平筛和旋筛测定土壤风蚀可蚀性的比较研究

Comparison of Flat Sieve and Rotary Sieve for Determining Soil Wind Erodibility of Different Land Uses

选取河北坝上康保县境内四种地类(草地、林地、留茬地、翻耕地)74个土壤样品,对土壤样品进行平筛、旋筛筛分,获取土壤干团聚体粒径分布。采用土壤风蚀度(EF,<0.84mm土壤干团聚体含量)、平均几何直径(GMD)两个干团聚体指标比较旋筛和平筛的筛分结果。通过Mann-Whitney U检验和相关性分析等统计学方法进行对比发现,经过平筛筛分处理后的EF,GMD普遍大于旋筛;同时将平筛、旋筛的筛分粒级(<0.5 mm,0.84~0.5 mm,2~0.84mm,5~2 mm,20~5 mm,>20 mm)分别进行差异性比较分析发现,大团聚体颗粒较多的土壤样品(>0.84mm)如草地、留茬地等出现较大差异性,在≤0.84mm粒级则差异性不显著,而GMD指标参数差异性显著。分析平筛和旋筛在土壤机械组成和土壤干团聚体指标上的差异性,揭示平筛和旋筛对于土壤可蚀性的影响,丰富土壤风蚀理论研究,为评价本地区土壤风蚀现状、制定风蚀防治措施提供理论依据。

74 soil samples of Kangbao County of Hebei Province including Grassland,tree windbreak,conservation tillage farmland,conventional tillage farmland were sieved by flat sieve and rotary sieve to determine geometric mean diameter(GMD)and erodible soil fraction(<0.84 mm dry soil aggregate,EF).The Mann-Whitney U Test and correlation analysis were used to investigate the differences of EF,GMD and<0.5 mm,0.84~0.5 mm,2~0.84 mm,5~2 mm,20~5 mm,>20 mm aggregates obtained from rotary sieve and those determined from flat sieve.The EF and GMD obtained from rotary sieve were lower than those obtained from the flat sieve.The results demonstrated that the difference of≤0.84 mm aggregates was not significant,in contrast,the differences of>0.84 mm aggregates and GMD of total aggregates were significant.These results further indicated that sieving methods and procedures could significantly influence on determination of soil wind erodibility.The conclusion can provide the theoretical basis for planning wind erosion control measures.