何志龍,夏文建,周維,田亞男,柳維揚(yáng),林杉*
添加秸稈生物質(zhì)炭對(duì)酸化茶園土壤N2O和CO2排放的短期影響研究
何志龍1,夏文建2,周維1,田亞男1,柳維揚(yáng)3,林杉1*
1. 華中農(nóng)業(yè)大學(xué)資源與環(huán)境學(xué)院//農(nóng)業(yè)部長江中下游耕地保育重點(diǎn)實(shí)驗(yàn)室,湖北 武漢 430070;2. 江西省農(nóng)業(yè)科學(xué)院土壤肥料與資源環(huán)境研究所,江西 南昌 330200;3. 塔里木大學(xué)植物科學(xué)學(xué)院,新疆 阿拉爾 843300
為明確秸稈生物質(zhì)炭對(duì)酸化茶園土壤改良及溫室氣體排放的影響,采用室內(nèi)培養(yǎng)試驗(yàn)方法,研究了小麥秸稈生物質(zhì)炭添加(對(duì)照CK:0 g·kg-1;低生物質(zhì)炭B1:8 g·kg-1;中生物質(zhì)炭B2:24 g·kg-1;高生物質(zhì)炭B3:48 g·kg-1)對(duì)茶園土壤pH值和溫室氣體排放的影響。結(jié)果表明,與對(duì)照組CK相比,添加生物質(zhì)炭顯著抑制了酸性茶園土壤N2O的排放(P=0.000),但抑制效應(yīng)并未隨生物質(zhì)炭添加量的增加而加強(qiáng),培養(yǎng)期間各處理N2O累積排放量分別為:CK 2.366 mg·kg-1,B1 0.444 mg·kg-1,B2 0.142 mg·kg-1,B3 0.207 mg·kg-1。低生物質(zhì)炭(8 g·kg-1)和中生物質(zhì)炭(24 g·kg-1)處理的綜合增溫潛勢(GWP)分別比對(duì)照組CK降低了33.45%和25.77%,而高生物質(zhì)炭處理(48 g·kg-1)與對(duì)照處理差異不顯著。這表明施用中低量生物質(zhì)炭更有利于茶園土壤的固碳減排。此外,生物質(zhì)炭顯著提高了酸化茶園土壤pH值,生物質(zhì)炭添加比例越大,pH值越高,故施用作物秸稈生物質(zhì)炭有利于酸化土壤改良。相關(guān)性分析結(jié)果表明,土壤N2O排放與pH值之間呈顯著負(fù)相關(guān)關(guān)系,土壤pH值的升高可能是引起N2O排放量降低的重要原因。
酸化茶園;小麥秸稈生物質(zhì)炭;pH值;N2O排放
引用格式:何志龍, 夏文建, 周維, 田亞男, 柳維揚(yáng), 林杉. 添加秸稈生物質(zhì)炭對(duì)酸化茶園土壤N2O和CO2排放的短期影響研究[J]. 生態(tài)環(huán)境學(xué)報(bào), 2016, 25(7): 1230-1236.
HE Zhilong, XIA Wenjian, ZHOU Wei, TIAN Yanan, LIU Weiyang, LIN Shan. Effects of Wheat-straw Derived Biochar on Acidified Tea Garden Soil N2O and CO2Em ission in Short-term Laboratory Experiments [J]. Ecology and Environmental Sciences, 2016,25(7): 1230-1236.
生物質(zhì)炭是指有機(jī)物料在缺氧或厭氧環(huán)境中經(jīng)高溫?zé)峤猱a(chǎn)生的一種富碳難溶性固態(tài)物質(zhì)(IBI Biochar Standards,2012)。其作為一種土壤改良劑和固碳物質(zhì)受到國內(nèi)外科技工作者的廣泛關(guān)注(何緒生等,2011)。有很多研究表明,在土壤中施用生物質(zhì)炭,可促進(jìn)土壤有機(jī)碳的固定,增強(qiáng)土壤肥力,降低土壤的酸度,減緩農(nóng)業(yè)面源污染,減少溫室氣體排放(Asai et al.,2009;Zw ieten et al.,2013;Liu et al.,2011)。但也有不少研究表明添加生物質(zhì)炭后促進(jìn)了土壤溫室氣體的排放(Bruun et al.,2011;Jujjuri et al.,2014)。不同研究者關(guān)于生物質(zhì)炭對(duì)土壤N2O和CO2排放作用的研究結(jié)果差異較大。一方面,這是由于生物質(zhì)炭的類型和施用量的不同造成的(Cayuela et al.,2014)10;另一方面,不同實(shí)驗(yàn)所用的土壤性質(zhì)存在差異,這也在一定程度上影響了生物質(zhì)炭對(duì)溫室氣體排放的作用效果(Ling et al.,2013)。
茶園是我國南方紅壤丘陵區(qū)主要土地利用類型之一,而紅壤區(qū)茶園土壤普遍存在酸化現(xiàn)象(張永利等,2011;楊向德等,2015)。茶園土壤pH值較低,不僅影響了茶葉的產(chǎn)量和品質(zhì),還促進(jìn)了土壤N2O的排放(韓文炎,2006)。小麥秸稈是農(nóng)業(yè)生產(chǎn)中常見的生物質(zhì)材料,把小麥秸稈制成生物質(zhì)炭添加到土壤中后,不僅能緩解茶園土壤酸化的問題,還能促進(jìn)資源的可持續(xù)利用并減少農(nóng)田土壤溫室氣體的排放(劉玉學(xué)等,2013)。目前,關(guān)于生物質(zhì)炭施用的研究多集中在其對(duì)農(nóng)業(yè)土壤改良方面(Sui et al.,2016;Case et al.,2014;Garland et al.,2011;Suddick et al.,2013),但關(guān)于生物質(zhì)炭對(duì)酸化茶園土壤改良及溫室氣體排放影響的研究較少。為此,本研究利用室內(nèi)培養(yǎng)試驗(yàn),通過向茶園土壤中添加不同量的生物質(zhì)炭,研究生物質(zhì)炭對(duì)酸性茶園土壤pH值和溫室氣體排放的影響,試圖尋找適宜的生物質(zhì)炭添加比例,以期為酸性土壤改良及溫室氣體減排提供理論依據(jù)。
1.1土壤和生物質(zhì)炭
供試土壤取自湖北省咸寧市(29°02′~30°18′N,133°31′~144°58′E)賀勝橋鎮(zhèn)茶園,植茶年限10年左右。當(dāng)?shù)啬昶骄鶜鉁?6.8 ℃,年平均降水量1577.4 mm,氣候溫和,降水充沛,屬于中亞熱帶向北亞熱帶過渡的氣候區(qū),呈較明顯的半濕性季風(fēng)氣候特點(diǎn)。按照對(duì)角線多點(diǎn)混合采集茶園0~20 cm表層土壤,同時(shí)取環(huán)刀土用于測土壤容重。將土樣帶回實(shí)驗(yàn)室,剔除可見有機(jī)物殘?bào)w和根系后,取部分鮮樣用于測定土壤銨態(tài)氮和硝態(tài)氮等指標(biāo),其余土壤風(fēng)干后研磨過2 mm篩,用于室內(nèi)培養(yǎng)試驗(yàn)。供試土壤基本理化性質(zhì)為:有機(jī)碳9.78 g·kg-1,總氮1.10 g·kg-1,容重1.31 g·cm-3,pH 4.50。
生物質(zhì)炭由小麥秸稈在缺氧環(huán)境中600 ℃熱裂解制備而成,過2 mm篩。生物質(zhì)炭基本理化性質(zhì):總氮11.801 g·kg-1,有機(jī)碳415.270 g·kg-1,銨態(tài)氮35.504 mg·kg-1,硝態(tài)氮37.011 mg·kg-1,pH 8.63。
1.2試驗(yàn)設(shè)計(jì)
室內(nèi)培養(yǎng)試驗(yàn)于2015年3月份進(jìn)行。試驗(yàn)共設(shè)置4個(gè)處理:(1)不施生物質(zhì)炭(CK);(2)低生物質(zhì)炭(B1,8 g·kg-1);(3)中生物質(zhì)炭(B2,24 g·kg-1);(4)高生物質(zhì)炭(B3,48 g·kg-1),分別相當(dāng)于田間施用量0、18、54、108 t·hm-2。試驗(yàn)培養(yǎng)溫度設(shè)置為(25±1)℃,土壤水分含量為65%土壤孔隙含水量(WFPS)。
稱500 g風(fēng)干過篩土樣,分別置于一組規(guī)格為1000 m L培養(yǎng)瓶中,并調(diào)節(jié)土壤含水量至40% WFPS后置于恒溫培養(yǎng)箱預(yù)培養(yǎng)7 d,以激活土壤微生物和消除干濕效應(yīng)(Dick et al.,2001)。預(yù)培養(yǎng)結(jié)束后生物質(zhì)炭按照設(shè)計(jì)比例與活化土壤充分混合,調(diào)節(jié)土壤含水量至65% WFPS。用中間帶有兩個(gè)小孔的硅橡膠塞塞住瓶口,其中一孔中插入套有三通閥軟管的玻璃管,作為氣體取樣口和交換口;另一孔中插入綁有氣球的玻璃管,用于平衡采氣樣時(shí)培養(yǎng)瓶中的壓強(qiáng)。檢查密封性后將培養(yǎng)瓶放入恒溫培養(yǎng)箱中培養(yǎng)22 d,每隔2 d用稱重法補(bǔ)充因蒸發(fā)損失的水分,以保持土壤含水量的恒定。每個(gè)處理設(shè)6個(gè)重復(fù),3個(gè)用于溫室氣體濃度的測定,3個(gè)用于土壤NH4+-N、NO3--N和pH值的動(dòng)態(tài)變化分析,并分別于第0、5、10、16天采集土樣,最大程度上保證稱樣后培養(yǎng)瓶中剩余土壤質(zhì)量相當(dāng)。
分別于培養(yǎng)的第0.5、1、2、3、4、5、6、8、 11、16、22天采集氣體樣品。采樣前,反復(fù)抽氣并通入大氣使瓶內(nèi)氣體濃度與瓶外大氣濃度平衡,采集培養(yǎng)瓶上部空間氣體樣本,作為初始?xì)怏w濃度,記錄采樣時(shí)間,密閉靜置培養(yǎng)2 h后,反復(fù)推拉注射器3次以混勻培養(yǎng)瓶中氣體,然后立即抽氣至預(yù)真空的集氣瓶中,再次記錄采樣時(shí)間。
1.3氣體及土壤樣品分析
N2O和CO2濃度由氣相色譜儀(Agilent 7890A)測定;硝態(tài)氮、銨態(tài)氮采用1 mol·L-1KCl振蕩浸提1 h,過濾,德國Seal Analytical AA3流動(dòng)分析儀測定;土壤pH采用1∶2.5土水比懸液,酸度計(jì)電位法測定;容重采用環(huán)刀法(鮑士旦,2000)測定。
1.4數(shù)據(jù)計(jì)算與統(tǒng)計(jì)
N2O和CO2排放通量按下式計(jì)算:
式中,F(xiàn)為N2O和CO2排放通量(μg·kg-1·h-1或mg·kg-1·h-1),正值為排放,負(fù)值為吸收;ρ為標(biāo)準(zhǔn)狀況下氣體的密度;V是培養(yǎng)瓶上部有效空間體積(L);m為土樣干質(zhì)量(g);△c/△t為在一特定時(shí)間內(nèi)的氣體濃度變化速率;T為絕對(duì)溫度;α為N2O換算為N(28/44)、CO2換算為C(12/44)的轉(zhuǎn)換因子。
N2O和CO2累積排放量按下式計(jì)算:
式中,M為土壤氣體累計(jì)排放量(μg·kg-1或mg·kg-1);F為氣體排放通量(μg·kg-1·h-1或mg·kg-1·h-1),i為采樣次數(shù),t為采樣時(shí)間(d)。
全球增溫潛勢(global warm ing potential,GWP)是一個(gè)用來表征溫室氣體對(duì)全球溫室效應(yīng)總影響的指標(biāo),該指標(biāo)以給定時(shí)間尺度的CO2質(zhì)量當(dāng)量計(jì)(CO2-eq)。對(duì)于100 a時(shí)間尺度的氣候變化,CO2、 CH4和N2O氣體的GWP分別為1、21和310(IPCC, 2013)。100 a時(shí)間尺度的CO2、CH4和N2O綜合增溫潛勢按下式計(jì)算:
式中,GWP單位為mg·kg-1(以CO2-eq計(jì));F2CO為CO2的排放量(mg·kg-1);F4CH為CH4的排放量(mg·kg-1);F ON2為N2O的排放量(mg·kg-1)。
所有試驗(yàn)結(jié)果均以3次重復(fù)的平均值±標(biāo)準(zhǔn)誤來表示,試驗(yàn)數(shù)據(jù)用Excel軟件進(jìn)行處理后,使用SPSS 16.0軟件進(jìn)行相關(guān)分析,采用Pearson方法分析生物質(zhì)炭添加量與N2O、CO2排放通量,以及N2O排放通量與NH4+-N、土壤pH之間的相關(guān)性,顯著性水平P=0.05,并用Origin 8.0軟件進(jìn)行圖形繪制。
2.1土壤礦質(zhì)態(tài)氮含量和氮素礦化量變化
培養(yǎng)期間,添加小麥秸稈生物質(zhì)炭后,土壤中NO3--N含量均逐漸提高(圖1)。培養(yǎng)末期添加生物質(zhì)炭處理(B1、B2和B3處理)的NO3--N含量均顯著高于對(duì)照處理(CK),不同生物質(zhì)炭處理之間NO3--N含量無顯著差異。對(duì)照處理土壤NO3--N含量于培養(yǎng)的第5天達(dá)到峰值,之后逐漸下降,并在試驗(yàn)結(jié)束時(shí)達(dá)到最低值且低于初始含量。不同處理下土壤NH4+-N含量在培養(yǎng)期間均呈逐漸下降趨勢,且隨著生物質(zhì)炭添加量的增加土壤中NH4+-N含量下降幅度逐漸增大(圖1)。試驗(yàn)結(jié)束時(shí)對(duì)照組CK,處理組B1、B2和B3土壤中NH4+-N含量較初始值分別減少了10.278%,51.650%、81.048%和83.541%。
2.2土壤pH變化
所有處理組土壤pH值在培養(yǎng)過程中均表現(xiàn)出先升高后下降趨勢(圖2)。其中以B2和B3處理組土壤pH值變化較大,且在試驗(yàn)結(jié)束時(shí)土壤pH值高于初始值;而CK和B1處理組土壤pH值波動(dòng)較小,試驗(yàn)結(jié)束時(shí)對(duì)照組CK和B1處理組土壤pH值基本與初始值持平。
圖1 土壤NH4+-N和NO3--N含量動(dòng)態(tài)變化Fig. 1 Temporal dynam ics of soil NH4+-N and NO3--N contents
圖2 土壤pH動(dòng)態(tài)變化Fig. 2 Temporal dynam ics of soil pH value
圖3 土壤N2O和CO2累積排放量動(dòng)態(tài)變化Fig. 3 Temporal dynamics of soil N2O and CO2cumulative emission
2.3土壤N2O和CO2的排放
為研究添加生物質(zhì)炭對(duì)茶園土壤N2O排放的影響,培養(yǎng)試驗(yàn)中測定的N2O累積排放量如圖3所示。對(duì)照組CK和生物質(zhì)炭處理組之間差異較大,對(duì)照組N2O累積排放量顯著高于添加生物質(zhì)炭處理組。不同量生物質(zhì)炭處理之間也存在差異,在一定范圍內(nèi),隨著生物質(zhì)炭添加量的增加,N2O平均排放通量總體呈降低趨勢(圖4)。生物質(zhì)炭添加比例(x)與N2O平均排放通量(y)之間滿足方程:y=0.516+6.104exp(-x/3.146)(r=-0.651,P=0.022,n=12)。然而,添加生物質(zhì)炭顯著增加了土壤CO2累積排放量,并隨著生物質(zhì)炭添加量的增加而增加,兩者呈較好的線性關(guān)系(圖4),生物質(zhì)炭添加比例(x)與CO2平均排放通量(y)之間滿足線性方程:y=0.352x+0.0215(r=0.951,P=0.000,n=12)。試驗(yàn)結(jié)束時(shí)B1、B2和B3處理組CO2累積排放量分別為對(duì)照組CK的1.56、2.02和2.78倍。
2.4N2O排放與土壤礦質(zhì)氮的關(guān)系
土壤礦質(zhì)態(tài)氮含量是影響土壤氧化亞氮排放的主要因素之一。相關(guān)性分析結(jié)果表明(圖5),茶園土壤氧化亞氮排放通量與銨態(tài)氮含量之間呈極顯著正相關(guān)關(guān)系(P=0.005),表明銨態(tài)氮含量越高,N2O排放的越多;而N2O排放通量與茶園土壤硝態(tài)氮之間不存在顯著相關(guān)性。
圖4 CO2和N2O排放通量與生物質(zhì)炭添加量之間的關(guān)系Fig. 4 The relationship between N2O and CO2fluxes and the biochar application amount
圖5 N2O排放通量與NH4+-N之間的關(guān)系Fig. 5 The relationship between N2O fluxes and NH4+-N content
圖6 土壤pH與N2O排放通量之間的關(guān)系Fig. 6 The relationship between pH and N2O emission
2.5N2O排放與土壤pH的關(guān)系
土壤pH值對(duì)茶園土壤N2O排放有顯著性影響(P=0.046),隨著pH值的升高,N2O排放通量逐漸降低(圖6),表明提高茶園土壤pH值,可減少N2O排放。
2.6土壤綜合增溫潛勢估算
試驗(yàn)期間,添加生物質(zhì)炭后土壤N2O排放被抑制但土壤CO2的排放卻得到促進(jìn)。為進(jìn)一步明確添加生物質(zhì)炭后的綜合溫室效應(yīng)(GWP),對(duì)所有處理組的N2O和CO2在100 a尺度上的綜合增溫潛勢進(jìn)行了估算。如表1所示,B1和B2處理的綜合溫室效應(yīng)均顯著低于CK處理,B1和B2處理的GWP較對(duì)照組CK分別減少604.874和480.033 mg·kg-1,降幅分別為34.667%和27.512%。
添加生物質(zhì)炭后,土壤pH值的變化主要是土壤中氮素的轉(zhuǎn)化過程和生物質(zhì)炭中堿性物質(zhì)釋放綜合作用的結(jié)果。開始階段,土壤中有機(jī)氮的礦化、有機(jī)陰離子的脫羧作用和生物質(zhì)炭中堿性物質(zhì)的釋放,造成生物質(zhì)炭處理組土壤pH值顯著升高,之后由于硝化作用釋放H+(王磊等,2013;W rageet al.,2001)以及土壤本身的緩沖作用,pH值逐漸下降。試驗(yàn)結(jié)束時(shí),生物質(zhì)炭處理組土壤pH值高于對(duì)照組,特別是在B2和B3處理組中生物質(zhì)炭的添加顯著提高了土壤pH值,這與張祥等(2013)的研究結(jié)果一致,隨著生物質(zhì)炭添加比例的增加,土壤pH升高效果愈明顯。試驗(yàn)過程中,各處理組N2O排放速率均逐漸降低,最終趨于平緩(圖3),這與很多學(xué)者的研究結(jié)果一致(張祥等,2015;陳玉真等,2015)。
隨著培養(yǎng)試驗(yàn)的進(jìn)行,土壤中的碳源和氮源不斷被消耗,硝化和反硝化作用的底物濃度逐漸降低,試驗(yàn)結(jié)束時(shí)N2O排放量降至很低的水平,CK、B1、B2和B3處理組N2O排放通量分別為2.374、0.337、0.245和0.068 μg·kg-1·h-1。添加生物質(zhì)炭顯著降低了土壤N2O的累積排放量,B1、B2和B3處理組N2O的累積排放量分別比對(duì)照組減少81.234%、94.006%和91.252%,這與Wang et al.(2011)得出的生物質(zhì)炭顯著降低水稻土N2O排放速率的研究結(jié)果相似。生物質(zhì)炭在熱解過程中會(huì)產(chǎn)生灰化堿等堿性物質(zhì),加入到酸性茶園土壤中有利于pH的提高。土壤N2O排放通量與pH之間的相關(guān)性表明(圖6),提高pH值有助于減少N2O的排放量。雖然pH的升高可促進(jìn)硝化作用,但同時(shí)也將增強(qiáng)反硝化菌氧化亞氮還原酶的活性(Yanai et al.,2007)。另外,在生物質(zhì)炭的內(nèi)部可能存在局部厭氧的微環(huán)境,比起N2O的產(chǎn)生有更多的N2O被還原為N2。加之生物質(zhì)炭具有大量的孔隙結(jié)構(gòu)和巨大的比表面積,NO3-被大量吸附在土壤中(Cheng et al.,2008),從而使得N2O排放量顯著降低。
表1 不同比例生物質(zhì)炭處理對(duì)土壤N2O、CO2排放總量及100年尺度全球增溫潛勢(GWP-100)的影響Table 1 Cumulative emissions of N2O and CO2from the soil and global warming potential as affected by different biochar rate
本研究與大部分室內(nèi)培養(yǎng)試驗(yàn)和短期田間試驗(yàn)得出的生物質(zhì)炭減少了土壤N2O排放的結(jié)果一致(Liu et al.,2012;Taghizadehtoosi et al.,2011),生物質(zhì)炭在緩解土壤酸化問題的同時(shí)降低了土壤N2O氣體的排放量。也有一些試驗(yàn)得出添加生物質(zhì)炭對(duì)N2O排放無影響或促進(jìn)了N2O排放的結(jié)論(Scheer et al.,2011;Saarnio et al.,2013;Suddick et al.,2013),試驗(yàn)結(jié)果不同主要是因?yàn)樯镔|(zhì)炭的原材料、熱解溫度、C/N、pH和施加比例等不同造成的(Cayuela et al.,2013)10-11。
有研究表明,生物質(zhì)炭添加到土壤中可有效提高土壤有機(jī)碳含量(柯躍進(jìn)等,201497-98;Woolf et al.,2010)。但生物質(zhì)炭會(huì)影響土壤有機(jī)碳組分和微生物活性(陳心想等,2014),進(jìn)而對(duì)土壤中有機(jī)碳的分解產(chǎn)生影響。目前關(guān)于生物質(zhì)炭對(duì)CO2排放的影響存在較大爭議??萝S進(jìn)等(2014)98的研究表明施用生物質(zhì)炭能降低CO2的排放,陳玉真等(2015)的研究則得出添加低量生物質(zhì)炭對(duì)土壤CO2排放無顯著影響,高量生物質(zhì)炭顯著促進(jìn)CO2排放。本試驗(yàn)中生物質(zhì)炭顯著促進(jìn)了CO2的排放,施用生物質(zhì)炭增加土壤CO2排放量一方面可能是由于生物質(zhì)炭可以提高土壤pH值,從而引起土壤呼吸速率的改變(范分良等,2012);另一方面可能是由于較強(qiáng)的化學(xué)分解造成的(Bird et al.,1997)。一般認(rèn)為低溫下(350~550 ℃)制備的生物質(zhì)炭芳香性差,不穩(wěn)定強(qiáng),更容易分解(Laird et al.,2010)。本試驗(yàn)所用生物質(zhì)炭是在中溫(600 ℃)條件下制備而來,生物質(zhì)炭含有較多的易分解有機(jī)碳及磷、鉀和鈣等速效養(yǎng)分,施加到土壤中會(huì)增強(qiáng)土壤中微生物的活性,進(jìn)而促進(jìn)土壤中碳的礦化(張祥等,2015;Cross et al.,2011),使土壤CO2累積排放量顯著增加。
為進(jìn)一步明確本試驗(yàn)中生物質(zhì)炭的綜合減排效果,對(duì)各處理組N2O和CO2的全球增溫潛勢GWP進(jìn)行了估算。數(shù)據(jù)表明,添加生物質(zhì)炭后,B1(18 t·hm-2)和B2(54 t·hm-2)處理的綜合增溫潛勢較對(duì)照組CK均出現(xiàn)了顯著下降,降幅分別為34.667%和27.512%,高德才等(2015)的研究也得出,當(dāng)生物質(zhì)炭施用量為20 t·hm-2時(shí)可顯著減弱綜合溫室效應(yīng)。可見,施用生物質(zhì)炭是一種能實(shí)現(xiàn)碳封存和減緩氣候變暖的有效措施。
(1)添加作物秸稈生物質(zhì)炭顯著提高了酸化茶園土壤pH值,且生物質(zhì)炭施加比例越大土壤pH值升幅越大,表明作物秸稈生物質(zhì)炭具有改良酸化茶園土壤質(zhì)量的潛力。
(2)室內(nèi)模擬試驗(yàn)表明,茶園土壤pH值對(duì)N2O排放通量有顯著影響,二者之間呈顯著負(fù)相關(guān)關(guān)系,土壤pH值的升高可能是引起N2O排放量降低的重要原因。
(3)添加秸稈生物質(zhì)炭短期內(nèi)顯著降低了中亞熱帶丘陵區(qū)酸化茶園土壤N2O的排放,但會(huì)促進(jìn)土壤CO2的排放,100年尺度的綜合增溫潛勢(GWP)數(shù)據(jù)表明,添加中低量(8 g·kg-1和24 g·kg-1)生物質(zhì)炭能顯著降低土壤增溫潛勢,其中B1(8 g·kg-1)處理組降幅達(dá)34.667%,固碳減排效果較明顯。
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Effects of Wheat-straw Derived Biochar on Acidified Tea Garden Soil N2O and CO2Emission in Short-term Laboratory Experiments
HE Zhilong1, XIA Wenjian2, ZHOU Wei1, TIAN Yanan1, LIU Weiyang3, LIN Shan1*
1. College of Recourses and Environment, Huazhong Agricultural University//Key Laboratory of Arable Land Conservation in Middle and Lower Reaches of Yangtze River, Ministry of Agriculture, Wuhan 430070, China;2. Institute of Soil Fertilizer and Resource Environment, Jiangxi Academy of Agricultural Sciences, Nanchang 330200, China;3. College of Plant Science and Technology, Tarim University, Alar 843300, China
Laboratory experiments were conducted to examine the effect of straw biochar addition on acidified tea garden soil amelioration and greenhouse gas emissions, different amounts of wheat-straw derived biochar (Control: 0 g·kg-1; Low biochar: 8 g·kg-1; Medium biochar: 24 g·kg-1; High biochar: 48 g·kg-1) were added to tea garden soil. The results indicated that the adding of biochar significantly reduced acidified tea garden soil N2O emissions compared with CK (no wheat-straw derived biochar).But the effect did not increase with increasing application rate of the straw biochar, with the 24 g·kg-1rate had the largest prominent effect. The cumulative N2O fluxes were 2.366, 0.444, 0.142 and 0.207 mg·kg-1for CK, B1,B2 and B3, respectively. Compared with CK treatment, the global warming potential of low biochar and medium biochar treatments decreased by 33.45% and 25.77%,respectively, while there was no significant difference between the high biochar treatment and control treatment. The result indicated that the low and medium biochar applied was more beneficial to carbon sequestration and reduce greenhouse gases emission in tea garden soil than the high biochar applied. Additionally, the biochar could significantly increase the pH value in acidified tea garden soil, indicating that the higher biochar addition with the higher soil pH value. Therefore, the straw biochar addition had better effect on acidic soil amelioration. The result showed that soil N2O flux was significantly correlated with soil pH, indicating that the increasing of soil pH may be an important factor to decrease N2O emission.
acidification of tea garden; wheat-straw derived biochar; pH values; N2O emissions
10.16258/j.cnki.1674-5906.2016.07.020
X144
A
1674-5906(2016)07-1230-07
國家自然科學(xué)基金項(xiàng)目(41201255;41171212;41561068);河南省科技攻關(guān)項(xiàng)目(162102110010)
何志龍(1991年生),男,碩士研究生,主要從事農(nóng)田溫室氣體研究。E-mail:hzlfaogeiing@163.com
,林杉,E-mail: linshan@mail.hzau.edu.cn
2016-06-30