The Effects of Afforestation on Physical Properties of Iron Tailings

To understand the effects of afforestation on physical properties of iron tailings, this study analyzed the difference in physical properties (including moisture content, bulk density, property and the texture) among iron tailings under different plantations, farmland soil and natural soil under shrub. The results show that the moisture content and the field moisture content of iron tailings were significantly lower than that of farmland soil, but the moisture content and field capacity of iron tailings under Hippophae rhamnoides plantation and Amorpha fruticosa plantation were higher than that of new tailings. The bulk density of all iron tailings were significantly higher than that of nature soil in shrub, and the former were 1.31-1.53 times the latter. The total porosity of iron tailings were significantly lower than that of natural soil, and the latter was approximately 1.12-1.20 times the former, but for non-capillary porosity, the former was 3.13-3.94 times the latter. Moreover, the percentage of fine mineral particles of iron tailings surface under plantations was higher than that of new tailings obviously, and for the percentage of coarse mineral particles, the former was lower than the latter. These results suggest that the texture of iron tailings become finer after afforestation, but this change happens only in surface tailings, rather than deep tailings. It is concluded that iron tailings contain more coarse mineral particles and have more coarse texture and higher non-capillary porosity, which causing lower abilities of water and fertility retention than nature soil, such as in shrub, but afforestation can improve these physical properties obviously.