生物炭及秸秆对水稻土各密度组分有机碳及微生物的影响

生物炭被认为是土壤碳封存的有效手段,但是关于生物炭对土壤不同密度组分有机碳影响的研究报道很少。以南方稻麦轮作区水稻土为研究对象,通过田间小区试验研究了不施有机物(CK)、玉米秸秆还田(CS)、施用300℃热解生物炭(300BC)、施用400℃热解生物炭(400BC)和施用500℃热解生物炭(500BC)处理对土壤轻重组分质量比例,土壤轻重组分有机碳和土壤微生物的影响。结果表明:1)施用生物炭显著提高了土壤轻组的质量比例和土壤轻组有机碳含量,轻组有机碳含量为500BC400BC300BCCSCK,对重组有机碳影响不显著,但重组有机碳在土壤中占重要比例;2)施加生物炭后土壤微生物量相比对照也有提高,但是与施加秸秆处理相比,微生物量提高幅度较小。研究表明,生物炭能提高土壤有机碳含量,尤其提高了土壤轻组有机碳的累积,但由于生物炭特殊的芳烃结构,其轻组组分化学性质稳定,这与传统的土壤有机碳轻组理论不同。与秸秆处理相比,生物炭处理具有较低的土壤微生物量与微生物商,有利于土壤碳的固定。     

低剂量生物质炭对旱地红壤增肥增产效果

针对江西旱地红壤粘重板结、肥力低下等突出问题,基于野外旱地红壤定位试验,研究了低剂量生物质炭对旱地红壤增肥增产效果的影响。试验设置3个试验处理,即0(CK)、758(BC1)、1515(BC2)kg·hm~(-2)·a~(-1)3种生物质炭施用水平。结果表明:与对照相比,施入低剂量生物质炭(即BC1、BC2处理),旱地红壤在0~60 cm土层土壤容重分别降低了0.57%~2.05%和0.87%~4.88%,土壤pH分别提高了2.51%~13.66%和8%~12%,阳离子交换量分别提高了3.73%~6.45%和4.91%~7.13%;施用低剂量生物质炭在一定程度上提高了旱地红壤有机质和N、P、K养分含量,且随着生物质炭施用量的增加,有机质、全钾、速效钾呈上升趋势;连续施用低剂量生物质炭,BC1、BC2处理红薯产量在2013年分别提高了19.08%和23.68%,2014年分别提高了18.01%和22.98%。研究表明,施用低剂量生物质炭能有效改善旱地红壤的土壤理化性质和养分状况,提高旱地红壤肥力,有效增加作物产量。从综合投入产出来看,低剂量生物炭的连续施用更有实际应用价值和前景。     

生物质调理剂对川西北高寒草地沙化土壤养分和微生物群落特征的影响

将农牧废弃物进行资源化处置制成生物质调理剂,用于沙化土壤改良是目前川西北沙化草地生态治理的有效途径之一.为了阐明不同原料调理剂在川西北高寒沙化草地上的实际应用效果,本研究以不施用调理剂为对照(CK),设置施用量均为12 t·hm-2的菌渣(JZ)、秸秆(JG)和生物炭(SWT)3种调理剂,分析了调理剂施用对土壤养分和微...     

生物炭与炭基肥对采煤塌陷复垦区土壤硝化和反硝化微生物群落的影响

作为一种新型土壤改良剂,生物炭对土壤微生物群落的影响已有报道,但在采煤塌陷复垦区土壤氮循环微生物群落对生物炭添加的响应鲜有报道。以生物炭和炭基肥为添加材料,以淮北地区塌陷复垦土为供试土壤,通过室外盆栽试验,采用荧光定量PCR(qPCR)和末端限制性片段长度多态性(T-RFLP)技术,研究不同生物炭处理的土壤硝化和反硝化微生物的菌群变化。试验共设5个处理:对照(CK)、常规化肥(CF)、炭基肥(BF)、2%生物炭配施化肥(LB)和4%生物炭配施化肥(HB)。结果表明: 与CK处理相比,各施肥处理均显著提高了土壤氨氧化古菌(AOA)、氨氧化细菌(AOB)、反硝化细菌nirK和nirS基因丰度。与CF处理相比,生物炭和炭基肥处理显著提高了AOB和nirK基因丰度,增幅分别达到42.9%～82.1%和33.5%～62.7%。冗余分析表明,土壤有机碳、pH、NH₄⁺-N和速效钾是显著影响AOB群落结构的主要因子,而土壤有机碳、pH和NO₃^--N含量是影响nirK型反硝化细菌群落结构的关键因子。因此,施用生物炭与炭基肥能改良采煤塌陷复垦区土壤质量,提高硝化和反硝化微生物丰度,并改变AOB和nirK型反硝化细菌群落结构。     

减氮配施稻秆生物炭对稻田土壤养分及植株氮素吸收的影响

通过2018年早稻和晚稻田间试验,研究化学氮肥减量及配施稻秆生物炭对稻田土壤养分特性及植株氮素吸收的影响。试验包括6个处理:不施氮(CK)、常规施氮(N₁₀₀)、减氮20%(N₈₀)、减氮20%配施生物炭(N₈₀+BC)、减氮40%(N₆₀)、减氮40%配施生物炭(N₆₀+BC)。结果表明: 与常规施氮相比,单纯减氮20%和40%或配施生物炭对早晚稻不同生育期土壤pH、有机质、全氮、铵态氮、全磷、有效磷、全钾、速效钾无显著影响;减氮20%配施生物炭显著增加晚稻分蘖期的土壤阳离子交换量(CEC),而减氮40%配施生物炭则显著增加晚稻抽穗期的电导率(EC)值。与单纯减氮相比,N₈₀+BC的土壤速效钾含量在早晚稻抽穗期均显著升高,土壤pH值、全氮在晚稻成熟期显著增加;N₆₀+BC的土壤全钾含量在早稻成熟期显著升高。不同处理早稻土壤硝态氮含量随生育进程逐渐降低,与分蘖期相比,抽穗期和成熟期的常规施氮土壤硝态氮含量分别降低50.0%和71.6%,而配施生物炭处理则降低6.3%～45.5%,减氮配施生物炭显著降低了硝态氮的流失。在晚稻抽穗期,减氮配施生物炭植株吸氮量显著高于常规施氮和单纯减氮,增加幅度为34.8%～52.4%。综上,适度的减氮或配施稻秆生物炭能有效保持土壤养分,促进水稻对氮素的吸收,提高氮素利用率。     

抗动物病原菌芽孢杆菌的筛选、初步鉴定和抗菌活性

从鸡肠道分离、挑选的18株芽孢杆菌经培养特征、形态观察、生理生化实验,初步被鉴定为枯草芽孢杆菌(Bacillus subtilus)、地衣芽孢杆菌(Bacillus licheniformis)、蜡状芽孢杆菌(Bacillus cereus)、巨大芽孢杆菌(Bacillus megaterium)和凝结芽孢杆菌(Bacillus coagulans)。同时测定了它们对5种常见动物病原菌大肠杆菌(E.coli)、金黄色葡萄球菌(Staphylococcus aureus)、肠炎沙门氏菌(Salmonella typhimurium)、猪链球菌(Streptococcus suis)、奇异变形杆菌(Proteus mirabilis)的抑菌活性,其中有4株芽孢杆菌对5种病原菌都有抑制作用。还分别测定了它们产木聚糖酶(从0.895 U1到3.239 U1)和纤维素酶活性(分别为0.391 U2和0.465 U2)。结果表明,芽孢杆菌分离株BC17、BC32、BC106、BC228、BC247和BC261具有作为益生菌的开发潜力。     

施用生物炭基肥对喀斯特石灰土磷元素特性的影响

以贵州省喀斯特山地石灰土为研究对象,采用盆栽试验方法,研究施用生物炭(稻壳炭)、猪粪堆肥和NPK肥3种肥料制成的生物炭基肥,测定土壤中不同形态磷含量、碱性磷酸酶活性及刺槐幼苗生物量。试验共设10个处理,分别为CK、M、F、MF、RH1MF、RH2MF、RH4MF、RH8MF、RH4M、RH4F(其中CK代表对照,M代表堆肥,F代表化肥,RH代表稻壳炭,数字代表生物炭按炭土质量比计算在生物炭基肥中的配比)。结果表明,施用生物炭基肥可显著提高喀斯特石灰土中总磷、有效磷、有机磷、微生物量磷含量及刺槐幼苗生物量,生物炭高施用量下处理(RH8MF)的效果更好,且4种不同形态的磷含量相互之间呈极显著正相关(P0.01);生物炭中等用量配比下生物炭基肥处理(RH2MF、RH4MF)的土壤碱性磷酸酶活性最高,分别比CK提高82.7%、63.4%。综上所述,施用生物炭基肥,尤其在生物炭较高施用量下,可以显著改善喀斯特石灰土中磷素含量,可改善石灰土中磷素含量较低状况,提高喀斯特山地人工幼林地生态恢复的成效。     

枯草芽孢杆菌生物茵剂对五味子白粉病防效及生长的影响

通过对不同年生五味子进行叶面喷施和根部灌施枯草芽孢杆菌生物菌剂进行田间试验,结果表明:(1)枯草芽孢杆菌生物菌剂对五味子白粉病有很好的抑制作用,喷施加灌施处理的发病率为13.0％,喷施的发病率为22.5％,清水对照的发病率为37.5％.对二年生、三年生、四年生五味子的防治效果分别为78.9％、77.8％、75.0％,这表明喷施加灌施枯草芽孢杆菌生物菌剂对五味子白粉病的防治效果最好.(2)枯草芽孢杆菌生物菌剂对五味子生长有明显的促进作用,对二年生、三年生、四年生五味子植株喷施加灌施的处理与清水对照相比叶面积总平均值分别增加了6.7％、42.4％、27.6％;单独喷施处理和喷施加灌施处理分别比清水对照处理的百果重增加了21.33％、28.79％;喷施加灌施处理的五味子醇甲含量最高达到0.74％.     

生物有机肥对菠萝心腐病及根际土壤细菌群落的影响

【目的】探明施用生物有机肥对菠萝心腐病的防控效果及对根际土壤微生物的影响。【方法】本研究采用高通量测序技术,综合分析不同施肥措施根际土壤微生物细菌群落多样性及群落特征。【结果】相比常规施肥处理(CK)和普通有机肥处理(YJ),生物有机肥处理KN (羊粪有机肥+泥炭土+枯草芽孢杆菌)和生物有机肥处理KY (羊粪有机肥+椰糠+枯草芽孢杆菌)均能显著降低菠萝心腐病的发病率,且KN处理的防控效果最佳。生物有机肥(KN、KY)施入后土壤细菌α多样性指数高于CK和YJ处理,并形成了明显不同的细菌群落结构。与CK相比,生物有机肥KN处理显著提高了拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)的丰度,KY处理中的酸杆菌门(Acidobacteria)、绿弯菌门(Chloroflexi)、芽单胞菌门(Gemmatimonadetes)、硝化螺旋菌门(Nitrospirae)丰度显著增加;属水平上,生物有机肥中的蔗糖伯克霍尔德菌属(Paraburkholderia)和黄杆菌属(Flavobacterium)丰度均显著提升。方差分区分析(variance partitioning analysis, VPA)表明,土壤化学性质(36.29%)对细菌群落影响最大,其中土壤速效钾和有机质是影响土壤细菌群落的关键因子,此外发病率(22.53%)和肥料偏生产力(16.42%)也是影响土壤细菌群落的重要因子。【结论】施用生物有机肥(KN、KY)能改变根际土壤细菌群落结构,降低发病率,对菠萝根际土壤生态系统稳定与健康具有重要意义。     

生物炭施用对桂北桉树人工林土壤酶活性的影响

为探究土壤酶活性对生物炭输入的响应特征，以及为合理应用桉树枝条生物炭提供理论参考，该研究基于桂北桉树人工林田间试验，以桉树人工林采伐剩余物枝条为原料，在500℃条件下厌氧制备生物炭，施用质量分数分别为0(CK)、0.5%(T1)、1%(T2)、2%(T3)、4%(T4)和6%(T5)的桉树枝条生物炭，输入1 a后，分析了不同处理下土壤酶活性的变化特征。结果表明：(1)沿着土层垂直深度，土壤酶含量减小。(2)各土层脲酶、过氧化氢酶、β-葡萄糖苷酶和脱氢酶的含量随生物炭施用量的增加而增大，在生物炭施用量为6%时含量最高。(3)酸性磷酸酶、蔗糖酶、亮氨酸氨基肽酶和纤维二糖苷酶的含量随着生物炭施用量的增加呈现先增加后减少的趋势，其中酸性磷酸酶和亮氨酸氨基肽酶在生物炭施用量为2%时含量最高，蔗糖酶和纤维二糖苷酶则在生物炭施用量4%时含量最高。总体上，桉树枝条生物炭施用不同程度地提高了桉树人工林的土壤酶活性。该研究结果可为林业废弃物制备生物炭资源化利用途径及其在桉树人工林的应用提供科学依据。     

植物、土壤及土壤管理对土壤微生物群落结构的影响

土壤微生物是土壤生态系统的重要组成部分,对土壤微生物群落结构多样性的研究是近年来土壤生态学研究的热点。本文综述了有关植物、土壤类型以及土壤管理措施对土壤微生物群落结构影响的最新研究结果,指出植物的作用因植物群落结构多样性、植物种类、同种植物不同的基因型,甚至同一植物不同根的区域而异;而土壤的作用与土壤质地和有机质含量等因素有关;植物和土壤类型在对土壤微生物群落结构影响上的作用存在互作关系。不同的土壤管理措施对土壤微生物群落结构影响较大,长期连作、大量的外援化学物质的应用降低了土壤微生物的多样性;而施用有机肥、免耕可以增加土壤微生物群落结构多样性,有利于维持土壤生态系统的功能。     

Effect of soil moisture on bioremediation of chlorophenol-contaminated soil

A chlorophenol-contaminated soil was tested for the biodegradability in a semi-pilot scale microcosm using indigenous microorganisms. More than 90% of 4-chlorophenol and 2,4,6-trichlorophenol, initially at 30 mg kg^–1, were removed within 60 days and 30 mg pentachlorophenol kg^–1 was completely degraded within 140 days. The chlorophenols were degraded more effectively under aerobic condition than under anaerobic condition. Soil moisture had a significant effect with the slowest degradation rate of chlorophenols at 25% in the range of 10–40% moisture content. At 25–40%, the rate of chlorophenol degradation was directly related to the soil moisture content, whereas at 10–25%, it was inversely related. Limited oxygen availability through soil agglomeration at 25% moisture content might decrease the degradation rate of chlorophenols.     

耕作方式对潮土土壤团聚体微生物群落结构的影响

为探究不同耕作方式对潮土土壤团聚体微生物群落结构和多样性的影响,采用磷脂脂肪酸(PLFA)法测定了土壤团聚体中微生物群落。试验设置4个耕作处理,分别为旋耕+秸秆还田(RT)、深耕+秸秆还田(DP)、深松+秸秆还田(SS)和免耕+秸秆还田(NT)。结果表明:与RT相比,DP处理显著提高了原状土壤和>5 mm粒级土壤团聚体中真菌PLFAs量和真菌/细菌,为真菌的繁殖提供了有利条件,有助于土壤有机质的贮存,提高了土壤生态系统的缓冲能力;提高了5～2 mm粒级土壤团聚体中细菌PLFAs量,降低了土壤革兰氏阳性菌/革兰氏阴性菌,改善了土壤营养状况;提高了<0.25 mm粒级土壤团聚体中微生物丰富度指数。总的来说,深耕+秸秆还田(DP)对土壤团聚体细菌和真菌生物量有一定的提高作用,并且在一定程度上改善了土壤团聚体微生物群落结构,有利于增加土壤固碳能力和保持土壤微生物多样性。冗余分析结果表明,土壤团聚体总PLFAs量、细菌、革兰氏阴性菌和放线菌PLFAs量与土壤有机碳相关性较强,革兰氏阳性菌PLFAs量与总氮相关性较强。各处理较大粒级土壤团聚体微生物群落主要受碳氮比、含水量、pH值和团聚体质量分数的影响,较小粒级土壤团聚体微生物群落则主要受土壤有机碳和总氮的影响。     

Available soil nitrogen in relation to fractions of soil nitrogen and other soil properties

The available N of 27 soils from England and Wales was assessed from the amounts of N taken up over a 6-month period by perennial ryegrass grown in pots under uniform environmental conditions. Relationships between availability and the distribution of soil N amongst various fractions were then examined using multiple regression. The relationship: available soil N (mg kg^–1 dry soil)=(N_min×0.672)+(N_inc×0.840)+(N_mom×0.227)–5.12 was found to account for 91% of the variance in available soil N, where N_min=mineral N, N_inc=N mineralized on incubation and N_mom=N in macro-organic matter. The N mineralized on incubation appeared to be derived largely from sources other than the macro-organic matter because these two fractions were poorly correlated. When availability was expressed in terms of available organic N as % of soil organic N (N_ao) the closest relationship with other soil characteristics was: N_ao=[N_inc×(1.395–0.0347×CN_mom]+[N_mom×0.1416], where CN_mom=CN ratio of the macro-organic matter. This relationship accounted for 81% of the variance in the availability of the soil organic N.The conclusion that the macro-organic matter may contribute substantially to the available N was confirmed by a subsidiary experiment in which the macro-organic fraction was separated from about 20 kg of a grassland soil. The uptake of N by ryegrass was then assessed on two subsamples of this soil, one without the macro-organic matter and the other with this fraction returned: uptake was appreciably increased by the macro-organic matter.     

Estimating respiration of roots in soil: Interactions with soil CO2, soil temperature and soil water content

Little information is available on the variability of the dynamics of the actual and observed root respiration rate in relation to abiotic factors. In this study, we describe I) interactions between soil CO₂ concentration, temperature, soil water content and root respiration, and II) the effect of short-term fluctuations of these three environmental factors on the relation between actual and observed root respiration rates. We designed an automated, open, gas-exchange system that allows continuous measurements on 12 chambers with intact roots in soil. By using three distinct chamber designs with each a different path for the air flow, we were able to measure root respiration over a 50-fold range of soil CO₂ concentrations (400 to 25000 ppm) and to separate the effect of irrigation on observed vs. actual root respiration rate. All respiration measurements were made on one-year-old citrus seedlings in sterilized sandy soil with minimal organic material.Root respiration was strongly affected by diurnal fluctuations in temperature (Q₁₀ = 2), which agrees well with the literature. In contrast to earlier findings for Douglas-fir (Qi et al., 1994), root respiration rates of citrus were not affected by soil CO₂ concentrations (400 to 25000 ppm CO₂; pH around 6). Soil CO₂ was strongly affected by soil water content but not by respiration measurements, unless the air flow for root respiration measurements was directed through the soil. The latter method of measuring root respiration reduced soil CO₂ concentration to that of incoming air. Irrigation caused a temporary reduction in CO₂ diffusion, decreasing the observed respiration rates obtained by techniques that depended on diffusion. This apparent drop in respiration rate did not occur if the air flow was directed through the soil. Our dynamic data are used to indicate the optimal method of measuring root respiration in soil, in relation to the objectives and limitations of the experimental conditions.     

The porosity of soil aggregates from bulk soil and from soil adhering to roots

Summary Total porosity and pore-size distribution (p.s.d.) were determined in soil aggregates taken in plots planted with maize and treated with farmyard manure and three rates of compost. Soil aggregates were collected from the soil adherent to the maize roots (root soil aggregates) and from bulk soil (bulk soil aggregates). Mercury intrusion porosimetry was used to evaluate the total porosity and the p.s.d. Treatments did not affect the total porosity of the bulk soil aggregates. The same was observed for the root soil aggregates. However the total porosity of the root soil aggregates was always lower than that of the bulk soil aggregates. The loss of total porosity was found to be due to a decrease in the percentage of larger pores with respect to the total.     

生物质炭对水稻土团聚体微生物多样性的影响

生物质炭施用对土壤微生物群落结构的影响已有报道,但土壤团聚体粒组中微生物群落对生物质炭施用的响应的研究还相对不足。以施用玉米秸秆生物质炭两年后的水稻土为对象,采用团聚体湿筛法,通过高通量测序对土壤团聚体的微生物群落结构与多样性进行分析,结果表明:(1)与对照相比,生物质炭施用显著促进了大团聚体(2000—250μm)的形成,并提高了团聚体的稳定性。(2)不同粒径团聚体间微生物相对丰度存在显著差异。在未施生物质炭的处理(C0)中,随着团聚体粒径增大,变形菌门、子囊菌门、β-变形杆菌目、格孢腔菌目的相对丰度逐渐降低,而酸杆菌门、担子菌门、粘球菌目、类球囊霉目的相对丰度逐渐升高。(3)生物质炭施用显著改变了团聚体间的微生物群落结构。与C0处理相比,生物质炭施用处理的大团聚体中变形菌门、鞭毛菌门和β-变形杆菌目的相对丰度分别显著提高了14.37%、33.28%和33.82%;微团聚体(250—53μm)中酸杆菌门、子囊菌门和粘球菌目的相对丰度分别显著降低了20.15%、19.93%和17.66%;粉、黏粒组分(<53μm)中担子菌门的相对丰度升高90.25%,而子囊菌门和鞭毛菌门的相对丰...     

酸性硫酸盐土水改旱后土壤化学性状的变异初报

探讨了酸性硫酸盐水稻土改为旱作后土壤化学性状的变异以及比较不同利用方式之间的经济效益．结果表明,酸性硫酸盐水稻土改种甜玉米和蔬菜后,土壤化学性状发生显著变化．耕层土壤酸度、水溶性硫酸根含量、土壤活性铝和活性铁含量均显著降低．经济效益得到显著提高．建议对水改旱后的环境效应进行深入研究以及进行定位观测,以便合理利用这一特殊的土壤资源     

Temporal dynamics of soil bacterial network regulate soil resistomes

Soil bacteria are diverse and form complicated ecological networks through various microbial interactions, which play important roles in soil multi-functionality. However, the seasonal effects on the bacterial network, especially the relationship between bacterial network topological features and soil resistomes remains underexplored, which impedes our ability to unveil the mechanisms of the temporal-dynamics of antibiotic resistance genes (ARGs). Here, a field investigation was conducted across four seasons at the watershed scale. We observed significant seasonal variation in bacterial networks, with lower complexity and stability in autumn, and a wider bacterial community niche in summer. Similar to bacterial communities, the co-occurrence networks among ARGs also shift with seasonal change, particularly with respect to the topological features of the node degree, which on average was higher in summer than in the other seasons. Furthermore, the nodes with higher betweenness, stress, degree, and closeness centrality in the bacterial network showed strong relationships with the 10 major classes of ARGs. These findings highlighted the changes in the topological properties of bacterial networks that could further alter antibiotic resistance in soil. Together, our results reveal the temporal dynamics of bacterial ecological networks at the watershed scale, and provide new insights into antibiotic resistance management under environmental changes.