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 p0.05.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.