离心法在土壤颗粒分级技术中的应用

An Application of Centrifugal Effect on Soil Particle Size Fractionation

用离心法进行土壤颗粒分级，优化了离心时间和转速。并对河北保定，浙江嘉兴、磐安、永康和温州五地典型土壤样品进行了土壤颗粒粒径分布的初步研究，探讨了土壤颗粒直径和土壤有机质、土壤pH值之间的相关关系。结果显示：离心法土壤分级技术的回收率为96．73％～99．74％，实验按照粒径尺寸将土壤样品分成四级，分别是砂粒（〉20μm）、粗粉砂（5～20μm）、细粉砂（2～5μm）和粘粒（〈2μm），保定土壤的砂粒含量最高，达92．68％．磐安土样的粗粉砂含量最高，达4．12％，各样品细粉砂颗粒含量相当，均值为1．73％，粘粒含量很少，均值为0．44％。土壤有机质含量以磐安土壤最高，达9．15％，而土壤pH值则是保定土壤最高，为8．14。

Typical surface soil samples were collected at five cities of Baoding in Hebei Province, and Jiaxing, Pan＇an, Yongkang and Wenzhou in Zhejiang Province. Centrifugal method was used in the experiment for fractionation of those soil samples and both parameters of centrifugal duration and rotating speed were optimized. The distribution characteristic of soil particles was then expatiated and furthermore the correlation between the distribution of soil particles and soil organic matter （SOM） as well as soil pH value were also illustrated. Experiment result showed that recovery of the centrifugal method in fractionation of soil particles reached 96.73% - 99.94%. Soil particle sizes could be classified into four grades, namely sand （〉20 μm）, coarse silt （5 -20 μm）, fine silt （2- 5μm） and clay （〈2 μm）. Contents of sand in the soil sample from Baoding city were the most reaching 92.68%, and that of coarse silt were the most in the soil sample from Pan＇an city reaching 4.12%. As far as fine silt and clay were concerned, contents of the former one in all soil samples were similar averaging out to 1.73%, whilst that of the latter one were quite little at a mean level of 0.44%. The highest SOM reaching 9.15% was found in the soil sample collected at Pan＇an city and the highest soil pH value up to 8.14 appeared in the soil sample collected at Baoding city.