秸秆对猪粪静态兼性堆肥无害化和腐熟度的影响

2023-06-12 05:22尹子铭唐若兰鲍紫阳李丽琼彭丽娟李国学
农业工程学报 2023年7期
关键词:堆体大肠菌群猪粪

尹子铭,杨 燕,唐若兰,鲍紫阳,李丽琼,彭丽娟,李国学,袁 京

秸秆对猪粪静态兼性堆肥无害化和腐熟度的影响

尹子铭,杨 燕,唐若兰,鲍紫阳,李丽琼,彭丽娟,李国学,袁 京※

(中国农业大学资源与环境学院农田土壤污染防控与修复北京市重点实验室,北京 100193)

为促进猪粪静态兼性堆肥产品无害化和腐熟,通过添加玉米秸秆调控堆体物理结构特性和碳氮比,采用传统自然发酵方式进行为期90 d的静态兼性堆肥试验,分别设置纯猪粪处理(P)和秸秆调控处理(PC)研究静态兼性堆肥过程腐熟度指标、粪大肠菌群以及微生物群落结构演变特征。结果表明,秸秆调控增加了堆体孔隙率(提高19.41%),促进氧气向堆体内部扩散,增强了好氧微生物对有机质的降解,降低NH4+-N,可溶性有机氮(dissolved total nitrogen, DTN)等植物毒性物质含量,提升了堆肥腐熟度,两组处理堆肥产品种子发芽指数分别为40.84%(P)和114.60%(PC)。静态兼性堆肥经过30~40 d自然发酵后,粪大肠菌群数量达到卫生安全标准,堆体温度、NH4+-N和有机酸含量均会影响粪大肠杆菌的活性。堆体中微生物以厚壁菌门、放线菌门、变形菌门等与木质纤维素降解相关的菌门为优势菌门,堆体自上而下由好氧菌属演替为厌氧菌属,并形成好氧、兼性、厌氧的微生物分层。秸秆调控增加了堆体的好氧区域,促进和提高了猪粪静态兼性堆肥无害化和腐熟度。

秸秆;品质控制;静态兼性堆肥;粪大肠菌群;微生物群落

0 引 言

随着经济的迅速发展以及人民生活水平的逐步提高,生猪养殖业规模不断加大,中国2020年生猪出栏数达4.07亿头,粪尿年产生量已达8.41亿t[1]。猪粪含有较高的有机质、N、P、K及微量元素,若未能得到有效的资源化处理,会导致严峻的环境污染问题[2]。同时,农业科技进步也带动农业生产水平大幅提升,农作物秸秆产量也随之增加[3],达到8亿t/a,居世界首位。对粪便和秸秆进行无害化处理并加以合理利用,不但能解决污染问题,而且能将其转化为农业生产的宝贵资源[4]。高温好氧堆肥技术具有周期短,腐熟彻底,腐殖化程度高等优点,是实现资源化利用的有效途径之一[5],但高温好氧堆肥技术需配备专业的机械设备,且为保障堆体内氧气含量满足微生物需求,常依赖于强制鼓风或翻堆处理,存在成本高等问题。目前在中国中小型养殖场和散养户,高温好氧堆肥处理技术并不普遍。

传统静态兼性堆肥技术无需专业的通风设备,主要通过空气自由扩散提供微好氧发酵条件,可通过有机质较长时间降解实现堆肥无害化和腐熟。与高温好氧堆肥相比,静态兼性堆肥温度整体较低,保持在20~40 ℃之间。受农业季节性用肥的原因,静态兼性堆肥技术是目前广泛采用的低成本轻简化的就地就近资源化利用方式,目前中国60%以上的畜禽粪便,尤其是猪粪,普遍采用静态兼性堆肥技术[6]。静态兼性堆肥过程空气扩散深度有限,堆体氧气含量低,呈现兼性好氧环境,导致微生物代谢活性低,不利于有机物降解,存在发酵周期较长、发酵温度低[7]、无害化不彻底以及产品腐熟度低等问题。

为提高静态兼性堆肥产品腐熟度,以堆体物理结构特性和物料碳氮比为出发点,采用猪粪和秸秆作为性能较好的互补辅料[8]。在猪粪中添加适宜比例的秸秆可增加堆体孔隙率并调节C/N[9],利于空气向堆体内部扩散,提高堆体微生物的代谢活性[10-11]。大量研究表明,畜禽粪便与作物秸秆协同堆肥可显著提高堆肥产品的稳定性和腐熟程度[12-13]。XU等[14]研究发现秸秆添加可以通过调节堆肥原料中氧气含量和C/N等特性缩短腐熟期。ZHOU等[15-16]利用锯末、秸秆和废蘑菇基质等碳源膨松剂调节原料C/N,可以减少温室气体和NH3的排放,并提高腐熟度。LIU等[17]在鸡粪、猪粪、牛粪中添加秸秆进行堆肥,发现秸秆调控可极大地促进有机质的降解,促进堆肥腐熟。但关于秸秆调控如何影响静态兼性堆肥腐熟度和微生物群落结构的研究还较少,尤其是对病原菌变化的影响几乎未有报道。

因此,本研究选择产量大且易获取的玉米秸秆作为调节猪粪静态兼性堆肥性质的辅料,通过研究猪粪静态兼性堆肥过程理化性质、腐熟度溶解性碳氮含量、粪大肠菌群变化和微生物群落演替,结合RDA(redundancy analysis)及相关性分析揭示猪粪静态兼性堆肥过程病原菌灭活和堆肥产物腐熟机制,拟为畜禽粪便静态兼性堆肥技术提供理论依据和技术标准化支撑。

1 材料和方法

1.1 供试材料

静态兼性堆肥试验原料为新鲜猪粪和玉米秸秆,猪粪取自畜禽分中心昌平试验基地,耕层土和玉米秸秆取自中国农业大学上庄实验站,玉米秸秆经自然风干后粉碎成10~50 mm的均匀小段,堆肥基本理化性质见表1。

表1 静态兼性堆肥原材料基本理化性质

注:a基于干基;b基于湿基。

Note: a is based on the dry weight, b is based on the wet weight.

1.2 试验设计

试验设置2个处理,猪粪不添加辅料作为对照,标记为P处理;猪粪与玉米秸秆按4:1的湿基质量比混合堆肥,标记为PC处理。为降低静态兼性堆肥过程污染气体排放,模拟小规模养殖场普遍采用的耕层土覆盖方式,在猪粪堆体(50 cm)表层覆盖耕层土(15 cm),静态兼性堆肥周期为90 d。试验装置为100 L法兰铁箍桶(图1),口径40 cm,桶体直径50 cm,底部直径35 cm,桶体高度80 cm。在堆体中间插入温度传感器,记录堆肥温度,发酵桶顶部敞开,呈自然通风方式。

分别在静态兼性堆肥的第0、10、20、50和80天称重取样,第90天取堆肥上层(Upper layers,U;0~15 cm)、中层(Middle layers,M;15~35 cm)和下层(Bottom layers,B;35~50 cm)样品。用四分法多点采集固体样品约200 g分两部分保存,一部分于4 ℃的冷藏冰箱保存,用于测定pH值、电导率(electrical conductivity,EC)、种子发芽指数(germination index,GI)、C/N、可溶性有机碳(dissolved organic carbon,DOC)、可溶性有机氮(dissolved total nitrogen,DTN)、铵态氮(NH4+-N)、硝态氮(NO3--N)、微生物群落及粪大肠菌群,另一部分经自然风干磨成粉末后测定总碳(total carbon,TC)和总氮(total nitrogen,TN)含量。

1.3 试验方法

温度由自动数字温度计(WD-6210,北京宏远鹏奥有限公司,中国)测定;含水率采用烘干法于105℃烘箱中烘至质量恒定后测定;O2含量由便携式沼气分析仪(Biogas 5000,Geotech,英国)测定;用元素分析仪(Elementar Analysen systeme,Hanau,德国)测定总碳和总氮的含量。可溶性有机碳和可溶性氮采用液相色谱法(TOC-L,日本岛津)测定。

堆体自由孔隙率根据Baptista等[18]中的公式计算。

NH4+-N和NO3--N的测定:用2 mol/L的KCl溶液,按照1∶10(固液比)同试样混合,震荡30 min、静置,过滤取其上清液经流动分析仪(Auto Analyzer3,Seal,德国)进行测定;

pH值、电导率和种子发芽指数的测定:将堆肥鲜样与去离子水按照1∶10(固液比)混匀,在170 r/min的转速下振荡30 min,静置10 min,通过0.45 μm滤膜过滤,收集上清液作为待测液,测定pH值、电导率和种子萌发指数。其中pH、EC采用多参数分析仪(DZS-706-A,雷磁,上海)进行测定;GI的测定方法为取待测液5 mL铺于有滤纸的培养皿中,均匀放置10粒萝卜种子,于(25±1)℃培养箱(SHP-250,精宏,上海)中避光培养48 h,测算GI,计算方法参照《有机肥料(NY/T525-2021)》。

微生物群落结构测定:根据制造商说明书,采用FastDNA SPIN试剂盒(MP Biomedicals,Solon,USA)从堆肥样品中提取基因组DNA。采用Illumina公司的Miseq PE300/NovaSeq PE250平台进行测序(上海美吉生物医药科技有限公司)。测序结果根据公司云平台计算软件进行数据处理分析。

粪大肠菌群的测定:按照GB/T19524.1-2004的规定方法测定。

利用Microsoft Excel 2019计算数据的平均值和标准偏差,使用Origin Lab 2022b绘图。采用Pearson相关分析方法,利用SPSS 26.0(SPSS Inc.,Chicago,USA)分析理化参数、微生物群落与腐殖化指标间的关系。网络分析采用MWNA(molecular ecological network analysis pipeline)(http://ieg4.rccc.ou.edu/mena/login.cgi)和RStudio进行(RStudio Inc.,波士顿,MA),由Gephi 0.9.2执行。

2 结果与讨论

2.1 温度和氧气

温度是评价堆肥稳定状态的直观指标,静态兼性堆肥过程中堆体温度维持在25.13~36.13 ℃(图2a)。静态兼性堆肥过程有机质降解缓慢,堆体没有明显高温期且随环境温度变化波动。堆肥初期,由于秸秆调控提高了堆体自由孔隙率(提高19.41%)和C/N,充足的氧气和碳源,使好氧微生物降解有机物速率加快,耗氧量增加(图2b),导致PC处理升温较快[19]。堆肥进行25 d后,P处理与PC处理温度表现出相同的趋势。因此,静态兼性堆肥方式下,改善堆体的物理结构和C/N能有效促进堆肥发酵进程。

O2含量与微生物代谢活动联系密切,能反映堆肥中好氧微生物活性[20]。O2含量在堆肥前期变化波动较大,堆肥进行40 d后,两组处理变化趋势基本相同(图2b)。堆肥前期,PC处理O2含量下降幅度更大(降低64.15%),是由于秸秆添加改善了堆体结构,微生物降解有机物更剧烈,O2消耗量更大。堆肥进行40 d后,两组处理的易降解有机物含量减少,微生物群落结构基本稳定,对O2需求量减少。经秸秆调控后,O2可经过堆体自由孔隙向内部扩散,激活堆体内部好氧微生物活性,促进了静态兼性堆肥进程。

图2 静态兼性堆肥过程中温度和氧气含量变化

2.2 堆肥腐熟度和卫生学指标

pH值变化主要由堆体中微生物活动和有机物降解产物共同决定[21]。两组处理pH值为6.99~8.35(图 3a),PC处理pH值显著高于P处理(<0.05),这可能是微生物作用使含氮化合物降解产生NH4+-N导致pH值上升。堆肥结束时,两组处理上层pH值差异较大,主要是PC处理微生物活性高,氮素转化较P处理提前,导致部分氮素以氨气形式损失,最终的pH值较低(7.04)。P处理的堆体物理结构紧实,O2难以深层扩散,厌氧环境产生有机酸,导致P处理中层和下层pH值较低。而PC处理中层pH值达到7.91,这是由于秸秆调控后,氧气扩散至堆体中层,满足好氧微生物降解氮源有机物条件,产生铵盐等碱性离子,使堆体pH值较高。

EC值可反映可溶性盐含量,是产生植物毒害作用的重要因素之一[22-23]。一般认为,EC<4 mS/cm不会对植物产生毒害作用[24]。静态兼性堆肥过程中,PC处理不同阶段的EC值显著低于P处理(<0.005)(图3b)。随堆肥进行,PC处理的EC值呈逐渐下降并稳定的趋势,堆肥结束时为1.57 mS/cm,可能是堆肥产生的NH4+-N转换为氨气释放及小分子有机酸分解导致[25]。P处理则呈先增加后降低的变化趋势,纯猪粪堆体自由孔隙率低,有机物转化缓慢,产生的水溶性矿物离子发生“浓缩效应”,堆肥进行20 d时达到峰值(3.18 mS/cm)。随后,微生物利用产生的NH4+-N,转化为微生物氮并合成大分子腐殖质,EC值略有下降[26],这与P处理NH4+-N含量变化结果一致。堆肥结束时,堆肥上层物料EC值含量低,主要是由于PC处理产生的NH4+-N等盐分离子挥发;堆肥中层物料两组处理EC值均达到峰值,为3.97~3.99 mS/cm,PC处理堆体中层呈兼性堆肥条件,利于好氧微生物降解有机物,产生大量盐分离子;堆体下层,两组处理形成厌氧环境,矿化程度低,EC值低于堆肥中层。

注:U、M、B分别为堆肥上层、中层和下层,下同。

堆肥C/N比是反映堆肥稳定性、腐殖化程度和微生物活性的重要指标[27]。静态兼性堆肥过程中,两处理C/N均为先升高后降低变化趋势(图3c)。堆肥前期,两组处理C/N逐渐升高,并在第20天达到峰值,可能是由于堆肥初有机氮的降解速率高于有机碳。堆肥后期,微生物增殖代谢导致有机质分解加快[28]以及氮的矿化使C/N均下降。一般认为,C/N越低代表堆体的腐熟程度越好[29],堆肥结束时,两组处理分层C/N自上而下逐渐增加,表明堆肥上层腐熟效果最好。

GI是判断堆肥无害化和腐熟度的权威和经典生物指标,被广泛应用于评价堆肥产品植物毒性,一般认为GI>70%时,堆肥达到腐熟[30]。静态兼性堆肥过程,两组处理的GI逐渐上升(图3d),PC处理GI始终高于P处理,至堆肥结束时,P处理GI为40.84%,未达到腐熟标准,PC处理的GI为114.60%,提高了73.76%,表明秸秆调控可有效促进堆肥腐熟并降低植物毒性。静态兼性堆肥不同层腐熟程度不同,堆肥上层,两处理堆肥腐熟效果均最好,GI分别达到90.23%(P)和93.21%(PC);堆肥中层,PC处理相比于P处理的GI提高61.34%,这是由于秸秆添加提高了堆体自由孔隙率(40.42%),增加了中层好氧微生物对有机物的好氧降解过程;堆肥下层,两组处理GI均为0%,厌氧环境产生的有机酸可能是胁迫种子萌发的主要因素[31]。

粪大肠菌群是表征有机肥料无害化程度的重要指标之一[30]。静态兼性堆肥过程中,粪大肠菌群数逐渐下降并趋于稳定(图4)。堆肥初期,两组处理原始物料中粪大肠菌群数均为350 cfu/g,堆肥进行20 d后,P处理粪大肠菌群数下降到安全阈值以下(<2 lgcfu/g),较PC处理提前20 d,主要是由于秸秆调控后,PC处理具备的良好堆体物理结构为粪大肠菌群提供了更适宜的存活环境。而P处理由于自由孔隙率低,且EC值和NH4+-N含量较高,抑制了粪大肠菌群活性[32]。经静态兼性堆肥,两处理粪大肠菌群数均满足畜禽粪便无害化处理技术规范(GB/T 36195-2018)中粪大肠菌群小于2 lgcfu/g要求。

图4 静态兼性堆肥过程中粪大肠菌群数量的变化

2.3 溶解性碳氮含量

静态兼性堆肥过程中,两处理无机态氮主要以NH4+-N形式存在(0.31~7.06 g/kg),NO3--N含量较低(0.002~0.27 g/kg)。P处理NH4+-N含量较高,主要由堆肥有机物被微生物缓慢分解和累积浓缩效应导致。秸秆调控后,PC处理自由孔隙率提高,NH4+-N以氨气形式损失,导致NH4+-N含量降低[33]。堆肥前期,含氮有机物矿化而转化为大量NH4+-N[21],使堆体NH4+-N含量逐渐增加;堆肥后期,有机质矿化作用减弱,硝化作用增强,堆体NH4+-N含量开始下降,特别是PC处理,下降幅度较大(89.49%),可能是由于秸秆调控后硝化细菌活性加强,使部分NH4+-N向NO3--N转化[34](图5b)。堆肥上层,两组处理NH4+-N和NO3--N含量均较低,可能是氨化、硝化和反硝化作用下转化为N2O和N2等含N气体损失;NO3--N主要在PC处理中层产生(0.45 g/kg),较高的pH值有利于硝化反应,因为硝化是一种碱度消耗过程[35],这与PC处理中层pH值较高结果一致(图3a)。

可溶性有机碳和可溶性氮是评价堆肥植物毒性的重要指标,反映堆肥有机物分解和转化情况[36]。P处理DOC和DTN含量始终维持在较高水平(图5),且DOC含量在堆肥过程变化不明显,但在PC处理中DOC含量呈降低趋势,从初始的9.75 g/kg下降至4.52 g/kg,两处理DTN含量分别下降65.66%(P)和13.28%(PC),主要是由于秸秆调控增强了微生物对于DOC和DTN的利用。DOC和DTN是抑制种子发芽的主要因素[37-38],两组处理DOC和DTN含量自上而下逐渐升高,这与GI结果一致(图3d)。PC处理中层物料DOC和DTN含量显著低于纯猪粪处理(<0.01),表明秸秆调控促进了有机质降解和堆肥腐熟,使物料腐熟区间扩大,有利于堆肥物料腐熟的均一化[39]。

图5 静态兼性堆肥过程中NH4+-N、NO3--N、DOC、DTN浓度变化

2.4 微生物群落演替及多样性的变化

Ace和Chao、Shannon和Simpson指数分别表示微生物群落的丰富性和多样性,较高的值表示较高的丰富性和多样性(表2)。在PC处理中,秸秆调控为微生物创造了良好的生存环境,且使堆体自上而下呈好氧、兼性、厌氧的堆肥环境,微生物的丰富度和多样性均较高。而P处理未添加秸秆进行调控,中层和下层堆体环境具有高度同质性,P处理中层微生物的丰富度和多样性显著低于PC处理。

表2 静态兼性堆肥微生物多样性指数

堆肥过程中有机质的降解通常伴随微生物演替[40](图6a),两组处理优势细菌门为厚壁菌门(Firmicutes)、放线菌门(Actinobacteria)和变形菌门(Proteobacteria),相对丰度占比达64.70%~99.91%。Firmicutes在堆肥过程中通常表现出较高的相对丰度,在P处理中层、下层和PC处理下层的相对丰度达80%以上,这与Firmicutes可在高NH4+-N、高有机酸的极端环境中生存有关。堆体中层,P处理相对丰度达96.11%,PC处理为63.63%,表明秸秆调控构建了较好的微生物生存环境。Actinobacteria可产生木质纤维素水解酶,在有机物的降解中发挥着重要的作用[41]。秸秆调控处理Actinobacteria从2.96%(20 d)升高至17.97%(50 d),Actinobacteria在一定程度上可表征堆肥腐熟程度[42],因此,PC处理获得了较高的腐熟度。Proteobacteria中包括大量碳氮循环代谢菌属,是有机质降解转化过程中关键菌门,因而在PC处理堆肥上层和中层相对丰度较高,分别为22.32%和20.37%,P处理仅在堆肥上层达到16.39%。细菌属水平种类及相对丰度更能反映堆肥中微生物群落结构变化[43],在静态兼性堆肥样本中检测的前20个属(相对丰度>0.01%)中,优势菌属主要为:、、、_1和(图6b)。P处理以厌氧微生物占主导地位,PC处理则以好氧微生物为优势菌群。此外,堆体不同分层微生物菌群也存在差异,自上而下由好氧菌属逐渐演替为厌氧菌属。

图6 细菌在门水平及属水平相对丰度变化

根据细菌属的相对丰度对两个处理堆肥90 d结束时上层、中层和下层的前6个细菌属进行差异分析(图7)。两组处理上层微生物菌属多样性均高于中层和下层,P处理中层和下层微生物群落结构相似,共有菌属达到141种;PC处理上层和中层微生物群落结构相似,且两处理下层堆体微生物群落结构更具相似性,共有菌属达119种。是一类好氧菌属,出现在两组处理堆肥上层(P:5.31%,PC:2.48%),说明堆肥上层具有适宜的好氧堆肥环境,_1为严格厌氧菌属,在堆肥下层具有较高的相对丰度(P:44.06%,PC:50.88%)。值得注意的是,和_1同时存在于PC处理中层,秸秆调控使堆体形成了良好的兼性堆肥结构。秸秆调控增加了堆体中微生物丰富度和多样性,使堆体自上而下形成了好氧、兼性、厌氧的堆肥条件。,,和在上层、中层和下层广泛存在。此外,是一种病原菌,其丰度的降低意味着疾病传播风险降低,且PC处理对其消减作用更强,进一步说明秸秆调控可影响堆体的微生物群落结构并对病原菌活性产生影响。

2.5 微生物与理化因子的相关性分析

通过网络分析堆肥理化参数(pH值、EC、O2、C/N、温度)及腐熟度指标(NH4+-N、NO3--N、DOC、DTN、GI)与微生物群落的相关关系。P和PC处理分别产生168、325个节点和258、719个边,秸秆调控的PC处理形成了更加复杂和稳定的微生物群落结构(图8)。静态兼性堆肥过程微生物群落均主要由Firmicutes、Actinobacteria和Proteobacteria组成,总相对丰度大于90%。P处理中菌属较单一,大部分菌属来自Firmicutes,从腐熟度指标来看,单个优势菌门对堆肥的影响并不明显。两组处理微生物群落均与氧气呈正相关关系,氧气扩散程度会直接影响堆肥过程微生物群落的演替及有机物的降解效率。NH4+-N和DTN与大部分微生物群落呈负相关关系,但P处理中与其相关的菌属明显少于PC处理,表明较高含量的氮(图5a,图5d)会抑制微生物群落演替,进而影响堆肥有机物的降解。总而言之,秸秆调控使PC处理中微生物具有较高的多样性和相对丰度,尤其是增加了与堆肥腐熟度相关的微生物菌属,促进了有机质降解和堆肥腐熟。

图7 P和PC处理90上(90U)、90中(90M)和90下(90B)层及前6个细菌属的差异分析

图8 P和PC处理中关键因子与相关细菌在属水平上的Pearson分析

3 结 论

1)秸秆调控可改善堆体孔隙率和物料C/N,使堆肥产品种子发芽指数(GI)提高了73.76%,促进猪粪静态兼性堆肥腐熟。静态兼性堆肥过程易形成物料腐熟分层化,堆体底层形成厌氧区域,腐熟度随堆体的深度逐渐降低,秸秆调控可改善厌氧区域,有利于堆体物料腐熟均一化。

2)猪粪静态兼性堆肥经过30~40 d堆沤后,粪大肠菌群数可降低至卫生安全标准以下(<2 lgcfu/g),堆体温度、NH4+-N和有机酸含量均会影响粪大肠菌群的活性。

3)秸秆调控增加了堆体微生物多样性和丰富度,使微生物群落结构更加复杂和稳定,减少了厌氧区域,增加了Firmicutes、Actinobacteria、Proteobacteria等与木质纤维素降解相关的菌属相对丰度以及等好氧菌属,提高了堆肥有机质降解和物料腐熟。

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Effects of maize stover on the harmlessness and maturity during the static facultative composting of pig manure

YIN Ziming, YANG Yan, TANG Ruolan, BAO Ziyang, LI Liqiong, PENG Lijuan, LI Guoxue, YUAN Jing※

(,,,100193,)

Static facultative composting is one of the most widely-used, cost-effective, lightweight, and simple technologies to utilize local resources in modern agriculture. More than 60% of livestock and poultry manure (especially pig manure) can be treated using static composting. Static facultative composting can also create an aerobic environment with low porosity and limited depth of air diffusion within the heap, resulting in the low metabolic activity of microorganisms. Degradation of organic matter can be inevitably delayed, due to the long fermentation cycles, low fermentation temperatures, incomplete harmlessness, and low product maturity. Alternatively, the straw can be added to adjust the physical structure, oxygen content, and C/N ratios of the heap, in order to effectively improve the rot degree of static facultative compost products for the short rot cycle. This study aims to explore the effects of straw control on the maturity and microbial community structure of static facultative composting, especially on pathogenic bacteria. The corn straw was taken to regulate the physical structure and C/N ratio of the pile. A 90-day static facultative composting experiment was conducted using traditional natural fermentation. A systematic investigation was made to clarify the maturation index, fecal coliforms, and microbial community structure in the static facultative composting. The composting device was set as a 100 L flanged iron hoop bucket. Two treatments were set up in total. The control group was set without pig manure to label as the P treatment. The mixed compost of pig manure and corn straw was labeled as the PC treatment. The wet base mass ratio of 4:1 was selected without ventilation and heap turning. The results showed that the straw regulation increased the porosity of the compost (increased by 19.41%), and then promoted the diffusion of oxygen to the interior of the compost for the better degradation of organic matter by aerobic microorganisms. Specifically, the contents of phytotoxic substances were reduced (such as NH4+-N and DTN) to improve the compost maturity. The seed germination indexes were 40.84% (P) and 114.60% (PC), respectively, in the two groups of compost products. As such, the compost maturation was accelerated during this time. The number of fecal coliforms reached the hygienic safety standard after 30 to 40 days of natural fermentation. Furthermore, the activity of fecal coliforms depended on the temperature of the pile, NH4+-N, and organic acid content. The corn straw was added to improve the diversity of bacteria and synergistic effect. Firmicutes, Actinobacteria, Proteobacteria, and other phylum related to lignocellulosic degradation were the dominant microbial phylum in the reactor, where the aerobic, facultative, and anaerobic microbial stratification was formed from the aerobic to anaerobic bacteria from the top to the bottom. Therefore, the corn straw regulation can be expected to increase the aerobic area of the pile in the process of static composting. The harmless and mature degree can be promoted in the static composting of pig manure. The finding can provide the theoretical basis and technical standardization support for the static composting of livestock and poultry manure.

stover; quality control; static facultative composting; fecal coliforms; microbial community

2022-10-19

2023-03-05

内蒙古自治区科技计划项目(2021GG0316);国家自然科学基金项目(42207380)

尹子铭,研究方向为固体废弃物资源化利用。Email:yinzm2021@163.com

袁京,博士,副教授,研究方向为固体废弃物资源化利用。Email:jingyuan@cau.edu.cn

10.11975/j.issn.1002-6819.202210143

S21; X713

A

1002-6819(2023)-07-0218-09

尹子铭,杨燕,唐若兰,等. 秸秆对猪粪静态兼性堆肥无害化和腐熟度的影响[J]. 农业工程学报,2023,39(7):218-226. doi:10.11975/j.issn.1002-6819.202210143 http://www.tcsae.org

YIN Ziming, YANG Yan, TANG Ruolan, et al. Effects of maize stover on the harmlessness and maturity during the static facultative composting of pig manure[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2023, 39(7): 218-226. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.202210143 http://www.tcsae.org

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