长期施肥对土壤有机碳和无机碳的影响

利用18年长期定位试验,研究了在不同施肥条件下,土壤有机碳和无机碳在0~50 cm土层分布特征。结果表明,施肥对土壤有机碳的影响随着土层深度的增加而下降,0~7.5 cm土层的土壤有机碳比7.5~15 cm、15~30 cm、30~50 cm分别增加了4.6%、22.0%、63.1%,而无机碳含量随着土层深度的增加而增加,与有机碳的变化规律正好相反。不同种类的肥料对土壤有机碳的影响也不相同,化肥、有机肥长期配合施用和长期施用有机肥可以在0~30 cm土层增加土壤有机碳含量,降低土壤中的无机碳含量,而长期单施化肥对土壤的有机碳和无机碳含量无明显差异。     

Phosphorus and carbon status of a paddy soil under different fertilization regimes

Purpose

Phosphorus (P) in soil particulate fraction (PF; >53 μm) is suggested to have a significant importance in soil P cycling. However, the effects of continuous fertilization on P-PF and its association with soil organic carbon (SOC) in paddy soils have not been well studied.

Materials and methods

We sampled paddy soils at 0–20 cm from a long-term field experiment (initiated in 1981) conducted under humid subtropical conditions in China, which has five fertilization treatments with equivalent P input (135 kg P₂O₅?ha^?1 year^?1) except the control treatment (CK). Changes in total P (Pt), inorganic P (Pi), organic P (Po), and SOC under different fertilization managements were evaluated in the whole soil, in the PF, and in the mineral-associated fraction (MAF; <53 μm).

Results and discussion

Continuous fertilization increased the contents of SOC and P in all soil fractions. Both Po and organic carbon in PF were the most sensitive variables to fertilization, indicating that they constitute a useful tool to detect the effects of management practices. Among the fertilization treatments, organic amendments significantly increased Po-PF contents more than chemical fertilizer applied only (p?<?0.05), although they had equivalent P input. The paddy soil without fertilization showed a more significant decrease in Pi compared with Po. The SOC/Po ratios were significantly lower in fertilization treatments (especially those with manure or straw incorporation) than in CK and decreased from PF to MAF. A significant relationship was found between Po-PF contents and rice P uptake during the growing season.

Conclusions

These results demonstrate that Po-PF may also play a significant role in P cycling of paddy soil, and thus, it would be better to consider Po-PF in soil diagnosis to promote P management of paddy soil, especially for that under long-term organic amendments.

     

长期施肥措施下土壤有机碳矿化特征研究

研究长期不同施肥措施下旱作农田土壤有机碳的矿化特征及其温度敏感性可为加深理解土壤碳循环过程提供理论依据。本文以半干旱黄土区粮-豆轮作体系为研究对象,通过两种不同温度(15℃和25℃)的室内培养试验,分析了长期不同施肥措施下土壤有机碳矿化的动力学特征及其温度敏感性。研究结果表明,土壤有机碳矿化速率在培养初期较高,之后缓慢下降。施肥措施和培养温度对土壤有机碳矿化均具有显著影响。与不施肥对照(CK)相比,在15℃培养条件下,长期单施磷肥(P)、氮磷配施(NP)和氮磷有机肥配施(NPM)处理的土壤有机碳累积矿化量(C_(min))分别增加41%、85%和89%,在25℃培养条件下,分别增加7%、46%和77%。另外,与CK处理相比,P、NP和NPM处理土壤有机碳矿化的温度敏感性(Q_(10))分别降低25%、21%和6%。施肥改变了土壤有机碳矿化的动力学参数,其改变程度与施肥种类和培养温度有关。与CK处理相比,在15℃培养条件下,P、NP和NPM处理的土壤潜在矿化有机碳量(C_p)分别增加29%、65%和48%;在25℃培养条件下,NP和NPM处理的C_p分别增加2%和21%,而P处理则减少36%。不同施肥处理土壤有机碳矿化速率常数(k)在15℃培养条件下变化较小,在25℃培养条件下则有较大幅度的增加。在25℃培养条件下,C_(min)和Cp随土壤有机碳和全氮含量的增加而显著增加。可见,长期施肥显著促进了半干旱黄土区粮-豆轮作体系土壤有机碳的矿化,减弱了土壤有机碳矿化的温度敏感性。     

添加牛粪对长期不同施肥潮土有机碳矿化的影响及激发效应

为了探讨长期不同施肥潮土有机碳矿化对添加牛粪的响应特征及添加牛粪对长期不同施肥潮土有机碳矿化的激发效应,以始建于1986年的长期定位试验为平台,通过室内恒温培养的方法研究添加等氮量牛粪后长期不同施肥(不施肥,CK;常量有机肥,SMA;常量化肥,SMF;常量有机无机配施,1/2(SMA+SMF))潮土有机碳矿化、土壤有机碳及活性碳库组分(微生物量碳、可溶性有机碳、颗粒有机碳和易氧化有机碳)含量的变化特征。结果表明:无论添加牛粪与否,长期不同施肥潮土有机碳矿化过程均符合一级动力学方程,而牛粪的添加显著增加了长期不施肥、长期单施化肥和长期有机无机配施土壤的有机碳矿化速率常数,增长幅度分别为21.74%、35.00%和45.00%;添加牛粪提高了长期不同施肥潮土有机碳、微生物量碳、颗粒有机碳和易氧化有机碳含量,却显著降低了可溶性有机碳含量;牛粪对长期不施肥、长期施用常量有机肥、常量化肥和常量有机无机配施潮土有机碳矿化的正激发效应分别达到了48.56%、3.60%、48.43%和3.92%,且对长期不施肥及长期施用常量化肥潮土的激发效应显著高于对长期施用常量有机肥及长期有机无机配施土壤;冗余分析显示添加牛粪对长期不同施肥土壤有机碳矿化的激发效应与土壤活性组分碳氮比呈正相关,与土壤养分含量呈负相关。该研究不仅为合理施用有机肥和实现农田生态系统的可持续发展提供理论依据,还有利于实现农业资源再利用及其效益最大化。     

Long-term organic fertilization changes soil active bacterial composition and multifunctionality: RNA-based bacterial community and qPCR-based SmartChip analysis

Journal of Soils and Sediments - Organic amendments greatly influence soil functions and biochemical processes that are driven by soil active microbiota. Yet, how organic fertilization impacts...     

长期不同施肥方式下土壤有机碳的垂直分布及碳储量

为了研究施肥对土壤有机碳含量的影响,在湖北省农业科学院南湖实验站进行了25年不同施肥方式的长期定位试验。研究结果表明:与对照相比,除单施氮肥与单施有机肥外,其他施肥方式均提高了0～20cm土壤有机碳含量与碳储量;与对照及单施化肥相比,有机肥配施化肥均提高了0～20cm及0～100cm土壤有机碳含量与碳储量。单施化肥与单施有机肥对各土层土壤有机碳含量影响较小,且土壤有机碳累积少;而化肥配施有机肥提高了0～20cm与20～40cm土壤有机碳含量与碳储量。除对照及氮磷钾肥配施过量有机肥处理外,其他处理土壤全氮与有机碳含量间具有显著相关性。有机肥与化肥配合施用是提高农田土壤有机碳,增加土壤碳储量的有效方法。     

Changes in soil organic carbon fractions and bacterial community composition under different tillage and organic fertiliser application in a maize−wheat rotation system

ABSTRACT

The objective of this study was to assess the impact of different tillage and organic fertiliser regimes on soil carbon fractions and bacterial community composition within a maize–wheat cropping system. We conducted a six-year experiment on the Huang-Huai-Hai Plain of China. Six treatments were established: deep tillage (DT), shallow tillage (ST), no-tillage (NT), deep tillage with organic fertiliser (DTF), shallow tillage with organic fertiliser (STF), and no-tillage with organic fertiliser (NTF). Results indicated that during the winter wheat growing season, the highest contents of soil organic carbon (SOC) and easily-oxidised organic carbon (EOC) were in the STF treatment. During the summer maizegrowing season, the DTF treatment had the highest SOC and EOC contents. Compared with the other treatments, the NTF treatment had higher Chao1 and Shannon indices for bacteria; however, the relative abundance of Proteobacteria is highest in all treatments. A redundancy analysis (RDA) revealed that bacterial community composition was correlated with variation of the SOC, DOC, EOC, and microbial biomass carbon (MBC). Our results showed that combining the two components of the SOC fractions and bacterial community composition, STF practice in a maize–wheat rotation was a sustainable approach to optimising soil structure and improving soil quality.     

长期不同施肥下塿土有机碳和全氮在团聚体中的分布

【目的】研究小麦/玉米轮作体系不同施肥方式下土壤有机碳(SOC)和全氮(TN)在(?)土不同水稳性团聚体中的分布特征,以期深入理解不同施肥方式对土壤碳、氮固持的机制。【方法】采集(?)土21年长期肥料定位试验不同施肥处理0-10 cm和10-20 cm土层土样,分析其水稳性团聚体(2 mm、2~1 mm、1~0.5 mm、0.5~0.25 mm以及0.25 mm)有机碳和全氮的分布特征。试验设不施肥(CK),化肥氮磷钾配施(N、NP、NK、PK、NPK)和秸秆还田配施氮磷钾(SNPK)以及两个水平有机肥与氮磷钾配施(M1NPK、M2NPK)9个处理。【结果】长期施肥0-10 cm土层土壤团聚体SOC和TN含量明显高于10-20 cm,平均增幅20%以上。2~1 mm或1~0.5mm团聚体中SOC和TN的含量最高,0.25 mm团聚体最低。长期不施磷肥处理的土壤团聚体SOC和TN含量均与CK相似。NP、NPK以及SNPK处理,0-10 cm土层SOC较CK分别增加16%~43%、9%~40%和22%~47%;TN增幅分别为28%~48%、39%~61%和39%~91%。10 20 cm土层,NP、NPK以及SNPK处理2mm、2~1 mm、1~0.5 mm土壤团聚体SOC较CK增幅分别为35%~49%、17%~40%和45%~46%,TN增幅分别为44%~47%、39%~54%和54%~64%。长期有机肥与氮磷钾配施处理(M1NPK、M2NPK),0-10 cm土层的团聚体SOC平均较CK分别增加68%~122%和61%~163%,TN平均分别增加84%~133%和97%~175%;10-20 cm土层,SOC较CK平均增幅分别为20%~61%和39%~118%,TN增幅平均分别为43%~86%和107%~136%。SOC和TN主要储存于0.25 mm团聚体中(40%)2~1 mm团聚体储存最少(10%)。长期不施氮或不施磷对SOC和TN在团聚体中的储存比例基本没有影响。长期NP、NPK以及M1NPK、M2NPK均降低了各土层SOC和TN在2 mm或2~1 mm的储存比例增加了在1~0.25 mm团聚体储存比例。2 mm或2~1 mm团聚体的C/N比值高于微团聚体(0.25 mm),而与CK相比,长期施肥降低了土壤团聚体的C/N比值。【结论】关中地区(?)土长期偏施化肥对有机碳和全氮在团聚体的含量及分布没有显著影响而长期氮磷或氮磷钾化肥配合、氮磷钾与有机物配合均明显增加土壤团聚体的有机碳及全氮含量,特别是长期氮磷钾配合有机肥能显著增加土壤1~0.25 mm团聚体对土壤有机碳和全氮的固存比例,提高土壤有机碳和全氮储量减少温室气体的排放。     

长期不同施肥模式下华北旱作潮土有机碳的平衡特征

【目的】研究土壤有机碳的平衡特征对于更好的了解土壤有机碳的稳定性和培肥效果具有重要意义。本研究以旱作潮土为研究对象揭示长期施肥对土壤有机碳平衡的影响并探讨可持续利用的培肥模式。【方法】以旱作潮土34年长期定位试验为依托,通过田间取样和室内分析,研究不同施肥条件下土壤有机碳的含量、平衡,并通过相关分析分析土壤有机碳与施肥年限和作物产量的关系。试验处理包括不施肥(CK)、单施氮肥(N)、氮磷配施(NP)、氮磷钾配施(NPK)、有机肥配施氮肥(NM)和秸秆配施氮肥(NS)处理。【结果】经过34年的不同培肥措施,有机无机配合施肥处理(NM、NS),施用化肥(N、NP、NPK)处理和CK处理土壤有机碳分别平均增加52.9%,29.0%和11.1%;不同施肥模式下有机碳的盈余量差异显著,施肥的各处理和不施肥处理土壤有机碳均有盈余,其中NM处理盈余量为C 6.61 t/hm~2,显著高于其它处理,其次是NS处理(C4.68 t/hm~2),不施肥处理盈余量最低,仅为C 0.21 t/hm~2,显著低于其它处理;旱作潮土有机碳的固定量与有机碳的投入量之间呈极显著的正相关性(r=0.86**);碳投入的平均转化效率为8.5%,要维持土壤有机碳的平衡,每年有机碳投入量为0.04 t/hm~2。土壤有机碳含量与小麦(r=0.37**)和玉米(r=0.42**)的产量呈极显著正相关。【结论】不同施肥处理(包括CK处理)土壤有机碳总体呈增加趋势,该地区旱作潮土有机碳仍具有一定的固碳潜力,其中有机肥与化肥配合施用是提高旱作潮土有机碳的最佳培肥措施,可以使土壤有机碳呈显著性增加,其次是氮磷钾肥配合施肥处理。     

长期不同施肥黑土细菌和古菌群落结构及主效影响因子分析

【目的】依据黑龙江省农科院34年的长期定位试验,探讨影响东北黑土细菌和古菌区系的主效环境因子。【方法】试验采集不施肥(CK)、施氮磷肥(NP)、施氮钾肥(NK)、施磷钾肥(PK)、施氮磷钾肥(NPK)5个施肥处理的耕层土样借助传统化学分析方法和Illumina Miseq高通量测序技术解析土壤化学性状和细菌与古菌的群落结构特征,并对细菌和古菌群落结构与环境因子进行相关性分析。【结果】1)不同施肥处理土壤细菌和古菌群落结构存在显著差异与CK相比,4种施肥处理均降低了古菌丰富度,NPK处理增加了土壤细菌的丰富度、多样性以及古菌的多样性;变形菌门(Proteobacteria)、酸杆菌门(Acidobacteria)是所有土样中的优势菌群,占细菌与古菌总量的38.2%~42.9%。施肥条件下,放线菌门(Actinobacteria)、浮霉菌门(Planctomycetes)、绿弯菌门(Chloroflexi)、蓝藻门(Cyanobacteria)的相对丰度降低芽单胞菌门(Gemmatimonadetes)、厚壁菌门(Firmicutes)的相对丰度升高而其他菌门的相对丰度对不同施肥处理的响应不同。2)施用氮肥显著改变了土壤化学性状,长期施氮(尿素)处理的土壤全氮、速效氮和有机质含量显著高于不施氮处理而pH则显著降低。3)RDA分析结果显示,pH对土壤细菌和古菌群落结构的影响最大解释了66.5%的变化;其他环境因子则共解释了细菌与古菌群落33.5%的变化各因子的贡献率依次为pH速效钾有效磷有机质。Pearson相关性分析结果也表明,细菌和古菌群落与土壤化学指标间存在密切的相关关系。【结论】解析了长期不同施肥条件下土壤细菌和古菌的群落结构特征,确定了pH是影响土壤细菌和古菌区系的主效环境因子,氮磷钾均衡施肥不仅显著提高了作物产量和丰富了土壤养分含量,同时也增加了土壤细菌的丰富度、多样性以及古菌的多样性,有利于维持良好的土壤生态环境。研究结果对揭示东北黑土肥力演变机制、建立合理的施肥制度具有重要的理论价值。     

Abundance and community composition of methanotrophs in a Chinese paddy soil under long-term fertilization practices

Background, aim, and scope  As the second most important greenhouse gas, methane (CH₄) is produced from many sources such as paddy fields. Methane-oxidizing bacteria (methanotrophs) consume CH₄ in paddy soil and, therefore, reduce CH₄ emission to the atmosphere. In order to estimate the contribution of paddy fields as a source of CH₄, it is important to monitor the effects of fertilizer applications on the shifts of soil methanotrophs, which are targets in strategies to combat global climate change. In this study, real-time polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) based on 16S rRNA and pmoA genes, respectively, were used to analyze the soil methanotrophic abundance and community diversity under four fertilization treatments: urea (N), urea and potassium chloride (NK), urea, superphosphate, and potassium chloride (NPK), and urea, superphosphate, potassium chloride, and crop residues (NPK+C), compared to an untreated control (CON). The objective of this study was to examine whether soil methanotrophs responded to the long-term, different fertilizer regimes by using a combination of quantitative and qualitative molecular approaches. Materials and methods  Soil samples were collected from the Taoyuan Experimental Station of Agro-ecosystem Observation at Changde (28°55′ N, 111°26′ E), central Hunan Province of China, in July 2006. Soil DNAs were extracted from the samples, then the 16S rRNA genes were quantified by real-time PCR and the pmoA genes were amplified via general PCR followed by DGGE, cloning, sequencing, and phylogenetic analysis. The community diversity indices were assessed through the DGGE profile. Results  Except for NPK, other treatments of N, NK, and NPK+C showed significantly higher copy numbers of type I methanotrophs (7.0–9.6 × 10⁷) than CON (5.1 × 10⁷). The copy numbers of type II methanotrophs were significantly higher in NPK+C (2.8 × 10⁸) and NK (2.5 × 10⁸) treatments than in CON (1.4 × 10⁸). Moreover, the ratio of type II to type I methanotrophic copy numbers ranged from 1.88 to 3.32, indicating that the type II methanotrophs dominated in all treatments. Cluster analyses based on the DGGE profile showed that the methanotrophic community in NPK+C might respond more sensitively to the environmental variation. Phylogenetic analysis showed that 81% of the obtained pmoA sequences were classified as type I methanotrophs. Furthermore, the type I-affiliated sequences were related to Methylobacter, Methylomicrobium, Methylomonas, and some uncultured methanotrophic clones, and those type II-like sequences were affiliated with Methylocystis and Methylosinus genera. Discussion  There was an inhibitory effect on the methanotrophic abundance in the N and a stimulating effect in the NK and NPK+C treatments, respectively. During the rice-growing season, the type II methanotrophs might be more profited from such a coexistence of low O₂ and high CH₄ concentration environment than the type I methanotrophs. However, type I methanotrophs seemed to be more frequently detected. The relatively complex diversity pattern in the NPK+C treatment might result from the strong CH₄ production. Conclusions  Long-term fertilization regimes can both affect the abundance and the composition of the type I and type II methanotrophs. The inhibited effects on methanotrophic abundance were found in the N treatment, compared to the stimulated effects from the NK and NPK+C treatments. The fertilizers of nitrogen, potassium, and the crop residues could be important factors controlling the abundance and community composition of the methanotrophs in the paddy soil. Recommendations and perspectives  Methanotrophs are a fascinating group of microorganisms playing an important role in the biogeochemical carbon cycle and in the control of global climate change. However, it is still a challenge for the cultivation of the methanotrophs, although three isolates were obtained in the extreme environments very recently. Therefore, future studies will be undoubtedly conducted via molecular techniques just like the applications in this study.     

长期施肥对旱作区农田土壤细菌群落组成和多样性的影响

为阐明长期有机、无机施肥对旱作区土壤细菌群落组成及多样性的影响机制,以农田土壤生态系统为研究对象,采用单因素随机区组设计,利用长期定位试验(11年)和高通量测序的方法,研究了不施肥(对照,T0)、单施化肥(T1)、化肥配施羊粪有机肥(T2)和化肥配施生物有机肥(T3)对土壤的影响,分析了处理间土壤细菌群落组成及多样性的差异,探究了驱动土壤细菌群落组成及多样性变化的主要土壤环境因子。结果表明:与T0相比,羊粪有机肥、生物有机肥与化肥配施能显著提高土壤全氮、全磷、有机质、碱解氮、有效磷和铵态氮的含量,其中T2处理效果最显著(P<0.05)。各施肥处理下土壤放线菌门(Actinobacteria)、变形菌门(Proteobacteria)、绿弯菌门(Chloroflexi) 细菌为优势菌门;羊粪有机肥、生物有机肥与化肥配施处理降低了土壤放线菌门的相对丰度,增加了绿弯菌门、拟杆菌门和厚壁菌门的相对丰度,T2处理与T0处理间有显著差异(P<0.05)。与T1处理相比,羊粪有机肥、生物有机肥与化肥配合施用使土壤硝化螺旋菌门的相对丰度显著降低。类诺卡氏菌属(Nocardioides)、KD4-96和Subgroup_6为土壤细菌群落的优势菌属。T2处理较T3处理更显著地降低了土壤类诺卡氏菌属(41.15%)、芽球菌属(41.67%)和红杆菌属(27.45%)的相对丰度。与T0处理相比,T2处理更显著增加了细菌群落物种数、群落辛普森指数、香农指数和Chao1 指数(P<0.05)。冗余分析表明,土壤有机质(P=0.001)、pH(P=0.003)是驱动土壤细菌群落组成及多样性变化的主要因素。土壤pH以及有机质含量高低对驱动旱作区土壤细菌群落组成以及土壤细菌多样性变化均产生直接效应。因此,化肥与羊粪有机肥相结合的长期施肥管理是优化旱作区区域农田养分管理、提升土壤肥力的有效途径。     

长期施肥下褐土易氧化有机碳及有机碳库的变化特征

本研究探讨了24年长期施肥对褐土土壤有机碳(TOC)、有机碳储量(TOCs)、净固碳效率(NCSE)和碳库管理指数(CPMI)的影响,为评价褐土土壤碳库变化与质量及科学施肥提供理论依据。研究以褐土肥力与肥料长期定位试验为平台,通过9个处理[A组:不施肥处理(N_0P_0、CK);B组:单施无机肥处理(N_1P_1、N_2P_2、N_3P_3和N_4P_4);C组:有机肥与无机肥配施处理(N_2P_1M_1、N_3P_2M_3和N_4P_2M_2);D组:单施高量有机肥处理(M_6)]测定土壤TOC与易氧化有机碳(ROOC)含量,并计算TOCs、NCSE及CPMI等相关指标。结果表明,在不同土层不同时期施用较高量有机肥配施无机肥及施用高量有机肥(N_3P_2M_3、N_4P_2M_2和M_6)均可提高TOC和ROOC含量,且随土层深度加深提升作用减弱。TOCs、NCSE与0~20 cm土层TOC含量在时间和空间上的变化规律基本一致。施用高量有机肥(C组、D组)可有效提高TOCs,A组、B组的TOCs均值分别比C组、D组低76.77%与17.36%。长期施肥处理可提高NCSE,尤其是施用有机肥处理可显著提高NCSE。NCSE为D组C组A组=B组;D组NCSE为1 152.27 kg·hm~(-2)·a~(-1),是C组的2.51倍,B组的16.20倍。与试验前相比,C组和D组的CPMI无显著变化,且C组与D组间差异不显著,但A组与B组比试验前降低16.38~40.02。与A组(CK)相比,B组中N1P1处理与C、D组处理显著影响CPMI,提高了23.30~45.67。在0~40 cm土层CPMI与ROOC含量呈显著正相关,CPMI可以很好地指示有机碳的变化。可见,施用高量有机肥或者较高量有机肥与无机肥配施可极显著提高褐土土壤TOCs、NCSE和CPMI,即施用高量有机肥或者较高量有机肥与无机肥配施(N_3P_2M_3和N_4P_2M_2)有利于褐土有机碳的固存,可减少无机肥的施用量,使土壤性质向良性方向发展,培肥土壤。     

长期施肥下灰漠土有机碳组分含量及其演变特征

采用湿筛和重液悬浮的物理分组方法分析了18年不同施肥模式下灰漠土有机碳组分含量差异及其演变特征。结果表明:与不施肥相比,长期有机无机肥配施(NPKM和1.5 NPKM)增加各有机碳组分的效果最显著,且粗和细自由颗粒有机碳、物理保护有机碳、矿物结合有机碳增加速率最高,平均分别达到0.12、0.06、0.08及0.17g/(kg.a);秸秆还田使粗和细自由颗粒有机碳分别以0.05和0.03 g/(kg.a)的速率增加,而撂荒和施化肥维持着各有机碳组分的含量。不同有机碳组分间存在显著的相关性,其中以粗自由颗粒有机碳含量增幅最高,不同施肥模式下平均增幅是其它有机碳组分的2.18~.0倍;以矿物结合有机碳所占比例最高,达到56.9%7~7.8%,说明粗自由颗粒有机碳对施肥较敏感,而矿物结合有机碳是灰漠土固存有机碳的主要形式。综上分析,长期有机无机肥配施是提高灰漠土有机碳组分含量和培肥土壤的有效模式。     

长期不同施肥条件下红壤性水稻土微生物群落结构的变化

以位于江西省红壤研究所内长期定位试验的水稻土(始于1981年)为研究对象,运用磷脂脂肪酸(phospholipid fatty acid,PLFA)和BIOLOG分析技术研究了不施肥(CK)、单施化肥(NPK)及有机肥与化肥混施(NPKM)三种施肥方式对土壤微生物群落结构的影响。结果表明:长期施化肥和有机肥与化肥混施处理的PLFA总量均高于未施肥处理,两者分别较未施肥处理高91%和309%;PLFA主成分分析(PCA)显示施肥促进了土壤微生物群落结构的变化,其中NPKM处理增加了革兰氏阴性细菌(G-细菌)、真菌、放线菌和原生动物的数量,NPK处理增加了革兰氏阳性细菌(G+细菌)的数量,不施肥处理较施肥处理提高了真菌/细菌比例,CK和NPK处理的微生物群落结构更为相似;各施肥处理间土壤的AWCD值(平均每孔颜色变化率,average well color development,AWCD)表明,NPKM处理能够促进土壤微生物群落对碳源的利用能力,进而增加土壤中微生物的整体活性,而NPK处理减弱了土壤微生物的活性。代谢功能多样性分析同时表明,NPKM处理增加了微生物群落的多样性,而NPK处理使土壤微生物的多样性降低;土壤PLFA与土壤养分的相关性分析显示,土壤总PLFA量与土壤有机质和全氮呈极显著相关(p0.01),与速效养分相关性不大。     

Response of soil organic matter fractions and composition of microbial community to long-term organic and mineral fertilization

The effects of organic and mineral fertilization on four soil organic matter (SOM) fractions (non-protected, physically protected, chemically protected, and biochemically protected) and microbial community composition were investigated by sampling soil of a 35-year-long fertilization experiment. The SOM fractions were investigated by combined physical and chemical approaches, while microbial community composition was determined by phospholipid fatty acid analysis (PLFA). Organic C (SOC) was primarily distributed within the microaggregate-protected particulate organic matter (iPOM) and the hydrolysable and non-hydrolysable silt-sized (H-Silt, NH-Silt) fractions, which accounted for 11.6–16.9, 23.4–28.9, and 25.4–30.6% of the total SOC content, respectively. The contributions of these “slow” fractions (iPOM, H-Silt, NH-Silt) to the increased SOC were 178–293, 118–209, and 85–109% higher after long-term sole manure or manure in combination with inorganic N fertilization compared with unfertilized soil (control). The combination of manure and mineral fertilizers increased the coarse and fine non-protected C (cPOM and fPOM) contents much more (34.1–60.7%) than did manure alone. PLFAs, bacteria, G (+) bacteria, and actinomycete abundances were the highest in soil with manure, followed by soil treated with manure combined with mineral N. The addition of inorganic and organic fertilization both altered the microbial community composition compared with the control. All SOM fractions contributed to 81.1% of the variance of the PLFAs-related microbial community composition by direct and indirect effects. The change in coarse unprotected particulate organic matter (cPOM) was the major factor affecting soil microbial community composition (p < 0.001). Our study indicates that physical, chemical, and biochemical protection mechanisms are important in maintaining high SOC level after the addition of manure. A close linkage between soil microbial community composition and cPOM suggests that C availability is an important factor for influencing microbial composition after long-term inorganic and organic fertilization.     

长期不同施肥措施下塿土细菌群落结构变化及其主要影响因素

? 【目的】 ?研究不同施肥处理下土壤细菌群落的特征,为建立促进土壤生态系统稳定和健康的养分管理制度提供依据。? 【方法】 ?陕西省杨凌示范区“国家黄土肥力与肥料效益监测基地”的28年长期定位试验始于1990年秋,种植制度为冬小麦–夏休闲,无灌溉。本研究选取定位试验中不施肥 (CK)、施用氮磷钾肥 (N、P₂O₅、K₂O分别为135、108、67.5 kg/hm2,NPK) 和有机无机肥配施 (70% N来自牛粪,MNPK) 3个处理。于2018年6月小麦收获后采集0—20 cm耕层土样,测定养分含量、含水量、微生物量碳含量、微生物量氮含量及目标土壤微生物。以1%琼脂糖凝胶电泳法检测土壤中DNA,根据97%相似度对序列进行OTU聚类、α多样性分析 (包括Shannon、ACE和Chao1等指数),使用CANOCO 4.5软件对土壤细菌门水平群落结构、细菌相对丰度等与土壤理化性质进行冗余分析。? 【结果】 ?与CK相比,NPK和MNPK处理显著提高了土壤有机碳、全氮、微生物量碳、微生物量氮、硝态氮和铵态氮含量,显著降低了土壤pH值。不同处理细菌基因拷贝数为每克干土6.69 × 109～16.46 × 109,与CK相比,NPK和MNPK处理细菌数量分别提高了77%和146%。MNPK处理的土壤细菌Shannon多样性指数显著高于CK和NPK处理,而Simpson指数显著低于CK和NPK处理,NPK与CK处理间两个指数无显著差异。3个处理的细菌丰富度指数 (Chao1指数和ACE指数) 和均匀度指数均没有显著差异。在门水平上,共获得35个细菌类群,其中,放线菌门 (Actinobacteria)、变形菌门 (Proteobacteria)、酸杆菌门 (Acidobacteria) 和绿弯菌门 (Chloroflexi) 为主要优势菌门 (相对丰度 > 10%),占到全部菌门的80.1%～81.7%。与CK相比,MNPK处理显著降低了放线菌门 (F = 5.845,P < 0.05) 的相对丰度,增加了拟杆菌门 (F = 4.461,P < 0.05) 的相对丰度,3个处理间其他菌门均无显著差异。冗余分析结果显示,CK与NPK、MNPK处理的土壤细菌群落结构具有明显差异,且MNPK处理对土壤细菌群落组成的影响更大。土壤理化性质对细菌菌群影响表现为:土壤硝态氮 > 可溶性有机碳 > pH > 铵态氮 > 有机碳 > 土壤含水量,这些理化因子均是影响微生物生长的关键因子。? 【结论】 ?关中土区旱作雨养条件下,化肥平衡施用和有机无机肥配施均显著提高了土壤中细菌数量、多样性和丰富度,有机无机肥配施还改变了细菌群落结构,特别是降低了放线菌门、增加了拟杆菌门的丰度,更有利于土壤生态系统的稳定和健康。     

黑土根际土壤有机碳及结构对长期施肥的响应

由于人类农业措施的干扰,氮肥和畜禽粪污大量输入到黑土中,对土壤有机碳库产生了较大负面影响。根际有机碳在调控土壤碳循环和养分转化中发挥着重要的作用。探明根际有机碳对不同养分的生态响应,可为不同施肥处理下黑土农田生态系统碳固持和农田可持续利用提供理论依据。该研究以黑土长期定位试验为基础,采集长期不施肥（CK）、常量氮（N）、二倍量氮（N2）、常量有机肥（M）、二倍量有机肥（M2）、常量有机肥+常量氮（MN）、二倍量有机肥+二倍量氮（M2N2）7个处理下大豆根际土壤,分析了根际有机碳和活性有机碳特征,同时利用固态核磁共振技术分析其光谱特征。结果表明,N、M2、MN和M2N2处理的根际土壤有机碳含量显著高于非根际水平,且以MN和M2N2处理的根际效应最显著,分别比非根际增加了18.3%和26.7%。分析核磁共振光谱显示,与非根际土壤相比,根际土壤具有较高的烷氧基碳比例和较低芳香碳比例,表明根际效应能够改变土壤有机碳结构比例。与不施肥处理相比,大部分施肥处理提升了黑土根际有机碳含量,其中以氮肥马粪配施和二倍量马粪（M2N2）处理提升幅度最高。由核磁共振图谱可知,M2和M2N2处理均增加根际土壤难降解成分烷基碳比例、芳香基碳比例、烷基碳与烷氧基碳比值、芳香碳与总碳比值,而MN处理仅增加烷基碳比例、烷氧基碳比例以及烷基碳与烷氧基碳比值。二倍量氮肥（N2）处理降低烷基碳比例、芳香碳比例和烷氧基碳比例,根际土壤难降解成分降低,不利于土壤固碳,同时证明固态 13C-核磁共振技术结合半定量分析能够准确地分析不同有机碳结构组分变化,深刻认识根际土壤有机碳的稳定机制。     

长期施用有机肥对稻麦轮作体系土壤有机碳氮组分的影响

【目的】 以湖北武汉地区长期稻麦轮作制度下施肥试验地作为研究对象,研究了长期不同施肥处理对耕层土壤有机碳、全氮及活性碳氮组分的影响,为优化稻麦轮作体系下施肥措施,实现土壤固碳减排,培肥土壤提供理论依据。 【方法】 长期施肥试验开始于1981年,试验处理包括不施肥 (CK)、施化学氮肥 (N)、施化学氮磷肥 (NP)、施化学氮磷钾肥 (NPK)、单施有机肥 (M) 及有机无机肥配施处理 (NPKM)。收集2017年小麦收获后耕层 (0—20 cm) 土壤,测定各小区土壤中的有机碳 (SOC)、全氮 (TN)、微生物量碳氮 (MBC、MBN)、水溶性碳 (DOC)、热水溶性有机碳 (HWSC)、颗粒有机碳氮 (POC和PON)、轻组有机碳氮 (LFOC和LFON) 及氯化钾浸提氮 (KEN,即水溶性无机氮) 的含量并分析各指标间的关系。 【结果】 1) 除KEN外,长期施用有机肥显著增加耕层土壤的各碳氮组分含量,特别是有机无机肥配施处理。2) 各活性有机碳组分占SOC的百分比由高到低排序为POC > LFOC > HWSC > MBC > DOC,各氮组分占TN的百分比由高到低排序为PON > LFON > MBN > KEN,其中POC占SOC的24.04%～37.64%,PON占TN的12.09%～20.24%,且有机肥处理下POC/SOC、PON/TN显著高于其余处理。3) 通过对土壤有机碳及各活性有机碳的对施肥的敏感性分析可得,各活性碳敏感性指数均显著高于SOC,且DOC的敏感性最高。4) 通过各组分间相关性分析可知,除KEN外,各碳、氮组分间显著正相关,其中DOC与SOC、PON与TN关系更为紧密,表明DOC及PON可较好地反应出SOC、TN的变化情况。 【结论】 在湖北稻麦轮作地区,长期有机无机肥配施处理显著增加了土壤碳库及氮库,促进了土壤碳、氮的积累,尤其是颗粒有机碳和有机氮 (POC和PON)。水溶性碳 (DOC) 对施肥反应最为敏感,可作为指示该地区有机物早期变化的指示物。