A Study of Magnetic Susceptibility in Some Aquic and Non-aquic Soils of Fars Province



Soil drainage conditions significantly affect the chemical properties of soil, particularly type and the extent of iron oxides. Soil magnetic susceptibility (?) has a close relationship with drainage conditions. Eight soil profiles, in four regions of Fars province, with aquic and non-aquic soil moisture regimes were studied to determine the effect of drainage conditions on ? and on chemical forms of Fe-oxide. A positive and significant correlation was noticed between ? and Fed. Aquic soils bore distinctly lower ?s than non-aquic soils (19.9 vs. 32.5). Magnetic susceptibility of surface horizons was greater than that of sub-surface horizons in most of the soils (31 vs. 19.6), which is probably a result of pedogenic formation of ferrimagnetic minerals in soil surface. Aquic and non-aquic soil lost 41 and 64 percent of their ? after CBD extraction, reflecting differences in the source of ?. Sequential heating of soil samples upto 550 °C resulted in more enhancement of ?, in aquic soils as compared with non-aquic soils, (451% vs. 155%) which was attributed to the conversion of canted antiferromagnetic minerals to ferromagnetic ones. The value of ? decreased when heated from 550 to 700 °C (about 100% in both soil groups).