Effect of AMF-maize combination on water and salt distribution in soil under the dump reconstruction mode of “topsoil-aquifer-aquitard”

The distribution of soil water and salt severely affects the ecological reconstruction and plant configuration modes at coal mine dumps. To investigate the characteristics of soil water and salt distribution under the three-layer reconstruction mode of “topsoil-aquifer-aquitard” in coal mine dump under the influence of mycorrhizal plants, laboratory soil column test was conducted, in which the soil was treated in three ways: planting maize and inoculating with arbuscular mycorrhizal fungi (YM+AMF), planting maize (YM) only, and no planting of maize + no inoculation with bacteria (CK). The results showed that: (1) The different treatments have no significant effect on the water migration characteristics at the bottom of the soil column, and the rise height of capillary water in the aquifer is about 10 cm in all treatments. (2) The distribution of water and salt is positively correlated with soil depth. AMF inoculation is beneficial to maintain the water content of soil in the surface layer, which was increased by 52.0% and 43.9% respectively compared with YM treatment at 0‒10 cm and 10‒20 cm. The salt content of soil at 10‒50 cm is reduced by inoculation, and the electrical conductivity of soil at 20‒30 cm, 30‒40 cm and 40‒50 cm is 41.0%, 14.1% and 8.1% lower than that of YM treatment, respectively. (3) The contribution rate of soil moisture at different depths to maize was quantified with the MIXSIAR model. The results indicate that the main water supply layer is located at 0‒10 cm for YM and YM+AMF treatments, of which the water supply rate is 44.3% and 30.5%, respectively. Besides, bacterial inoculation significantly increases the water contribution rate of the middle and deep soil profile (20‒70 cm), with a cumulative increase of 13.8%. The research results have important scientific guiding significance for the ecological reclamation of “planting with water” in the western mining area.