李 琦， 馬 莉， 趙 躍， 王得平， 侯振安

(石河子大學(xué)農(nóng)學(xué)院資源與環(huán)境科學(xué)系，新疆石河子 832003)

不同溫度制備的棉花秸稈生物碳對棉花生長及氮肥利用率(15N)的影響

李 琦， 馬 莉， 趙 躍， 王得平， 侯振安*

(石河子大學(xué)農(nóng)學(xué)院資源與環(huán)境科學(xué)系，新疆石河子 832003)

【目的】生物碳可提高土壤肥力，增強(qiáng)土壤對養(yǎng)分的保持能力，減少養(yǎng)分損失，提高肥料利用率。研究不同溫度熱解制備的生物碳對棉花生長和肥料利用率的差異，可以為提高生物碳的有效利用提供依據(jù)。【方法】 供試生物碳由棉花秸稈分別在450℃、600℃和750℃高溫限氧條件下熱解制備而成。本試驗為兩因素(生物碳、氮)溫室盆栽試驗， 生物碳處理包括3種不同熱解溫度生物碳處理(分別以450BC、600BC、750BC表示)和1個空白對照(CK)； 每個生物碳土壤設(shè)置3個施氮水平0、 2.1和4.2 g/pot(分別以N0、N1、N2表示)，用15N同位素示蹤方法分析不同施氮水平下3種熱解溫度生物碳對棉花生長、15N回收和淋洗損失的影響。【結(jié)果】1)施用3種生物碳處理棉花干物質(zhì)重總體表現(xiàn)為750BC>600BC、450BC>CK，450BC、600BC和750BC處理分別較對照平均增加了9.2%、12.6%和17.3%；并且棉花總干物質(zhì)重隨施氮量的增加而增加，但生物碳作用隨之降低; 2)3種生物碳處理棉花氮素吸收總量總體也表現(xiàn)為750BC > 600BC、450BC > CK。不施氮肥條件下(N0)，600BC和750BC處理棉花氮素吸收總量顯著高于CK，但450BC處理與與CK無顯著差異；施氮肥條件下(N1、N2)，3種生物碳處理均顯著高于CK，450BC、600BC和750BC處理棉花氮素吸收總量平均較CK分別增加29.5%、37.1%和48.8%; 3)15N標(biāo)記試驗結(jié)果表明， 450BC、600BC和750BC處理植株15N回收率顯著高于對照，分別較CK平均提高27.46%、36.44%和42.87%。而N1和N2水平下3種生物碳處理之間植株15N回收率均沒有顯著差異; 4)450BC、600BC和750BC處理土壤15N殘留率分別較對照平均增加101.4%、147.3%和200.7%。土壤15N殘留率在N1水平下隨著生物碳熱解溫度的升高而增加，而在N2水平下750BC處理顯著高于450BC和600BC處理，但是后二者之間沒有顯著差異。土壤15N殘留率隨著施氮量的增加而降低; 5)施用生物碳可以顯著降低土壤15N的淋洗，并且不同施氮水平下(N1、N2)淋洗率都隨著生物碳熱解溫度的升高而降低。【結(jié)論】施用生物碳可促進(jìn)棉花生長，增加棉花氮素吸收，提高氮肥利用率，降低氮素?fù)p失，并且生物碳的熱解溫度越高效果越明顯；但是隨著氮肥施用量的增加生物碳作用減弱。

生物碳； 制備溫度； 棉花； 氮素吸收； 氮肥利用率

農(nóng)田氮肥的損失途徑主要有氨揮發(fā)、硝化-反硝化、淋洗和徑流，其損失量分別占總施氮量的11%、17%、3%和8%左右[6]。施用有機(jī)肥以及秸稈還田等是減少氮肥損失，提高氮肥利用率的主要措施之一。研究表明，秸稈還田可以增加土壤有機(jī)質(zhì)和表層土壤有機(jī)氮含量[7]，提高土壤潛在氮素礦化勢[8]，減少氮肥損失和提高氮素利用率[9]。近年來，將農(nóng)田廢棄物(如秸稈)制成生物碳還田被認(rèn)為是土壤增匯減排的一種關(guān)鍵途徑[10]。生物碳是生物體在完全或部分缺氧的情況下高溫?zé)峤獾漠a(chǎn)物，有機(jī)碳含量高且穩(wěn)定性強(qiáng)。生物碳具有豐富的孔隙結(jié)構(gòu)，巨大的表面積和吸附能力。研究表明，生物碳和化學(xué)肥料配施可以降低氮素?fù)p失，提高氮肥的利用率[11-12]。但是制備原料和溫度的不同，使得生物碳對氮素的吸附也有很大差異。Yao等[13]研究了四種原料在3種溫度下制備的生物碳對氮素的吸附，發(fā)現(xiàn)不同類型生物碳對銨氮的吸附量從1.8%到15.7%不等，并且在相同溫度(600℃)下四種不同原料的生物碳對硝氮的吸附量也有非常大的差異。Kameyama等[14]研究發(fā)現(xiàn),700℃以上制成的生物碳才出現(xiàn)對硝態(tài)氮的吸附現(xiàn)象。

棉花是新疆的主要經(jīng)濟(jì)作物，棉花秸稈資源豐富，在農(nóng)業(yè)生產(chǎn)中通常采用直接還田利用的方式。對于棉花秸稈生物碳對氮肥利用率影響的研究還鮮見報道。本研究以棉花秸稈為原料，在不同熱解溫度下制備生物碳。采用15N同位素示蹤法，研究不同熱解溫度生物碳和氮肥用量對棉花生長和氮肥利用率的影響，為生物碳的合理利用和提高氮肥利用率提供理論依據(jù)。

1 材料與方法

1.1 試驗材料

試驗于2011年在新疆石河子大學(xué)農(nóng)學(xué)院試驗站溫室進(jìn)行。供試土壤采自石河子大學(xué)農(nóng)學(xué)院試驗站農(nóng)田，采樣深度為0—20 cm耕層。土壤類型為灌耕灰漠土，質(zhì)地為壤土，pH 7.8，有機(jī)質(zhì)12.43 g/kg，全氮0.78 g/kg，堿解氮34.3 mg/kg，速效磷22.51 mg/kg，速效鉀239.8 mg/kg。棉花秸稈采自當(dāng)?shù)孛尢?，烘干粉碎后用于制備生物碳。分別在450°C、600°C和750°C下厭氧熱解6 h后制得3種生物碳(表1)。供試棉花品種為新陸早33號。

表1 供試生物碳的養(yǎng)分含量

1.2 試驗設(shè)計

試驗采用生物碳和施氮量兩因素設(shè)計，生物碳類型設(shè)3個處理：(1)450℃生物碳(450BC)；(2)600℃生物碳(600BC)；(3)750℃生物碳(750BC)；并以空白土壤作對照(CK)。施氮(N)量設(shè)3個水平為0、2.1、4.2 g/pot(分別記為N0、N1、N2)。隨機(jī)區(qū)組設(shè)計，12個處理，每個處理重復(fù)3次，共36個土柱。生物碳的施用量為1%(占干土重)，在裝土前與供試土壤混勻后一次性施入。氮肥使用15N同位素標(biāo)記尿素(15N豐度為10%)，全部作追肥。

1.3 測定指標(biāo)及方法

試驗結(jié)束后將棉花植株自基部剪下用去離子水洗凈后分成葉、莖、鈴殼(含花蕾)三部分。將以上棉花各部分烘干稱重,粉碎后測定其全氮和15N豐度。土壤和植物全氮采用開氏定氮法[15]，土壤和植物15N豐度采用穩(wěn)定性同位素質(zhì)譜儀進(jìn)行測定[16]。土壤有機(jī)質(zhì)用重鉻酸鉀容量法—外加熱法，堿解氮采用堿解擴(kuò)散法測定[15]，速效鉀采用1 mol/L NH4Ac浸提—火焰光度法測定[15]，速效磷采用0.5 mol/L NaHCO3浸提—鉬銻抗比色法測定[15]。

1.4 數(shù)據(jù)處理

數(shù)據(jù)通過SPSS 16.0進(jìn)行施氮量和生物碳類型的兩因素方差分析。不同處理間的多重比較分析采用Duncan法(P<0.05)。

2 結(jié)果與分析

2.1 棉花干物質(zhì)積累

隨著施氮量的增加，棉花植株各器官(莖、葉、蕾鈴)干物質(zhì)重均顯著增加(表2)。施用生物碳對棉花莖、葉干物質(zhì)重的影響不顯著(P>0.05)，而對蕾鈴干物質(zhì)重的影響在不同氮水平下存在差異。在N0和N1水平下，生物碳處理棉花蕾鈴干物質(zhì)重均顯著高于CK，但三種生物碳之間差異不顯著；N2水平下，750℃生物碳(750BC)蕾鈴干重最高，而600℃生物碳(600BC)和450℃生物碳(450BC)處理與對照(CK)均無明顯差異。

施氮量和生物碳處理對棉花植株總干物質(zhì)重影響顯著，但二者交互作用的影響不顯著。棉花總干物質(zhì)重隨施氮量顯著增加，N1和N2水平下棉花植株總干物質(zhì)重平均較N0分別高59.8%和73.9%。不同生物碳處理棉花植株總干物質(zhì)重表現(xiàn)為750BC > 600BC、450BC > CK，施用生物碳處理450BC、600BC和750BC棉花總干物質(zhì)重平均(三個氮水平下)較CK分別增加9.2%、12.6%和17.3%。

表2 不同處理棉花植株干物質(zhì)重(g/pot)

注(Note): 同列數(shù)據(jù)后不同字母表示處理間差異達(dá)到5%顯著性水平 Different lowercase letters within a column mean significant differences at the 5% level; **表示在1%水平下達(dá)到顯著，ns表示不顯著 Indicate significant differences at the 1% probability levels and ns indicate no difference.

2.2 棉花氮素吸收量

施氮量對棉花氮素吸收的影響與棉花干物質(zhì)重相似，均表現(xiàn)為棉花植株各器官及氮素吸收總量隨施氮量增加顯著增加(表3)。不同施氮水平下(N0、N1、N2)，施用生物碳都可以提高棉花莖、葉和蕾鈴的氮素吸收量，尤其在蕾鈴上效果更加明顯。三種生物碳450BC、600BC和750BC處理棉花蕾鈴氮素吸收量分別比CK增加了59.8%、64.5%和104.8%。

不同生物碳處理棉花氮素吸收總量為750BC > 600BC、450BC > CK。施氮水平和生物碳處理對棉花氮素吸收總量的交互作用影響表現(xiàn)為：不施氮肥條件下(N0)，450BC處理與CK差異不顯著；600BC和750BC處理顯著高于CK。施氮肥條件下(N1、N2)，三種生物碳處理均顯著高于CK，450BC、600BC和750BC處理棉花氮素吸收總量平均較CK分別增加29.5%、37.1%和48.8%。

2.315N棉花植株回收率

表3 不同處理棉花植株氮素吸收量(g/pot)

注(Note): 同列數(shù)據(jù)后不同字母表示處理間差異達(dá)5%顯著性水平 Different lowercase letters within a column mean significant differences at the 5% level；*，**分別表示在5%、 1%水平下達(dá)到顯著，ns表示不顯著 Asterisks indicate significant differences at the 0.05(*) and 0.01(**) probability levels, and ns indicate no difference.

圖1 不同處理的棉花植株15N回收率Fig.1 15N recovered by cotton plants in different treatments [注(Note): 柱上不同字母表示處理間在P<0.05水平差異顯著 Different letters above the bars indicate a significant difference among treatments at P< 0.05 level.]

2.415N在土壤中的殘留率和淋洗率

圖2 不同處理氮肥(15N)在土壤中殘留率和淋洗率Fig.2 15N fertilizer residual in the soil and leaching loss in the treatments with biochar type and N rate [注(Note): 柱上不同字母表示處理間在P<0.05水平差異顯著 Different letters above the bars indicate a significant difference among treatments at P< 0.05 level.]

3 討論

生物碳是有機(jī)體在高溫限氧條件下熱解得到的產(chǎn)物，不同的制備原料和熱解溫度使得生物碳的性質(zhì)有所不同。目前研究認(rèn)為生物碳中養(yǎng)分元素和金屬元素含量主要受制備原料影響[17]，而熱解溫度主要影響可揮發(fā)性物質(zhì)的含量[18]。本試驗中生物碳以棉花秸稈為原料，在三種溫度(450、600、750℃)下熱解得到。所得生物碳全磷、全鉀和有機(jī)碳含量隨熱解溫度升高而增加，全氮含量隨熱解溫度升高而降低，這與Rajkovich等[19]的結(jié)果一致。

生物碳作為一種土壤改良劑，施入土壤后有利于改善土壤物理化學(xué)性質(zhì)，固持土壤養(yǎng)分，提高養(yǎng)分利用率，改善微生物環(huán)境，從而對提高土壤肥力和增加作物產(chǎn)量也有積極的作用[20-21]。本研究結(jié)果表明，施用生物碳和氮肥無論是對棉花總干重還是棉花植株的氮素吸收量都有顯著影響。施用生物碳可以顯著提高棉花總干物質(zhì)重和氮素吸收總量，分別較對照平均提高了14.3%和44.9%。目前多數(shù)研究結(jié)果也表明，施用生物碳可以顯著提高作物產(chǎn)量[22]；Zwieten等[23]也發(fā)現(xiàn)施用生物碳可以顯著提高棉花氮素吸收量。本試驗還發(fā)現(xiàn)生物碳熱解溫度越高，棉花總干物質(zhì)重和氮素吸收總量提高越明顯。750BC處理下棉花總干物質(zhì)重和氮素吸收總量分別較對照平均提高17.3%和48.8%。Rajkovich等[19]以四種熱解溫度(300、400、500、600℃)下制得的生物碳為材料也做了相關(guān)研究，結(jié)果表明500℃下制得的生物碳促進(jìn)玉米生長的效果最好，這與本試驗結(jié)果略有差異，可能與制備生物碳原料有關(guān)。本試驗中隨著施氮量的增加，生物碳對棉花總干物質(zhì)重和氮素吸收量的增加作用降低，但高氮肥用量(N2)配施生物碳處理棉花的干物質(zhì)重和氮素吸收量最大。以上結(jié)果可能是由于在不施氮肥下，施加生物碳提高了土壤有機(jī)碳含量，增強(qiáng)了土壤對養(yǎng)分的吸附能力，增加了土壤肥力，從而促進(jìn)棉花生長；生物碳與高施氮量(N2)配施(C/N約為30%)比生物碳與低施氮量(N1)配施(C/N約為60%)更接近于作物生長的土壤C/N比25 ∶1，減少了微生物和棉花對氮的競爭，從而提高了產(chǎn)量。劉玉學(xué)[24]大田試驗研究表明，在不施用尿素下，添加1%的水稻秸稈碳可以提高水稻產(chǎn)量19.9%，在添加尿素下水稻產(chǎn)量提高11.2%，這與本研究結(jié)果相符，增加氮肥用量，生物碳增產(chǎn)幅度降低。

4 結(jié)論

土壤中施用生物碳可以顯著提高棉花的總干物質(zhì)重和氮素吸收總量，并且生物碳熱解溫度越高， 效果越明顯。生物碳提高了棉花植株的15N回收率和土壤中15N的殘留率，但是不同熱解溫度的生物碳之間沒有顯著差異。生物碳減少了15N的淋洗率，并且生物碳熱解溫度越高其作用越明顯。隨著施氮量增加，生物碳促進(jìn)棉花生長和提高氮肥利用率的作用降低，并且不同生物碳之間差異減小。因此，生物碳具有促進(jìn)棉花生長、減少氮素?fù)p失和提高氮肥利用率的作用，并且生物碳熱解溫度越高效果越好；生物碳合理配施氮肥有助于生物碳作用的體現(xiàn)，也有利于促進(jìn)作物生長和提高氮肥利用率。

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Growth and15N use efficiency in cotton affected by biochar made in different temperatures

LI Qi, MA Li, ZHAO Yue, WANG De-ping, HOU Zhen-an*

(DepartmentofResourcesandEnvironmentalScience,ShiheziUniversity,Shihezi832003,Xinjiang,China)

【Objectives】 Biochar are found having efficacy of retaining ions and reducing nutrient loss when applied into soils. The differences of their beneficial effects of biochar made in different temperatures were studied to provide a base for efficient biochar manufacture and reasonable use in cotton production. And the effect of three N fertilizer rates on cotton growth, N use efficiency and N leaching was studied using15N tracer techniques. 【Methods】 Cotton straw was thermodynamic decomposed to make biochar at 450℃(450BC), 600℃(600BC) and 750℃(750BC), respectively. A two-factor pot experiment was designed using the three kinds of biochar and three levels of nitrogen. The three kinds of biochar recorded as 450BC, 600BC and 750BC, with no biochar addition as control(CK). In each kind of biochar treatment, three levels of15N labeled nitrogen fertilizer: 0(N0), 2.1(N1) and 4.2 g/pot(N2) were added. The biomass and yield of cotton and the N use efficiency were measured. 【Results】 1) The cotton dry weights were generally increased in order of 750BC>600BC、450BC > CK，the increase in cotton dry weights was averaged 9.2% in the 450BC treatments, 12.6% in 600BC treatments and 17.3% in the 750BC treatments. The cotton dry weights increased with the increased rate of N application. 2) The N uptake in cotton was generally increased，and the increase in the 750BC treatments was higher than in 600BC treatments, and also higher than in 450BC treatments regardless of the N application rates. When the N rate was N0, the nitrogen uptakes in the cotton in both the 750BC and the 600BC treatments were significantly higher than in CK，not significantly higher than in 450BC treatment. The input of N increased the N uptake in cotton in all the biochar treatments. The biochar addition averagely increased the N uptake by 29.5% in 450BC treatments, 37.1% in 600BC treatments, and 48.8% in 750BC treatments，respectively. 3) The15N tracer data showed that compared with the CK treatment, plant15N recovery in the 450BC treatment increased by 27.46% and plant15N recovery in the 600BC treatment increased by 36.44%, and plant15N recovery in the 750BC treatment increased by 42.87%. But in two N rates(N1, N2), there were no significant difference among the three biochar treatments. 4) Soil15N recovery in the 450BC treatment increased by 101.4%, and 147.3% in the 600BC treatment, and 200.7% in the 750BC treatment relative to the CK treatment. In case of lower N rates(N1), soil15N recovery increased as the biochar pyrolysis temperature increased. In N2 treatments, the soil15N recovery in the 750BC was significantly higher than in both the 450BC and the 600BC treatments, but the difference between the 600BC treatment and the 450BC treatment was not significant. Soil15N recovery decreased as N application rate increased in all three biochar amended treatments. 5) The15N leaching in the biochar amended treatments was significantly lower than that in the CK treatment. Furthermore,15N leaching decreased as the biochar pyrolysis temperature increased. 【Conclusions】 The beneficial effects of biochar increase as the pyrolysis temperature increased, and decrease as the N application rate increased. Therefore, cotton straws are recommended to be treated at high temperature, and the N input should be reduced for the maximum positive effects of biochar on crop growth and N use efficiency.

biochar; preparation temperature; cotton; nitrogen uptake; nitrogen use efficiency

2014-03-05 接受日期： 2014-09-16 網(wǎng)絡(luò)出版日期: 2015-02-13

國家自然科學(xué)基金(31160415)；新疆生產(chǎn)建設(shè)兵團(tuán)杰出青年創(chuàng)新資金專項(2014CD002)資助。

李琦(1989—)，男，陜西漢中人，碩士研究生，主要從事農(nóng)業(yè)資源高效利用的研究。E-mail：liqi472560420@163.com * 通信作者 E-mail：hzatyl@163.com

S156.2

A

1008-505X(2015)03-0600-08