吉林黑土区不同施肥处理对农田土壤昆虫的影响

为研究不同施肥处理与农田土壤昆虫群落之间的关系,对吉林黑土区不同施肥处理对农田土壤昆虫群落的影响进行了研究.在12个处理小区内,即（1）撂荒（不施肥、不耕作、不种植,ABAND）、（2）对照（种植、不施肥,CK）、（3）施氮肥（N）、（4）施氮磷肥（NP）、（5）施氮钾肥（NK）、（6）施磷钾肥（PK）、（7）施氮磷钾化肥（NPK）、（8）施氮磷钾化肥＋有机肥处理（有机N 和化肥N 的比例为2：1）（M1NPK）、（9）增加50 %用量化肥配施有机肥（1.5 MNPK）、（10）化肥配施秸秆（SNPK）、（11）玉米、大豆2：1轮作,施肥量同处理8（Rot）、（12）施氮磷钾化肥＋有机肥处理（有机N 和化肥N 的比例为1：1）（M2NPK）,共采集144个定点土壤样品.通过手捡法和改良干漏斗法（Modified Tullgren ）共获得土壤昆虫9922只（未知标本187只）,隶属9目48科.调查结果显示,12种施肥小区内,大型土壤昆虫个体数和类群数依次是：ABAND＞NP＞N＞1.5MNPK＞Rot.＞PK＞NK＞NPK＞M2NPK＞CK＞M1NPK＞SNPK,N＞NK＞ABAND=1.5MNPK＞NP=NPK＞PK＞CK=Rot.＞M2NPK=M1NPK＞SNPK;中小型土壤昆虫数依次是ABAND＞1.5MNPK＞PK＞M2NPK＞CK＞Rot.＞NPK＞SNPK＞NK＞NP＞N＞M1NPK,Rot.＞NPK＞ABAND=NP=1.5MNPK=PK=NK=M2NPK=CK=M1NPK=SNPK＞N.大型土壤昆虫个体数和类群数撂荒中分布最多,中小型土壤昆虫则分别在撂荒和轮作中分布最多.多样性分析表明,1.5MNPK处理中大型农田土壤昆虫组成最丰富,M1NPK处理中小型农田土壤昆虫组成最丰富;CK处理与其他11处理之间群落相似程度最小,Rot.与其他处理之间的群落相似程度较大.Kruskal- Wallis检验法分析表明,施肥对农田土壤昆虫分布影响极显著（X0.05（11）=10.25,p〈0.05）,反映出不同施肥对土壤生态系统内部环境,进而对土壤动物群落产生的影响.多元统计分析表明,轮作对土壤昆虫优势类群具有负向作用,而M2NPK则具正向作用.各种施肥对农田土壤昆虫影响不平衡,其中对农田土壤昆虫个体数影响最大,对中小型土壤昆虫均匀性影响最小.     

陕西黄土区不同施肥条件下农田土壤动物的群落组成和结构

为探明长期施肥与土壤动物群落之间的关系,于2001年6月至2002年10月,在陕西黄土区对不同施肥条件下的农田土壤动物类群的群落组成和结构进行了研究.在6种不同施肥处理的小区内,即对照组(不施肥,简称CK)、撂荒(不施肥、不耕作、不种植,简称ABAND)、施氮磷钾(简称NPK)、施氮磷钾+秸秆(简称SNPK)、施氮磷钾+有机肥(简称MNPK)和施1.5倍MNPK(简称1.5MNPK),两年4次共采集了72个定点土壤样品.采用手捡法和Cobb过筛法共获得农田土壤动物标本5495个,隶属6门11纲22目61科2亚科35属.结果显示6种施肥处理中,大型农田土壤动物的个体总数从多到少依次为SNPK＞1.5MNPK＞NPK＞ABAND＞MNPK＞CK,类群数依次是1.5MNPK＞NPK＞SNPK＞CK＞ABAND=MNPK.中小型农田土壤动物个体总数由多到少依次为1.5MNPK＞MNPK＞ABAND＞SNPK＞NPK＞CK,类群数依次是SNPK=MNPK＞CK=NPK=1.5MNPK＞ABAND.大型农田土壤动物个体数和类群数分布最多的分别是SNPK和1.5MNPK处理,而中小型农田土壤动物则分别是1.5MNPK和SNPK处理.表明农田土壤动物类群分布与施肥处理有关.农田土壤动物优势类群分布以施氮磷钾(NPK)小区最多,常见类群以对照组(CK)最多,极稀有类群以施1.5倍MNPK小区最多.群落相似性指数分析结果表明,在不同施肥处理之间,农田土壤动物的相似性系数一般较低,而其群落组成的异质性较高如大型土壤动物群落在撂荒地与其他施肥处理之间的相似性明显低于其他各施肥处理之间;而中小型土壤动物群落在对照小区与其他施肥之间的相似性指数明显低于其他各施肥处理之间,反映出不同施肥处理对土壤生态系统内部环境,进而对土壤动物群落产生的影响.     

用PCR-DGGE研究长期施用无机肥对种稻红壤微生物群落多样性的影响

以中国科学院红壤生态试验站的发育于第四纪红粘土的种稻红壤为研究对象,采用PCR-DGGE方法研究了长期施用无机肥对土壤微生物群落多样性的影响。在种植双季稻、连续13a施用不同无机肥后,土壤中细菌、古菌、放线菌和真菌的群落结构发生了较大的变化。未种植水稻的土壤与种稻土壤间四类微生物SSUrDNADGGE带谱相似性只有33%~66%。施磷肥的处理NP、PK、NPK之间微生物群落结构相似性较高,4类微生物的SSUrDNADGGE带谱相似性高达75%~81%。施氮钾肥(NK)、不施肥(CK)处理与施磷肥处理间土壤微生物群落结构的差异较大,其四类微生物的SSUrDNADGGE带谱相似性分别为69%~77%、55%~77%。研究的目的是深入地了解土壤中微生物群落的多样性,为科学施肥、合理利用土壤、保护微生物多样性和实现农业生态系统的可持续发展提供科学依据。     

添加毛叶苕子对红壤旱地土壤真菌群落的影响

【目的】长期高强度的连作及大量化肥施用导致红壤旱地退化和土传植物病原菌累积。真菌是农业生态系统中与土壤健康密切相关的微生物。本文通过研究土壤真菌群落的变化,探究施用毛叶苕子对红壤旱地农业生态系统的影响。【方法】采用定量聚合酶链式反应和高通量测序技术,研究红壤旱地真菌群落对单施矿质肥(mineral nitrogen,phosphorus and potassium fertilization,NPK)与矿质肥配施毛叶苕子(mineral nitrogen,phosphorus and potassium fertilization with hairy vetch,NPKG) 2种施肥措施的响应。【结果】与对照NPK相比,NPKG显著提高土壤肥力、花生产量和土壤真菌丰度,降低土壤p H和土壤真菌多样性。不同处理显著改变土壤真菌群落组成。与对照NPK相比,NPKG处理土壤腐生营养型真菌相对丰度显著提高37.42%,花生尾孢菌(Cercospora arachidicola)和可可毛色二孢菌(Lasiodiplodia theobromae) 2种花生病原菌相对丰度分别降低89.11%和8...     

紫色土线虫对长期不同施肥措施的响应

土壤线虫在农田生态系统中数量丰富且对土壤环境变化敏感, 可用于评估不同田间管理条件下的土壤健康。本文探究了紫色土区长期不同施肥措施及土壤团聚体粒径对线虫群落的分布及其生态功能多样性的影响。试验设置了5个施肥处理: 不施肥(对照, CK)、单施化肥(NPK)、生物炭 + 化肥(BCNPK)、商品猪粪 + 化肥(OMNPK)和秸秆 + 化肥(RSDNPK)。团聚体粒径分为: 原状土(BS)、大团聚体(> 2 mm; LA)和小团聚体(0.25-2 mm; SA)。结果表明, 与对照相比, 施肥可促进线虫数量增长, 其中单施化肥处理下增幅最小(66%); 有机物料与化肥配施对线虫数量的提升更为显著, 秸秆 + 化肥处理下增幅达206%。不同施肥处理间线虫类群相对丰度差异显著, 大小均表现为: 食细菌线虫(BA) > 杂食/捕食线虫(OP) > 植食线虫(PP) > 食真菌线虫(FU)。小团聚体较其他土壤团聚体的杂食/捕食线虫丰度更低, 食细菌线虫丰度较高。秸秆与化肥配施处理下线虫群落结构指数和富集指数显著增加, 且各施肥处理下线虫功能足迹呈现明显差异。有机肥与化肥配施(尤其是秸秆 + 化肥)可提高土壤养分供应且有利于形成稳定健康的土壤生态系统, 助推区域农业的可持续发展。     

长期有机无机肥配施对稻田杂草生长动态的影响

利用中国农业科学院红壤实验站红壤稻田长期定位试验,于2011年研究了在以无机肥(化肥NPK)与有机肥(M)氮磷钾养分等量条件下,长期有机无机肥配施水稻生育期间杂草种类和生物量变化。结果表明:30a后,早稻和晚稻施肥处理中:PK+M处理下杂草种类最多,NPK+M处理下杂草种类和优势杂草种类较少,且种类数量稳定,早稻和晚稻杂草种类数量前者比后者分别高出19.7%和9.8%;施肥处理中:两季杂草总生物量NPK+M处理最高,NP+M处理最低,且NPK+M、NK+M、PK+M和CK处理比NP+M处理分别高出31.3%、26.5%、8.3%和5.6%,早稻NPK+M处理杂草总生物量和浮生杂草总生物量最多,NK+M处理湿生杂草总生物量最多,晚稻NK+M处理杂草总生物量和湿生杂草总生物量最多,NPK+M处理浮生杂草总生物量最多;土壤碱解氮和有效磷与杂草总生物量、湿生杂草总生物量、浮生杂草总生物量显著正相关(相关系数依次分别为0.508*和0.578**、0.552*和0.453*、0.410*和0.802**),p H值与三者显著负相关(相关系数依次分别为-0.516*、-0.531*和-0.698*)。土壤p H受土壤有效磷和碱解氮及其他因子的共同作用对杂草总生物量产生影响。通过施肥措施调节土壤适宜p H及碱解氮和有效磷含量,能有效调控农田中湿生和浮生杂草生长,使杂草种类和生物量在农业生产中达到有益平衡。     

不同施肥对农田黑土微生物群落的影响

以未施肥(CK)和休闲(Fallow)处理为对照,研究黑土肥料定位站NP、NPK、MCK(有机肥)、MNP(有机肥 氮磷)、MNPK(有机肥 氮磷钾)等长期有机、无机肥施用对土壤基本理化性质、磷脂脂肪酸(PLFA)、酸(碱)性磷酸酶、微生物量碳或氮(SMBC或SMBN)等影响.结果表明,有机肥施用有效地提高了土壤有机质、总氮及速效氮、磷、钾等养分含量,显著地增加了SMBC(SMBN)和真菌、细菌的PLFA含量以及磷酸酶活力,极大地提高了土壤真菌/细菌比值;而长期NP或NPK处理不但未明显改善土壤养分状况,甚至抑制了磷酸酶活性及大多数菌群生长.总细菌PLFA与饱和脂肪酸或单烯脂肪酸与环化脂肪酸之间呈极显著正相关(p<0.01).PLFA主成分分析表明,有机肥与化肥处理微生物群落结构显著不同;个别PLFA载荷值分析表明,真菌脂肪酸易受无机肥施用影响,而G-菌或G 菌脂肪酸更易受有机肥影响.休闲处理高水平微生物活性与生物量的主要贡献者是黑土细菌群落而不是真菌.     

长期施肥对黄淮海平原农田中小型土壤节肢动物的影响

在2008年9月和2009年2月,采用改良干漏斗方法(Modified Tullgren)对黄淮海地区长期定位施肥试验下中小型土壤节肢动物进行调查。试验包括氮磷钾(NPK)、氮磷(NP)、氮钾(NK)、磷钾(PK)、有机肥(OM)、1∶1化学氮肥与有机氮肥(OMNPK)和不施肥(CK)7个处理。结果表明:OM和OMNPK处理有利于提高土壤动物丰富度和多样性;NK处理不利于土壤动物的生存和发展,缺磷影响了土壤动物数量的增长;从优势类群弹尾目和蜱螨目来看,OM和OMNPK处理对弹尾目等节跳科、棘跳科和球角跳科的生长有利,而圆跳科在NPK处理下具有更高的数量;OMNPK处理对蜱螨目中气门亚目有显著的正效应,对前气门亚目和甲螨亚目也有一定的正向作用;氮肥对弹尾目没有表现出正相关关系,但在一定程度上增加了蜱螨目的数量。     

黄泥田土壤真菌群落结构和功能类群组成对施肥的响应

研究长期不同施肥黄泥田土壤真菌群落组成和功能特性,深入认识真菌对不同施肥的响应机理,可以为合理施肥和保证农田土壤健康发展提供科学依据.设置不施肥(CK)、单施无机肥(NPK)、无机肥配施农家肥(NPKM)、无机肥加秸秆还田(NPKS)4个处理,采用Illumina高通量测序和FUNGuild对不同施肥处理下黄泥田土壤真菌群落结构和功能群进行分析.结果表明:从门水平上看,土壤真菌群落主要由子囊菌、担子菌和接合菌构成,且以子囊菌为主(47%~74%).NPKM和NPKS处理中子囊菌的相对丰度分别为49%和47%,显著低于CK(71%)和NPK(74%)处理,从目水平上看,减少的主要为肉座菌、格孢腔菌和散囊菌.NPKM和NPKS处理担子菌相对丰度分别为18%和28%,高于CK(14%)和NPK(10%)处理,从目水平上看,增加的主要为银耳菌、糙孢伏革菌和伞菌.与CK相比,单施无机肥降低了担子菌含量.不同施肥处理均在一定程度上增加了接合菌门的丰度,从目水平看,以内囊霉菌和粪蛙霉菌为主.NPK处理真菌α多样性指数显著低于其他处理,NPKM和NPKS处理的丰富度指数(Chao1和ACE)高于CK和NPK处理.不同处理之间真菌的营养类型以腐生营养型为主(48%~57%),NPKM和NPKS处理的共生营养型真菌相对丰度为17%,显著高于CK和NPK处理,增加的以丛枝菌根真菌、外生菌根真菌为主.NPK处理动物病原菌含量(10%)显著高于其他处理.冗余分析(RDA)结果表明,土壤含水量、孔隙度和盐度是影响真菌群落结构和功能类群组成的主要因子,其次为有机质和总氮.长期单施无机肥降低真菌种群多样性,增加致病菌含量,不利于土壤健康,而有机无机肥配施可在一定程度上提高真菌种群丰富度指数和共生真菌比例,有利于保持黄泥田稻田土壤健康的生态环境和真菌群落的多样性.     

黄壤稻田土壤微生物生物量碳磷对长期不同施肥的响应

本研究以进行了22年的黄壤稻田长期定位试验为依托,分析了不同施肥模式下土壤碳(C)、磷(P)与微生物生物量C(MBC)、P(MBP)的变化及其耦合特征,旨在探讨黄壤地区合理培肥模式以提高土壤磷素有效性.试验包括10个处理,分别为不施肥(CK)、单施氮肥(N)、磷钾配合(PK)、氮钾配合(NK)、氮磷配合(NP)、氮磷钾配合(NPK)、单施有机肥(M)、3种有机无机肥配施(1/4M+3/4NP、0.5MNP、MNPK).结果表明:与不施肥相比,N和NK处理土壤有机碳(TOC)、全磷(TP)、MBC、MBP均有不同程度的降低,施磷处理(PK、NP、NPK)则有不同程度的提升;与不施肥和施用无机肥相比,施用有机肥各处理TOC、MBC、MBP及MBP/TP均显著增加,其中M和MNPK处理增幅最大.MBC/MBP、TOC/MBP、MBC/TP以施用有机肥处理最低,N处理最高.土壤MBC、MBP及其耦合关系与土壤TOC和有效磷均呈极显著相关,TOC是影响MBC、MBP、MBP/TP的直接因素,而有效磷则是影响MBC/MBP、TOC/MBP、MBC/TP的直接因素.土壤MBP及碳、磷耦合关系各指标可以有效区分单施化肥和施用有机肥的不同施肥方式,可作为评价黄壤稻田磷素肥力的生物学指标.配施有机肥是增加黄壤稻田磷有效性、提高土壤供磷潜力和保持土壤生物健康的有效途径.     

Response of soil nematode communities to long-term application of inorganic fertilizers in the black soil of Northeast China

The effects of inorganic fertilizers on soil nematode communities were studied in a long-term fertilization experimental field in the Black Soil Region of Northeast China,where no fertilizer (CK),N fertilizer (N),combined application of N and P (NP),combined application of N and K (NK),and combined application of N,P and K (NPK) were compared.The results showed that the total nematode abundance was not affected significantly by inorganic fertilizers in the long-term field experiment.The numbers of bacterivores increased significantly in the NP treatment compared to the CK treatment,and those of fungivores and plant-parasites were inhibited in the NPK treatment.The similarity between CK and NPK treatment and the nematode diversity were higher than in other treatments.The stability of the soil ecosystem was disturbed by the inorganic fertilizers,as indicated by the change in MI values under different treatments.The response of soil nematodes mainly depended on the types of inorganic fertilizers applied.     

Response of soil nematode communities to long-term application of inorganic fertilizers in the black soil of Northeast China

The effects of inorganic fertilizers on soil nematode communities were studied in a long-term fertilization experimental field in the Black Soil Region of Northeast China, where no fertilizer (CK), N fertilizer (N), combined application of N and P (NP), combined application of N and K (NK), and combined application of N, P and K (NPK) were compared. The results showed that the total nematode abundance was not affected significantly by inorganic fertilizers in the long-term field experiment. The numbers of bacterivores increased significantly in the NP treatment compared to the CK treatment, and those of fungivores and plant-parasites were inhibited in the NPK treatment. The similarity between CK and NPK treatment and the nematode diversity were higher than in other treatments. The stability of the soil ecosystem was disturbed by the inorganic fertilizers, as indicated by the change in MI values under different treatments. The response of soil nematodes mainly depended on the types of inorganic fertilizers applied.     

Fertilization regimes affect the soil biological characteristics of a sudangrass and ryegrass rotation system

The sudangrass (Sorghum sudanense) and ryegrass (Lolium multiflorum L.) rotation is an intensive and new cropping system in Central China. Nutrient management practices in this rotation system may influence soil fertility, the important aspects of which are soil biological properties and quality. As sensitive soil biological properties and quality indicators, soil microbial community activity, microbial biomass, enzyme activities, soil organic matter (SOM) and total N resulting from different fertilization regimes in this rotation system were studied through a four-year field experiment from April 2005 to May 2009. Treatments included control (CK), fertilizer phosphorus and potassium (PK), fertilizer nitrogen and potassium (NK), fertilizer nitrogen and phosphorus (NP) and a fertilizer nitrogen, phosphorus and potassium combination (NPK). Soil microbial community activities in the NK, NP and NPK treatments were significantly lower than those in the CK and PK treatments after the sudangrass and ryegrass trial. The highest microbial biomass C, microbial biomass N, SOM, total N, sucrase and urease activities were found in the NPK treatment, and these soil quality indicators were significantly higher in the NK, NP and NPK treatments than in the PK and CK treatments. Soil microbial biomass and enzyme activities were positively associated with SOM in the sudangrass and ryegrass rotation system, indicating that fertilization regimes, especially N application, reduced microbial community activity in the soil. Proper fertilization regimes will increase microbial biomass, enzyme activity and SOM and improve soil fertility.     

长期施肥对小麦-玉米作物系统土壤颗粒有机碳和氮的影响

通过对华北平原小麦-玉米轮作农田生态系统18年田间施肥试验,研究了长期不同施肥处理对耕层(0～20 cm)土壤颗粒有机碳和氮及矿质结合有机碳和氮的影响.施肥处理包括化肥NPK不同组合（NPK、NP、NK、PK）、全部施用有机肥(OM)、一半有机肥+化肥NPK(1/2OMN)及不施肥(CK)共7个处理.结果表明：各施肥处理均能在不同程度上增加土壤颗粒有机碳和氮及矿质结合有机碳和氮含量,提高土壤颗粒有机碳和氮分配比例及颗粒有机质C/N.施肥处理颗粒有机碳和氮储量较不施肥处理分别增加11.7%～196.8%和13.0%～152.2%,土壤颗粒有机碳对总有机碳储量增加的贡献率为31.5%～67.3%,土壤颗粒有机氮对全氮储量增加的贡献率为14.3%～100.0%;矿质结合有机碳和氮储量较不施肥处理分别增加2.0%～75.0%和0.0%～69.8%.各处理颗粒有机碳和氮及矿质结合有机碳和氮储量均以OM处理最高,且有机肥与化肥NPK配施高于单施化肥各处理,而化肥处理中NPK均衡施用效果最好.说明施用有机肥、有机肥与化肥NPK配施及化肥NPK均衡施用是增加土壤颗粒有机碳和氮及矿质结合有机碳和氮的关键.     

Soil fertility and its significance to crop productivity and sustainability in typical agroecosystem: a summary of long-term fertilizer experiments in China

Aims and background

Soil fertility quality index is a useful indicator that helps to improve sustainable land use management and achieve economical yield in agriculture production. The objectives of this study were to evaluate the changes of soil fertility quality between the 1980s and 2000s in different cropping systems and its significance to crop productivity and sustainability.

Methods

We collected all published data on crop yields and soil parameters from 58 long-term experiments in three typical double-cropping systems in China, including maize-wheat (M-W), rice-rice (R-R) and rice-wheat (R-W) cropping systems, and selected seven fertilizer treatments in each experiment, including inorganic fertilizer [nitrogen and phosphorus fertilizer (NP), nitrogen and potassium fertilizer (NK), phosphorus and potassium fertilizer (PK) and balanced mineral fertilizer (NPK)], combined NPK with farmyard manure (NPKM) or crop straw (NPKS), and no fertilizer application (served as control). For comparison, an integrated fertility quality index (IFQI) was used to estimate the variations in soil fertility in different cropping systems. Moreover, the mean production variability index (PVI, %) in each cropping system was calculated to evaluate the stability of crop production.

Results

Over cropping systems, the averaged relative yields of PK, NK and NP ranged from 38.0 to 97.4 %, while the mean yields can be increased by 2.4–5.1 % in NPKM, compared to NPK. The mean yields were similar between NPK and NPKS for maize and wheat crops, but the yield was increased by 4.3–10.0 % in NPKS. Among the different treatments, the highest variability of cereal productivity was obtained in NK, PK or Control, while the lowest value was mostly recorded in NPKM or NPKS in these three cropping systems. Relative to the control, the IFQIs in fertilization treatments were increased by 9.4–150.0 %, 6.2–41.5 % and 1.3–17.5 % in M-W, R-W and R-R systems, respectively (except for PK treatment in R-R system). However, changes of IFQI in topsoil differed among fertilizer treatments, and greater increases existed in the treatments receiving organic residues (NPKM and NPKS).

Conclusions

The increase in crop yield is exponentially correlated with the increased IFQI over treatments in three cropping systems. Over the treatments and systems, production variability among years is shown to be negatively, linearly related to IFQI (P?<?0.001). Therefore, the high grain yield and low production variability can be simultaneously achieved by increasing soil fertility in all three cropping systems.     

Quantitative analyses of the abundance and composition of ammonia-oxidizing bacteria and ammonia-oxidizing archaea of a Chinese upland red soil under long-term fertilization practices

The abundance and composition of soil ammonia-oxidizing bacteria (AOB) and ammonia-oxidizing archaea (AOA) were investigated by using quantitative real-time polymerase chain reaction, cloning and sequencing approaches based on amoA genes. The soil, classified as agri-udic ferrosols with pH (H(2)O) ranging from 3.7 to 6.0, was sampled in summer and winter from long-term field experimental plots which had received 16 years continuous fertilization treatments, including fallow (CK0), control without fertilizers (CK) and those with combinations of fertilizer nitrogen (N), phosphorus (P) and potassium (K): N, NP, NK, PK, NPK and NPK plus organic manure (OM). Population sizes of AOB and AOA changed greatly in response to the different fertilization treatments. The NPK + OM treatment had the highest copy numbers of AOB and AOA amoA genes among the treatments that received mineral fertilizers, whereas the lowest copy numbers were recorded in the N treatment. Ammonia-oxidizing archaea were more abundant than AOB in all the corresponding treatments, with AOA to AOB ratios ranging from 1.02 to 12.36. Significant positive correlations were observed among the population sizes of AOB and AOA, soil pH and potential nitrification rates, indicating that both AOB and AOA played an important role in ammonia oxidation in the soil. Phylogenetic analyses of the amoA gene fragments showed that all AOB sequences from different treatments were affiliated with Nitrosospira or Nitrosospira-like species and grouped into cluster 3, and little difference in AOB community composition was recorded among different treatments. All AOA sequences fell within cluster S (soil origin) and cluster M (marine and sediment origin). Cluster M dominated exclusively in the N, NP, NK and PK treatments, indicating a pronounced difference in the community composition of AOA in response to the long-term fertilization treatments. These findings could be fundamental to improve our understanding of the importance of both AOB and AOA in the cycling of nitrogen and other nutrients in terrestrial ecosystems.     

氮磷输入对过度放牧退化草原土壤线虫群落的影响

线虫是陆地生态系统中数量最多的一类无脊椎后生动物,在土壤碎屑食物网中占据多个营养级,并在能量流动和养分循环中发挥重要的生态功能.土壤线虫的群落结构和多样性水平可以反映生态系统功能的变化.多年来,过度放牧等不合理的开发利用导致我国大面积的草原处在不同程度的退化之中,外源性养分输入是维持其养分平衡进而恢复其生态和生产功能的重要措施.本研究以内蒙古锡林郭勒退化草原为对象,就氮磷输入对土壤线虫丰度和群落结构的单独效应和交互效应进行了研究.本研究获得线虫38属,其中垫咽属、滑刃属、索努斯属和盾垫属是该退化草原线虫群落优势属.氮输入降低了土壤线虫总丰度、捕食杂食线虫丰度以及植物寄生线虫丰度,而磷输入提高了土壤线虫总丰度、食真菌线虫丰度、捕食杂食类线虫丰度以及植物寄生线虫丰度,氮输入抑制了磷输入对线虫总丰度、捕食杂食线虫和植物寄生线虫丰度的促进作用.氮磷输入对线虫多样性无影响,可能与不同养分输入下稳定的植物群落多样性有关.氮输入显著提升了退化草原线虫成熟度指数,降低了植物寄生线虫成熟度指数(PPI),并且能缓解磷输入对PPI和瓦斯乐斯卡指数的负面作用,表明氮输入提高退化草地土壤健康程度,促进线虫群落和食物网的稳定性.上述研究结果有助于从土壤生物学角度理解氮磷输入对退化草地恢复的影响机理.     

长期氮磷钾肥配施对贵州黄壤玉米产量和土壤养分可持续性的影响

为明确长期氮磷钾肥配施下贵州典型黄壤玉米产量、氮磷钾肥增产效应及土壤养分的演变特征,利用国家贵阳黄壤肥力与肥效长期定位试验,研究氮磷钾平衡施肥(NPK)与缺素施肥(N、NK、NP、PK)对玉米相对产量、氮磷钾肥增产贡献率及土壤氮磷钾素养分可持续性指数等的影响.结果表明: 氮磷钾平衡施肥有显著增产效果,玉米相对产量均值为:NPK>NP>NK>PK>CK;氮、磷、钾肥增产贡献率和农学利用率均为氮肥>磷肥>钾肥,施肥依存度为氮、磷、钾肥配施>氮肥>磷肥>钾肥,但缺磷处理(NK)玉米相对产量以每年1.4%的速度极显著下降,磷肥贡献率和依存度则以每年2.3%和1.4%的速度极显著上升,最终磷肥对玉米生产的影响逐渐与氮肥持平;缺磷处理土壤pH值和有机质含量均最低,而缺氮处理则较高;施用化学磷肥可提高黄壤磷素可持续性指数,但氮肥和钾肥对黄壤氮素和钾素可持续性指数无显著影响.综上,平衡施肥是贵州典型黄壤地区玉米高产的重要保障,其中磷肥与氮肥同等重要,但长期单施化肥尤其是缺磷处理不利于黄壤养分的可持续利用.     

长期不同施肥方式对黄潮土肥力特征的影响

依托黄潮土35 年长期定位试验,以2种土壤物理肥力指标、8种土壤化学肥力指标和5种土壤生物肥力指标进行主成分分析,最后将各主成分得分系统进行聚类分析.结果表明: 不同施肥方式对土壤肥力指标影响显著.施用有机肥处理(M、MN、MNP、MNPK)与NPK处理相比,土壤容重显著降低,而土壤孔隙度、有机质、全氮、碱解氮、全磷、有效磷、微生物生物量和过氧化氢酶、脲酶、碱性磷酸酶活性均显著增加;通过主成分分析可将原15个土壤指标降维,提取出2个主成分,反映了原信息量的85.5%,且无原变量丢失.土壤容重、孔隙度、有机质、全氮、碱解氮、全磷、有效磷、速效钾、微生物生物量、过氧化氢酶、脲酶、碱性磷酸酶、蔗糖酶活性在第1主成分上有较高因子负荷,全钾和pH在第2主成分上有较高因子负荷;以2个主成分得分为新指标进行聚类,得到长期不同施肥方式对黄潮土的培肥效果排序为MNPK＞MNP＞M、MN＞NPK＞N、NP＞CK.可见施用有机肥对黄潮土培肥效果更显著,以有机肥配施氮磷钾化肥方式效果最优.