Ammonia oxidizer abundance in paddy soil profile with different fertilizer regimes

Studies about ammonia-oxidizing bacteria (AOB) and archaea (AOA) are often focused on topsoil, but little is known about their activity and distribution in subsoil. A long-term fertilizer experiment was conducted to assess the effects of different fertilizer treatments on AOB and AOA in vertical soil profiles of paddy soil plots that received no nitrogen fertilizer control (CK), NPK chemical fertilizers (CF), organic–inorganic mixed fertilizer (OIMF) and organic fertilizer (OF). Soil properties, potential nitrification rate (PNR) and amoA gene abundance of AOB and AOA were measured and analyzed by two-way ANOVA and correlation analysis. Quantitative PCR analysis of amoA genes showed that AOA were more abundant than AOB in all the soil samples. AOB declined sharply with soil depth. Compared with CK and OF treatments, CF and OIMF treatments had higher abundance of AOB throughout the soil profiles. However, AOA tend less responsive to soil depth and fertilizers compared to AOB. This caused the AOA/AOB ratios in subsoil higher than in topsoil, and in CK and OF higher than in CF and OIMF treatments. These results suggest that AOA are more abundant and can be better adapted to nutrient-poor subsoils than AOB, and autotrophic nitrification could likely be determined by a complex suite of environmental factors in vertical profiles of the paddy soil tested.     

长期施肥对农田土壤真菌的影响

不合理施肥所引发的土壤环境问题逐渐成为制约我国农业可持续发展的重要因素之一,而土壤真菌作为一类重要的土壤微生物,研究施肥措施对真菌群落的影响对促进农业生产具有重要意义。本研究以有20年历史的长期定位试验田为研究对象,利用末端限制性片段长度多态性分析技术,对长期定位施肥农田生态系统中不同施肥方式对土壤真菌群落的影响以及时间变化规律进行了系统研究。长期施肥定位试验包括EM堆肥(EM)、传统堆肥(OF)、化肥(CF)和不施肥(CK)处理。主要研究结果如下:在0~20 cm土层,施肥处理对土壤真菌多样性有显著影响,Shannon-Weiner多样性指数为2.64~3.53,Simpson集中性指数为0.03~0.08;EM和OF处理的Shannon-Weiner多样性指数均显著高于CF和CK;在3月、6月和10月,EM和OF处理与CF和CK处理相比,有较高的真菌多样性;Simpson集中性指数最高的是3月的CK处理,最低的是10月的EM和OF处理。冗余分析结果表明,土壤pH、有机质、总氮、有效磷和有效钾等对真菌影响显著。因此,长期施用有机肥与化肥相比可以提高土壤真菌多样性,改变其群落结构;与化肥处理相比,施用EM堆肥,不仅可以保持土壤可持续利用性,同时改善0~20 cm土层土壤真菌的生存环境;3种施肥处理对土壤真菌群落结构影响程度由强到弱:EMOFCF。     

Bioorganic fertilizer maintains a more stable soil microbiome than chemical fertilizer for monocropping

Understanding the responses of soil microbiome composition to various farming practices is important for selecting suitable managements to maintain soil functions. In this study, the influences of heavy chemical fertilizer application (CF) and reduced chemical fertilizer supplemented with organic (OF) or bioorganic fertilizer (BF, BF = OF + Trichoderma) on composition of soil microbiome were investigated for monocropping cucumber systems using a five-season continuous pot experiment. The MiSeq sequencing data indicated that the CF treatment resulted in the lowest fungal diversity and the BF treatment resulted in a relatively higher one close to the initial soil (CK). The BF and OF treatments had similar impacts on the composition of bacterial community, and the CF treatment significantly reduced bacterial diversity. Although both OF and BF treatments had better plant growth responses, they had less disturbance on the composition of fungal community relative to the CF treatment. The BF treatment is more predictable than the other treatments for postponing fungal diversity as the inoculated fungal species significantly (p < 0.05) affected the fungal community. In conclusion, the combination of bioorganic fertilizers with reduced chemical fertilizer application can maintain a diverse soil microbiome in cucumber monocropping.     

菜田种养结合模式下施肥方式对土壤编码碱性磷酸酶基因微生物群落的影响

为明确菜田种养结合模式下施肥方式对土壤编码碱性磷酸酶基因phoD的微生物群落结构和多样性的影响机制,通过Illumina MiSeq高通量测序手段,系统分析了4种不同施肥方式,即不施肥（CK）、施常规化肥（CF）、施有机肥（OF）、有机无机肥混施（MF）对花菜收获时0−20cm土层土壤理化性质、碱性磷酸酶（ALP）、微生物量磷（MBP）以及phoD微生物群落的影响。结果表明：（1）与CK相比,OF处理可显著提高土壤有机质、总氮、速效磷和Ca含量47.83%、38.46%、104.81%和69.21%（P<0.05）;OF和MF处理均显著提高ALP活性;CF和OF分别显著增加MBP含量56.12%和195.16%,OF处理中MBP含量最高（105.40mg·kg⁻¹）;（2）菜田种养结合模式不同施肥处理中假单胞菌属（Pseudomonas）为优势属,CF和MF较CK显著降低了假单胞菌属相对丰度33.39%和45.52%;施肥降低土壤phoD微生物Chao1指数,MF提高其多样性（Simpson）和均匀度（Simpsoneven）;（3）影响phoD微生物群落结构的关键环境因子为MBP、AP、ALP;phoD微生物α多样性指数与土壤性状指标无显著相关性。因此,菜田种养结合模式下,不同施肥处理改变了土壤理化和生物性质,从而驱动了土壤phoD微生物群落组成、结构和多样性变化。     

长期有机无机肥配施对东北黑土真菌群落结构的影响

【目的】分析长期有机无机肥配施对土壤真菌丰度、多样性及其群落特征的影响,探讨东北黑土真菌群落变化与施肥的相关性,为进一步调节土壤微生物结构,改善其生态功能提供参考依据。【方法】依托黑龙江省农业科学院36年长期定位试验站,选取4个不同施肥处理:不施肥处理（CK）、有机肥处理（M）、氮磷钾无机肥处理（NPK）和有机肥配施无机肥处理（MNPK）的耕作层土壤为研究对象,以真菌ITS基因为分子标靶借助qPCR技术和Illumina Miseq高通量测序平台,研究不同施肥处理对黑土中真菌群落丰度、多样性和组成的影响,并与土壤化学性质进行偶联分析,揭示群落与施肥的相关性。【结果】长期施用无机肥显著降低土壤pH,而有机无机配施可以有效缓解土壤酸化。NPK处理的ITS基因丰度显著高于MNPK;MNPK处理的细菌/真菌比值（26.91104）显著大于NPK,各处理比值由高到低为MNPK M CK NPK。细菌/真菌比值与土壤pH正相关;MNPK处理的真菌多样性指数值略大于NPK。Ascomycota和Zygomycota为土壤中主要真菌门,不同施肥处理之间真菌组成的相对丰度存在显著差异,对照处理Ascomycota的相对丰度为45.35%,MNPK和NPK处理分别为50.93%和56.16%。有机肥有利于降低病原真菌相对丰度,具有高度侵染性的Cochliobolus在MNPK（0.41%）和M（0.39%）中的相对丰度显著小于CK（3.25%）和NPK（2.08%）。CCA分析表明,土壤理化性质共解释土壤真菌群落结构变化的73.3%,有效磷（贡献量为32.4%,P=0.002）、铵态氮（贡献量为14.8%,P=0.01）和硝态氮（贡献量为16.2%,P=0.048）是3个重要的影响因子。【结论】不同施肥条件下土壤真菌丰度、多样性,以及菌群组成特征不同。与无机肥相比,有机肥无机肥配施能够有效改善真菌群落结构,降低真菌的丰度,增加真菌多样性,并提高土壤pH,减缓土壤酸化。土壤有效磷、铵态氮和硝态氮含量是影响黑土土壤真菌群落结构变化重要因素。     

减施化肥配施有机肥对荔枝生长、产量品质及肥料利用率的影响

针对我国荔枝园化肥施用量过高而存在的土壤质量下降、酸碱失衡和产量下降等问题，综合考虑荔枝施肥养分投入与带走量，研究减施化肥配施有机肥对荔枝生长、产量品质及肥料利用率的影响，旨在为荔枝提质增效提供施肥指导。以妃子笑荔枝为研究对象，设置单施化肥（CF）、减施化肥30%分别配施普通商品有机肥5kg/株（OF5）和10kg/株（OF10）、减施化肥30%配施生物有机肥5 kg/株（BIO5）和10kg/株（BIO10）5个处理，比较不同施肥处理对荔枝生长、养分供应、产量品质、肥料利用率及经济效益的影响。结果表明：（1）化肥减施30%的情况下，配施有机肥未明显减缓荔枝梢期生长。与CF相比，OF5显著促进新梢生长，BIO5显著提高梢期叶片叶绿素含量（SPAD值）；有机肥处理的百叶重及梢粗较化肥处理显著降低。（2）总体来看，在梢期与果实成熟期，各处理间叶片养分含量无显著差异，在二蓬梢期及末次梢期，OF10与BIO5叶片氮含量显著高于CF处理；各处理叶片氮含量均处于适宜范围，各养分含量与变化趋势均符合荔枝生长规律。（3）与CF相比，BIO5、OF10、BIO10处理均显著提高荔枝单株产量，其增幅分别为44.77%、35.81%、18.23%；有机肥处理均有提高荔枝单果重、纵径与横径的趋势；有机肥处理下荔枝果实内在品质高于CF处理，可溶性固形物含量平均增加1.76%-3.22%，可溶性糖含量平均增加11.96%-21.84%，可滴定酸含量平均降低15.38%-35.35%；产量品质综合评价BIO5>BIO10>CF>OF10>OF5。（4）各有机肥处理氮素偏生产力均显著高于化肥处理，BIO5与OF10氮、磷、钾肥偏生产力与农学利用率均显著高于其它处理。OF10、BIO5、BIO10均能显著提高荔枝收益。综合考虑荔枝生长、果实产量及品质、肥料利用效率以及经济效益，该园区在减少30%化肥养分投入下株施5kg生物有机肥处理表现最佳，其次是株施10kg普通商品有机肥。     

有机无机复混肥施用量对热带水稻土微生物群落和酶活性的影响

  【目的】  研究一次性施用不同量的有机无机复混肥对热带地区水稻产量及土壤微生物群落与酶活性的影响,为该区域水稻高效肥料管理提供科学依据。  【方法】  水稻田间试验连续进行了3季 (2018年早稻–晚稻,2019年早稻)。施肥设5个处理:不施肥对照 (CK),常规化肥分3次施用 (CF),采用一次性基施的等量、减10%和减20%氮磷钾养分投入量的有机无机复混肥处理 (OF、–10%OF和–20%OF)。2019年早稻收获后测产,同时取0—20 cm土壤样品,分析土壤理化性质和酶活性,采用Illumina高通量测序技术测定土壤细菌和真菌群落组成、多样性和结构。  【结果】  OF、–10%OF和 –20%OF处理的水稻产量没有显著差异,均与化肥处理 (CF) 相当。与CF相比,3个有机无机复合肥处理显著提高了土壤pH,对土壤全量氮磷钾没有显著影响;OF处理显著提高了土壤有机质含量;–20%OF处理显著提高了土壤碱解氮 (15.40%)、速效钾含量 (39.75%);OF和–10%OF处理显著提高了土壤有效磷 (49.82%、46.02%) 和速效钾含量 (91.40%和30.44%);有机无机复混肥处理对土壤酶活性没有显著影响。施用有机无机复混肥影响了真菌和细菌的多样性。其中–20%OF处理显著提高了细菌、真菌的Chao1指数和真菌的物种丰富度指数。在群落结构方面,–20%OF处理的土壤变形菌门和酸杆菌门的丰度显著高于CF处理,分别提高6.64%和8.37%,厚壁菌门丰度较CK显著降低了72.67%;–20%OF处理较CF处理显著增加土壤接合菌门丰度 (77.40%),而–10%OF土壤真菌球囊菌门较CK处理降低了117.38%。相关性分析表明,土壤细菌多样性与土壤速效磷呈正相关,真菌多样性与土壤碱解氮呈正相关。冗余分析表明,细菌群落的主要驱动因子为酸性磷酸酶、速效钾、有效磷和碱解氮,而碱解氮、全钾、有效磷和脲酶是土壤真菌群落的主要限制因子。  【结论】  施用有机无机复混肥能显著改善南方红壤水稻土速效养分含量和pH,减少10%～20%的常规养分投入量,对水稻产量没有明显影响,但是比施用化肥明显提高了土壤中有效磷、钾含量,同时提高了土壤细菌和真菌群落的数量和多样性。     

Effect of long-term fertilization on bacterial communities in wheat endosphere

Fertilization has been shown to exert a significant influence on soil microorganisms and directly and indirectly influences plant growth and survival in agroecosystems. However, it is unknown whether fertilization affects endophytic microbial communities, which are ubiquitous and intimately associated with plant growth and health. Herein, we investigated endophytic bacterial communities in wheat leaves and roots under different long-term fertilization regimes, including NPK chemical fertilizer and NPK chemical fertilizer combined with wheat straw, pig manure, or cow manure. Endophytic bacterial community composition considerably differed in leaves and roots. Although different fertilization treatments did not affect the endophytic bacterial species richness or phylogenetic diversity in either leaves or roots, the community composition was significantly altered, particularly in roots. The endophytic bacterial co-occurrence network in leaves was more complex and stable than that in roots. Furthermore, many of the keystone species that were identified by their topological positions in the co-occurrence networks of leaves and roots were involved in plant growth and fitness. The total relative abundance of keystone species was the highest in the NPK plus cow manure treatment in both leaves and roots. Overall, our results suggest that different fertilization regimes can strongly affect endophytic bacterial communities, and the combination of NPK fertilizer and cow manure promoted the relative abundance of the key endophytic bacterial microbiota in both leaves and roots, which might be beneficial for plants in agroecosystems.     

Short-term effects of organic and inorganic fertilizers on soil microbial community structure and function

A field study was carried out to analyze the short-term impacts of replacing mineral by organic fertilizers on the microbial and biochemical parameters relevant for soil fertility and crop yield. Three types of fertilization regimes were compared: (1) conventional fertilizer regime with inorganic fertilizer, and combined integrated fertilizer regimes in which 25 % of the nutrients were supplied by either (2) rabbit manure or (3) vermicompost. The effects on microbial community structure and function (phospholipid fatty acid [PLFA] profiles, bacterial growth, fungal growth, basal respiration, β-glucosidase, protease and phosphomonoesterase activities), soil biochemical properties (total C, dissolved organic carbon [DOC], N-NH₄ ⁺, N-NO₃ ^?, PO₄, total K) and crop yield were investigated in the samples collected from the experimental soil at harvest, 3 months after addition of fertilizer. The integrated fertilizer regimes stimulated microbial growth, altered the structure of soil microbial community and increased enzyme activity relative to inorganic fertilization. Bacterial growth was particularly influenced by the type of fertilizer regime supplied, while fungal growth only responded to the amount of fertilizer provided. The use of manure produced a fast increase in the abundance of PLFA biomarkers for Gram-negative bacteria as compared to inorganic fertilizer. Nutrient supply and crop yield with organic fertilizers were maintained at similar levels to those obtained with inorganic fertilizer. The effects of the organic amendments were observed even when they involved a small portion of the total amount of nutrients supplied; thereby confirming that some of the beneficial effects of integrated fertilizer strategies may occur in the short term.     

不同有机无机复混肥对小麦产量、氮效率和土壤微生物多样性的影响

通过田间试验,研究了菜粕堆肥、猪粪堆肥和中药渣堆肥有机无机复混肥与无机复混肥等价格施入对小麦产量、氮素利用率以及土壤微生物多样性的影响。结果表明,3种堆肥原料有机无机复混肥处理的小麦子粒产量（5838.8～6243.1 kg/hm2）为化肥处理（5880.4 kg/hm2）的99.3%～106.2%,差异不显著。猪粪处理和菜粕处理的小麦子粒的氮素累积量（分别为100.2 kg/hm2和95.8 kg/hm2）显著高于化肥处理（85.9 kg/hm2）和中药渣堆肥有机无机复混肥处理（84.5 kg/hm2）;3种有机无机复混肥的氮肥回收效率和氮素利用率（包括氮素生理利用效率和氮素子粒生产效率）都高于化肥处理的氮肥回收效率和氮素利用率。对各处理土壤DNA条带采用邻接法分析表明,施入外源有机物质(菜粕堆肥、猪粪堆肥与中药渣堆肥)可以改变土壤的微生物细菌群落结构,而施入化肥对土壤的微生物细菌群落结构影响较小。本试验条件下,施用3种堆肥原料的有机无机复混肥可以获得与施用化肥相当的小麦子粒产量,提高小麦的氮素回收和利用效率,改变土壤微生物细菌群落结构。     

Soil Bacterial Communities Under Different Long-Term Fertilization Regimes in Three Locations Across the Black Soil Region of Northeast China

Although soil bacteria play critical roles in agro-ecosystems, the knowledge of their response to long-term fertilization across the black soil region of Northeast China is limited. In this study, we sequenced 16 S rRNA genes to assess the effects of four long-term fertilization regimes—non-fertilization(NoF), chemical fertilizer(CF), manure(M), and chemical fertilizer plus manure(CFM)—on soil properties and bacterial communities in three locations, the northern, middle, and southern parts, across the black soil region. Results showed that the influence of fertilization regimes on soil properties varied significantly among the three locations. Manure fertilization significantly increased microbial biomass carbon and relative abundance of copiotrophic bacteria. Principal component analysis(PCA)showed that the total bacterial communities were separated into three groups according to the sampling location despite long-term fertilization, and that soil pH was the most important factor in shifting bacterial communities. In addition, similar fertilization regimes resulted in different influences on bacterial community composition, and the most influential soil properties varied among the three locations. Our results highlighted that geographical separation was a more dominant factor affecting bacterial communities than fertilization, and that long-term similar fertilization regimes did not induce consistent changes in bacterial community composition in the black soil region.     

Long-term fertilization regimes affect bacterial community structure and diversity of an agricultural soil in northern China

Background, Aims, and Scope  Knowledge about shifts of microbial community structure and diversity following different agricultural management practices could improve our understanding of soil processes and thus help us to develop sound management strategies. A long-term fertilization experiment was established in 1989 at Fengqiu (35°00′N, 114°24′E) in northern China. The soil (sandy loam) is classified as aquic inceptisols and has received continuous fertilization treatments since then. The fertilization treatments included control (CK, no fertilizer), chemical fertilizers nitrogen (N) and potassium (K) (NK), phosphorous (P) and K (PK), NP, NPK, organic manure (OM), and half chemical fertilizers NPK plus half organic manure (1/2NPKOM). The objective of this study was to examine if the microbial community structure and diversity were affected by the long-term fertilization regimes. Materials and Methods  Soil samples were collected from the long-term experimental plots with seven treatments and four replications in April 2006. Microbial DNAs were extracted from the soil samples and the 16S rRNA genes were PCR amplified. The PCR products were analyzed by DGGE, cloning and sequencing. The bacterial community structures and diversity were assessed using the DGGE profiles and the clone libraries constructed from the excised DGGE bands. Results  The bacterial community structure of the OM and PK treatments were significantly different from those of all other treatments. The bacterial community structures of the four Ncontaining treatments (NK, NP, NPK and 1/2NPKOM), as well as CK, were more similar to each other. The changes in bacterial community structures of the OM and PK treatments showed higher richness and diversity. Phylogenetic analyses indicated that Proteobacteria (30.5%) was the dominant taxonomic group of the soil, followed by Acidobacteria (15.3%), Gemmatimonadetes (12.7%), etc. Discussion  Irrespective of the two fertilization treatments of OM and PK, the cluster analysis showed that bacterial communities of the remaining five treatments of CK, NK, NP, NPK and 1/2NPKOM seemed to be more similar to each other, which indicated the relatively weak effects of the four N-containing treatments on soil bacterial communities. N fertilizer may be considered as a key factor to counteract the effects of other fertilizers on microbial communities. Conclusions  Our results show that long-term fertilization regimes can affect bacterial community structure and diversity of the agricultural soil. The OM and PK treatments showed a trend towards distinct community structures, higher richness and diversity when compared to the other treatments. Contrasting to the positive effects of OM and PK treatments on the bacterial communities, N fertilizer could be considered as a key factor in the soil to counteract the effects of other fertilizers on soil microbial communities. Recommendations and Perspectives  Because of the extremely high abundance and diversity of microorganisms in soil and the high heterogeneity of the soil, it is necessary to further examine the effects of fertilization regimes on microbial community and diversity in different type soils for comprehensively understanding their effects through the appropriate combination of molecular approaches. ESS-Submission Editor: Chengrong Chen, PhD (c.chen@griffith.edu.au)     

Chronic effects of different fertilization regimes on nirS-type denitrifier communities across the black soil region of Northeast China

Denitrification is one of the major processes causing nitrogen loss from arable soils.This study aimed to investigate the responses of nir S-type denitrifier communities to different chronic fertilization regimes across the black soil region of Northeast China.Soil samples were collected from sites located in the north(NB),middle(MB),and south(SB)of the black soil region of Northeast China,each with four chronic fertilization regimes:no fertilizer(No F),chemical fertilizer(CF),manure(M),and chemical fertilizer plus manure(CFM).Methods of quantitative polymerase chain reaction(q PCR)and Illumina Mi Seq sequencing were applied to assess the abundance and composition of denitrifier communities by targeting the nir S gene.The results showed that the M and CFM regimes significantly increased the abundances of nir S-type denitrifiers compared with No F at the three locations.The majority of nir S sequences were grouped as unclassified denitrifiers,and the different fertilizers induced little variation in the relative abundance of known nir S-type denitrifier taxa.Over 90%of the sequences were shared among the four fertilization regimes at each location,but none of the abundant operational taxonomic units(OTUs)were shared among the three locations.Principal coordinate analysis(PCo A)revealed that the communities of nir S-type denitrifier were separated into three groups that corresponded with their locations.Although similar fertilization regimes did not induce consistent changes in the nir S-type denitrifier communities,soil p H and NO-3-N content simultaneously and significantly influenced the structure of nir S-type denitrifier communities at the three locations.Our results highlight that geographical separation rather than chronic fertilization was the dominant factor determining the nir S-type denitrifier community structures,and similar chronic fertilization regimes did not induce consistent shifts of nir S-type denitrifier communities in the black soils.     

不同有机替代减肥方式对玉米生长及土壤肥力的影响

研究不同有机替代减肥方式对玉米生长及土壤肥力的影响,为玉米生产中减肥增效提供经济可行的施肥方案和理论依据。通过大田试验,设置不施肥空白(CK)、常规施肥(CF)、腐植酸有机肥+氮肥减量10%+磷钾肥(HF)、肥料增效剂+氮肥减量10%+磷钾肥(BN)、商品有机肥+氮肥减量10%+磷钾肥(OF)5个处理。结果表明:较CF处理,HF、BN和OF处理促进了玉米的生长,增加不同生育期的玉米株高和茎粗;有效改善玉米穗部性状和产量构成,玉米产量分别增加了11.12%,6.47%,14.43%,净收益分别增加了217.24,564.99,-506.46元/hm~2;提高玉米生育期内的土壤碱解氮、速效磷和速效钾的含量;提高了肥料利用率、养分偏生产力和养分农学利用效率,其中氮肥分别显著提高了8.15%,9.34%,14.08%(P0.05),钾肥分别显著提高15.92%,21.13%,29.36%(P0.05)。因此,HF和BN处理可以促进玉米生长,增产增效,提高肥料利用率和土壤肥力,为有玉米生产中减肥增效提供了经济可行的施肥方案和理论依据。     

生物有机肥对烟草根际微生物群落及青枯雷尔氏菌丰度的影响

【目的】探究生物有机肥施用对烟草根际土壤细菌、真菌群落结构和青枯雷尔氏菌丰度的影响机理。【方法】选用长沙市某公司生产的生物有机肥和常规烟草专用肥,在湘西花垣县长期定位试验点连续5年开展大田试验,研究施肥对土壤理化性质和微生物群落的影响。试验设置两种施肥处理：常规烟草专用肥（CF）和生物有机肥（BOF）。【结果】与CF相比,施用生物有机肥处理的土壤烟草青枯病发病率降低了89.8%,同时青枯雷尔氏菌相对丰度也显著降低,降幅达40.1%;土壤pH、碱解氮和有效磷显著增加,分别增加了1.2%、12.1%和60.2%;施用生物有机肥后根际土壤微生物如Roseiflexaceae,Gemmatimonadaceae,Nitrospira,Ramophialophora,Preussia等显著富集,且这些潜在有益菌与青枯雷尔氏菌相对丰度呈显著负相关关系。通过ABT预测模型分析发现潜在有益菌是影响青枯雷尔氏菌相对丰度的最主要生物因子。【结论】连续5年的试验结果表明,施用生物有机肥不仅改善了作物生长的土壤环境,显著提高了土壤pH和土壤速效养分含量,还促使潜在有益菌在根际土壤中富集,抑制了青枯雷尔氏菌的生...     

不同有机物料与化肥配施对土壤真菌群落结构和生态功能的影响

为减少土壤土传病害,保障农田土壤健康,指导有机物料合理利用,在有机物料用量和化肥用量一致的基础上,设置单施化肥（CK）、羊粪+化肥（A）、木薯渣+化肥（P）、木本泥炭+化肥（M）、味精废浆料+化肥（I）5个处理,以玉米为供试作物进行了有机物料与化肥配施试验,观察了不同处理下土壤真菌群落结构的变化。结果表明：施用有机物料降低了土壤真菌群落多样性,但提高了真菌群落丰富度,其中味精废浆料配施化肥处理的真菌群落丰富度最高,各处理土壤中优势真菌门类均为子囊菌门、担子菌门和被孢菌门。施用有机物料后,木薯渣、木本泥炭和味精废浆料处理的子囊菌门的相对丰度均增加,担子菌门的相对丰度均降低;而羊粪处理表现出相反趋势,子囊菌门的相对丰度降低,担子菌门的相对丰度增加。冗余分析结果表明,土壤pH是影响真菌群落的主要环境因子,其次为有机质、电导率和速效钾,而碱解氮和有效磷的影响较小。另外,有机物料与化肥配施可以提高腐生营养型和共生营养型真菌的比例,减少病原菌的数量,其中以木本泥炭与化肥配施的效果更显著,这有利于维持土壤生态系统的稳定,为作物生产提供健康的土壤条件。     

不同施肥处理对梁平柚产量、品质和土壤肥力的影响

通过连续3 a (2014—2017年)的田间试验,以10 a生梁平柚为研究对象,研究不施肥(CK)、单施化肥(CF)、50%化肥+50%有机肥(CF+OF)和单施有机肥(OF)下梁平柚产量、品质和土壤肥力的影响。结果表明,在不同施肥处理中,CF+OF、OF和CF的单果重均无显著性差异(P0.05),但CF+OF的柚子单株果实数最高,柚子产量分别高出OF、CF和CK 8.2%、31.2%和11.82%;CF+OF处理中,柚子果实中的果汁含量、总糖、游离氨基酸和维生素C比CK分别提高20.40%、18.95%、64.34%和27.06%,而柚子果皮厚度、种子数和总酸度显著降低,品质改善;施肥显著提高土壤微生物生物量碳氮,在不同施肥处理中,微生物生物量碳氮比介于7.39～13.89,且差异显著(P0.05)。CF+OF处理中,柚子成熟期土壤可培养细菌、真菌、放线菌数量显著高于或相似于单施化肥,说明化肥和有机肥配施能促进微生物生长繁殖,协调土壤养分供应,改善柚子营养。虽然不同施肥处理对土壤pH无显著影响(P0.05),但是与CK相比,OF和CF+OF处理有机质和速效钾含量增加,CF处理无显著差异(P0.05);CF、OF和CF+OF处理有效磷含量分别比CK增加6.53%、22.74%和34.72%,且差异显著(P0.05);CF+OF碱解氮含量最高,CF和OF次之,CK最低。此外,有机无机配施还可提高土壤蔗糖酶、脲酶、磷酸酶和过氧化氢酶活性,有益于土壤有机质循环、氮磷养分转化、活性氧消除。总之,在不同施肥处理中,有机无机配施显著提高柚子产量,品质得到明显改善,且土壤养分供应协调,土壤微生物数量增加,土壤酶活性增强,有益于土壤养分转化和保持健康。因此,在梁平柚施肥中,提倡有机无机配施很有必要。     

麦秸秆和沼液配施对水稻苗期生长和土壤微生物的调控

研究了等量氮素肥料处理下小麦秸秆全量还田结合化肥(S-CF)、小麦秸秆全量还田结合沼液(S-BS)和全量化肥(CF)处理对水稻幼苗生长、氮磷积累及土壤微生物群落的影响。结果表明,不同施肥处理的水稻幼苗生长明显被促进,其中CF处理的促进效果最好,其次是S-BS处理。S-BS处理的水稻叶片可溶性糖含量明显高于其他施肥处理,其叶片含氮量也明显高于CF处理。CF处理的土壤细菌总量明显高于S-BS处理,而S-BS处理的土壤细菌总量均显著高于对照(CK,不施肥)和S-CF处理;其中CF处理变形菌门细菌相对丰度显著高于其他处理。而CK和S-CF处理的真菌总量明显高于S-BS和CF处理,S-BS处理的真菌总量最低,其中,CK土壤优势真菌子囊菌门、担子菌门的相对丰度显著高于其他处理,S-CF处理土壤的壶菌门真菌相对丰度也显著高于其他处理。S-CF和S-BS处理的细菌Chao1丰富度指数和香农(Shannon)多样性指数要明显高于CF处理和CK,而S-CF处理的土壤真菌的Chao1指数和香农指数要明显高于CK,CF处理的土壤真菌Chao1指数和香农指数最低。秸秆、沼液短期替代化肥的处理下水稻植株生长低于全化肥处理的,但秸秆、沼液、化肥结合施用对水稻幼苗的促生作用依然很明显,尤其是秸秆还田结合沼液灌溉的全量替代化肥处理。全量替代化肥处理下,即秸秆和沼液处理的土壤质量和细菌丰富度及多样性即使在短期施用条件下也被明显促进。     

长期不同施肥对黄泥田土壤酶活性和微生物的影响

以农业部耕地保育福建观测实验站的长期肥料试验为平台,研究了长期不同施肥对黄泥田土壤酶活性和微生物的影响。结果表明:与不施肥(CK)相比,单施NPK(NPK)、NPK配施牛粪(NPKM)及NPK配施秸秆(NPKS)的土壤酶活性均有不同程度的提高,其中NPKM可显著提高转化酶活性,NPKS可显著提高脲酶活性。施肥均不同程度地提高了土壤细菌、真菌及放线菌的数量,尤其是放线菌数量,提高幅度均达到显著性水平;NPKS可显著提高土壤细菌数量,NPKM可显著提高土壤真菌数量。施肥均会对真菌群落产生重要影响;单施化肥对土壤细菌群落的影响不大,增施有机物料会对细菌群落产生明显影响;施用牛粪会对放线菌优势群落产生影响。以上结果表明,有机无机配施更有利于提高土壤酶活性和土壤微生物数量,提升土壤生物肥力。     

Responses of soil nematode community structure to different long-term fertilizer strategies in the soybean phase of a soybean–wheat–corn rotation

The impact of long-term application of fertilizers in soybean fields on soil nematode community structure was studied. The long-term application model of fertilizers lasted 13 years in a soybean–wheat–corn rotation, and included three treatments: no fertilizer (NF), chemical fertilizer (urea and ammonium phosphate, CF), and pig manure combined with chemical fertilizer (MCF). The soil nematode community structures and ecological indices were determined from soil samples taken at five soybean growth stages from May to October in the soybean phase of the rotation. Fertilizer application had significant effects on abundance of plant parasites, bacterivores and fungivores (P < 0.05), but had no significant effects on total nematodes and omnivores-predators. Abundance of plant parasites was higher in NF than in MCF and CF, and abundance of bacterivores was highest in MCF. Fertilizer application significantly affected Plant-parasitic Nematode Maturity Index (PPI) and Nematode Channel Ratio (NCR) ecological indices (P < 0.05). Shannon–Weaver Index (H′) and Species Richness (SR) indices were higher in MCF than in either NF or CF. The abundances of total nematode and plant parasites showed increasing trend with soybean growth in all three treatments. This is probably due to soil environment being more suitable for soil nematode survival with more food available for plant parasites as the soybean grows. Soybean growth stage significantly affected the H′, Free Living Nematode Maturity Index (MI) and PPI. Bacterivores significantly correlated with soil nutrient status suggesting that they could be used as a potential indicator of soil fertility.