用氯化铵提取法测定石灰性土壤中碳酸盐含量

测定石灰性土壤中的碳酸盐,通常采用气量法。但气量法测出的是CaCO₃及MgCO₃等碳酸盐的总和,称之为“CaCO₃相当物”,而不能分别检出CaCO₃和MgCO₃。     

石灰性土壤无机磷分级的测定方法

本分级体系适用于石灰性土壤、中性土壤以及无机磷酸盐中磷酸钙占有较大比例的土壤或其它沉积物。     

旱地土壤微生物磷测定方法研究

介绍了国外关于土壤微生物磷测定方法的研究进展 ,讨论了常用的几种方法所存在的问题 ,介绍了主要操作过程要求。对我国 5种主要母质类型的土壤 (pH 3 .3～ 7.4,1molL- 1KCl)的对比研究表明 ,我国土壤采用氯仿熏蒸、0 .5molL- 1NaHCO3在 1∶2 0土水比提取测定无机磷 (Pi)、并以同时测得的培养土壤微生物的磷的回收率作为计算常数得到的结果最佳。测定的大多数南方土壤的微生物磷占土壤全磷的比例小于 1 .5 % ,微生物碳磷比值大于 3 0∶1 ,反映南方土壤磷的生物活性较低 ,土壤微生物对磷的作物供应调节能力不强。     

石灰性土壤交换性钙和镁测定方法的研究

石灰性土壤交换性盐基组成的测定,通行的方法是采用70%乙醇溶液反复洗盐,再经pH 8.50.1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液进行多次交换处理,测定交换液中的K+、Na+、Ca2+、Mg2+浓度。但此方法常常受操作步骤繁琐,以及土壤中碳酸盐的溶解量因多次浸提而增加的困扰,最终导致测定结果偏高。基于上述原因,选择不同浓度、不同pH的NH4OAc和NH4Cl 10种交换剂,对比分析10种交换剂中的碳酸盐溶解度和土壤交换性钙镁含量。结果表明,pH=8.5 1 mol L-1氯化铵-70%乙醇(CH3CH2OH)溶液较适合石灰性土壤交换性盐基的测定。此新方法是先经70%乙醇(CH3CH2OH)溶液洗盐,再用pH8.5 1 mol L-1氯化铵(NH4Cl)-70%乙醇(CH3CH2OH)溶液进行一次性交换处理,然后测定交换液的K+、Na+、Ca2+、Mg2+浓度,简化了操作程序的同时有效抑制了土壤碳酸盐的溶解,降低了测定结果的偏差。     

土壤活性有机质测定方法的比较

用 16种化学方法对红壤、黑土、垆土、褐土、灰漠土五个典型土壤活性有机质进行测定 ,结果表明 ,333mmol/LKMnO4常温振荡 1h的方法测定结果变异系数小 ,重现性好 ,且操作简便快速 ,可作为土壤活性有机质测定的基本方法。虽然不同方法测定的活性有机质数量不同 ,但它们之间表现出较好的相关性 ,说明它们在一定程度上都可反映土壤有机质的活性     

应用^32P研究水溶性磷在石灰性土壤中的形态转化及其有效性

＾３２Ｐ示踪试验表明，加入石灰性土壤中的水溶性磷最初主要转化成Ｃａ２－Ｐ，Ｃａ８－Ｐ次之，随着时间的推移，Ｃａ２－Ｐ不断减少，Ｃａ８－Ｐ和Ｆｅ－Ｐ有所增加，Ａｌ－Ｐ在一周前后已达到平衡，从比活度看，Ｃａ２－Ｐ有效性最高，是石灰性土壤中的速效磷源，Ｃａ８－Ｐ，Ａｌ－Ｐ，Ｆｅ－Ｐ的有效性接近，是土壤中的缓效磷源。     

土壤有机质测定方法述评与展望

有机质是土壤的重要组成部分,是判定土壤质量动态变化的重要标准。为了便于了解当前土壤有机质测定方法的优点和局限性,利于今后有机质研究和测定工具的开发,本文对当前测定有机质的方法,包括干烧法、湿烧法、化学氧化法、灼烧法和土壤有机质光谱测定法进行了阐述,分析了各方法的优缺点以及研究中适宜选择的方法,并对当今农业的需求和测定方法的不足,提出了研究无损、原位测量有机质工具的构想,展望了土壤有机质快速测定方法的发展趋势,以此为精准农业的实施和农业的可持续发展,提供基本的信息及建议。     

土壤活性有机碳库测定方法研究进展

就目前国内外土壤活性有机碳库的各种测定方法及其特点作了较为详细的阐述,并就各种方法的适用范围和存在的问题进行了较为深入的分析,提出了进一步完善土壤活性有机碳的测定方法是将来的研究重点。     

碳酸钙对石灰性土壤颗粒组成测定的影响

采取化学分析和Tessier连续提取法,对西宁市6个功能区城市土壤重金属Cu、Zn、Pb和Cd的含量及形态进行研究。结果表明:西宁市各功能区土壤的Cu、Zn、Pb和Cd的全量分别是全国土壤相应重金属几何平均值的1.9~5.2,1.9~6.9,0.8~4.0,7.4~11.1倍,4种重金属污染比较严重。6个功能区的重金属Cu、Zn、Pb和Cd含量进行差异显著性分析,结果是广场区Cu的含量与风景区的差异不显著(P>0.05),但与其他4个功能区差异显著(P<0.05);风景区与开发区差异显著(P<0.05),但与其他4个功能区差异不显著(P>0.05);开发区Zn的含量与商业区和居民区的差异显著(P<0.05),而其他各功能区间差异均不显著(P>0.05);各功能区Pb和Cd的含量均无显著差异(P>0.05)。研究土壤中重金属的化学形态有较大的差异,Cu以残渣态和有机结合态为主;Zn以残渣态和铁锰氧化物结合态为主;Pb和Cd以残渣态为主。Cu活性相对较高的土壤出现在风景区、矿冶区和居民区,Zn活性相对较高的土壤出现在风景区和广场区,Pb活性相对较高的土壤出现在风景区和居民区,Cd活性相对较高的土壤出现在矿冶区和开发区,研究土壤中4种重金属均具有一定的生物有效性和潜在的生态危害性。     

土壤总砷测定前处理方法探讨

采用加标回收方法比较研究了5种土壤总砷测定的前处理方法(分别为浓HNO3-浓H2SO4-HC1O4法、王水法、浓HNO3-浓H2SO4-V2O5法、浓HNO3-浓H2SO4-V2O5Ⅰ法和浓HNO3-浓H2SO4-V2O5Ⅱ法),结果表明,5种前处理方法的加标回收率在89.9%～102%之间,变异系数在0.56%～5.27%之间。其中,浓HNO3-浓H2SO4-V2O5Ⅰ法处理,土壤所用消解时间40min左右,其回收率较高,在98.5%～99.1%之间,变异系数较小,在0.56%～0.85%之间;该前处理方法具有消解时间最短、加标回收率和精密度高及重现性最好的特点,优于其他4种前处理方法,可作为推荐方法应用。     

西北石灰性土壤阳离子交换量测定方法比较

阳离子交换量是评价土壤保肥性能和缓冲性能的重要指标,也是改良土壤和合理施肥的重要依据之一。为了给西北石灰性土壤阳离子交换量的测定提供科学依据,通过平行性实验、标准物质检测、实际样品检测,分析比较了目前普遍采用的测定方法乙酸钙交换法和三氯化六氨合钴浸提-分光光度法的优劣。结果表明,2种分析方法均具有较好的精密度和准确度,均适合西北地区石灰性土壤阳离子交换量的测定。从测定结果来看,三氯化六氨合钴浸提-分光光度法的土壤阳离子交换量测定值略高于乙酸钙交换法,在实际样品检测中相对标准偏差介于3.47%～9.46%。但相比之下乙酸钙交换法具有试剂成本较低的优势,而三氯化六氨合钴浸提-分光光度法具有节省时间的优势,检测人员可根据实际情况灵活选择使用。     

Acidity Changes of Foreign Acidic Soils Introduced into Calcareous Soil Environment

Abstract

Many tropical plant species originated in areas with acidic soils and do not grow well in calcareous (high pH) soils. It is impossible to acidify soils that have high contents of calcium carbonate in south Florida. Replacing calcareous soils with acidic soils obtained from distant regions is an alternative. Unfortunately, such introduced acidic soils may eventually be neutralized by irrigation and ground water that is saturated with calcium carbonate. The objective of this investigation was to examine the acidity changes and buffering capacities of three types of acidic soils (silica sand soil, red loamy sand soil, and a mixed soil) used to establish tropical plants in a rainforest exhibition at Fairchild Tropical Garden, Miami, FL. The three areas were excavated to remove native calcareous soil, limestone bedrock, and filled with acidic soils. Various rainforest plants were planted. Soil samples were collected in contiguous 10 cm‐deep segments from the soil surface to the bedrock shortly after deposition of the soils and one year later. Soil pH, EC, particle distribution, buffering capacity were determined. Results showed that both silica sand and mixed soils had been neutralized and the soil pH values had risen over 7 in all soil depths after one year. However, less than 10 cm of the surface and bottom soil layers of red loamy sand had been neutralized and the soil pH in the middle of soil profile remained unchanged due to its higher buffering capacity. A column leaching study showed that the acidity in the red loamy sand soil would be neutralized by irrigation water and by capillary movement of groundwater with a high concentration of calcium bicarbonate. Buffering curves indicate that it is easier to maintain acidity in sandy soil than of loamy sand and mixed soils with acidified irrigation water. Indeed it is difficult to acidify the mixed soils with high organic matter content after these soils have been neutralized.     

种植模式对川中丘陵石灰性紫色土结构和地力的影响

基于田间长期定位试验,通过原位监测和计算机断层微扫描技术相结合的方法,分析种植模式对川中丘陵石灰性紫色土结构和地力的影响.结果表明,玉米-小麦(MW)模式耕层土壤孔隙配比合理且连通性好,有利于耕层保水保肥和土壤可持续利用,但该模式土壤动物丰富度和经济效益偏低.玉米-油菜(MR)模式土壤孔隙结构较玉米-小麦模式差,但腐食...     

火焰原子吸收光谱法间接测定土壤中有效硫

试验旨在建立火焰原子吸收光谱法间接测定土壤中有效硫,试验原理基于SO42-和BaCrO3溶液反应生成BaSO4沉淀,置换出定量的CrO42-,通过原子吸收法测定Cr,通过换算得知有效硫的含量。试验优化了影响结果的浸提剂、静置时间、陈化时间等因素;通过标准土样的验证,结果可靠、稳定。     

碳酸盐渍土的膨胀特性研究

在新疆省道201线克拉玛依—榆树沟段改建工程段采集土样,通过室内试验研究影响碳酸盐渍土膨胀的主要因素。首先讨论盐渍土地层的自然垂直分布对碳酸盐渍土膨胀特性的影响,得到膨胀率随土样深度的变化发生变化,在25—75cm时膨胀最为明显;考虑到季节变化和温度的影响,进行了碳酸盐渍土的多次冻融循环盐胀特性的研究,发现温度对碳酸盐渍土的膨胀特性影响很小。为了分析含盐量对碳酸盐渍土膨胀特性的影响,室内配制含盐量为0.5%,1.0%,1.5%,2.0%的土样进行膨胀试验,结果表明,含盐量从0.5%增加到2.0%时,其最大膨胀率从10.0%增加到22.5%。     

Comparison of Soil Sampling Devices for Soil Bulk Density Determination for Carbon Sequestration Monitoring

Soil bulk density is often used to adjust soil carbon (C) values for changes in soil density because of management differences in C-sequestration studies. Often hand-sampling devices used for soil fertility monitoring may be used for sampling soil to a depth of up to 30 cm. Four sampling devices of differing characteristics that can be used with hand-sampling equipment across full tillage, reduced tillage, and no-tillage to determine soil bulk density were evaluated. There were no significant differences in soil bulk density values between three cylindrical devices, which measured from 19 to 31 mm in diameter. However, a 21 mm × 76 mm rectangular device gave significantly lower bulk density values than the cylindrical devices. Calculation of soil organic carbon (SOC) mass per unit area showed similar results for the cylindrical devices with the rectangular device giving a significantly lower value than the cylindrical devices. Using a cylindrical device on a hand probe in a consistent manner will give satisfactory results when sampling surface soils.     

Sodium Hydroxide Direct Distillation: A Method for Estimating Total Nitrogen in Soil

Soil total nitrogen (N) concentration is commonly measured by Kjeldahl and combustion methods. In this study, a method based on determination of ammonium (NH₄)‐N produced by steam distillation of the soil sample with sodium hydroxide solution (NaOH‐DD) is developed and evaluated for estimating soil total N concentration. The method was evaluated using two sample sets: (A) 44 samples collected from contrasting land uses in central Iran and (B) 344 samples collected from contrasting arable soils across Canada and Maine, USA. Based on this experiment, 10‐min distillation of 5.0 g soil with 20 mL 12.5 M NaOH were selected as the optimum conditions. The NH₄‐N released by the NaOH‐DD method was highly correlated with total N concentration in the sample sets A and B (r = 0.79 and 0.94, respectively). The NaOH‐DD method provides a simple, rapid means of analysis with reduced measurement cost and better health and safety precautions than the traditional Kjeldahl method. Current address for Mehdi Sharifi: Nova Scotia Agricultural College, Department of Plant and Animal Science, Truro, Canada.      

土壤样品中多环芳烃分析方法研究进展

概述了国内外土壤样品中多环芳烃(PAHs)测定方法的研究状况,其中提取方法包括加速溶剂萃取方法、固相微萃取方法、超临界流体萃取方法、亚临界水萃取方法和流化床提取方法等,测定方法有HPLC法、GC法和免疫分析法等。重点介绍了PAHs的提取过程,同时总结了各种方法的优缺点。