雷宏軍,劉 歡,臧 明,潘紅衛(wèi),陳德立

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曝氣灌溉條件下土壤N2O排放特征及影響因子分析

雷宏軍1*,劉 歡1,臧 明1,潘紅衛(wèi)1,陳德立2

(1.華北水利水電大學水利學院,河南 鄭州 450046；2.墨爾本大學糧食與土地資源學院,澳大利亞 維多利亞 3010)

為了明確曝氣灌溉下土壤N2O排放特征及主要影響因子,實驗設(shè)置了2個灌水量(70%和90%田間持水量)和2個增氧水平(5,40mg/L),采用靜態(tài)箱法和qPCR技術(shù)對土壤N2O通量及土壤關(guān)鍵功能基因進行測定,研究不同灌水量和增氧水平對土壤充水孔隙度、溶解氧、氧化還原電位(h)、礦質(zhì)氮及氨氧化古菌(AOA)、氨氧化細菌(AOB)和反硝化基因(和)的影響.結(jié)果表明:培養(yǎng)過程中,各處理N2O排放通量均呈現(xiàn)先增加后降低的趨勢,于灌溉后1d達到峰值;曝氣量和灌水量的增加可顯著增加土壤N2O的排放通量和排放峰值.灌溉造成土壤含水量增加的同時,降低了土壤溶解氧和h;曝氣可提高土壤溶解氧和h,改善土壤通氣性(<0.05),而對土壤充水孔隙度無顯著影響.土壤充水孔隙度、h、NO3--N含量是曝氣灌溉下驅(qū)動土壤N2O排放的主要理化因子.曝氣顯著增加了AOA的基因拷貝數(shù), 且N2O排放與AOA的基因拷貝數(shù)呈顯著正相關(guān)關(guān)系(<0.05).研究結(jié)果為進一步明確曝氣灌溉對土壤N2O排放的影響機制和曝氣灌溉模式下農(nóng)田N2O排放管理提供支撐.

曝氣灌溉；N2O排放；溶解氧；氧化還原電位；基因；拷貝數(shù)；影響因子

氧化亞氮(N2O)是全球氣候變暖的主要元兇,其增溫潛力是CO2的300倍左右[1],持續(xù)破壞大氣臭氧層[2].農(nóng)業(yè)土壤是全球N2O排放的主要來源,占人為N2O排放量的84%[3].

土壤N2O排放的影響因素是多種環(huán)境因子的相互疊加[4].土壤中CO2、CH4和N2O排放主要受到基因和細胞水平上的微生物途徑驅(qū)動[5].影響N2O排放的微生物群可分為2類:參與硝化反應的氨氧化古菌(AOA)和氨氧化細菌(AOB);參與異養(yǎng)反硝化微生物的關(guān)鍵功能基因、、和等[6]. Han等[7]研究了不同灌水量下溫室番茄地土壤N2O排放和AOA、AOB、反硝化細菌基因(亞硝酸還原酶/和NO還原酶)之間的關(guān)聯(lián)關(guān)系, 結(jié)果表明不同灌溉方式僅影響AOA的拷貝數(shù).土壤非生物因子不僅可通過調(diào)節(jié)微生物豐度和活性間接地影響N2O的排放,而且可通過影響氣體擴散速率直接影響N2O的排放[8].G?dde等[9]研究表明土壤水分和溫度可掩蓋其他土壤因子對N2O排放的影響,且25℃的標準化土壤溫度可有效降低土壤溫度對N2O排放的掩蓋效應.土壤的礦質(zhì)氮濃度亦會影響土壤N2O的產(chǎn)生和排放.Wang等[10]研究了硝酸鹽的添加對土壤N2O排放的影響,結(jié)果表明N2O排放量隨著NO3--N添加濃度的增加而增加,且10cm土層的N2O濃度最高.

曝氣灌溉(Aerated irrigation, AI)是通過滴灌或地下滴灌系統(tǒng)將微納米氣泡水輸送至作物根區(qū)的新型高效節(jié)水灌溉技術(shù)[11-12],已廣泛應用于設(shè)施農(nóng)業(yè)[13-14].

曝氣灌溉改變著土壤的水分分布和通氣狀況,可有效降低作物根區(qū)土壤的緊實度,維持良好的土壤充氣孔隙度[15].曝氣灌溉可提高根區(qū)土壤pH值,為微生物的生長和繁殖營造良好的化學環(huán)境,提高土壤酶活性[16].曝氣灌溉可有效緩解灌溉造成的根區(qū)土壤缺氧脅迫,促進土壤中好氧微生物的活動和繁殖[17].李元等[18]研究了曝氣灌溉對大棚甜瓜土壤細菌、真菌和放線菌數(shù)量的影響,結(jié)果表明土壤中細菌和放線菌的數(shù)量隨著土壤加氣量和加氣頻率的增加而顯著增加.曝氣灌溉改變著土壤的物理、化學和生物學因子,勢必會影響土壤的硝化和反硝化過程,進而影響著土壤N2O的排放.目前關(guān)于曝氣灌溉條件下土壤N2O排放量及其影響因子的研究較少.

為了明確曝氣灌溉對土壤N2O排放的影響,實驗中于設(shè)施菜地采集原狀土進行室內(nèi)恒溫培養(yǎng),通過對N2O排放通量及相關(guān)物理、化學和生物學因子的監(jiān)測,擬明確曝氣灌溉下土壤N2O排放特征,并分析N2O排放與土壤物理、化學和生物學因子之間的相關(guān)關(guān)系,辨識曝氣灌溉下土壤N2O排放的主要影響因子.

1 材料和方法

1.1 實驗概況

實驗于鄭州設(shè)施菜地采集原狀土,土柱直徑為30cm,高度為40cm,在華北水利水電大學農(nóng)業(yè)高效用水實驗室(34°47′23″N, 113°47′41″E)開展室內(nèi)培養(yǎng)實驗.供試土壤的砂粒(0.02~2mm)、粉粒(0.002~ 0.02mm)和黏粒(<0.002mm)質(zhì)量分數(shù)分別為42.87%、35.26%和21.87%,為壤質(zhì)黏土.土壤的田間持水量為36.64%,土壤容重1.20g/cm3, NO3-- N5.68mg/kg, NH4+-N3.36mg/kg,速效鉀3.42mg/kg,速效磷9.98mg/kg,有機質(zhì)21.54g/kg, pH值6.30.

1.2 實驗設(shè)計

實驗中采用微納米氣泡水制備技術(shù)[19]進行曝氣, 設(shè)置了2個增氧水平(40,5mg/L,記為DA和DC)和2個灌水量(灌溉至90%和70%田間持水量,記為W1和W2),共4個處理,分別為DAW1、DAW2、DCW1和DCW2,每個處理4次重復.供試土壤初始體積含水率為22.17%,經(jīng)預備實驗計算,W1和W2分別為2.0, 1.0L.實驗中取每個土柱上層10cm原狀土進行拌肥,稱量3.397g NH4NO3(相當于基肥用量180kg N/hm2)溶于100mL去離子水中,均勻噴灑于土壤表面,靜置15min,拌勻后回填于土柱至原容重.實驗中采氣與采土土柱分開,于灌溉后的0,0.25,0.5,1,2,4,6,8d進行氣樣采集.實驗中土壤溫度控制為25℃.

實驗中采用的滴頭為壓力補償式滴頭(NETAFIM,以色列奈特菲姆灌溉公司), 額定流量為2.2L/h,埋深為5cm.滴灌毛管從距土柱上沿向下2cm處打孔穿出,用膠密封.首部供水壓力設(shè)置為0.10MPa.灌溉裝置如圖1所示.

圖1 灌溉裝置示意Fig.1 Schematic diagram of irrigation device

1.循環(huán)曝氣裝置; 2.常規(guī)滴灌供水裝置; 3.儲水箱; 4.閘閥1; 5.水泵1; 6.壓力表1; 7.氧氣罐; 8.減壓閥; 9.水泵2; 10.文丘里; 11.承壓水罐; 12.排氣閥; 13.壓力控制器; 14.溶解氧控制器; 15.水表; 16.壓力表2; 17.閘閥2; 18.閘閥3; 19.壓力補償式滴頭; 20.土柱; 21.供水毛管; 22.供水干管

1.3 樣品采集及指標測定

采氣靜態(tài)箱為圓柱體,直徑為30cm,高為10cm.于靜態(tài)箱側(cè)壁中部打孔,向內(nèi)延伸裝入平衡軟管,用于平衡箱內(nèi)壓強,直徑為4mm,長度為10cm.采氣時,分別于蓋上靜態(tài)箱后的0,10,20,30min,用50mL帶三通閥的注射器采集30mL箱內(nèi)氣體,注入12mL的真空氣瓶中,2周內(nèi)完成測量.

實驗前對土柱側(cè)壁進行壓實、灌漿和凡士林澆筑,以防止灌溉過程中灌溉水沿側(cè)壁滲漏.采氣的同時監(jiān)測土柱0~10cm的土壤含水率、溶解氧和氧化還原電位(h).采用光纖式溶氧測量儀連接溶解氧敏感探針(PyroScience GmbH,德國Aachen公司)測定土壤溶解氧含量;通過h電極(IQ150,美國SPECTRUM公司)監(jiān)測土壤h;采用土壤水分速測儀監(jiān)測(TRIME-T3/T3C,德國TRIME-FM公司) 0~10cm的土壤平均含水率.采氣的同時進行破壞性取土,測定NO3--N和NH4+-N含量.土壤NO3--N和NH4+-N以2mol/L KCl為提取劑,利用紫外分光光度計測定;土壤速效鉀的測定以乙酸銨為提取劑,采用火焰光度法測定;速效磷的測定以碳酸氫鈉為提取劑,采用鉬銻抗比色法測定;土壤有機質(zhì)采用重鉻酸鉀容量法測定[20].

1.4 相關(guān)指標計算

1.4.1 N2O排放通量計算,利用氣相色譜儀(GC- 2010PLUS,日本島津有限公司)測定氣體樣品中的N2O濃度,N2O排放通量[21]的計算如式(1)所示.

=××273/(273+) ×(/0)×d/d(1)

式中:為標準氣體的濃度,g/cm3,為1.96g/cm3;為土面距離靜態(tài)箱頂部距離,m,為0.15m;為采集N2O時靜態(tài)箱內(nèi)的溫度,℃;為采集N2O時靜態(tài)箱內(nèi)的壓強,mm Hg;0為標準大氣壓,mm Hg;為測定的氣體濃度,mg/L; d/d為mg/(m3·h);為N2O排放通量,mg/(m3·h).

1.4.2 N2O排放總量計算 N2O排放總量的計算如式(2)[7]所示.

式中:為N2O排放通量,mg/(m3·h);為第次測量的時間,h;(t+1-t)為2次測量之間的時間間隔,h.

1.4.3 充水孔隙度 土壤充水孔隙度(WFPS)是反映土壤水分狀況的重要指標,其計算公式如式(3)所示.

WFPS=θ/(1-/2.65) (3)

式中:θ為土壤的體積含水率,%;為土壤容重,g/cm3.

1.5 DNA提取及qPCR分析

實驗中于灌溉后1d采集0~10cm的土壤,混勻后保存于-80℃的冰箱中,用于DNA提取和qPCR分析.土壤樣品中微生物DNA總量提取方法參照Chen等[22]提供的方法.利用核酸測定儀(Nanodrop ND- 1000UV-Vis分光光度計)測定DNA濃度.PCR引物序列信息列于表1.AOA和AOB實時定量PCR擴增條件均為:95℃預變性2min,95℃ 5s,55℃ 30s, 72℃ 10s,40個循環(huán); 95℃ 15s,60℃ 15s,95℃ 15s.土壤反硝化基因和實時定量PCR擴增條件均為:95℃預變性30s,95℃ 5s,60℃ 30s,72℃10s, 40個循環(huán); 95℃ 15s,60℃ 15s,95℃ 15s.

表1 PCR引物序列信息

1.6 數(shù)據(jù)分析

采用EXCEL 2013軟件進行數(shù)據(jù)分析;采用SPSS 22統(tǒng)計軟件進行顯著性和相關(guān)性分析.顯著性分析采用Fisher LSD方法,檢驗水平為0.05.

2 結(jié)果與分析

2.1 曝氣灌溉對土壤N2O排放的影響

如圖2所示,實驗中各處理N2O排放通量均呈現(xiàn)先增加后降低的變化趨勢,于灌溉后1d出現(xiàn)排放峰值,之后下降,于灌溉后4d趨于穩(wěn)定,且呈現(xiàn)較低排放水平.在培養(yǎng)期內(nèi),各處理N2O排放通量的關(guān)系:DAW1>DCW1> DAW2>DCW2.

圖2 曝氣灌溉下土壤N2O排放特征

DA為曝氣灌溉;DC為常規(guī)滴灌;W1為高濕度處理;W2為低濕度處理,下同

由表2可知,曝氣可顯著增加土壤N2O的排放通量、排放峰值和排放總量(<0.05).與常規(guī)滴灌相比,W1和W2水量下曝氣處理的土壤N2O排放通量、排放峰值、排放總量分別增加了41.08%和58.70%、158.79%和167.30%、127.46%和97.27%.

表2 不同處理下土壤N2O排放通量、峰值及排放總量

注:同列不同小寫字母表示差異性顯著(<0.05).

灌水量的增加可顯著增加N2O排放通量和排放峰值(<0.05).另外,灌水量的增加可顯著提高曝氣條件下的N2O排放總量(<0.05),而對常規(guī)滴灌的N2O排放總量無顯著影響(>0.05).曝氣條件下高濕度處理(W1)的N2O排放總量較低濕度處理(W2)增加了73.46%.

2.2 曝氣灌溉下土壤N2O排放的影響因子

各處理的充水孔隙度隨著培養(yǎng)時間的增加而逐漸降低(圖3a).曝氣處理的土壤溶解氧呈現(xiàn)“N”型變化,于灌水后0.5d降到最低,之后逐漸上升,于灌水后2d逐漸趨于穩(wěn)定;常規(guī)滴灌的土壤溶解氧呈現(xiàn)先降低后增加的變化趨勢,于灌溉后0.5d達到最低,之后逐漸上升,于灌溉后4d逐漸趨于穩(wěn)定(圖3b).培養(yǎng)過程中土壤h的變化與常規(guī)滴灌條件下土壤溶解氧的變化趨勢一致,但于灌水后1d達到最低值(圖3c).培養(yǎng)期內(nèi)各處理土壤溶解氧含量和h的關(guān)系均為DAW2>DAW1>DCW2>DCW1.由于灌水和曝氣的差異造成土壤氮素的遷移和轉(zhuǎn)化.在培養(yǎng)過程中,土壤的NO3--N和NH4+-N含量均呈現(xiàn)逐漸降低的變化趨勢(圖3d和圖3e).

由表3可知,曝氣可顯著提高土壤溶解氧和h(<0.05),改善土壤通氣性, 而對土壤充水孔隙度無顯著影響(>0.05).W1水量下,曝氣條件的土壤溶解氧和h均值較對照分別提高了7.79%和4.72%;W2水量下,曝氣條件的土壤溶解氧和h均值較對照分別提高了7.52%和4.00%.

灌水量的增加可顯著增加充水孔隙度,降低土壤溶解氧含量(<0.05).曝氣條件下,W1水量的充水孔隙度較W2增加了14.88%,而溶解氧降低了3.23%.常規(guī)滴灌下, W1水量的充水孔隙度較W2增加了14.33%,而溶解氧降低了3.47%.

DO為土壤溶解氧

表3 影響土壤N2O排放的物理化學因子平均值

注:同列不同小寫字母表示差異性顯著(<0.05).

曝氣可增加土壤NO3--N含量(<0.05),而對土壤NH4+-N含量無顯著性影響(>0.05).低濕度處理的土壤NO3--N含量顯著高于高濕度處理(<0.05).

由表4可知,曝氣可顯著增加高濕度處理下土壤拷貝數(shù),減少低濕度處理下反硝化基因nosZ拷貝數(shù)(<0.05).灌水量的增加可增加古菌拷貝數(shù)(<0.05).曝氣條件下,W1水量的拷貝數(shù)較W2增加了21.21%;常規(guī)滴灌條件下,W1水量的土壤古菌拷貝數(shù)較W2增加了20.95%.

表4 培養(yǎng)1d的土壤硝化與反硝化基因拷貝數(shù)

注:同列不同小寫字母表示差異性顯著(<0.05).

2.3 曝氣灌溉下土壤N2O排放與各影響因子間的關(guān)系

由表5可知,高濕度處理下,土壤充水孔隙度、NO3--N含量和古菌拷貝數(shù)均與N2O排放呈顯著的正相關(guān)關(guān)系(<0.05),而h與N2O排放呈極顯著的負相關(guān)關(guān)系(<0.01).低濕度處理下,土壤充水孔隙度和古菌拷貝數(shù)與N2O排放之間分別呈極顯著正相關(guān)關(guān)系(<0.01)和顯著正相關(guān)關(guān)系(<0.05),而土壤h與N2O排放之間呈顯著的負相關(guān)關(guān)系(<0.05).綜上所述,實驗中土壤充水孔隙度、h、NO3--N含量和AOA為曝氣灌溉下N2O排放的主要影響因子.

表5 曝氣灌溉下N2O排放與各影響因子間的相關(guān)系數(shù)

注:*表示在<0.05水平顯著相關(guān),**表示在<0.01水平顯著相關(guān).

3 討論

土壤從干燥或適當干燥的環(huán)境變成濕潤的環(huán)境會增加土壤碳氮的可利用性,造成土壤微生物量劇增[25].土壤微生物的迅速繁殖,促進土壤N2O的產(chǎn)生和排放[5].實驗中灌溉后的土壤平均質(zhì)量含水率達32.72%(初始平均質(zhì)量含水率為22.17%),增加了土壤微生物數(shù)量,促進了土壤N2O的排放.灌溉會造成土壤含水量劇增,促進N2O排放峰值的出現(xiàn)[26],故灌溉后的N2O排放劇烈增加,并于灌水后1d出現(xiàn)N2O排放峰值,與W?odarczyk等[25]研究結(jié)果相似.有研究表明,當土壤WFPS在35%~60%時,N2O排放主要來源于硝化反應,當WFPS超過70%時,土壤N2O排放主要來源于反硝化反應[27-28].實驗中高濕度處理的平均WFPS在60%以上,低濕度處理的平均WFPS達53%,故從土壤水分含量角度,高濕度處理下造成N2O排放可能以反硝化反應為主,而低濕度處理下以硝化反應為主.

土壤通氣狀況從2個方面影響著土壤N2O的排放:一方面是土壤的氧氣含量影響著硝化和反硝化過程,從而制約了土壤N2O的產(chǎn)生數(shù)量;另一方面土壤孔隙為N2O排放至空氣提供通道,通氣性好壞決定了土壤N2O的排放數(shù)量[29].常規(guī)灌溉下由于水分的入滲驅(qū)替了土壤孔隙中的空氣而造成土壤厭氧環(huán)境,導致土壤N2O產(chǎn)生主要來源于反硝化作用[30].曝氣灌溉不僅為作物根系土壤提供充足的水分,還可有效彌補常規(guī)灌溉造成的土壤氧氣逃逸[14],保持良好的氣體交換通道.曝氣激發(fā)了土壤好氧微生物的繁殖潛力,促進了土壤硝化作用,并提供了氣體擴散的通道,增加了土壤N2O的排放.

土壤氧化還原狀況和土壤水分含量密切相關(guān),影響著土壤N2O的排放.Liu等[31]研究了水田淹水-落干過程中h對N2O排放的影響,結(jié)果表明稻田土壤中N2O排放與土壤h顯著相關(guān).侯會靜等[32]研究表明土壤N2O排放通量的峰值出現(xiàn)在土壤h值為207.5~275.2mV,而h值低于120mV或者高于300mV時,土壤N2O排放通量處于較低水平.本研究中N2O排放峰值亦出現(xiàn)在該h范圍,且在h值高于300mV時,N2O排放通量較低.有研究表明,當h在+300~ +400mV時,硝化作用是控制氮素轉(zhuǎn)化反應的主要過程,反硝化作用相對較弱;當h介于+200mV和+300mV間時,反硝化作用出現(xiàn)且0mV時N2O排放量達到最高[33].研究中在灌溉后0.25~2d內(nèi)土壤h均在＋300mV以下,開始出現(xiàn)反硝化作用,而其他培養(yǎng)時間段內(nèi)土壤h均在+300mV以上,以硝化反應為主.

土壤NO3--N易溶于水,且易隨水分的入滲而遷移,而土壤NH4+-N不易在土壤中流失[34],故實驗中低濕度處理的NO3--N含量顯著高于高濕度處理,且隨著培養(yǎng)時間的增加呈現(xiàn)降低的變化趨勢.土壤NH4+-N是硝化微生物的作用底物,在各種氧化酶的作用下生成NO2--N和NO3--N[35].土壤NO3--N是反硝化作用的直接底物,缺氧條件下NO3--N被逐步還原為N2O和N2,底物供應充足可能直接促進反硝化作用強度[36].實驗中曝氣處理向土壤提供了充足的有效氧含量,在好氧微生物作用下,土壤NH4+-N逐步生成NO2--N和NO3--N,故土壤NH4+-N含量呈現(xiàn)降低的趨勢,且高濕度處理和低濕度處理下N2O排放與NO3--N含量呈正相關(guān)關(guān)系,表明曝氣條件下N2O排放以硝化反應為主.

微生物是驅(qū)動土壤氮元素生物地球化學循環(huán)的關(guān)鍵驅(qū)動力.灌溉不僅引起土壤含水量和Eh的變化,還可引起微生物群落結(jié)構(gòu)發(fā)生變化[37].當土壤pH值在4.9~7.5時,有利于AOA基因拷貝數(shù)的增加和活性的表達,并且其拷貝數(shù)和表達活性隨pH值的降低而升高[38].研究表明,AOA是水稻根際土壤的優(yōu)勢微生物,且AOA比AOB更易受土壤氧氣含量的影響[39].實驗中供試土樣的pH值為6.30,為弱酸性土壤,有利于AOA的生存和繁殖.另外,土壤氧氣含量的增加激發(fā)了AOA的繁殖潛力,故AOA的基因拷貝數(shù)顯著高于AOB,且AOA基因拷貝數(shù)與N2O排放通量呈極顯著正相關(guān)關(guān)系(<0.01),表明曝氣灌溉條件下土壤以硝化反應為主,與Han等[7]研究結(jié)果相似.曝氣灌溉對土壤硝化和反硝化過程N2O產(chǎn)生的來源及貢獻分析對明確曝氣滴灌條件下N2O排放機制有重要意義,有待進一步研究.

4 結(jié)論

4.1 實驗中各處理N2O排放通量均呈現(xiàn)先增加后降低的趨勢,于灌溉后1d達到峰值,于灌溉后的4d趨于穩(wěn)定,且呈現(xiàn)較低排放水平.曝氣可顯著增加N2O的排放通量、排放峰值和排放總量.灌水量的增加可顯著增加N2O的排放通量和排放峰值.

4.2 灌溉造成土壤含水量增加的同時,降低了土壤溶解氧和h.曝氣可提高土壤溶解氧和h,改善土壤通氣性(<0.05),而對土壤的充水孔隙度無顯著影響(>0.05);低濕度處理的土壤NO3--N含量顯著高于高濕度處理(<0.05).

4.3 通過相關(guān)性分析,土壤充水孔隙度、h和NO3--N含量為曝氣灌溉下土壤N2O排放的主要理化因子.另外,AOA對曝氣灌溉下土壤N2O排放起著重要的作用.

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致謝：本研究得到“中國科學院亞熱帶農(nóng)業(yè)生態(tài)研究所”和“中國農(nóng)業(yè)科學院農(nóng)田灌溉研究所”支持,在此表示感謝.

Characteristics and influencing factors of N2O emission from incubated soil under aerated irrigation.

LEI Hong-jun1*, LIU Huan1, ZANG Ming1, PAN Hong-wei1, CHEN De-li2

(1.School of Water Conservancy, North China University of Water Conservancy and Electric Power, Zhengzhou 450046, China；2.Faculty of Land and Food Resources, University of Melbourne, Victoria 3010, Australia)., 2019,39(5)：2115~2122

To clarify the characteristics of soil N2O emission and identify the main factors under aerated irrigation (AI), the soil culture experiments were conducted at 2 irrigation levels with upper soil moisture limit as 70% and 90% of field capacity and 2 dissolved oxygen (DO) levels at 5 and 40mg/L. Soil N2O emission fluxes were monitored using static chamber-gas chromatography method and the copy number of nitrification and denitrification gene were determined using the real-time quantitative polymerase chain reaction (qPCR) technique. In addition, the main factors on soil N2O fluxes were analyzed, including soil water filling porosity (WFPS), DO, redox potential (h), mineral nitrogen content (NO3--N and NH4+-N), as well as the abundance of soil ammonia-oxidizing bacterial (AOB) and ammonia-oxidizing archaea (AOA) and denitrifier genes (and). Results showed that soil N2O flux increased from the beginning, peaked at 1d after irrigation, dropped in the following 3days, and then stabilized. An increase of aeration and irrigation amount resulted in the increase of average values and peak values of soil N2O fluxes. Irrigation caused an increase of WFPS, while a decrease of soil DO andh. Aeration treatments increased soil DO concentration andh (<0.05), improved soil aeration. However, aeration treatments showed no significant impact on WFPS. The WFPS,h and NO3--N content were the main physical, chemical influencing factors driving soil N2O emission under AI. The AI significantly affected AOA copy numbers. In addition, soil N2O fluxes were significantly correlated with AOA copy number (<0.05). The results could provide scientific support for the influential mechanism of AI on soil N2O and the farmland N2O emission management.

aerated irrigation；N2O emission；dissolved oxygen；redox potential；gene；copy numbers；influencing factor

X511,S275

A

1000-6923(2019)05-2115-08

雷宏軍(1975-),男,湖北大冶人,博士,博士生導師,主要從事節(jié)水灌溉理論與技術(shù)研究.發(fā)表論文100篇.

2018-10-19

國家自然科學基金資助項目(U1504512,51779093);河南省科技創(chuàng)新人才項目(174100510021);華北水利水電大學研究生創(chuàng)新課題(YK2017-02);中原科技創(chuàng)新領(lǐng)軍人才項目(194200510008)

*責任作者, 教授, hj_lei2002@163.com