不是很明确, 因为它本身会释放出多环芳烃(PAHs)等有害物质, 抑制硝化和反硝化过程[43-44]。但是Alburquerque等[45]研究结果却又与此相悖, 作者提出高浓度的PAHs(萘、菲和芘等)并不会减弱生物质炭对N2O排放的抑制作用。

在前人的研究中就生物质炭的作用机理也做出了很多假设: 降低反硝化速率[18,46], 促进完全反硝化[41,47], 或二者结合[48-49]。降低反硝化速率主要是因为生物质炭可改善土壤通气性或减少无机氮等底物, 从而抑制反硝化过程。本试验结果与van Zwieten等[5]和Harter等[47]在石灰性土壤中施加生物质炭的研究一致, 作者提出的机理主要是因为生物质炭提高了土壤pH进而增大了还原N2O的细菌活性和基因表达, 促进完全反硝化。但是生物质炭增大土壤pH从而降低N2O排放并不是唯一机理[50]。有研究发现, pH增大后甚至还可能促进硝化作用和N2O排放[51]。Shan等[52]分别向酸性土和碱性土中加入生物质炭, 发现两种土壤的pH都有所上升, 且增大了碱性土中的基因丰度, 但是对酸性土中的基因并无影响。生物质炭含有的易分解有机碳(如可溶性有机碳等)含量较高时, 也可增强基因型的微生物活性, 促进N2O生物消耗过程[53]。向土壤中添加生物质炭后, 它本身含有的碳元素也会影响土著微生物群落结构。而且基因型微生物对外源加入的碳十分敏感, 极易受到影响[54]。值得一提的是, 本研究中添加1%生物质炭处理对功能基因的影响最为明显, 而添加5%生物质炭处理与不添加对照间无显著差异。这可能与生物质炭含有的某些化学物质有关: 低添加量时, 可促进反硝化菌生长; 高剂量时则表现出一定的毒物效应, 抑制反硝化基因表达。这种双向反应也被称为hormesis效应[55], 并且生物质炭对微生物的影响并不是简单的线性关系, 而存在一个最优剂量[56]。在本试验中, 生物质炭的最佳添加量为土壤质量的1%。

4 结论

在厌氧培养试验中, 褐土中添加生物质炭显著提高了和基因型反硝化细菌的丰度, 促进N2O彻底还原成N2。生物质炭对于N2O主要影响机理是增大了还原氧化亚氮的细菌活性, 促进完全反硝化。与添加1%生物质炭相比, 添加5%生物质炭对N2O的影响并不明显, 原因可能是生物质炭含有的某些化学物质在高浓度时具有一定的生物毒性。

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Biochar’s effect on soil N2O consumption and the microbial mechanism*

HE Chaohui1,2,3, DONG Wenxu2, HU Chunsheng2**, LI Jiazhen2,3

(1. Sino-Danish College of University of Chinese Academy of Sciences, Beijing 100049, China; 2. Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences / Hebei Laboratory of Soil Ecology / Key Laboratory of Agricultural Water Resources, Chinese Academy of Sciences, Shijiazhuang050022, China; 3. University of Chinese Academy of Sciences, Beijing 100049, China)

Biochar is a promising material for mitigating greenhouse gas emissions. In addition to carbon sequestration, it has positive effect on the ozone-depleting gas nitrous oxide (N2O), which is with long residence time and strong warming potential. In this research effort, an anaerobic incubation experiment was conducted. Three treatments with different biochar application rates were set, taking account of biochar to soil ratio (/): 0 (0BC), 1% (1%BC) and 5% (5%BC). Soil gravimetric water content was controlled at 20%. According to the robotized incubation platform providing real-time determination of N2O and N2concentrations and soil denitrification functional gene abundance measurement, we analyzed the impact of biochar on N2O consumption and biological mechanisms. The main results indicated that after a 20-hour anaerobic incubation, the denitrification functional gene abundance of 0BC treatment was 6.80×107(), 5.59×108(), 1.22×108() gene copies per gram soil, respectively. Compared with 0BC treatment, thegene abundance of 1%BC treatment increased from the initial 2.65×108to 7.43×108gene copies per gram soil, while, thegene abundance increased by an order of magnitude from 4.82×107to 1.50×108gene copies per gram soil. However, there was no significant change ingene abundance. And the denitrification functional gene abundance of 5%BC treatment did not show marked variations. In conclusion, the N2/(N2O+N2) ratio of treatments with biochar application was clearly higher than 0BC treatment. The results of correlation analysis showed thatandgene abundance was significantly correlated with the N2O concentration at 0.01 level, and the abundance ofandgenes all increased as N2O concentration declined at the end of the experiment. Therefore, in the present trial, a 1% biochar addition significantly increased the abundance of denitrifying bacteria withandgenotypes and N2/(N2O+N2) ratio, and promoted the complete reduction of N2O to N2. The main mechanism of the biochar effect on N2O emission was the enhanced reduction activities and gene expression of-containing microorganisms, resulting in complete denitrification.

Biochar; Greenhouse gases emission reduction; Soil microbe; N2O consumption; Denitrification; Gene abundance

, E-mail: cshu@sjziam.ac.cn

Mar. 8, 2019;

Apr. 20, 2019

S154.1; S154.36

2096-6237(2019)09-1301-08

10.13930/j.cnki.cjea.190175

* 国家重点研发计划项目(2017YFD0800601)和中国科学院重点项目(ZDRW-ZS-2016-5-1)资助

胡春胜, 主要研究方向为农田生态系统碳、氮、水循环及土壤生态过程。E-mail: cshu@sjziam.ac.cn 贺超卉, 主要研究方向为土壤氮循环过程。E-mail: Chaohui_He@outlook.com

2019-03-08

2019-04-20

* This study was supported by the National Key Research and Development Project of China (2017YFD0800601) and the Key Program of Chinese Academy of Sciences (ZDRW-ZS-2016-5-1).

贺超卉, 董文旭, 胡春胜, 李佳珍. 生物质炭对土壤N2O消耗的影响及其微生物影响机理[J]. 中国生态农业学报(中英文), 2019, 27(9): 1301-1308

HE C H, DONG W X, HU C S, LI J Z.Biochar’s effect on soil N2O consumption and the microbial mechanism[J]. Chinese Journal of Eco-Agriculture, 2019, 27(9): 1301-1308