裴廣廷，馬紅亮,*，林 偉，高 人，尹云鋒，楊柳明

1 濕潤亞熱帶山地生態(tài)國家重點(diǎn)實(shí)驗(yàn)室培育基地，福州 350007 2 福建師范大學(xué)地理科學(xué)學(xué)院，福州 350007

氨基酸添加對亞熱帶森林紅壤氮素轉(zhuǎn)化的影響

裴廣廷1,2，馬紅亮1,2,*，林 偉1,2，高 人1,2，尹云鋒1,2，楊柳明1,2

1 濕潤亞熱帶山地生態(tài)國家重點(diǎn)實(shí)驗(yàn)室培育基地，福州 350007 2 福建師范大學(xué)地理科學(xué)學(xué)院，福州 350007

氨基酸；土壤水分；森林土壤；氮素轉(zhuǎn)化

在森林生態(tài)系統(tǒng)中，氮是植物吸收最多的必需營養(yǎng)元素，土壤氮素轉(zhuǎn)化在有機(jī)質(zhì)的分解、土壤供氮能力及有效氮的維持中扮演著重要的角色，強(qiáng)烈影響著森林生產(chǎn)力[1]。除了溫度和水分外，外源性N素輸入也是影響森林土壤氮素轉(zhuǎn)化的關(guān)鍵因子之一，在自然條件下，凋落物歸還和氮沉降是森林土壤N最主要的來源[2]。已有研究表明，氨基酸是凋落物歸還土壤過程中有機(jī)氮分解的重要產(chǎn)物，也是大氣有機(jī)氮沉降的組成部分[3]，氨基酸-N不僅能在土壤中迅速礦化成無機(jī)氮，而且與無機(jī)氮存在著密切的動態(tài)轉(zhuǎn)化關(guān)系，對土壤氮素保持和遷移轉(zhuǎn)化過程起重要作用[4]，因此在近年來引起了眾多學(xué)者的關(guān)注。

1 材料與方法

1.1 供試土壤

土壤采自福建省建甌萬木林自然保護(hù)區(qū)(118°02′—118°09′E，27°02′—27°03′N)，土壤為山地紅壤。研究區(qū)屬中亞熱帶季風(fēng)氣候，樣地海拔390m，坡向330°，坡度20°，郁閉度為0.8，年平均降水量為731.4 mm，年平均氣溫19.4 ℃，相對濕度81%，全年無霜期達(dá)227 d，植物群落眾多，植被以常綠闊葉林為主。喬木層中主要的樹種有浙江桂(Cinnamomumchekiangense)、假蚊母樹(Distyliopsisdunnii)、少葉黃杞(Engelhardtiafenzelii)、桂北木姜子(Litseasubcoriace)等，優(yōu)勢樹種為浙江桂(Cinnamomumchekiangense)。灌木層比較稀疏，主要有杜莖山(Maesajaponica)、薄葉山礬(Symplocosanomala)、沿海紫金牛(Ardisiapunctata)等。而草本層主要有草珊瑚(Sarcandraglabra)、飛揚(yáng)草(Euporbiahirta)和狗脊蕨(Woodwardiajaponica)類等。樣地附近1 km內(nèi)沒有農(nóng)業(yè)活動，無人為的氮輸入[16]。在樣地的上、中、下坡隨機(jī)選取10個(gè)采樣點(diǎn)，采集樣地表層(0—15cm)土壤，挑除石塊和凋落物，充分混勻土壤帶回實(shí)驗(yàn)室，過2 mm篩，裝自封袋保存于4 ℃冰箱中待用。土壤基本理化性質(zhì)為：pH值(4.15±0.01)，土壤飽和持水量(673.59±12.43)g/kg，全碳(39.56±0.49)g/kg，全氮(2.80±0.04)g/kg，C/N比值(14.13±0.27)，銨態(tài)氮(32.73±1.08)mg/kg，硝態(tài)氮(16.06±0.14)mg/kg，亞硝態(tài)氮(0.11±0.01)mg/kg，可溶性有機(jī)氮(40.76±5.41)mg/kg，速效鉀(72.15±4.32)mg/kg，速效磷(2.01±0.06)mg/kg。

1.2 實(shí)驗(yàn)處理

表1 氨基酸基本理化性質(zhì)Table 1 The physicochemical characteristics of amino acids

1.3 測定方法

1.4 計(jì)算方法和數(shù)據(jù)處理

土壤可溶性有機(jī)氮含量的計(jì)算[19]：

土壤N2O-N產(chǎn)生量的計(jì)算方法[16]：

F=k·v/m·c· 273/(273+T)

式中,F表示氣體N2O-N產(chǎn)生量(μg/kg)；k為常數(shù)，N2O-N取1.248；v為培養(yǎng)瓶容量體積(mL)；m為干土重(mg)；c為N2O氣體濃度(μL/L)；T為培養(yǎng)溫度(℃)。

采用 Excel 2003和origin 7.5對數(shù)據(jù)進(jìn)行處理和作圖，測定結(jié)果均以土壤干重計(jì)算。運(yùn)用SPSS 18.0中單因素方差分析(One way ANOVA)中的最小顯著差異法(LSD)分析不同處理之間的差異顯著性，用曲線估計(jì)選擇最優(yōu)擬合方法分析土壤pH值和可溶性有機(jī)碳與氮素之間的相關(guān)性，并采用三因素重復(fù)測量方差(氨基酸、含水量與時(shí)間為主因素)進(jìn)行影響因素分析。

2 結(jié)果與分析

圖1 兩種含水量條件下不同氨基酸處理土壤銨態(tài)氮的變化Fig.1 Dynamics of incubated with amino acids under two soil moisture conditionsCK：對照；Glu：添加谷氨酸處理；Lys：添加賴氨酸處理；Ala：添加丙氨酸處理；Met：添加甲硫氨酸處理；均值：36d培養(yǎng)時(shí)間段內(nèi)的平均值(n=6);折線圖中所有數(shù)值均是平均值±標(biāo)準(zhǔn)偏差(n=3)

圖2 兩種含水量條件下不同氨基酸處理土壤硝態(tài)氮的變化

2.3 不同氨基酸處理土壤可溶性有機(jī)氮(SON)特征

如圖3所示，氨基酸添加處理土壤SON含量呈先降低后升高趨勢。60%WHC條件下，Glu、Lys、Ala、Met在第2天迅速降低至與CK差異不顯著，并在第8天降至最低且分別比CK下降了14.61%、16.24%、42.95%(P<0.05)、84.24%(P<0.01)。Glu、Lys、Ala到12d(Met到16d)回升至與CK含量相當(dāng)。除了第8天Ala顯著低于Glu和Lys，Glu、Lys、Ala三者之間無顯著差異。

90%WHC條件下，Glu、Lys、Ala、Met同樣在第2天迅速降低至與CK差異無顯著，并在12d降至最低。除了第16天Met、Ala顯著高于CK和Glu(P<0.05)，第2天后Glu、Lys、Ala、Met均與CK無顯著差異，且Glu、Lys、Ala三者之間差異不顯著。

圖3 兩種含水量條件下不同氨基酸處理土壤可溶性有機(jī)氮的變化Fig.3 Dynamics of SON incubated with amino acids under two soil moisture conditions

2.4 不同氨基酸處理土壤氧化亞氮(N2O)排放特征

從圖4可看出，60%WHC條件下，土壤N2O-N釋放量在第8天最大，隨后迅速降低，CK、Glu、Lys、Ala、Met最大值依次為22.03、22.99、23.46、22.08、16.00μg/kg。Glu、Lys、Ala 三者與CK差異不顯著，且三者之間無顯著差異。Met在第8天顯著低于CK(P<0.05)，隨后又顯著高于CK(P<0.05)，然而從0至36d平均值看，Met(10.65 μg/kg)大于CK(8.46 μg/kg)，總體上增加了N2O排放的可能性。

當(dāng)土壤含水量增至90%WHC，N2O-N釋放量在第2天迅速增至最大值，CK、Glu、Lys、Ala、Met最大值依次為273.43、312.99、308.97、399.50、193.12 μg/kg，是60%WHC最大值的100多倍。Glu、Lys、Ala 三者與CK差異不顯著，且三者之間無顯著性差異。與CK相比，Met表現(xiàn)與60%WHC時(shí)相似，并在第36天降低至與CK無顯著差異，Met的36d平均值(87.95 μg/kg)仍大于CK(68.10μg/kg)。

圖4 兩種含水量條件下不同氨基酸處理土壤氧化亞氮的變化Fig.4 Dynamics of N2O-N incubated with amino acids under two soil moisture conditions

2.5 土壤pH值的變化及其與土壤氮素相關(guān)關(guān)系

如圖5結(jié)果所示，60%WHC條件下，從0至12d土壤pH值迅速增大，隨后變化平緩。氨基酸添加處理的土壤pH值均高于CK處理，在第2天、12天、36天Glu、Lys、Ala、Met均與CK達(dá)到顯著差異(P<0.05)，在各氨基酸處理中Met處理的土壤pH值較高。90%WHC條件下，土壤pH值在短暫(2d)的降低后又升高，與60%WHC相比變化幅度更大。除第2天的Ala和第12天的Lys略低于CK外，氨基酸處理的土壤pH值均大于CK處理，第8天后Met均顯著高于CK(P<0.05)，Glu、Lys、Ala處理之間差異不顯著(P> 0.05)。

圖5 兩種含水量條件下不同氨基酸處理土壤pH值的變化Fig.5 Dynamics of soil pH incubated with amino acids under two soil moisture conditions

圖6 兩種含水量條件下不同氨基酸處理土壤pH值與土壤氮素的相關(guān)關(guān)系Fig.6 Relationship between soil pH and soil nitrogen in different soil moisture conditions

2.6 土壤可溶性有機(jī)碳(SOC)的變化

由于土壤SOC含量與土壤氮素?zé)o明顯相關(guān)性，在此只對土壤SOC含量的變化特征進(jìn)行分析。從圖7中可知，在兩種土壤含水量條件下，土壤SOC含量隨時(shí)間的變化趨勢均為先降低后升高再降低。60%WHC條件下，Lys、Ala、Met土壤SOC含量在第8天均顯著大于CK處理(P<0.05)；第12、16天氨基酸處理降低為低于CK處理。90%WHC條件下，土壤SOC含量在第12天最大，在第8、12天氨基酸處理均大于CK處理且Ala與CK差異顯著(P<0.05)，第16天氨基酸處理均低于CK處理，于第36天各處理降至最低且無顯著差異。

圖7 兩種含水量條件下不同氨基酸處理土壤可溶性有機(jī)碳的變化Fig.7 Dynamics of SOC incubated with amino acids under two soil moisture conditions

2.7 多因素統(tǒng)計(jì)分析

表2 氨基酸、培養(yǎng)時(shí)間、土壤含水量對土壤氮素含量和pH值以及可溶性有機(jī)碳含量影響的重復(fù)測量方差分析(P)

Table 2 Results of repeated measures ANOVA on the effects of amino acid N addition, incubation time, soil moisture content and their interactions on soils nitrogen, soil pH and soluble organic carbon

影響因素Impactfactor銨態(tài)氮NH+4-N硝態(tài)氮NO-3-N可溶性有機(jī)氮SON氧化亞氮N2O土壤pH值SoilpH可溶性有機(jī)碳SOC氨基酸Aminoacid<0．001<0．001<0．0010．860<0．0010．441培養(yǎng)時(shí)間Time<0．001<0．001<0．001<0．001<0．001<0．001含水量Soilmoisturecontent0．001<0．0010．013<0．001<0．0010．003氨基酸×培養(yǎng)時(shí)間Aminoacid×Time<0．001<0．001<0．0010．650．1030．004氨基酸×含水量Aminoacid×Soilmoisturecontent0．0390．009<0．0010．8610．2340．354含水量×培養(yǎng)時(shí)間Soilmoisturecontent×Time<0．001<0．001<0．001<0．001<0．001<0．001氨基酸×培養(yǎng)時(shí)間×含水量Aminoacid×Time×Soilmoisturecontent0．2300．010<0．0010．6230．0140．105

3 討論

3.1 氨基酸添加對土壤氮素含量及轉(zhuǎn)化的影響

3.2 氨基酸理化性質(zhì)與土壤氮素轉(zhuǎn)化的關(guān)系

4 結(jié)論

[1] LeBauer D S, Treseder K K. Nitrogen limitation of net primary productivity in terrestrial ecosystems is globally distributed. Ecology, 2008, 89(2):371- 379.

[2] 陳伏生, 曾德慧, 何興元. 森林土壤氮素的轉(zhuǎn)化與循環(huán). 生態(tài)學(xué)雜志, 2004, 23(5):126- 133.

[3] 鄭利霞, 劉學(xué)軍, 張福鎖. 大氣有機(jī)氮沉降研究進(jìn)展. 生態(tài)學(xué)報(bào), 2007, 27(9):3828- 3834.

[4] Rothstein D E. Soil amino-acid availability across a temperate-forest fertility gradient. Biogeochemistry, 2009, 92(3):201- 215.

[5] Kielland K. Amino acid absorption by arctic plants:implications for plant nutrition and nitrogen cycling. Ecology, 1994, 75(8):2373- 2383.

[6] Finzi A C, Berthrrong S T. The uptake of amino acids by microbes and trees in three cold-temperate forests. Ecology, 2005, 86(12):3345- 3353.

[7] Miller A E, Bowman W D, Suding K N. Plant uptake of inorganic and organic nitrogen:neighbor identity matters. Ecology, 2007, 88(7):1832- 1840.

[8] Werdin- Pfisterer N R, Kielland K, Boone R D. Soil amino acid composition across a boreal forest successional sequence. Soil Biology and Biochemistry, 2009, 41(6):1210- 1220.

[9] Senwo Z N, Tabatabai M A. Amino acid composition of soil organic matter. Biology and Fertility of Soils, 1998, 26(3):235- 242.

[10] 李世清, 李生秀, 楊正亮. 不同生態(tài)系統(tǒng)土壤氨基酸氮的組成及含量. 生態(tài)學(xué)報(bào), 2002, 22(3):379- 386.

[11] Campbell C A, Zentner R P, Knipfel J E, Sohnitzer M, Lafond G P. Thirty- year crop rotations and management practices effects on soil and amino nitrogen. Soil Science Society of America Journal, 1991, 55(3):739- 745.

[12] Greenwood D J, Lees H. Studies on the decomposition of amino acids in soils. Plant and Soil, 1956, 7(3):253- 268.

[13] Jones D L, Kielland K. Soil amino acid turnover dominates the nitrogen flux in permafrost-dominated taiga forest soils. Soil Biology and Biochemistry, 2002, 34(2):209- 219.

[14] Mclain J E T, Martens D A. Nitrous oxide flux from soil amino acid mineralization. Soil Biology and Biochemistry, 2005, 37(2):289- 299.

[15] Quastel J H, Scholefield P G. Influence of organic nitrogen compounds on nitrifications in soil. Nature, 1949, 164(4182):1068- 1072.

[16] 陳仕東, 馬紅亮, 高人, 閆聰微, 尹云鋒, 楊玉盛. 高氮和NO-2對中亞熱帶森林土壤N2O和NO產(chǎn)生的影響. 土壤學(xué)報(bào), 2013, 50(1):120- 129.

[17] Jones D L, Kielland K. Amino acid, peptide and protein mineralization dynamics in a taiga forest soil. Soil Biology and Biochemistry, 2012, 55:60- 69.

[18] 張萬儒, 楊光澄, 屠星南. 森林土壤分析方法. LY/T 1210-1999. 北京:中國標(biāo)準(zhǔn)出版社, 1999.

[19] Yang K, Zhu J J, Yan Q L, Zhang J X. Soil enzyme activities as potential indicators of soluble organic nitrogen pools in forest ecosystems of Northeast China. Annals of Forest Science, 2012, 69(7):795- 803.

[20] 李貴才, 韓興國, 黃建輝, 唐建維. 森林生態(tài)系統(tǒng)土壤氮礦化影響因素研究進(jìn)展. 生態(tài)學(xué)報(bào), 2001, 21(7):1187- 1195.

[21] 陶運(yùn)平, Adams W A. 硫代硫酸銨對土壤硝化作用的影響. 土壤學(xué)報(bào), 1997, 34(4):467- 474.

[22] Curtin D, Campbell C A, Jalil A. Effects of acidity on mineralization:pH- dependence of organic matter mineralization in weakly acidic soils. Soil Biology and Biochemistry, 1998, 30(1):57- 64.

[23] Sherigara B S, Bhat K I, Pinto I, Gowda N M M. Oxidation of L-aspartic acid and L-glutamic acid by manganese(III) ions in aqueous sulfuric acid, acetic acid, and pyrophosphate media---A kinetic study. International Journal of Chemical Kinetics, 1995, 27(7):675- 690.

[24] Hobbie J E, Hobbie E A. Amino acid cycling in plankton and soil microbes studied with radioisotopes:measured amino acids in soil do not reflect bioavailability. Biogeochmistry, 2012, 107(1- 3):339- 360.

[25] Anraku Y, Kin E, Tanaka Y. Transport of sugars and amino acids in bacteria XV. Comparative studies on the effects of various energy poisons on the oxidative and phosphorylating activities, and energy coupling reactions for the active transport systems for amino acids inE.coli.. The Journal of Biochemistry, 1975, 78(1):165- 179.

[26] Kay W W, Gronlund A F. Transport of aromatic amino acids bypseudomonasaeruginosa. Journal of Bacteriology, 1971, 105(3):1039- 1046.

[27] Skopp J, Jawson M D, Doran J W. Steady-state aerobic microbial activity as a function of soil water content. Soil Science Society of America Journal, 1990, 54(6):1619- 1625.

[28] Kielland K, Olson K, Ruess R W, Boone R D. Contribution of winter processes to soil nitrogen flux in taiga forest ecosystems. Biogeochemistry, 2006, 81(3):340- 360.

[29] Juliette L Y, Hyman M R, Arp D J. Inhibition of ammonia oxidation innitrosomonaseuropaeaby Sulfur compounds:thioethers are oxidized to sulfoxides by ammonia monooxygenase. Applied and Environmental Microbiology, 1993, 59(11):3718- 3727.

[30] Avrahami S, Conrad R, Braker G. Effect of soil ammonium concentration on N2O release and on the community structure of ammonia oxidizers and denitrifiers. Applied and Environmental Microbiology, 2002, 68(11):5685- 5692.

[31] Wolf I, Brumme R. Dinitrogen and nitrous oxide formation in beech forest floor and mineral soils. Soil Science Society of America Journal, 2003, 67(6):1862- 1868.

[32] Arshad M, Hussain A, Javed M, Frankenberger Jr W T. Effect of soil applied L-methionine on growth, nodulation and chemical composition ofAlbizialebbeckL. Plant and Soil, 1993, 148(1):129- 135.

[33] Bonde T A, Nielsen T, Miller M, S?rensen J. Arginine ammonification assay as a rapid index of gross N mineralization in agricultural soils. Biology and Fertility of Soils, 2001, 34(3):179- 184.

[34] Vinolas L C, Healey J R, Jones D L. Kinetics of soil microbial uptake of free amino acids. Biology and Fertility of Soils, 2001, 33(1):67- 74.

[35] Rothstein D E. Effects of amino-acid chemistry and soil properties on the behavior of free amino acids in acidic forest soils. Soil Biology and Biochemistry, 2010, 42(10):1743- 1750.

Effects of amino acid additions on nitrogen transformation in subtropical forest soil

PEI Guangting1,2, MA Hongliang1,2,*, LIN Wei1,2, GAO Ren1,2, YIN Yunfeng1,2, YANG Liuming1,2

1CultivationBaseofStateKeyLaboratoryofHumidSubtropicalMountainEcology,Fuzhou350007,China2SchoolofGeographicalSciences,FujianNormalUniversity,Fuzhou350007,China

Research on the nitrogen cycle of forest soils has traditionally focused on the mechanisms regulating the turnover of inorganic N. However, the key role of organic N in soil nitrogen transformation tends to be overlooked. Over recent decades, researchers have assessed the relative importance of organic N on the nutritional requirements of plants in forest ecosystems. Most studies have revealed that soil amino acids are important sources of organic N in forest ecosystems. Although the fluxes of organic N in forest ecosystems have been studied in detail, we have a poor understanding about the role of amino acids in soil nitrogen transformation in the subtropical region of China. In this study, subtropical broad-leaved forest soil was collected from Wan Mulin Natural Reserve located at Fujian Province, southeast China. We selected four types of amino acids, including L-Glutamic acid, L-Lysine, L-Alanine, and L-Methionine as the study materials, which represented acidic, basic, neutral, and sulfur amino acids, respectively. Soils were incubated for 0, 2, 8, 12, 16, and 36 days in the laboratory after adding 0and 40mg N /kg amino acid. Soil moisture was maintained at 60%WHC (water-holding capacity) or 90%WHC. Ammonium N, nitrate N, soluble organic N, nitrous oxide, soil pH, and soluble organic C content were determined. Data were subjected to analysis of variance (ANOVA) with the SPSS version 18.0, and significant differences between treatments were compared by the LSD test atP<0.05.The results showed that soil NH+4-N content significantly increased with the addition of amino acids, with the repression of NH+4-N production under high soil moisture content conditions (90%WHC) being relieved to some extent. Soil pH was increased by the addition of amino acids, and was closely correlated with soil NH+4-N and NO-3-N. These results support the finding that an increase in soil pH may promote N mineralization in acidic forest soils. Acidic, basic, and neutral amino acids increased NH+4-N production in soil, but had little or no influence on NO-3-N production and nitrous oxide emission. Soil nitrification was significantly inhibited by the addition of methionine, resulting in the accumulation of NH+4-N. Nitrous oxide emission from soil as a whole increased with the addition of methionine. The decrease in SON under the amino acid treatments was more evident under 60%WHC than 90%WHC conditions. The turnover of amino acids in forest soil is very rapid, with NH+4-N being the major N form in soil. Nitrogen transformation in forest soil is probably related to the decomposed products of amino acid mineralization, rather than the charge of amino acids. These findings indicate that nitrogen transformation varies with amino acid type, and that the mechanism inhibiting methionine during nitrification needs further research. In conclusion, amino acids might represent the intermediate products between organic nitrogen and mineral nitrogen, regulating nitrogen transformation in forest soils.

amino acid; soil moisture content; subtropical forest soil; nitrogen transformation

國家自然科學(xué)基金項(xiàng)目(40901115, 41271282, 31070549, 31170578)；教育部創(chuàng)新團(tuán)隊(duì)項(xiàng)目(IRT0960)；福建省高校杰出青年科研人才培育計(jì)劃(JA12058)和福建師范大學(xué)優(yōu)秀青年骨干教師培養(yǎng)基金資助(fjsdjk2012069)

2014- 05- 11; < class="emphasis_bold">網(wǎng)絡(luò)出版日期:

日期:2015- 05- 18

10.5846/stxb201405110957

*通訊作者Corresponding author.E-mail:mhl936@163.com

裴廣廷，馬紅亮，林偉，高人，尹云鋒，楊柳明.氨基酸添加對亞熱帶森林紅壤氮素轉(zhuǎn)化的影響.生態(tài)學(xué)報(bào),2015,35(23):7774- 7784.

Pei G T, Ma H L, Lin W, Gao R, Yin Y F, Yang L M.Effects of amino acid additions on nitrogen transformation in subtropical forest soil.Acta Ecologica Sinica,2015,35(23):7774- 7784.