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1.
激光粒度仪与沉降一吸管法测定褐土颗粒组成的比较 总被引：1，自引：0，他引：1
土壤颗粒组成是土壤的基本物理属性之一,沉降—吸管法是传统土壤颗粒分析的主要方法,激光粒度仪法是近年来新兴的粒度分析方法。为了研究二者的差异,选取了23个黏粒含量差异较大的褐土样品,采用上述两种方法对土样进行了分析。结果表明:激光粒度仪检测<0.002mm颗粒含量低于吸管法,但二者有较好的相关性,决定系数为0.97;在检测<0.02mm颗粒含量时两者比较接近,并且相关性很好,决定系数为0.99;检测<0.05mm颗粒含量时两者也比较接近,决定系数为0.91。激光粒度仪检测结果通过转换模型修正后,可以较好地反映褐土土壤颗粒组成情况。 相似文献
2.
《土壤通报》2020,(3):574-579
为了比较湿筛-沉降法和激光粒度仪法测定玄武质火山碎屑物发育土壤的颗粒组成的结果,对供试土壤进行了比重值测定,并采用实测比重值和常用比重值(2.65)分别进行了湿筛-沉降法的土壤颗粒组成测定,同时又对样品进行了激光粒度仪法测定。结果表明:玄武质火山碎屑物发育土壤的比重值较土壤的常用比重值有一定的差异,进而导致了两种比重值条件下湿筛-沉降法测定的土壤颗粒组成的差异,但相差不大。激光粒度仪法测定的土壤颗粒组成与湿筛-沉降法比较,黏粒含量偏低,粉粒含量偏高,绝大多数砂粒含量偏高。导致这种差异的原因之一是两种方法的测定原理不同,分别测定的是同一颗粒的不同特征;其次是测定的粒径范围不同,湿筛-沉降法测定<2 mm的全部土粒,但激光粒度仪法对小于某粒径(MS3000激光粒度仪的测量范围是0.01～3500μm)的土粒不做测量;此外,还受黏土矿物的层状构造及土壤分散方法的影响。由于不同生产厂家、不同型号的激光粒度仪,其测量范围不同,对土壤颗粒组成的测定结果会产生一定的影响。所以,建议在应用激光粒度仪测定土壤颗粒组成时,标示仪器的生产厂家和型号。 相似文献
3.
应用激光粒度仪分析土壤机械组成的实验研究 总被引：17，自引：0，他引：17
土壤机械组成是最基本的土壤参数之一。探讨了应用激光粒度仪分析土壤机械组成的实验条件、检测结果与精度,并与传统的吸管法加以比较。对9个土壤样品分别用激光粒度分析和吸管法作对比测试实验,结果显示:两种方法原理的不同产生了在颗粒含量上激光粒度分析得到的粘粒含量显著低于吸管法,但是两种方法在质地分类上的结果是基本一致的。总之,运用激光粒度分析土壤机械组成是可行的。 相似文献
4.
5.
激光粒度仪测量风成堆积物粒度的实验研究 总被引：2，自引：1，他引：2
中国北方第四纪风成堆积物的粒度是研究古气候与古环境的一个重要代用指标。粒度测量结果受到前处理方法的深刻影响。在黄土高原西部从北往南5个具有代表性的黄土剖面采集样品25块，对每个样品用不同的前处理方法处理后，用激光粒度仪进行测量。结果显示不同的前处理方法对黄土粒度测量结果会产生很大的影响。原始样品经过超声波振荡和加（NaPO3）6分散剂后，颗粒明显分散变细。在单独加入H2O2除去有机质和加入的HCl除去碳酸盐后，粒度也明显变细，而且南部的样品的差异比北部的要大。在黄土高原北部，石膏对粒度测量的影响较小。 相似文献
6.
以延安新区I期工程的马兰黄土为研究对象,分别采用筛分法、离心机法和静水沉降法对其进行颗粒分离试验,并利用激光粒度仪对3种分离方法的试验结果进行跟踪对比,以研究最适用于黄土颗粒的分离方法。结果表明:筛分法主要适用于粒径大于0.05mm的黄土颗粒的分离,对粒径小于0.05mm的黄土颗粒分离效果较差,筛分结果的可靠性偏低。离心机法由于自身的局限性且受影响因素较多,试验结果的可靠性较低;静水沉降法主要适用于粒径小于0.05mm的黄土颗粒的分离,颗粒分级效果显著,试验结果的可靠性较高,且试验精度满足要求,但对于粒径小于0.002mm的颗粒分离时间较长。通过3种试验方法的对比可知,在对黄土进行颗粒分离试验时,宜采用筛分—沉降相结合的分离方法,对于大于0.05mm的颗粒宜采用筛分,对于小于0.05mm的颗粒宜采用静水沉降法。 相似文献
7.
激光法与湿筛－吸管法测定土壤颗粒组成的转换及质地确定 总被引：18，自引：0，他引：18
湿筛-吸管法是测定土壤颗粒组成(PSD)的传统方法,而激光法则是新兴的土壤颗粒测定方法,为了明确二者测定数据间的转换关系,应用两种方法分别测定了中国6个主要土纲的265个土壤样品。结果表明,激光法测定的土壤黏粒含量明显地小于湿筛-吸管法测定的数据,激光法测定的土壤粉粒含量明显地大于湿筛-吸管法测定的数据,而对于土壤砂粒含量的测定结果二者互有高低。两种方法测定的黏粒、粉粒和砂粒间均分别具有很好的相关性,甚至按照美国的7级分类标准,每个粒度级别在两种方法间均具有很好的相关性。按照激光法和吸管法测定数据间的转换关系式得出了用激光法测定数据的砂土、壤土和黏土质地划分界限,从而能够应用激光法测定的数据直接进行质地划分,这对于推动激光法在土壤学中的进一步应用和推动土壤科学的发展均具有重要意义。 相似文献
8.
《土壤通报》2015,(1):148-152
前处理方法的优化研究是促进激光粒度仪分析技术在南方红土区推广的关键环节。以黄土粒度前处理方法为基础,设定不同的H2O2、HCl和分散剂(Na PO3)6的加入剂量以及不同的反应温度和超声波震荡时间来处理采自云南高原程海地区海拔2000 m的碳酸盐岩红土样品,结果发现:(1)加入HCl处理会使激光粒度仪测量结果偏粗,不加HCl只加H2O2可以获得较细的粒度测量结果;(2)加(Na PO3)6分散剂后样品测试结果重现性较高,但粒度偏粗,当加入剂量超过5 ml(0.05 mol l-1)后加入剂量的多少对测试结果影响不大,未加(Na PO3)6的样品测试结果重现性差,但粒度总体偏细;(3)加热处理比未加热处理样品的粒度偏粗,加热不利于样品的分散;(4)经超声波震荡的样品较未震荡的样品颗粒分散程度高,但震荡时间超过2分钟后,增加震荡时间对分散结果影响不大。 相似文献
9.
近年来常有南方红壤样品在加酸处理后粒度不但没有减小反而增粗的现象报道。为了探究这一现象存在的规律及其原因,本研究在滇东高原选取了西南地区分布最广的3类母岩(碳酸盐岩、玄武岩、泥页岩)发育的红壤开展研究,结果发现:3种母岩发育的红壤加HCl处理后,2μm的颗粒组分明显减小,中值粒径和平均粒径明显增粗,其中以碳酸盐岩红壤粒度增粗幅度最大。元素和矿物分析结果显示,3种红壤氧化铁含量都超过100 g/kg,碳酸盐岩红壤主要黏土矿物为三水铝石和高岭石,玄武岩红壤为高岭石,泥页岩红壤为三水铝石和蒙脱石。用DCB(citrate-bicarbonate-dithionite)法除去土壤氧化铁,样品再进行加酸消解处理后粒度均变细。结合两性胶体的电荷零点理论,本研究认为加酸促使红壤样品中的氧化铁和三水铝石胶体(两性胶体)带更多正电荷,与带负电荷的黏土矿物胶体之间的黏附作用增强,从而导致粒度变粗。这一结果说明加酸消解前处理方法可能不适用于南方风化程度较高的红壤的激光粒度测试。 相似文献
10.
激光粒度仪法作为测量土壤机械组成的新型方法,具有操作简单、速度快的优势,但其适用性与可靠性尚未达成广泛共识。为探究激光粒度仪测定土壤机械组成的准确性与适用性,采集7种退化程度共21份栗钙土土样,使用激光粒度仪与吸管法测定土样机械组成并对比分析。结果显示:激光法测定结果黏粒偏小,而砂粒、粉粒偏大,且随粒径减小误差增大。将两种测定结果进行回归分析,发现砂粒与粉粒转换模型拟合效果理想,黏粒拟合效果差。建立质地三角图发现两种方法得到的质地差异较大,采用转换后数据分析质地,发现质地接近、正确率高,转换效果好。通过扫描电镜对土粒形态观察,发现标准流程不同分散方法下土粒形状与数量均有差异,推测分散方法会影响土壤机械组成的测定结果。激光粒度仪的适用性据测定对象的不同而有差异,对黏粒精度要求高的情况下不宜使用该法,而其他情况下需要对测定结果进行数据转换。 相似文献
11.
Grain-size analysis by laser diffractometry: comparison with the sieve-pipette method 总被引：3，自引：0，他引：3
Results of a traditional sedimentation technique for grain-size analysis (the sieve-pipette method) were compared with those of a laser diffraction grain-size analyser, the Coulter LS-100. Milled quartz samples and silty soil samples were used to investigate the effect of particle shape. The reproducibility of the Coulter LS-100 was better than that of the sieve-pipette method, except for the sand fraction. The agreement between the two methods is strongest for the milled quartz samples. The Coulter LS-100 underestimated the clay content of the silty soil samples and generally overestimated the clay content of the milled quartz samples. This indicates the importance of particle morphology. The milled quartz grains are very angular and somewhat elongated whereas the clay minerals in the clay fraction of the silty soil samples usually have a platy shape. Reduced major axis relationships are calculated which may be used to convert Coulter LS-100 results to those of the sieve-pipette method. Correlation is strongest for percentiles size data. The Coulter LS-100 underestimates the clay, but correctly estimates the sand fraction. This results in a weak relationship for the total silt fraction as measured by the two techniques. Therefore, an alternative method is proposed for estimating this fraction. A comparison of our data with published data and relationships suggests that the calibration relationships are quite robust as long as the clay mineralogy of the samples is similar. 相似文献
12.
Particle size fraction(clay, silt, and sand) is an important characteristic that influences several soil functions. The laser-diffraction method(LDM) provides a fast and cost-effective measurement of particle size distribution, but the results usually differ from those obtained by the traditional sieve-pipette method(SPM). This difference can persist even when calibration is applied between the two methods. This partly relates to the different size ranges of particles measured by the two methods as a result of different operational principles, i.e., particle sedimentation according to Stokes’ Law vs. Mie theory for laser beam scattering. The objective of this study was to identify particle size ranges of LDM equivalent to those measured by SPM and evaluate whether new calibration models based on size range correction can be used to improve LDM-estimated particle size fractions, using 51 soil samples with various texture collected from five soil orders in New Zealand. Particle size distribution was determined using both LDM and SPM. Compared with SPM, original data from LDM underestimated the clay fraction(< 2 μm), overestimated the silt fraction(2–53 μm), but provided a good estimation of the sand fraction(53–2 000 μm).Results from three statistical indices, including Pearson’s correlation coefficient, slope, and Lin’s concordance correlation coefficient, showed that the size ranges of < 2 and 2–53 μm defined by SPM corresponded with the < 5 and 5–53 μm size ranges by LDM, respectively. Compared with the traditional calibration(based on the same particle size ranges), new calibration models(based on the corrected size ranges of these two methods) improved the estimation of clay and silt contents by LDM. Compared with soil-specific models(i.e., different models were developed for different soils), a universal model may be more parsimonious for estimating particle size fractions if the samples to be assessed represent multiple soil orders. 相似文献
13.
Soil texture is an important factor governing a range of physical properties and processes in soil. The clay and fine fractions of soil are particularly important in controlling soil water retention, hydraulic properties, water flow and transport. Modern soil texture analysis techniques (x‐ray attenuation, laser diffraction and particle counting) are very laborious with expensive instrumentation. Chilled‐mirror dewpoint potentiameters allows for the rapid measurement of the permanent wilting point (PWP) of soil. As the PWP is strongly dictated by soil texture, we tested the applicability of PWP measured by a dewpoint potentiameter in predicting the clay, silt and sand content of humid tropical soils. The clay, silt, and sand content, organic matter and PWP were determined for 21 soils. Three regression models were developed to estimate the fine fractions and validated using independent soil data. While the first model showed reasonable accuracy (RMSE 16.4%; MAE 13.5%) in estimating the clay, incorporating the organic matter into the equation improved the predictions of the second model (RMSE 17.3%; MAE 10.9%). When used on all soil data, the accuracy of the third model in predicting the fine fraction was poor (RMSE 31.9%; MAE 24.5%). However, for soils with silt content greater than 30%, the model prediction was quite accurate (RMSE 7–12%; MAE 7–9%). The models were used to estimate the sand content and soil textures of soils, which proved relatively accurate. The dewpoint potentiometer can serve a dual purpose of rapidly estimating the PWP and the clay, fine fraction, and soil texture of soils in a cost efficient way. 相似文献
14.
Straw incorporation and soil organic matter in macro-aggregates and particle size separates 总被引：5，自引：0，他引：5
BENT T. CHRISTENSEN 《European Journal of Soil Science》1986,37(1):125-135
Two field experiments in which straw has been removed or incorporated for 17 yr (loamy sand) and 10 yr (sandy clay loam) were sampled to examine the effect of straw on the C and N contents in whole soil samples, macro-aggregate fractions and primary particle-size separates. The particle size composition of the aggregate fractions was determined. Aggregates were isolated by dry sieving. Straw incorporation increased the number of 1–20 mm aggregates in the loamy sand but no effect was noted in the sandy clay loam. Straw had no effect on the particle size composition of the various aggregate fractions. After correction for loose sand that accumulated in the aggregate fractions during dry sieving, macro-aggregates appeared to be enriched in clay and silt compared with whole soil samples. Because of the possible detachment of sand particles from the exterior surface of aggregates during sieving operations, it was inferred that the particle size composition of macro-aggregates is similar to that of the bulk soil. The organic matter contents of the aggregate fractions were closely correlated with their clay + silt contents. Differences in the organic matter content of clay isolated from whole soil samples and aggregate fractions were generally small. This was also true for the silt-size separates. In both soils, straw incorporation increased the organic matter content of nearly all clay and silt separates; for silt this was generally twice that observed for clay. The amounts of soil C, derived from straw, left in the loamy sand and sandy clay loam at the time of sampling were 4.4 and 4.5 t ha?1, corresponding to 12 and 21% of the straw C added. The C/N ratios of the straw-derived soil organic matter were 11 and 12 for the loamy sand and sandy clay loam, respectively. 相似文献
15.
The choice of analytical method and sample pretreatment has significant consequences for the shape of particle‐size distribution (PSD) frequency curves, and therefore for the evaluation of soil textural parameters. Here, the comparison of several granulometric methods based on different physical principles is presented: wet sieving (WS), based on gravity and the mechanical force of water, was combined with pipette (PP) sedimentation/settling velocity, Micromeritics SediGraph (MS) sedimentation/x‐ray attenuation and Coulter Counter (CC) electroresistance particle counting. The Malvern Mastersizer (MM), an instrument based on laser diffraction, was used without WS. Twelve typical temperate‐region soil types were chosen for this study on the basis of their mineral composition, organic matter content, conductivity and magnetic susceptibility. The modalities of PSD frequency curves obtained by different methods were compared. The results showed considerably larger clay‐fraction contents determined with the sedimentation techniques, PP and MS, than that obtained by CC or MM. Statistical correlation and regression models were used to compare the fractions of clay, silt and sand obtained with different methods. Linear correlations were found in almost all cases, except those comparing clay fractions obtained by CC with those obtained by MM, PP and MS methods. These correlations were non‐linear. The observed difference was attributed to the presence of aggregates and/or magnetic properties of soil particles. However, more data are needed to verify this hypothesis. The implications of sample pre‐treatment with dispersant and hydrogen peroxide (H2O2) were evaluated by the MS and CC techniques and observed by the scanning electron microscope. H2O2 was found to be an efficient disaggregating agent. The use of dispersant resulted in the increased amount of the clay fraction measured by the MS method. 相似文献
16.
V. S. Kryshchenko I. V. Zamulina T. V. Rybyanets N. E. Kravtsova O. A. Biryukova O. M. Golozubov 《Eurasian Soil Science》2016,49(6):640-651
Monitoring of soil dispersivity and humus state has been performed in the stationary profile of ordinary chernozem in the Botanic Garden of the Southern Federal University in 2009–2014. The contents of physical clay and sand are almost stable in time, which indicates a quasi-static (climax) equilibrium in the soil. Another (reversible dynamic) process occurs simultaneously: seasonal and annual variation in the mass fractions of clay and silt in physical clay. Variations of humus content in the whole soil and in its physical clay are also observed on the background of seasonal changes in precipitation and temperature. A procedure has been developed for the analysis of the polydisperse soil system with consideration for the quasi-static and dynamic equilibriums. A two-vector coordinate system has been introduced, which consists of scales for changes in the contents of physical clay and physical sand in 100 g of soil and changes in the fractions of clay and silt in 100 g of physical clay. Co-measurements of two dispersivity series of soil samples—actual dynamic and calculated under quasi-static equilibrium (ideal)—have been performed. Dynamic equilibrium coefficients, which cumulatively reflect the varying proportions of physical clay and physical sand in the soil and the mass fractions of clay and silt in physical clay, have been calculated. 相似文献
17.
Soil water-retention characteristics at measurement scales are generally different from those at application scales, and there is scale disparity between them and soil physical properties. The relationships between two water-retention parameters, the scaling parameter related to the inverse of the air-entry pressure (αvG, cm-1) and the curve shape factor related to soil pore-size distribution (n) of the van Genuchten water-retention equation, and soil texture (sand, silt, and clay contents) were examined at multiple scales. One hundred twenty-eight undisturbed soil samples were collected from a 640-m transect located in Fuxin, China. Soil water-retention curves were measured and the van Genuchten parameters were obtained by curve fitting. The relationships between the two parameters and soil texture at the observed scale and at multiple scales were evaluated using Pearson correlation and joint multifractal analyses, respectively. The results of Pearson correlation analysis showed that the parameter αvG was significantly correlated with sand, silt, and clay contents at the observed scale. Joint multifractal analyses, however, indicated that the parameter αvG was not correlated with silt and sand contents at multiple scales. The parameter n was positively correlated with clay content at multiple scales. Sand content was significantly correlated with the parameter n at the observed scale but not at multiple scales. Clay contents were strongly correlated to both water-retention parameters because clay content was relatively low in the soil studied, indicating that water retention was dominated by clay content in the field of this study at all scales. These suggested that multiple-scale analyses were necessary to fully grasp the spatial variability of soil water-retention characteristics. 相似文献
18.
Different extraction methods are used world‐wide in routine soil analysis to estimate long‐term potassium (K) reserves for plants. In Sweden, K extracted with 2 M HCl at 100°C (KHCl) is frequently used, although with limited understanding of the phases extracted. In the present study, we quantified the effects of this extraction on soil minerals in particle size fractions ranging from clay to sand, and estimated their relative contribution to KHCl. The study included three Swedish long‐term agricultural field experiments with texture ranging from loamy sand to silty clay, as well as mineral specimens of K feldspar. Total weight loss of particle size fractions was determined, and quantitative and differential X‐ray powder diffraction (QXRD, DXRD), applied on solids before and after extraction, was used to quantify the dissolution of individual mineral phases. QXRD and DXRD included spray‐drying of samples, addition of an internal standard and full pattern fitting, where a combination of mineral‐standard XRD traces was matched with the experimental one. Our results show that KHCl was primarily associated with clay minerals concentrated in the two finest fractions (2–20 and < 2 μm). Highly expandable and mixed‐layer phyllosilicates were quantitatively the most important minerals dissolved. The K was released from micaceous layers in mixed‐layer phyllosilicates with a vermiculitic character. Whether di‐ or trioctahedral, a shared property of the dissolved phases was that they were rich in Fe. In the loamy sand, the coarser fractions (20–2000 μm), where feldspars were prominent, accounted for 35% of KHCl. According to DXRD, there was no significant decrease in K feldspars in any of the samples, and KHCl data for the feldspar specimens suggest that clay minerals contributed at least 70% of KHCl also in the loamy sand. Our study provides insights about the soil minerals that contribute to the long‐term K delivery capacity of soils and an explanation for the prior observation that KHCl is a dynamic fraction that can be affected by management. 相似文献