栗方亮,王煌平,張 青,王利民,安夢(mèng)魚(yú),3,羅 濤**

(1.福建省農(nóng)業(yè)科學(xué)院土壤肥料研究所 福州 350013; 2.中國(guó)科學(xué)院南京土壤研究所土壤與農(nóng)業(yè)可持續(xù)發(fā)展國(guó)家重點(diǎn)實(shí)驗(yàn)室 南京 210008; 3.福建農(nóng)林大學(xué)資源與環(huán)境學(xué)院 福州 350002)

室內(nèi)恒溫條件下稻田土壤中菌渣的分解過(guò)程及CO2釋放特征*

栗方亮1,2,王煌平1,張 青1,王利民1,安夢(mèng)魚(yú)1,3,羅 濤1**

(1.福建省農(nóng)業(yè)科學(xué)院土壤肥料研究所 福州 350013; 2.中國(guó)科學(xué)院南京土壤研究所土壤與農(nóng)業(yè)可持續(xù)發(fā)展國(guó)家重點(diǎn)實(shí)驗(yàn)室 南京 210008; 3.福建農(nóng)林大學(xué)資源與環(huán)境學(xué)院 福州 350002)

菌渣是栽培食用菌后的下腳料,可作為有機(jī)肥再利用。本文通過(guò)實(shí)驗(yàn)室條件下培養(yǎng)不同比例的菌渣和稻田土壤混合物[不施用菌渣(TS),土壤與菌渣質(zhì)量比為 10∶1(SM1)、5∶1(SM2)和 2∶1(SM3),全部菌渣(TM)],研究不同處理有機(jī)碳和全氮的變化,探討菌渣在稻田土壤中的分解過(guò)程,并分析 CO2釋放特征,為菌渣合理利用提供參考。結(jié)果表明,在相同培養(yǎng)時(shí)間,添加不同比例菌渣處理有機(jī)碳和氮含量均比 TS處理高,其中TM處理的有機(jī)碳和全氮分別比TS處理提高了10.7倍和11.0倍。有機(jī)碳、氮含量的提高量主要依賴(lài)于菌渣的添加量。總體來(lái)說(shuō),各處理隨培養(yǎng)時(shí)間的延長(zhǎng),由于碳氮的分解,有機(jī)碳、氮均有下降趨勢(shì); 在35 d后TM處理有機(jī)碳氮下降較快。添加菌渣越多,有機(jī)碳?xì)埩袈室苍酱?。在培養(yǎng)63 d后,菌渣有機(jī)碳(YC)和氮(YN)的分解殘留率與菌渣添加量(X)的關(guān)系式分別為:YC=71.26X-0.607 5,r2=1.000 0**和YN=74.039X-0.413 3,r2=0.999 9**。各處理土壤CO2釋放速率均表現(xiàn)出先增后降然后趨于穩(wěn)定趨勢(shì)。菌渣用量越高,CO2釋放速率越高,各處理在不同培養(yǎng)時(shí)間CO2釋放速率均表現(xiàn)為T(mén)M＞SM3＞SM2＞SM1＞TS。在第7 d時(shí)各處理CO2釋放速率最高,在第14 d時(shí)漸漸處于平穩(wěn)下降狀態(tài),培養(yǎng)35 d后,各處理土壤有機(jī)碳礦化強(qiáng)度很小,大部分有機(jī)碳被固定在土壤中,其中TM處理有機(jī)碳礦化強(qiáng)度最小?？傊?還田菌渣越多,土壤中被固定的碳越多。

菌渣; 稻田土壤; 有機(jī)碳; 全氮; 分解過(guò)程; CO2釋放

我國(guó)是食用菌的主產(chǎn)國(guó),每年因此產(chǎn)生的菌渣數(shù)量巨大[1]。菌渣是栽培食用菌后的下腳料[2-3],含有豐富的纖維素、木質(zhì)素、維生素、抗生素、礦質(zhì)元素和其他生物活性物質(zhì)等[2,4],可作為有機(jī)肥料或土壤改良劑還田再利用,還可用于植物激素提取、動(dòng)物飼料、能源原料[3,5-6]、作物育苗和生長(zhǎng)基質(zhì)等[7-9]。有關(guān)菌渣還田方面的研究主要以施用菌渣后植物生理指標(biāo)變化為主,如已有研究表明,施用菌渣可提高菠蘿[Ananas comosus(Linn.) Merr.]葉長(zhǎng)、葉片數(shù)、葉面積、株高等生理指標(biāo)[6]。姬松茸(Agaricus blazeiMurr.)和香菇[Lentinus edodes(Berk.) sing]菌渣可以促進(jìn)萵苣(Lactuca sativaL.)生長(zhǎng)和土壤修復(fù)[10],40%的菌渣用量對(duì)甜瓜(Cucumis meloL.)幼苗生長(zhǎng)最好[11]。菌渣的施用還可提高土壤微生物生物量碳和葡萄糖的含量[12-13],提高微生物的多樣性和酶活性[11],在一定程度上可改變土壤團(tuán)聚體分布[14]。而對(duì)于菌渣的分解特征方面則研究的較少。

土壤CO2的釋放是生態(tài)系統(tǒng)碳收支的重要組成部分之一[15-16]。施用有機(jī)物料能夠促進(jìn)土壤 CO2排放[17-21]。土壤CO2的釋放隨著土壤有機(jī)碳的增加而增加[22-24]。菌渣等有機(jī)物料還田后,一部分作為土壤有機(jī)碳的來(lái)源被土壤固定下來(lái),另一部分被固定的碳通過(guò)微生物的周轉(zhuǎn),又被以CO2形式釋放到大氣中[25]。Medina等[26]發(fā)現(xiàn)施用菌渣增加了土壤呼吸速率和磷酸酶活性。也有研究表明菌渣的施用并沒(méi)有顯著提高土壤CO2釋放[13,16],可能由于土壤呼吸受土壤類(lèi)型、濕度、溫度等限制[27],因此還需要進(jìn)一步深入研究。

土壤有機(jī)質(zhì)是平衡施肥的一個(gè)重要指標(biāo),其形成量不僅取決于進(jìn)入土壤的有機(jī)肥料數(shù)量,還取決于其腐解殘留率的大小[28]。摸清菌渣的分解規(guī)律,對(duì)科學(xué)地補(bǔ)償和更新土壤有機(jī)質(zhì),制定合理的菌渣培肥措施具有一定的理論和實(shí)際意義。盡管施用有機(jī)肥可以顯著增加 CO2的排放量[17-18,29],但不同有機(jī)物料中碳的轉(zhuǎn)化特征不同。而對(duì)于菌渣在稻田土壤中的施用效果及分解過(guò)程、菌渣的施用量與土壤呼吸的關(guān)系及CO2釋放特征,目前仍然研究得較少。本文即利用稻田施用菌渣定位試驗(yàn)基地為依據(jù),在實(shí)驗(yàn)室條件下探索菌渣在土壤中的分解過(guò)程及 CO2釋放特征,弄清菌渣施用量與土壤有機(jī)碳分解過(guò)程的定量關(guān)系,以期為土壤有機(jī)碳循環(huán)和 CO2源匯特征的理論奠定基礎(chǔ),為科學(xué)施用菌渣提供理論依據(jù),對(duì)土壤與農(nóng)業(yè)的可持續(xù)發(fā)展具有一定的意義。

1 材料與方法

1.1 采樣區(qū)自然概況

采集的水稻土來(lái)自菌渣肥施用長(zhǎng)期定位觀測(cè)站,該站位于福建省龍海市角美臺(tái)商投資區(qū)龍江村(117°53′46″E,24°34′16″N)。于2007年開(kāi)始種植雙季稻,水稻品種為雜交水稻‘豐兩優(yōu)1號(hào)’。試驗(yàn)初始時(shí)土壤基礎(chǔ)化學(xué)性狀為: pH 6.07,有機(jī)碳9.66 g·kg–1,全氮 2.70 g·kg–1,堿解氮 101.2 mg·kg–1,有效磷35.42 mg·kg–1,速效鉀99.03 mg·kg–1。

供試菌渣來(lái)自當(dāng)?shù)仉p孢蘑菇栽培戶(hù),經(jīng)過(guò)預(yù)處理粉碎測(cè)定其有機(jī)碳、全氮、全磷和全鉀含量為398.45 g·kg–1、18.8 g·kg–1、4.61 g·kg–1和6.37 g·kg–1,碳氮比為33.2。

1.2 試驗(yàn)設(shè)計(jì)與樣品采集

試驗(yàn)共設(shè)計(jì)5個(gè)處理。處理1: 不施用蘑菇菌渣(TS),全部為水稻土; 處理 2: 按土壤∶蘑菇菌渣= 10∶1(SM1)的質(zhì)量比在水稻土加入蘑菇菌渣; 處理3: 按土壤∶蘑菇菌渣=5∶1(SM2)的質(zhì)量比在水稻土加入蘑菇菌渣; 處理 4: 按土壤∶蘑菇菌渣=2∶1 (SM3)質(zhì)量比在水稻土加入蘑菇菌渣; 處理 5: 全部菌渣(TM),處理全部為蘑菇菌渣,3次重復(fù)。

分別稱(chēng)取以上比例過(guò)2 mm篩的水稻土和菌渣,充分混勻,每處理合計(jì)共200 g,置于1 000 mL塑料瓶中,調(diào)節(jié)土壤水分為田間飽和持水量的 70%,預(yù)培養(yǎng) 7 d,預(yù)培養(yǎng)環(huán)境同培養(yǎng)條件,目的是使土壤微生物活化。塑料瓶用保鮮膜封口以保持水分不致快速蒸發(fā),并針扎若干小孔以保證通氣,然后置于 25 ℃的恒溫培養(yǎng)箱中培養(yǎng),培養(yǎng)期間定期補(bǔ)水以維持試驗(yàn)設(shè)定的水分含量。在培養(yǎng)過(guò)程中的第7 d、21 d、35 d、49 d、63 d取樣,取樣時(shí)先將塑料瓶?jī)?nèi)土渣樣品充分混勻,取樣量約30 g,樣品于4 ℃下冷藏保存,并盡快進(jìn)行相關(guān)指標(biāo)的分析測(cè)定,3次重復(fù)。

另分別稱(chēng)取以上比例過(guò)2 mm篩的水稻土和菌渣混合物,每處理50 g,置于1 000 mL培養(yǎng)瓶中平鋪于瓶底部,調(diào)節(jié)土壤含水量為土壤最大持水量的70%。預(yù)培養(yǎng)7 d后,將盛有5 mL 0.6 mol·L–1NaOH溶液的特制容量瓶小心地置于培養(yǎng)瓶?jī)?nèi),將培養(yǎng)瓶加蓋密封,于(28±1) ℃的恒溫箱中培養(yǎng)。在培養(yǎng)的第1 d、3 d、7 d、14 d、21 d、28 d、35 d取出容量瓶,洗至錐形瓶中,加入1 mol·L–1BaCl2溶液2 mL,加兩滴酚酞指示劑,用標(biāo)準(zhǔn)酸滴定至紅色消失,計(jì)算CO2的釋放量[30],3次重復(fù)。

1.3 測(cè)定方法

土壤碳、氮的測(cè)定: 取樣土壤烘干稱(chēng)重后磨細(xì)過(guò) 100目篩,進(jìn)行土壤碳、氮含量的測(cè)定。有機(jī)碳用H2SO4-K2CrO7外加熱法測(cè)定,全氮用凱氏法測(cè)定[31]。

1.4 數(shù)據(jù)處理與統(tǒng)計(jì)分析

有機(jī)物料菌渣有機(jī)碳和氮的分解殘留率計(jì)算公式為:

式中:rC和rN分別表示有機(jī)碳和有機(jī)氮?dú)埩袈?g1C和g1N分別表示物料菌渣加土經(jīng)一定時(shí)間分解后的碳和氮含量,g2C和g2N分別表示對(duì)照土壤經(jīng)一定時(shí)間分解后的碳、氮含量,gC和gN分別表示加入的物料菌渣的碳、氮含量[32-33]。

土壤CO2釋放速率[mg(C)·kg–1·d–1]為單位質(zhì)量土壤(干土)單位時(shí)間內(nèi)礦化釋放的碳量(CO2-C)。土壤CO2累積釋放量[mg(C)·kg–1]為單位質(zhì)量土壤(干土)在某段培養(yǎng)期內(nèi)土壤礦化釋放的總碳量(CO2-C)。土壤有機(jī)碳礦化強(qiáng)度(礦化率)為在一定時(shí)間內(nèi)土壤CO2累積釋放量與土壤有機(jī)碳含量的比值。

由于在培養(yǎng)期間供試土壤的有機(jī)碳、氮也發(fā)生分解,添加的菌渣質(zhì)量則因礦化分解而下降,因此在計(jì)算中均進(jìn)行了校正(減去了對(duì)照土壤)。

采用Microsoft Excel軟件進(jìn)行數(shù)據(jù)整理,采用SPSS 16.0和DPS (v3.01專(zhuān)業(yè)版)軟件相結(jié)合進(jìn)行統(tǒng)計(jì)分析。

圖1 添加不同比例菌渣后不同時(shí)間水稻土有機(jī)碳含量的變化Fig.1 Changes of organic carbon contents in paddy soil after adding different proportions of spent mushroom substrates for different times

2 結(jié)果與分析

2.1 添加不同比例菌渣后土壤有機(jī)碳含量

從圖1可見(jiàn),在同一時(shí)間,添加不同比例菌渣后均能提高土壤有機(jī)碳的含量,且添加菌渣越多,土壤有機(jī)碳含量越高,土壤有機(jī)碳大小具體表現(xiàn)為: TM＞SM3＞SM2＞SM1＞TS,有機(jī)碳含量的提高量主要依賴(lài)于菌渣的添加量,且在同一時(shí)間,不同處理間土壤有機(jī)碳含量均達(dá)到顯著水平。

在培養(yǎng) 63 d后,不同比例菌渣 SM1、SM2和SM3處理土壤有機(jī)碳分別比不施蘑菇菌渣 TS處理提高86.7%、171.4%和351.4%,而全部菌渣處理TM有機(jī)碳比TS處理提高了10.7倍。

在35 d之后,TM處理有機(jī)碳下降相對(duì)較快,如49 d比35 d下降9.8%,差異顯著?？傮w來(lái)說(shuō),添加不同比例菌渣后,隨著培養(yǎng)時(shí)間的延長(zhǎng),土壤有機(jī)碳有下降趨勢(shì),但差異不太明顯(TM 處理除外),主要是由于碳的分解比較緩慢。

2.2 添加不同比例菌渣后有機(jī)碳分解殘留率

如圖2所示,在同一培養(yǎng)時(shí)間,添加菌渣越多,土壤有機(jī)碳?xì)埩袈试礁?土壤有機(jī)碳?xì)埩袈示唧w表現(xiàn)為: TM＞SM3＞SM2＞SM1＞TS,且在同一時(shí)間,不同處理間有機(jī)碳?xì)埩袈示_(dá)到顯著差異。

圖2 添加不同比例菌渣后不同時(shí)間水稻土碳的分解殘留率的變化Fig.2 Changes of decomposition rates of carbon in paddy soil after adding different proportions of spent mushroom substrates for different times

添加不同比例菌渣后,經(jīng)過(guò)63 d的培養(yǎng),不同處理中有機(jī)碳的分解是先經(jīng)歷相對(duì)快速分解的階段,之后進(jìn)入相對(duì)緩慢分解階段(圖2)。添加菌渣越多,有機(jī)碳分解殘留率也越大。在培養(yǎng)第7 d時(shí)，SM1、SM2、SM3和TM處理的有機(jī)碳分解殘留率分別為7.09%、13.39%、28.76%和94.33%,在培養(yǎng)第63 d時(shí),SM1、SM2、SM3和TM處理的有機(jī)碳分解殘留率分別為5.73%、11.34%、23.25%和70.62%。在63 d的培養(yǎng)后,不同比例菌渣有機(jī)碳分解殘留率與菌渣添加量呈極顯著正相關(guān)(YC=71.26X–0.607 5,r2=1.0**)。

2.3 添加不同比例菌渣后土壤全氮含量

土壤全氮含量通常用于衡量土壤氮素的基礎(chǔ)肥力,可反映土壤氮素的儲(chǔ)備情況。從圖3可見(jiàn),在同一時(shí)間,添加不同比例菌渣后均能提高土壤全氮的含量,且添加菌渣越多,土壤全氮含量越高,土壤全氮大小具體表現(xiàn)為: TM＞SM3＞SM2＞SM1＞TS,氮含量的提高量主要依賴(lài)于菌渣的添加量,且在同一時(shí)間,不同處理間全氮含量均達(dá)到顯著水平。

在培養(yǎng)63 d后,SM1、SM2和SM3處理的土壤全氮量分別比 TS處理提高 95.3%、186.7%和362.4%(圖3),而TM處理的土壤全氮量比TS處理提高11倍?？傮w表現(xiàn)為,添加菌渣后,隨著培養(yǎng)時(shí)間的延長(zhǎng),各處理土壤全氮有下降趨勢(shì),但差異不太明顯,主要是由于氮的分解比較緩慢; TM處理在35 d之后則土壤全氮下降相對(duì)較快,如49 d比35 d下降10.9%,差異顯著。

圖3 添加不同比例菌渣后不同時(shí)間水稻土全氮含量的變化Fig.3 Changes of total nitrogen contents in paddy soil after adding different proportions of spent mushroom substrates for different times

2.4 添加不同比例菌渣后土壤氮分解殘留率

氮分解殘留率是指有機(jī)物料中的有機(jī)氮礦化分解一定時(shí)間后的殘留率[33]。如圖4所示,在同一培養(yǎng)時(shí)間,添加菌渣越多,土壤氮分解殘留率越高,土壤氮分解殘留率具體表現(xiàn)為: TM＞SM3＞SM2＞SM1＞TS,且在同一時(shí)間,不同處理間氮分解殘留率均達(dá)到顯著差異。

由圖4可以看出,添加不同比例菌渣后,經(jīng)過(guò)63 d的培養(yǎng),氮的分解趨勢(shì)與有機(jī)碳大體相同,不同處理中氮的分解也是先經(jīng)歷相對(duì)快速分解階段,之后進(jìn)入相對(duì)緩慢分解階段。在培養(yǎng)第7 d時(shí)，SM1、SM2、SM3和TM處理氮分解殘留率分別為7.17%、13.40%、27.05%和91.36%; 當(dāng)培養(yǎng)第63 d時(shí),SM1、SM2、SM3和TM處理氮分解殘留率分別為6.28%、12.29%、23.87%和73.70%。在63 d的培養(yǎng)后,不同處理菌渣氮的分解殘留率與菌渣添加量呈極顯著正相關(guān)(YN=74.039X–0.413 3,r2=0.999 9**)。

圖4 添加不同比例菌渣后不同時(shí)間水稻土氮的分解殘留率的變化Fig.4 Changes of decomposition rates of nitrogen in paddy soil after adding different proportions of spent mushroom substrates for different times

2.5 添加不同比例菌渣后 CO2釋放速率和釋放量的變化

添加不同比例菌渣后，各處理土壤CO2釋放速率隨培養(yǎng)時(shí)間的動(dòng)態(tài)變化如圖5所示。35 d的培養(yǎng)期內(nèi),各處理土壤 CO2釋放速率均表現(xiàn)為先增加后降低然后趨于穩(wěn)定的趨勢(shì)。菌渣用量越高,CO2釋放速率越高,且各處理在第7 d時(shí)的CO2釋放速率最高,如TM處理在第7 d時(shí)為67.23 mg(C)·kg–1·d–1,其次為SM3處理為55.89 mg(C)·kg–1·d–1,且各處理在第7 d時(shí)CO2釋放速率與其他培養(yǎng)時(shí)間的CO2釋放速率差異顯著(P＜0.05)。各處理在第14 d時(shí)漸漸處于平穩(wěn)下降的狀態(tài)。各處理在各培養(yǎng)時(shí)間的CO2釋放速率大小為T(mén)M＞SM3＞SM2＞SM1＞TS。

圖5 添加不同比例菌渣后不同時(shí)間水稻土CO2釋放速率(a)和累積釋放量(b)的變化Fig.5 Changes of CO2release rates (a) and cumulative release rates (b) in paddy soil after adding different proportions of spent mushroom substrates for different times

土壤有機(jī)碳累積礦化釋放的CO2-C量是在一定時(shí)間內(nèi)土壤有機(jī)碳礦化為無(wú)機(jī)碳后所釋放的CO2數(shù)量(每千克干土釋放的 CO2-C釋放量計(jì)),它是土壤有機(jī)碳礦化速率的表征之一[34]。總體表現(xiàn)為，各處理土壤 CO2的累積釋放量呈前期增長(zhǎng)快,后期增長(zhǎng)慢的趨勢(shì)(圖5),與 CO2釋放速率的變化規(guī)律相符合。經(jīng)過(guò)35 d的培養(yǎng),各處理土壤CO2累積釋放量大小順序?yàn)?TM＞SM3＞SM2＞SM1＞TS,且各處理之間差異顯著。添加菌渣各處理(TM、SM3、SM2、SM1)分別比TS處理土壤CO2累積釋放量高8.9倍、6.4倍、3.5倍和2.0倍。

2.6 添加不同比例菌渣后土壤有機(jī)碳礦化強(qiáng)度變化

土壤有機(jī)碳礦化強(qiáng)度(礦化率)為在一定時(shí)間內(nèi)土壤 CO2累積釋放量與土壤有機(jī)碳含量的比值[34-35]。從圖6可以看出,經(jīng)過(guò)35 d的培養(yǎng)，添加不同比例菌渣處理的土壤有機(jī)碳礦化強(qiáng)度很小,大部分有機(jī)碳被固定在土壤中。不同土渣比(SM1、SM2、SM3)的土壤有機(jī)碳礦化強(qiáng)度分別比 TS處理高 57.61%、49.08%和41.07%,且達(dá)到顯著差異(P＜0.05),但SM1、SM2、SM3處理之間差異并不顯著; 而TM處理土壤有機(jī)碳礦化強(qiáng)度最小,且與其他處理差異顯著。

圖6 添加不同比例菌渣后不同時(shí)間水稻土的有機(jī)碳礦化強(qiáng)度Fig.6 Mineralization intensities of organic carbon in paddy soil after adding different proportions of spent mushroom substrates for different times

3 討論

3.1 菌渣在稻田土壤中的分解規(guī)律

有機(jī)物料的分解速率是評(píng)價(jià)有機(jī)物料在保持和改善土壤有機(jī)質(zhì)狀況、土壤肥力等方面所需的一項(xiàng)重要指標(biāo)。它受有機(jī)物料的種類(lèi)、化學(xué)組成、土壤類(lèi)型和分解環(huán)境等多種因素影響[36]。探明有機(jī)肥料的分解規(guī)律,對(duì)科學(xué)地補(bǔ)償和更新土壤有機(jī)質(zhì),制定合理的培肥措施等具有一定的理論和實(shí)際意義[28]。

當(dāng)不同類(lèi)型有機(jī)肥在等量施用時(shí),由于其來(lái)自不同動(dòng)、植物,所含有的碳、氮等元素成分質(zhì)量并不相同,施用后也可能造成不同的土壤 CO2排放量和分解速率。如李傳章[24]研究發(fā)現(xiàn)玉米秸稈分解速率最快,年分解率達(dá)到 74.53%; 草炭分解最慢,年分解率僅為 28.31%,這可能與有機(jī)物料的性質(zhì)及C/N差異有關(guān),草炭本身性質(zhì)穩(wěn)定,最難分解。本研究發(fā)現(xiàn),添加不同比例菌渣后,經(jīng)過(guò) 63 d的培養(yǎng),不同處理有機(jī)碳和氮的分解是先有一個(gè)相對(duì)快速分解階段,之后進(jìn)入相對(duì)緩慢分解階段。這主要是因?yàn)樵诜纸馇捌诰械目扇苄杂袡C(jī)物較多,加之菌渣還田為微生物提供了大量的碳源和能源,微生物數(shù)量增多,活性增強(qiáng),隨著腐解的進(jìn)行,菌渣中可溶性有機(jī)物逐漸減少,且微生物活性隨著有機(jī)物料的消耗而降低,菌渣的腐解也就隨之變慢[37]。同樣柳敏等[32]研究玉米秸稈和豬糞的分解進(jìn)程發(fā)現(xiàn),有機(jī)物料中有機(jī)碳和有機(jī)氮的分解進(jìn)程與本研究一致。本研究還發(fā)現(xiàn),有機(jī)碳的分解殘留率稍微低于氮,這一方面是因?yàn)榉纸膺^(guò)程中碳的損失大于氮,另一方面是因?yàn)榫哂懈逤/N的物料在分解過(guò)程中可能發(fā)生自生固氮作用[36]。而柳敏等[32]證明秸稈和豬糞等有機(jī)物料中有機(jī)氮的礦化速率均明顯低于有機(jī)碳,其有機(jī)氮的殘留率遠(yuǎn)高于有機(jī)碳,豬糞處理分解緩慢,其C/N值接近土壤腐殖質(zhì)的C/N,約為10,已完成其腐殖化過(guò)程,其有機(jī)碳的分解殘留率遠(yuǎn)高于玉米秸稈處理。這說(shuō)明,有機(jī)物料類(lèi)型(不同 C/N比)、不同氣候類(lèi)型、不同土壤性質(zhì)都是影響有機(jī)碳和有機(jī)氮分解殘留率不同的因素。

總體來(lái)說(shuō),本研究證明添加菌渣的分解速率比添加其他有機(jī)物料要慢。同樣婁燕宏等[33]研究發(fā)現(xiàn)菌渣處理分解緩慢,其氮的分解殘留率遠(yuǎn)高于雞糞。菌渣處理分解緩慢的原因,一方面可能是由于易分解的氮在出菇的過(guò)程中已有一部分完成礦化分解; 另一方面可能是高 C/N的有機(jī)物料在分解過(guò)程中礦質(zhì)氮可能重新被土壤微生物吸收,成為微生物固持的氮[32]。

3.2 添加菌渣后土壤CO2的釋放特征

土壤有機(jī)碳礦化是土壤有機(jī)碳循環(huán)的重要過(guò)程,是有機(jī)碳輸出的重要途徑,直接影響到土壤中養(yǎng)分元素釋放與供應(yīng)、CO2氣體的排放等[34,37]。土壤有機(jī)碳礦化強(qiáng)度能反映土壤中有機(jī)質(zhì)分解及土壤養(yǎng)分供應(yīng)狀況[37]。大量研究表明施用有機(jī)物料能夠促進(jìn)土壤中CO2的釋放[17-18]。

如戴萬(wàn)宏等[38]發(fā)現(xiàn)施用廄肥和秸稈的土壤 CO2釋放量明顯高于不施肥處理。李夢(mèng)雅等[39]的研究表明,不同施肥處理紅壤潛在有機(jī)碳礦化 CO2-C釋放量的大小順序?yàn)槭┯袡C(jī)肥＞有機(jī)肥配合化肥＞秸稈還田配合化肥＞不施肥。施入秸稈和有機(jī)肥而導(dǎo)致的CO2排放量的增加,并不對(duì)大氣 CO2升高有直接貢獻(xiàn),相反可以增加土壤對(duì)碳的固定,緩解土壤碳釋放對(duì)大氣CO2濃度升高的影響[39]。本研究結(jié)果表明,添加不同比例菌渣后在 35 d的培養(yǎng)期內(nèi),各處理土壤CO2釋放速率均表現(xiàn)出先增加后降低然后趨于穩(wěn)定的趨勢(shì),與前人研究的添加秸稈等結(jié)果類(lèi)似[23,35,40-42]。這主要是因?yàn)樘砑泳?由于食用菌菌渣中富含蛋白質(zhì)、氮磷鉀、以及中、微量元素等主要營(yíng)養(yǎng)元素,還含有灰分、粗脂肪、粗蛋白、粗纖維和多種氨基酸等。菌渣作為外援有機(jī)物施入土壤,為微生物提供易利用的營(yíng)養(yǎng)物質(zhì)和能源物質(zhì),從而促進(jìn)了土壤呼吸。在前期,菌渣和土壤中易分解組分快速分解,土壤有機(jī)碳的礦化速率和礦化量增長(zhǎng)迅速,但是隨著培養(yǎng)時(shí)間的延長(zhǎng),易分解組分被微生物利用殆盡,開(kāi)始轉(zhuǎn)向利用較難分解組分,礦化速率隨之減緩,有機(jī)碳分解量也相應(yīng)下降。

添加不同比例菌渣培養(yǎng)35 d后,土壤有機(jī)碳礦化強(qiáng)度均很小,大部分有機(jī)碳被固定在土壤中,其中 TM 處理有機(jī)碳礦化強(qiáng)度最小,這說(shuō)明還田菌渣越多,被固定的碳越多,這與秸稈還田效果類(lèi)似[23]。

4 結(jié)論

在同一時(shí)間,添加不同比例菌渣后均能提高土壤有機(jī)碳和全氮的含量,且添加菌渣越多,土壤有機(jī)碳和全氮含量越高,土壤有機(jī)碳和全氮大小具體表現(xiàn)為: TM＞SM3＞SM2＞SM1＞TS,有機(jī)碳、氮含量的提高量主要依賴(lài)于菌渣的添加量,且在同一時(shí)間,不同處理間土壤有機(jī)碳和全氮均達(dá)到差異顯著水平。

總體來(lái)說(shuō),各處理隨培養(yǎng)時(shí)間的延長(zhǎng),由于碳氮的分解,有機(jī)碳、氮均有下降趨勢(shì)。添加不同比例菌渣后,經(jīng)過(guò)63 d的培養(yǎng),不同處理有機(jī)碳和氮的分解是先有一個(gè)相對(duì)快速分解階段,之后進(jìn)入相對(duì)緩慢分解階段。在培養(yǎng) 63 d后,菌渣有機(jī)碳(YC)和氮(YN)的分解殘留率與菌渣添加量(X)的關(guān)系式分別為:YC=71.26X-0.607 5,r2=1.000 0**和YN=74.039X-0.413 3,r2=0.999 9**。各處理土壤CO2釋放速率均表現(xiàn)出先增后降然后趨于穩(wěn)定趨勢(shì)。菌渣用量越高,CO2釋放速率越高,各處理在不同培養(yǎng)時(shí)間 CO2釋放速率均表現(xiàn)為T(mén)M＞SM3＞SM2＞SM1＞TS。在第7 d時(shí)各處理CO2釋放速率最高,在第14 d時(shí)漸漸處于平穩(wěn)下降狀態(tài),培養(yǎng) 35 d后,各處理土壤有機(jī)碳礦化強(qiáng)度很小,大部分有機(jī)碳被固定在土壤中,其中TM處理有機(jī)碳礦化強(qiáng)度最小,還田菌渣越多,被固定的碳也越多。

本研究是在室內(nèi)、小樣本、恒溫培養(yǎng)條件下進(jìn)行的,而在大田條件下,影響菌渣的分解及土壤CO2釋放的因素比較復(fù)雜,因此還需要進(jìn)一步驗(yàn)證。

References

[1]翁伯琦,廖建華,羅濤,等.發(fā)展農(nóng)田秸稈菌業(yè)的技術(shù)集成與資源循環(huán)利用管理對(duì)策[J].中國(guó)生態(tài)農(nóng)業(yè)學(xué)報(bào),2009,17(5): 1007–1011 Weng B Q,Liao J H,Luo T,et al.Integrative technology of straw-edible fungi industry and management countermeasure for resource recycling utilization[J].Chinese Journal of Eco-Agriculture,2009,17(5): 1007–1011

[2]Stewart D P C,Cameron K C,Cornforth I S.Effects of spent mushroom substrate on soil chemical conditions and plant growth in an intensive horticultural system: A comparison with inorganic fertiliser[J].Australian Journal of Soil Research,1998,36(2): 185–198

[3]Phan C W,Sabaratnam V.Potential uses of spent mushroom substrate and its associated lignocellulosic enzymes[J].Applied Microbiology and Biotechnology,2012,96(4): 863–873

[4]Wang S X,Xu F,Li Z M,et al.The spent mushroom substrates ofHypsizigus marmoreuscan be an effective component for growing the oyster mushroomPleurotus ostreatus[J].Scientia Horticulturae,2015,186: 217–222

[5]Kalembasa D,Becher M.Speciation of carbon and selected metals in spent mushroom substrates[J].Journal of Elementology,2012,17(3): 409–419

[6]Adedokun O M,Orluchukwu J A.Pineapple: Organic production on soil amended with spent mushroom substrate[J].Agriculture and Biology Journal of North America,2013,4(6): 590–593

[7]Medina E,Paredes C,Pérez-Murcia M D,et al.Spent mushroom substrates as component of growing media for germination and growth of horticultural plants[J].Bioresource Technology,2009,100(18): 4227–4232

[8]Sharma H S S,Furlan A,Lyons G.Comparative assessment of chelated spent mushroom substrates as casing material for the production ofAgaricus bisporus[J].Applied Microbiology and Biotechnology,1999,52(3): 366–372

[9]Zhou Q,Gong W Q,Li Y B,et al.Biosorption of Methylene Blue onto spent corncob substrate: Kinetics,equilibrium and thermodynamic studies[J].Water Science and Technology,2011,63(12): 2775–2780

[10]Ribas L C C,de Mendon?a M M,Camelini C M,et al.Use of spent mushroom substrates fromAgaricus subrufescens(syn.A.blazei,A.brasiliensis) andLentinula edodesproductions in the enrichment of a soil-based potting media for lettuce (Lactuca sativa) cultivation: Growth promotion and soil bioremediation[J].Bioresource Technology,2009,100(20): 4750–4757

[11]Tam N V,Wang C H.Use of spent mushroom substrate and manure compost for honeydew melon seedlings[J].Journal of Plant Growth Regulation,2015,34(2): 417–424

[12]Peregrina F,Larrieta C,Colina M,et al.Spent mushroom substrates influence soil quality and nitrogen availability in a semiarid vineyard soil[J].Soil Science Society of America Journal,2012,76(5): 1655–1666

[13]René M,Rémi C.Long-term additions of organic amendments in a Loire valley vineyard.Ⅰ.Effects on properties of a calcareous sandy soil[J].American Journal of Enology and Viticulture,2008,59(4): 353–363

[14]栗方亮,王煌平,張青,等.稻田施用菌渣土壤團(tuán)聚體的組成及評(píng)價(jià)[J].生態(tài)與農(nóng)村環(huán)境學(xué)報(bào),2015,31(3): 340–345 Li F L,Wang H P,Zhang Q,et al.Effect of application of mushroom residue on composition of soil aggregates in paddy field and its evaluation[J].Journal of Ecology and Rural Environment,2015,31(3): 340–345

[15]Zhang Y,Li C S,Zhou X J,et al.A simulation model linking crop growth and soil biogeochemistry for sustainable agriculture[J].Ecological Modelling,2002,151(1): 75–108

[16]Carlisle E A,Steenwerth K L,Smart D R.Effects of land use on soil respiration: Conversion of oak woodlands to vineyards[J].Journal of Environmental Quality,2006,35(4): 1396–1404

[17]Ding W X,Meng L,Yin Y F,et al.CO2emission in an intensively cultivated loam as affected by long-term application of organic manure and nitrogen fertilizer[J].Soil Biology and Biochemistry,2007,39(2): 669–679

[18]Singh K P,Ghoshal N,Singh S.Soil carbon dioxide flux,carbon sequestration and crop productivity in a tropical dryland agroecosystem: Influence of organic inputs of varying resource quality[J].Applied Soil Ecology,2009,42(3): 243–253

[19]Priha O,Smolande A.Fumigation-extraction and substrateinduced respiration derived microbial biomass C,and respiration rate in limed soil of scots pine sapling stands[J].Biology and Fertility of Soils,1994,17(4): 301–308

[20]Xiao Y,Xie G D,Lu C X,et al.The value of gas exchange as a service by rice paddies in suburban Shanghai,PR China[J].Agriculture,Ecosystems & Environment,2005,109(3/4): 273–283

[21]Zheng J F,Zhang X H,Li L Q,et al.Effect of long-term fertilization on C mineralization and production of CH4and CO2under anaerobic incubation from bulk samples and particle size fractions of a typical paddy soil[J].Agriculture,Ecosystems & Environment,2007,120(2/4): 129–138

[22]Mariscal-Sancho I,Santano J,Mendiola M á,et al.Carbon dioxide emission rates and β-Glucosidase activity in Mediterranean ultisols under different soil management[J].Soil Science,2010,175(9): 453–460

[23]強(qiáng)學(xué)彩,袁紅莉,高旺盛.秸稈還田量對(duì)土壤 CO2釋放和土壤微生物量的影響[J].應(yīng)用生態(tài)學(xué)報(bào),2004,15(3): 469–472 Qiang X C,Yuan H L,Gao W S.Effect of crop-residue incorporation on soil CO2emission and soil microbial biomass[J].Chinese Journal of Applied Ecology,2004,15(3): 469–472

[24]李傳章.不同有機(jī)肥分解轉(zhuǎn)化特性及土壤培肥效果的研究[D].南寧: 廣西大學(xué),2012 Li C Z.The research on decomposition properties of different organic fertilizer and effect of increasing soil fertility[D].Nanning: Guangxi University,2012

[25]嚴(yán)紅,湜魏 ,張雷,等.有機(jī)物料施用量對(duì)土壤CO2排放速率的影響[J].大連大學(xué)學(xué)報(bào),2005,26(4): 46–50 Yan H,Wei S,Zhang L,et al.Influence of organic material amount on CO2released rate from the soil[J].Journal of Dalian University,2005,26(4): 46–50

[26]Medina E,Paredes C,Bustamante M A,et al.Relationships between soil physico-chemical,chemical and biological properties in a soil amended with spent mushroom substrate[J].Geoderma,2012,173–174: 152–161

[27]Steenwerth K L,Pierce D L,Carlisle E A,et al.A vineyard agroecosystem: Disturbance and precipitation affect soil respiration under Mediterranean conditions[J].Soil Science Society of America Journal,2010,74(1): 231–239

[28]遲鳳琴,匡恩俊,宿慶瑞,等.不同還田方式下有機(jī)物料有機(jī)碳分解規(guī)律研究[J].東北農(nóng)業(yè)大學(xué)學(xué)報(bào),2010,41(2): 60–65 Chi F Q,Kuang E J,Su Q R,et al.Study on organic carbon decomposition regularity of organic materials in different incorporation methods[J].Journal of Northeast Agricultural University,2010,41(2): 60–65

[29]Galantini J,Rosell R.Long-term fertilization effects on soil organic matter quality and dynamics under different production systems in semiarid Pampean soils[J].Soil and Tillage Research,2006,87(1): 72–79

[30]李忠佩,吳曉晨,陳碧云.不同利用方式下土壤有機(jī)碳轉(zhuǎn)化及微生物群落功能多樣性變化[J].中國(guó)農(nóng)業(yè)科學(xué),2007,40(8): 1712–1721 Li Z P,Wu X C,Chen B Y.Changes in transformation of soil organic carbon and functional diversity of soil microbial community under different land use patterns[J].Scientia Agricultura Sinica,2007,40(8): 1712–1721

[31]魯如坤.土壤農(nóng)業(yè)化學(xué)分析方法[M].北京: 中國(guó)農(nóng)業(yè)科技出版社,2000 Lu R K.Analytical Methods for Soil and Agricultural Chemistry[M].Beijing: China Agricultural Science and Technology Press,2000

[32]柳敏,張璐,宇萬(wàn)太,等.有機(jī)物料中有機(jī)碳和有機(jī)氮的分解進(jìn)程及分解殘留率[J].應(yīng)用生態(tài)學(xué)報(bào),2007,18(11): 2503–2506 Liu M,Zhang L,Yu W T,et al.Decomposition process and residual rate of organic materials C and N in soils[J].Chinese Journal of Applied Ecology,2007,18(11): 2503–2506

[33]婁燕宏,諸葛玉平,魏猛,等.外源有機(jī)物料對(duì)土壤氮礦化的影響[J].土壤通報(bào),2009,40(2): 315–320 Lou Y H,Zhuge Y P,Wei M,et al.Effect of extraneous organic materials on the mineralization of nitrogen in soil[J].Chinese Journal of Soil Science,2009,40(2): 315–320

[34]李順姬,邱莉萍,張興昌.黃土高原土壤有機(jī)碳礦化及其與土壤理化性質(zhì)的關(guān)系[J].生態(tài)學(xué)報(bào),2010,30(5): 1217–1226 Li S J,Qiu L P,Zhang X C.Mineralization of soil organiccarbon and its relations with soil physical and chemical properties on the Loess Plateau[J].Acta Ecologica Sinica,2010,30(5): 1217–1226

[35]張杰,黃金生,劉佳,等.秸稈、木質(zhì)素及其生物炭對(duì)潮土CO2釋放及有機(jī)碳含量的影響[J].農(nóng)業(yè)環(huán)境科學(xué)學(xué)報(bào),2015,34(2): 401–408 Zhang J,Huang J S,Liu J,et al.Carbon dioxide emissions and organic carbon contents of fluvo-aquic soil as influenced by straw and lignin and their biochars[J].Journal of Agro-Environment Science,2015,34(2): 401–408

[36]任秋容.菌渣還田腐解特性及其對(duì)土壤養(yǎng)分和作物產(chǎn)量的影響研究[D].雅安: 四川農(nóng)業(yè)大學(xué),2009 Ren Q R.Study on decomposition characteristics of mushroom residue returning to soil and its effect on soil nutrient and crop yield[D].Ya’an: Sichuan Agricultural University,2009

[37]李忠佩,張?zhí)伊?陳碧云.可溶性有機(jī)碳的含量動(dòng)態(tài)及其與土壤有機(jī)碳礦化的關(guān)系[J].土壤學(xué)報(bào),2004,41(4): 544–552 Li Z P,Zhang T L,Chen B Y.Dynamics of soluble organic carbon and its relation to mineralization of soil organic carbon[J].Acta Pedologica Sinica,2004,41(4): 544–552

[38]戴萬(wàn)宏,劉軍,王益權(quán),等.不同培肥措施下土壤CO2釋放及其動(dòng)力學(xué)研究[J].植物營(yíng)養(yǎng)與肥料學(xué)報(bào),2002,8(3): 292–297 Dai W H,Liu J,Wang Y Q,et al.Study on CO2emissions and its kinetics of soils with different fertilization systems[J].Plant Nutrition and Fertilizer Science,2002,8(3): 292–297

[39]李夢(mèng)雅,王伯仁,徐明崗,等.長(zhǎng)期施肥對(duì)紅壤有機(jī)碳礦化及微生物活性的影響[J].核農(nóng)學(xué)報(bào),2009,23(6): 1043–1049 Li M Y,Wang B R,Xu M G,et al.Effect of long-term fertilization on mineralization of organic carbon and microbial activity in red soil[J].Journal of Nuclear Agricultural Sciences,2009,23(6): 1043–1049

[40]Kemmitt S J,Lanyon C V,Waite I S,et al.Mineralization of native soil organic matter is not regulated by the size,activity or composition of the soil microbial biomass—a new perspective[J].Soil Biology and Biochemistry,2008,40(1): 61–73

[41]West T O,Marland G.A synthesis of carbon sequestration,carbon emissions,and net carbon flux in agriculture: Comparing tillage practices in the United States[J].Agriculture,Ecosystems & Environment,2002,91(1/2/3): 217–232

[42]Mohamad R S,Verrastro V,Bitar L A,et al.Effect of different agricultural practices on carbon emission and carbon stock in organic and conventional olive systems[J].Soil Research,2016,54(2): 173–181

Decomposition process and CO2release characteristics of spent mushroom substrate in paddy soils*

LI Fangliang1,2,WANG Huangping1,ZHANG Qing1,WANG Limin1,AN Mengyu1,3,LUO Tao1**
(1.Institute of Soil and Fertilizer,Fujian Academy of Agricultural Sciences,Fuzhou 350013,China; 2.State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China; 3.College of Resources and Environmental Sciences,Fujian Agriculture and Forestry University,Fuzhou 350002,China)

Spent mushroom substrate (SMS),leftovers after cultivation of mushroom,could serve as an organic fertilizer.Inthis study,different proportions of SMS were mixed into paddy rice soils under laboratory conditions to study the relationship between application of SMS and soil organic carbon decomposition,and further provide reference for the rational utilization of SMS for sustainable agricultural development.The study consisted of 5 treatments—no SMS application (TS),SMS mix with paddy rice soil at 10∶1 (SM1),SMS mix with paddy rice soil at 5∶1 (SM2),SMS mix with paddy rice soil at 2∶1 (SM3) and sole SMS medium (TM).Then changes in soil organic carbon and nitrogen,decomposition process of organic carbon in soils and CO2release characteristics in each treatment were determined.The results showed that soil organic carbon and total nitrogen contents under different proportions of SMS treatments were significantly higher than those under TS treatment for the same incubation time.Increase in organic carbon and total nitrogen contents mainly depended on the amount of SMS added to the soil.TM treatment showed the most obvious effect,which increased soil organic carbon and total nitrogen contents by 10.7 and 11.0 times,respectively.With increasing duration of incubation time,soil organic carbon and nitrogen decreased with the decomposition of carbon and nitrogen in all the treatments.Also organic carbon and nitrogen decreased relatively quickly under TM treatment after 35 d.The more SMS supply,the greater was the residue rate.After 63 d of cultivation,the relationships between the residue rates of organic carbon (YC) and nitrogen (YN) with the amount of SMS (X) were as follows:YC= 71.26X- 0.607 5 (r2= 1.000 0**) andYN= 74.039X- 0.413 3 (r2= 0.999 9**).The release rates of CO2in all the treatments increased initially and then decreased before stabilization.The higher the amount of SMS,the higher was the release rate of CO2.On the 7thd after cultivation,the release rate of CO2was highest in each treatment.After 14 d of cultivation,the release rate of CO2in each treatment gradually decreased at a steady state.The order of the release rate of CO2during the culturing period was TM ＞ SM3 ＞ SM2 ＞ SM1 ＞ TS.The cumulative release of CO2showed a rapid growth in the early and slowed growth in the late periods.Mineralization intensity of soil organic carbon was very small after 35 d of cultivation and most of the organic carbon was fixed in the soil.In all the treatments,TM showed the lowest organic carbon mineralization intensity,indicating that SMS was beneficial for soil carbon sequestration.

Spent mushroom substrate (SMS); Paddy rice soil; Organic carbon; Total nitrogen; Decomposition process; CO2release

S158.2

: A

: 1671-3990(2017)02-0267-09

10.13930/j.cnki.cjea.160678

栗方亮,王煌平,張青,王利民,安夢(mèng)魚(yú),羅濤.室內(nèi)恒溫條件下稻田土壤中菌渣的分解過(guò)程及CO2釋放特征[J].中國(guó)生態(tài)農(nóng)業(yè)學(xué)報(bào),2017,25(2): 267-275

Li F L,Wang H P,Zhang Q,Wang L M,An M Y,Luo T.Decomposition process and CO2release characteristics of spent mushroom substrate in paddy soils[J].Chinese Journal of Eco-Agriculture,2017,25(2): 267-275

* 土壤與農(nóng)業(yè)可持續(xù)發(fā)展國(guó)家重點(diǎn)實(shí)驗(yàn)室(中國(guó)科學(xué)院南京土壤研究所)開(kāi)放基金(Y412201437)、福建省屬公益類(lèi)基本科研專(zhuān)項(xiàng)(2015R1022-8)和“十二五”國(guó)家科技支撐計(jì)劃(2012BAD14B15)資助

** 通訊作者: 羅濤,主要從事農(nóng)業(yè)環(huán)境研究。E-mail: luotaofjfz@188.com

栗方亮,主要從事農(nóng)業(yè)環(huán)境與土壤生態(tài)研究。E-mail: lifl007@qq.com

2016-08-03 接受日期: 2016-10-09

* Supported by the Open Foundation of State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences (Y412201437); the Basic Scientific Research Projects for Public Welfare of Fujian Province (2015R1022-8); and the National Key Technologies R&D Program of China (2012BAD14B15)

** Corresponding author,E-mail: luotaofjfz@188.com

Received Aug.3,2016; accepted Oct.9,2016