吸管法与激光粒度仪法测定土壤机械组成的比较研究

Comparative Study on Soil Particle Size Distribution Measured by Pipette Method and Laser Diffraction Method

[目的]为研究采用吸管法和激光粒度仪法测定土壤机械组成的结果差异及相关性。[方法]应用吸管法和激光粒度仪法,测定20个红壤和19个黑土样品的机械组成,并且进行对比分析。[结果]采用吸管法和激光粒度仪法测得红壤黏粒含量分别是16.1%和3.3%,粉粒含量分别是47.7%和60.8%,砂粒含量分别是36.2%和35.9%;采用吸管法和激光粒度仪法测得黑土黏粒含量分别是23.9%和3.8%,粉粒含量分别是19.9%和34.7%,砂粒含量分别是56.2%和61.5%。同时,得到2种方法测得各个粒级之间的线性转换关系式,黏粒:y红=0.222 1x(R2=0.909 1),y黑=0.163 8x(R2=0.897 0);粉粒:y红=1.275 9x(R2=0.947 7),y黑=1.768 6x(R2=0.911 1);砂粒:y红=1.002 2x(R2=0.984 5),y黑=1.097 1x(R2=0.968 4)。式中,x是吸管法测定的相应各粒级的质量百分比,y是激光粒度仪法测定的相应各粒级的体积百分比。[结论]无论是红壤还是黑土,采用激光粒度仪法测得的黏粒含量明显低于吸管法,而粉粒含量高于吸管法,2种方法测得的砂粒含量比较接近。2种方法测得的黏粒、粉粒和砂粒各个粒级含量均呈0.01水平显著的线性相关关系。土壤类型不同,得到的转换关系有一定的差异,因此针对不同的土壤类型,可能需要分别建立2种方法测定结果之间的转换关系式。

[Objective]The purpose was to explore the differences and relativity between the pipette method and laser diffraction method used in terms of primary particle size measurement. [Method]20 samples of red soil and 19 samples of black soil were collected to measure their primary particle size distribution using the pipette method and laser diffraction. [Result]For red soil,the clay content were respectively 16. 1%and 3. 3%,determined by the pipette and laser diffraction method. The silt percent were 47. 7% and 60. 8%,respectively. The sand proportion was 36. 2% and 35. 9%,respectively. In black soil,the clay content was 23. 9% and 3. 8%,respectively,measured by the pipette and laser diffraction method. The silt proportion was respectively 19. 9% and 34. 7%. The sand percent was 56. 2% and 61. 5%,respectively.The linear transformational relations of each grade between the two methods were established,e. g. clay： yred= 0. 222 1x（ R^2= 0. 909 1）,yblack= 0. 163 8x（ R^2= 0. 897 0）,silt： yred= 1. 275 9x（ R^2= 0. 947 7）,yblack= 1. 768 6x（ R^2= 0. 911 1）,sand： yred= 1. 002 2x（ R^2=0. 984 5）,yblack= 1. 097 1x（ R^2= 0. 968 4）,X is quality percentage of each grade measured by pipette method,and y is volume percentage of each grade measured by laser diffraction method）. [Conclusion]The clay content measured using the laser diffraction method was obviously lower than that determined by the pipette method for the red soil and black soil,while the silt percent made by the former was higher than that by the latter,and the sand content determined by the two methods was similar. Significant linear correlations were found between the measurements of two methods for clay,silt and sand contents. And the conversion models between the two methods were established. However,there were some differences of the conversion models between the two soil types. Therefore,it was possible to establish the conversion models between the two methods according to different soil types,respectively.