激光法与传统方法比较测定土壤粒度分布的研究

激光法测定土壤粒度是近年来应用的新方法，它的特点是测定速度快、效率高，比传统的经典测定法省时省力省试剂消耗，实验室对环境的二次污染也小，特别是在处理和测定大量样品时，它的优势更为明显。本文作者选择内蒙古地区有代表性的暗棕壤、草甸土、黑土、黑钙土、栗钙土、棕钙土和风沙土7种土壤类型共42个土壤样本为例，采用激光法与传统比重计法对土壤粒度分布测定进行了方法比对研究，设计了激光法三个参数三个水平的正交实验，结果表明粘粒含量激光法测定低于传统方法，粉粒含量则相反，砂粒含量两种方法测定结果最接近；得出了两种方法之间的相关系数和回归方程，P〈0．05时，最大相关系数是：粘粒含量r=0．5822，粉粒含量r=0．9094，砂粒含量r=0．9152；本研究结果还表明激光法与传统比重计法两种方法确定的质地大致相同，认为虽然土壤的粘粒部分就目前的测定结果来看不适合用激光法测定，但粉粒部分和砂粒部分可以用激光法测定后通过两种方法之间的线性回归方程换算，从而提高测定效率。这一研究结果明确了激光法与传统比重计法测定土壤粒度分布的差异，对使用两种不同方法研究土壤颗粒组成具有借鉴作用，并且在土壤批量样品粒度的分析测定中具有非常实用的推广意义。

COMPARATIVE STUDY ON DISTRIBUTION OF SOIL PARTICLE SIZE USING LASER AND TRADITIONAL METHODS

The laser diffraction method was a new method for determination of soil particle size distribution in the recent years. Compared with the traditional method, the new method has many advantages such as quick speed, high efficiency, saving time and reagents,less secondary pollution to the samples and so on. Its advantages will be more obvious when much of samples processed and determined. In this work, 42 soil samples attributed to 7 soil orders, which is ark brown soil, meadow soil, black soil, chernozem, chestnut soil, brown calcic soil and sand soil according to the Inner Mongolia Soil Taxonomy, were selected, and the distributions of soil particle sizes were carried out using the Laser diffraction method and traditional hydrometer method. In the experiments three parameters of the Laser diffraction were set and three level orthogonal tests were carried out at the same time. The results showed that the clay contents determined by the laser diffraction method were obviously lower than those by the hydrometer method, while the silt contents determined by the former were higher than those by the latter. The sand contents determined by the two methods were similar to each other. Based on the statistical analysis, the correlation coefficients and the regression equations were obtained between the two methods. The maximum correlation coefficients of clay, silt and sand contents were 0.5822,0. 9094 and 0.9152 respectively when p 〈 0.05. The results also showed that the classification results on soil texture by using the two methods accorded with each other. Although some clay content measured results by the laser method was not suitable, but the silt and the sand parts can be determined by the linear regression between the two methods after determination by the laser diffraction method, which highly enhanced the determination efficiency. This study identified the difference between laser diffraction method and hydrometer method, which has important use for reference on the distribution of soil particle sizes using the two different methods, and has the very practical values of popularization for size determinations of bulk soil samples.