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1.
基于不同方法测定土壤酸性磷酸酶活性的比较 总被引：2，自引：0，他引：2
土壤酸性磷酸酶与有机磷的矿化及植物的磷素营养关系最为密切。目前国内学者在测定酸性磷酸酶活性时主要参照关松荫《土壤酶及其研究法》中以磷酸苯二钠为基质的测定方法,而国外学者主要参照Dick《Methods of Soil Enzymology》中以对硝基苯磷酸二钠为基质的测定方法(PNPP)。但是,在以磷酸苯二钠为基质测定生成物的过程中,常出现显色程度不明显的问题;另外,采用不同基质测定酸性磷酸酶活性也造成了测定方法选择的困难。为合理选择土壤酸性磷酸酶活性的测定方法,本研究选用酸性、中性和碱性土壤各10个土样,分别采用以磷酸苯二钠为基质,且在显色阶段分别加入pH5.0醋酸盐缓冲液(DPP 1)和pH9.4硼酸盐缓冲液(DPP 2)的方法,以及PNPP方法测定土壤酸性磷酸酶活性。同时也研究了不同pH缓冲液和苯酚浓度对生成物显色反应的影响。结果表明:以磷酸苯二钠为基质、在显色反应阶段加入pH≤6的缓冲液时,苯酚和2,6-二溴苯醌氯亚胺不显色;当加入pH≥8的缓冲液时,两者之间显色且苯酚浓度和吸光值的Pearson相关系数极显著。这说明pH低是导致高苯酚浓度和2,6-二溴苯醌氯亚胺显色效果差的一个主要原因。此外,采用PNPP方法测定时,在酸性、中性和碱性土壤中,10个样本酸性磷酸酶活性的变异系数分别较DPP 2增加了70.04%、42.44%和21.17%;极差分别是DPP 2的27.18倍、26.85倍和39.43倍。总之,如果选用磷酸苯二钠为基质测定土壤酸性磷酸酶活性,应在显色阶段加入碱性硼酸盐缓冲液;选用对硝基苯磷酸二钠为基质,是更为简单和灵敏的方法。 相似文献
2.
基于不同基质测定土壤碱性磷酸酶活性的比较 总被引：2，自引：0，他引：2
《土壤通报》2015,(5):1133-1137
土壤磷酸酶对有机磷的矿化及植物的磷素营养有重要影响。目前测定土壤磷酸酶活性采用的基质主要有磷酸苯二钠(CAS编号:3279-54-7)和对硝基苯磷酸二钠(CAS编号:4264-83-9)两种。国际上对土壤磷酸酶活性的测定普遍采用对硝基苯磷酸二钠,而国内大部分学者主要采用磷酸苯二钠。由于不同类型的基质对磷酸酶活性的测定结果有很大影响,所以选择适宜的基质种类对磷酸酶活性进行测定有很大的不确定性。为探讨碱性磷酸酶活性的测定方法,以磷酸苯二钠和对硝基苯磷酸二钠为基质,选用酸性、中性和碱性土壤各10个土样,比较了依据《土壤酶及其研究法》(DPP1),《Method in Soil Biology》(DPP2)和《Methods of Soil Enzymology》(PNPP)书中所介绍的测定方法所获结果之间的差异。结果表明:三种方法所测的三种类型土壤磷酸酶活性的变化趋势基本一致,但不同土壤之间差异性的变化幅度有明显不同。在酸性土壤和碱性土壤中,DPP1和DPP2所测十个土样碱性磷酸酶活性之间的变异系数属于中度变异,而PNPP则属于高度变异;在中性土壤中,DPP1和DPP2属于低度变异,PNPP属于中度变异。总的来看,PNPP比DPP1和DPP2敏感。此外,由于PNPP具有高精确度、培养时间短和实验操作简便等优点,我们建议采用PNPP进行碱性磷酸酶活性的测定。 相似文献
3.
为了明确影响啤酒大麦籽粒脂氧合酶(LOX-1)活力的参数,以甘啤4号啤酒大麦籽粒为研究对象,采用紫外分光光度法探究底物浓度、提取缓冲液p H、反应体系缓冲液p H、提取时间、粗酶加入量∶底物加入量等对LOX-1活力的影响。结果表明,LOX-1活力随底物浓度的增加表现为先增加后减小的趋势,当底物浓度达到0.30mmol·L~(-1)时,LOX-1活力显著高于其它处理;随提取缓冲液p H的增加,LOX-1活力表现为双峰变化趋势,且在p H值5.0处,酶活力为9.85U·g~(-1),显著高于其它处理;粗酶提取时间为30min时,LOX-1活力显著高于其它处理,低于或者高于30min,酶活力均呈现降低趋势;LOX-1活力随反应体系p H的增加,表现为双峰变化趋势,当p H值为6.4时,酶活力最大,且与其它处理间存在显著差异;在其它条件不变,粗酶加入量为50μL的情况下,增加底物加入量,LOX-1活力表现为先增加后减小的趋势,且底物加入量为200μL时,酶活力显著高于其它处理。最终确定紫外分光光度法的测定参数:粗酶提取时间为30min,底物浓度为0.25mmol·L~(-1),提取液和反应体系缓冲液分别为p H值5.0醋酸盐缓冲液与p H值6.4磷酸盐缓冲液,粗酶加入酶量∶底物加入量为1∶4。研究结果为紫外分光光度法在啤酒大麦籽粒LOX-1活力测定中的应用提供了参考。 相似文献
4.
可溶性盐对土壤pH测定的影响及消除初探 总被引：2，自引：0，他引：2
在我国大量施肥的背景下,最近几十年农田土壤酸化速率加快,尤其是设施栽培体系土壤。在淋洗强度较弱的情况下,土壤可伴随有次生盐渍化现象,而可溶性盐的存在对土壤p H(H2O)(用水浸提土壤测得的p H)的测定有显著影响。由于p H是酸化评估的重要指标之一,有必要深入探究农田土壤常见可溶性盐对p H(H2O)测定的影响。本研究中,为精确评估积盐农田土壤的酸化状况,以潮土、褐土、水稻土和红壤为研究对象,研究了农田土壤尤其是设施土壤中常见六种可溶性盐(Ca(NO3)2、KNO3、Mg SO4、K2SO4、Ca Cl2、KCl)对土壤p H测定的影响;并以硝酸钾为研究对象,对比分析了四种消除可溶性盐对p H(H2O)测定影响的方法,这四种方法分别为:用石灰位代替p H(H2O);用0.01 mol L-1Ca Cl2浸提代替水浸提;先用模型计算出盐分对p H(H2O)测定的影响,然后从p H(H2O)中减去;用蒸馏水或50℃的50%酒精溶液将土壤中可溶性盐洗除后风干再测定p H(H2O)。结果表明:10 g kg-1可溶性盐的存在可使土壤p H下降0.09~0.87个单位,可溶性盐浓度及土壤电导率(EC)均与p H、△p H(p H的下降程度)之间具有显著的自然对数相关性。同种土壤,不同盐类对p H测定的影响程度不同,强弱顺序因离子组成和土壤类型而异,总体表现为硝酸盐和氯化物对p H测定的影响高于硫酸盐,氯化钙的影响程度高于钾盐及硝酸钙和硫酸镁,三种钾盐之间差异不明显;同种盐类,四种土壤受盐分影响的程度强弱顺序为:褐土水稻土潮土红壤。四种方法均可以减弱或消除硝酸钾对p H测定的影响,6.9 g kg-1硝酸钾施入土壤中可使土壤p H下降0.24~0.71个单位,消除影响后,硝酸钾仅可使土壤p H下降-0.38~0.19个单位。四种方法的简单有效程度为:石灰位0.01 mol L-1Ca Cl2浸提测定p H模型拟合计算洗盐处理。消除可溶性盐对p H测定的影响可以使积盐的农田土壤酸化评估更为精确,使土壤酸化风险预测更为准确,有利于制定合理有效的风险应对措施。 相似文献
5.
滴灌枸杞对龟裂碱土几种酶活性的改良效应 总被引：3，自引：0，他引：3
在盐碱地改良利用过程中,有必要研究土壤酶活性变化,以评价土壤环境质量的改善。龟裂碱土重度盐碱荒地主要分布在我国西北旱区,该土壤碱化度高,结构差,导水率极低。2009年,采用滴头下设置沙穴的方式滴灌种植枸杞,开垦利用该盐碱荒地。2011年枸杞生长季末,在不同种植年限地块土壤剖面上网格状密集取土,进行土壤脲酶、碱性磷酸酶和蔗糖酶活性的测定。结果表明,未种植土壤3种酶活性极低;滴灌种植之后,随着根区土壤水盐特性和养分状况的改善,土壤酶活性显著增加。就整个土壤剖面而言,土壤酶活性自根区向四周逐渐降低,表现出较大的空间变异性。相关性和通径分析结果显示,土壤p H始终是影响该土壤酶活性的主要因子,且在p H7.38~10.00的范围内,3种酶活性随土壤p H的增大呈指数式减小(p0.01)。总之,滴灌种植枸杞之后,龟裂碱土重度盐碱荒地土壤生物学性质得到显著改善。 相似文献
6.
田间玉米和蚕豆对低磷胁迫响应的差异比较 总被引：1，自引：1，他引：0
【目的】植物在长期进化过程中形成了一系列适应机制,以应对低磷胁迫。本文提出玉米主要通过根系形态变化适应低磷胁迫的假设,并通过与蚕豆植株在根系形态与生理方面对低磷胁迫反应的比较试验加以验证。【方法】在中国农业大学上庄长期定位试验田进行两年田间实验,玉米和蚕豆分别单作,重复3次。在玉米抽雄前的拔节至大喇叭口期和蚕豆的初花至盛花期两次取样(两年的两次取样时间间隔10~12天),比较研究了不供磷和供磷100 kg/hm2下玉米和蚕豆生长和磷素吸收、根系在0—40 cm土层中分布、以及根际p H值和酸性磷酸酶活性的差异。【结果】1)玉米植株的生物量和含磷量远远高于蚕豆;第一次取样时蚕豆的根冠比高于玉米,而且两种植物低磷下的根冠比高于供磷充足处理。两次取样时玉米的总根长大于蚕豆,两种植物的大部分根系分布在0—20 cm表层土壤,玉米根系在0—10 cm土层的分布更多。2)蚕豆根系的比根长明显大于玉米,但单位根长吸磷量低于玉米,两种植物间的上述差异不受取样时间和供磷水平的影响。3)两次取样时,蚕豆根表的酸性磷酸酶活性均明显高于玉米。玉米根表的酸性磷酸酶活性在两个供磷水平下没有差异。第一次取样时,缺磷蚕豆根表的酸性磷酸酶活性高于供磷充足的蚕豆植株。4)缺磷蚕豆的根际土壤p H值明显低于供磷充足蚕豆;但玉米根际土壤p H值在缺磷和供磷充足条件下无显著差异。【结论】低磷条件下两种植物的根冠比均明显增加。玉米根系单位根长的吸磷量高于蚕豆,并且在含磷量丰富的表层土壤分布有更多根系,但缺磷条件下玉米没有增加根系的质子和酸性磷酸酶的分泌,主要以根系形态变化来适应低磷胁迫。结果支持本文提出的玉米主要通过根系形态变化适应低磷胁迫的假设。但蚕豆在低磷条件下除了增加根系生长外,还具有通过增加质子分泌和根表酸性磷酸酶活性提高根际土壤有效磷浓度的潜力。 相似文献
7.
分别采用硫代硫酸钠滴定法、高锰酸钾滴定法、TTC-脱氢酶活性测定法和磷酸苯二钠比色法测定龙胆GAP基地土壤中转化酶、过氧化氢酶、脱氢酶和磷酸酶的活性。对不同月份、种植不同年生龙胆根际土及非根际土中酶活性的测定结果进行分析表明:土壤过氧化氢酶活性在6月份出现一较高值,脱氢酶活性较高时期在7月份,土壤转化酶活性较大值出现在7、8月份,磷酸酶活性则逐月增高至9月份达到最大值,土壤总体酶活指标极大值出现在8月份;随着龙胆种植年限的增加,土壤过氧化氢酶和脱氢酶活性有所提高,而磷酸酶和转化酶活性没有明显变化,种植不同年生龙胆土壤中酶的活性随季节波动不尽相同。比较GAP基地龙胆根际土与非根际土中酶活性,土壤转化酶和过氧化氢酶的活性均表现为根际土非根际土,而土壤磷酸酶和脱氢酶的活性则为非根际土根际土;相关分析结果显示,过氧化氢酶活性与酸性及中性磷酸酶活性显著负相关;酸性、中性及碱性三种磷酸酶活性之间存在极显著正相关;总体酶活指标与转化酶、酸性磷酸酶、中性磷酸酶活性呈显著正相关。本研究完善了中药材龙胆GAP种植基地土壤酶的信息,为综合评价基地土壤肥力提供了科学数据,为药用植物龙胆的合理施肥、品质的提高提供了科学依据。 相似文献
8.
以滇中植烟土壤为研究对象，设置不同厨余垃圾堆肥(基肥)施用量：不施肥对照(CK)、低施肥量8 t/hm2 (FWL)、中施肥量16t/hm2 (FWM)、高施肥量24t/hm2 (FWH)，研究厨余垃圾堆肥施用后土壤酶活性和细菌群落结构的变化特征，为厨余垃圾堆肥农田推广使用提供依据。结果表明：与CK相比，FWH处理可显著提高土壤的p H、有机碳、全氮、全磷、碱解氮、有效磷、脲酶活性、酸性磷酸酶活性、荧光素二乙酸水解酶活性(↑0.39%～89.42%)、土壤细菌OUT数目(↑12.91%)、Chao指数(↑11.20%)、Ace指数(↑11.37%)。变形菌门(Proteobacteria)的相对丰度随施肥量的增加而增加，而酸杆菌门(Acidobacteria)则相反；细菌群落的膜运输和碳水化合物代谢功能均在施肥后显著增强。脲酶活性、酸性磷酸酶活性、p H、全氮、全磷、碱解氮、有效磷指标对土壤细菌的群落组成和多样性均有影响，其中碱解氮和脲酶活性是调控菌群最主要的因子。 相似文献
9.
生物炭对镉污染土壤有效态镉及土壤酶活性的影响 总被引：2，自引：0，他引：2
《土壤通报》2020,(4)
为研究添加生物炭对两种镉(Cd)污染土壤(分别采自安徽铜陵和江西萍乡)pH,土壤有效镉和土壤酶活性的影响,在两种Cd污染的土壤中添加不同量的生物炭,分别在培养20天和180天测定土壤pH,土壤有效态Cd和酶活性,初步探讨了生物炭对两种镉污染土壤酶活性和土壤有效Cd的影响。结果表明,随着生物炭量的增加均能降低两种土壤中有效态Cd含量,且在萍乡土壤上钝化效果更明显;在培养初期,土壤pH值随着生物炭量的增加逐渐增加,但培养180天后,添加生物炭后的两种土壤pH值较对照组无显著变化;在整个培养期,土壤酸性磷酸酶活性随生物炭量的添加受到抑制外,土壤脲酶和蔗糖酶的酶活性均增加,而过氧化氢酶含量在铜陵土壤上呈现出显著的升高趋势,但在萍乡土壤上则出现了降低。 相似文献
10.
长期不同施肥棕壤玉米地的酶活性之时空变化 总被引：2，自引：0，他引：2
为揭示长期不同施肥对棕壤玉米地酶活性时空变化的影响,利用31年长期肥料定位试验研究了玉米生育期内3种主要土壤酶活性的时空变化及其与土壤理化性质的关系。结果表明,棕壤上各种酶随玉米生育期推进而有规律地变化。土壤脲酶、转化酶活性高峰出现在玉米拔节期,酸性磷酸酶活性高峰出现在玉米大喇叭口期;玉米收获后,土壤转化酶、脲酶均高于播前或与播前相当,而酸性磷酸酶活性则低于播前。在同样化肥水平上增施有机肥能增加脲酶、转化酶活性,而降低酸性磷酸酶活性;3种酶活性的空间分布规律均遵循随土层深度加深而不断减小的规律,长期培肥对深层土壤酶活性亦有影响。相关分析结果显示,土壤脲酶同转化酶呈极显著正相关（r=0.636**）;脲酶、转化酶同土壤有机碳、pH、含水量、碱解氮、速效磷基本呈极显著正相关;酸性磷酸酶同各因子无显著关系。土壤酶与土壤肥力因素关系密切,可作为衡量土壤肥力的敏感指标。 相似文献
11.
The pH buffer capacity of a soil (pHBC) determines the amount of lime required to raise the pH of the soil layer from its initial acid condition to an optimal pH for plant growth and the time available under current net acid addition rate (NAAR) until the soil layer acidifies to a critical pH leading to likely production losses. Accurate values of pHBC can also be used to calculate NAAR from observed changes in soil pH. In spite of its importance, there is a critical shortage of pHBC data, likely due to the long period of time needed for its direct measurement. This work aimed to develop quick, simple and reliable methods of pHBC measurement and to test these methods against a slow (7‐day) titration used as benchmark. The method developed here calculates pHBC directly from the pH buffer capacity of the buffer solution and the increase in soil pH and corresponding decrease in pH of the buffer solution following mixing and equilibration. The pHBC values calculated using Adams and Evans or modified Woodruff buffers were in accord with those measured by slow titration. Buffer methods are easily deployed in commercial and research laboratories as well as in the field. The advantage of using buffer solutions to calculate pHBC instead of lime requirement is the broad application of this soil property. The pHBC of a soil is an intrinsic property that would not be expected to need remeasurement over periods of less than decades. Recurring lime requirement can be calculated from the soil's pHBC, initial and target pH values. A large proportion of the variability in pHBC was explained by the soil organic carbon content. This relationship between pHBC and soil organic carbon content allowed us to develop local pedotransfer functions to estimate pHBC for different regions of Australia. 相似文献
12.
湘西典型植烟土壤酸碱缓冲特性及影响因素 总被引：3，自引：0，他引：3
为探明山地植烟土壤酸碱缓冲特性,采集了湘西山区烤烟典型生产区的28个土壤样本,采用酸碱滴定法和灰色关联法分析了湘西山地植烟土壤酸碱缓冲特性以及土壤缓冲容量与各影响因素之间的量化关系。结果表明：湘西山地植烟土壤酸碱缓冲量为11.35~43.29 mmol·kg-1,平均为17.26 mmol·kg-1,黄棕壤的酸碱缓冲量（11.35~43.29 mmol·kg-1）显著高于黄壤（11.79~20.70 mmol·kg-1）。有78.57%的样本对酸碱敏感,黄壤土是否对酸敏感由有机质含量决定,黄棕壤土是否对酸敏感与pH和有机质含量密切相关。对于同一土壤类型,有机质和黏粒含量与酸碱缓冲容量显著正相关;对于黄棕壤,酸碱缓冲容量还与pH和阳离子交换量呈显著正相关,与交换性酸和交换性铝呈显著负相关。主要土壤类型之间缓冲性能存在较大差异,黄壤土酸碱缓冲性能主要受土壤有机质、阳离子交换量和黏粒含量的影响;黄棕壤土酸碱缓冲性能主要受pH、阳离子交换量和有机质的影响。在生产中应采用合理施用化肥、增施有机肥、调节土壤酸性等措施提高植烟土壤酸碱缓冲性能,为优质烟叶生产创造良好的生态环境。 相似文献
13.
Jared L. DeForest 《Soil biology & biochemistry》2009,41(6):1180-1186
The purpose of this experiment was to evaluate whether soil storage and processing methods significantly influence measurements of potential in situ enzyme activity in acidic forest soils. More specifically, the objectives were to determine if: (1) duration and temperature of soil storage; (2) duration of soil slurry in buffer; and (3) age of model substrates significantly influence the activity of six commonly measured soil extracellular enzymes using methylumbelliferone (MUB)-linked substrates and l-dihydroxyphenylalanine (l-DOPA). Soil collected and analyzed for enzyme activity within 2 h was considered the best measure of potential in situ enzyme activity and the benchmark for all statistical comparisons. Sub-samples of the same soil were stored at either 4 °C or −20 °C. In addition to the temperature manipulation, soils experienced two more experimental treatments. First, enzyme activity was analyzed 2, 7, 14, and 21 days after collection. Second, MUB-linked substrate was added immediately (i.e. <20 min) or 2 h after mixing soil with buffer. Enzyme activity of soil stored at 4 °C was not significantly different from soil stored at −20 °C. The duration of soil storage was minimal for β-glucosidase, β-xylosidase, and peroxidase activity. N-acetyl-glucosaminidase (NAGase), phosphatase, and phenol oxidase activity appeared to change the most when compared to fresh soils, but the direction of change varied. Likewise, the activities of these enzymes were most sensitive to extended time in buffer. Fluorometric MUB and MUB-linked substrates generally had a 3-day shelf life before they start to significantly suppress reported activities when kept at 4 °C. These findings suggest that the manner in which acidic forest soils are stored and processed are site and enzyme specific and should not initially be trivialized when conducting enzyme assays focusing on NAGase, phosphatase, and phenol oxidase. The activities of β-glucosidase, β-xylosidase, and peroxidase are insensitive to storage and processing methods. 相似文献
14.
Ecotoxicological tests based on soil enzyme activity are widely used to assess the terrestrial ecotoxicology of metals in soils. However, several standard enzymatic methods use buffers that may alter the chemical pseudoequilibrium of soils and affect metal speciation, and, in turn, the metal effects on enzymes and enzyme kinetics. Researchers have suggested the use of H2O as a solvent rather than chemical buffers, but opponents are concerned about pH fluctuations during incubation and the resulting difficulty in comparing enzymatic studies. Enzyme assays were conducted on 10 pairs of Zn-contaminated soils to evaluate 1) the buffer effect on Zn lability 2) the pH fluctuation during enzymatic assays conducted in water and 3) the comparison of enzymatic results obtained using chemical buffers versus water. Four standard enzymatic methods covering the major biogeochemical cycles were targeted: arylsulfatase (acetate pH 5.8), urease (borate pH 10), acid phosphatase (modified universal buffer pH 6.5) and protease (THAM pH 8.1). Furthermore, deionized water was tested in parallel as a surrogate solvent for these four methods. With the exception of the acetate buffer, the tested solvents did not significantly change the labile Zn concentration in the soil samples. The pH slightly fluctuated by +0.57 pH unit, corresponding to the intrinsic variability of soils. Enzymatic methods using buffers showed similar results compared to those using water, except for urease. These observations suggest that enzymatic methods setting alkaline conditions should be used with caution and that H2O could be used as surrogate solvent in this context. 相似文献
15.
外源低分子量有机酸对碳酸钙预处理的酸性土壤中活性铝钙镁影响的研究 总被引：1，自引：0，他引：1
通过在所研究的第四纪红黏土发育的红壤中混入CaCO3,研究在pH缓冲体系中外加低分子量有机酸对土壤中Al、Ca和Mg的影响。结果表明:无论加CaCO3与否,在pH 4.5的条件下外源草酸、柠檬酸、苹果酸的加入均使土壤可溶性Al显著提高,交换性Al显著下降和交换性Ca显著升高;加入CaCO3的情况下,3种有机酸处理的交换性Mg均显著提高。3种有机酸促进Al溶解能力的大小顺序为:柠檬酸>草酸>苹果酸,这一结果与有机酸和Al形成络合物的稳定常数大小一致。另一方面,3种有机酸处理下,CaCO3预处理均引起可溶性Al的显著升高和交换性Al的下降。双因素方差分析表明,有机酸通过络合作用或沉淀作用对可溶性和交换性Al、Ca和Mg均具有绝对的影响优势,CaCO3仅对可溶性和交换性Al、交换性Ca有显著影响,由于实验中pH缓冲体系的控制,这种影响主要通过Al与Ca、Mg的竞争交换作用实现。总体来说,外源低分子量有机酸的加入使土壤活性Al显著升高,活性Ca、Mg略有升高,有机酸在酸性土壤中的作用需从有机酸溶解阳离子的角度进一步评价。 相似文献
16.
Phytoextraction of soil Cd and Zn may require reduction in soil pH in order to achieve high metal uptake. Reducing the pH of high metal soil, however, could negatively affect soil ecosystem function and health. The objectives of this study were to characterize the quantitative causal relationship between pH and soil biological activities in two Zn and Cd contaminated soils and to investigate the relationship between metals and soil biological activities under low pH. Soils were adjusted to five or six different pH levels by sulfur addition, followed by salt leaching. Thlaspi caerulescens was grown for 6 months, and both the rhizosphere and non-rhizosphere soil biological activities were tested after harvest. Reducing pH significantly lowered soil alkaline phosphatase activity, arylsulphatase activity, nitrification potential, and respiration. However, acid phosphatase activity was increased with decreasing pH. The relationship between soil biological activities and pH was well characterized by linear or quadratic regression models with R2 values ranging from 0.57 to 0.99. In general, the three enzyme activities, nitrification potential, and the ratio of alkaline phosphatase to acid phosphatase activity were very sensitive indicators of soil pH status while soil respiration was not sensitive to pH change. The rhizosphere soil had higher biological activities than non-rhizosphere soil. The negative effects observed in the non-rhizosphere soil were alleviated by the rhizosphere influence. However, rhizosphere soil after 6 months phytoextraction showed lower nitrification potential than non-rhizosphere soil, probably due to substrate limitation in our study. 相似文献
17.
《Communications in Soil Science and Plant Analysis》2012,43(15-16):2005-2014
Abstract Many soil analysis labs routinely determine lime requirement of acidic soils using different buffer solutions for optimum plant growth. The Adams‐Evans lime determination solution was introduced more than 40 years ago and has been used by many soil analysis labs. Even though many buffer solutions have been developed since then, very little attention has been paid to address the toxic nature of chemicals involved in buffer solutions. The most commonly used buffer solutions, such as the Adams-Evans, Shoemaker‐McLean‐Pratt (SMP), Woodruff, and others, contain p‐nitrophenol, which is toxic to humans and the environment. Use of p‐nitrophenol requires prescribed containment and disposal procedures, that creates extra burden on soil analysis labs that provide their invaluable service at low cost. Replacing p‐nitrophenol with monobasic potassium phosphate (KH2PO4), which has similar buffering capacity but with no known toxicity, is beneficial to soil testing labs and the environment. The original Adams‐Evans buffer solution was compared with the modified Adams‐Evans buffer solution with soils of different pH, cation exchange capacity and lime requirement. The linear regression between the buffer pH values and lime recommendations made by Adams‐Evans and the modified Adams‐Evans solutions were highly significant. Thus, the modified Adams‐Evans buffer solution can be used without loss of established recommendation criteria as the original buffer solution. 相似文献
18.
《Communications in Soil Science and Plant Analysis》2012,43(15-16):1865-1882
Abstract Total ionic strength buffers based on citrate at pH 7.5 and cyclohexylenediaminetetra‐acetic acid (CDTA) at pH 5.2 were evaluated for use when determining fluoride (F) concentration in soil solutions. Both buffers achieved acceptable recoveries of F added to ultra‐filtered (0.025 μm) solutions. Recovery of F added to unflltered and 0.22 μm filtered solution was low when the CDTA buffer was used. This effect was attributed to the adsorption of F by micro‐particulate materials present in these samples. The use of this buffer would need to be restricted to samples in which micro‐particulates were not present. The performance of the citrate buffer was not affected by the presence of microparticulates; however, electrode response times, and departure from Nernstian response at low F concentrations, were greater when this buffer was employed. Fluoride was found to be present at low concentrations in the soil solution of the 60 virgin highly weathered soils tested. The F concentration in 75% of the surface samples was <3 μM, while all subsoil samples had soil solution F concentrations <1 μM. 相似文献
19.
《Communications in Soil Science and Plant Analysis》2012,43(10):1436-1448
The adsorption and specific activities of acid phosphatase on soil colloids and minerals in oxalate systems with different pH values were studied using the batch method. Results indicated that the amount of phosphatase adsorption decreased in the following order: goethite ? yellow-brown soil (YBS) > kaolinite > latosol, and the specific activities of immobilized phosphatase were goethite > latosol > kaolinite > YBS. The profiles of enzymatic adsorption and specific activity on soil minerals were bell shaped, and their change tendencies were out of sync. The optimal pH for phosphatase adsorption was located between the isoelectric point of phosphatase and the zero point of charge of the studied soil minerals, and the optimal pH for the specific activity of the immobilized enzyme either did not change or shifted toward alkalinity. Enzymatic adsorption amounts and specific activities were greater when the enzyme was added before oxalate than when enzyme was added after oxalate. 相似文献