太湖流域水稻土的磁化率剖面

土壤磁学是一门新兴的土壤学分支学科。它以研究土壤磁性为中心内容,把现代磁学理论以及磁测、磁查和磁诊断等研究手段和方法应用到土壤学中来^[2]。土壤磁性的强弱,可用磁化率作为指标。土壤磁化率的大小,主要决定于含铁矿物的种类和数量,特别是强磁性矿物(亚铁磁性的磁铁矿Fe₂O₃·FeO和磁赤铁矿γ-Fe₂O₃)的数量。

THE MAGNETIC SUSCEPTIBILITY PROFILE OF PADDY SOILS IN TAI HU BASIN

The present paper deals with the application of magnetic susceptibility of soil for classification of paddy soils of Tai Hu basin. The results obtained has showed that (1) the magnetic susceptibility X value of paddy soils is much lower than that of their corresponding upland soils derived from same parent material;(2) the X value of the old paddy soils is lower than that of the young paddy soils derived from same parent materials;and (3) the higher.the magnetic susceptibility of the original upland soil, the more remarkable the decrease in the X value of the soil after putting under paddy cultivation. Evident differences of the magnetic susceptibility have been found in profiles of various paddy soils, because different soil moisture regimes and patterns of soil profile may affect the processes of oxidation and reduction of soils, crystallization and decrystallization, leaching and accumulation of ferromanganese minerals, as well as the movement of clay particles which are the principal carriers of secondary ferromagnetic minerals. Therefore, each type of paddy soils in Tai Hu basin has its own unique distribution of magnetic susceptibility in the profile. It may be used as a diagnostic criterion for identification and classification of paddy soils.