Responses of Melilotus officinalis Growth to the Composition of Different Topsoil Substitute Materials in the Reclamation of Open-Pit Mining Grassland Area in Inner Mongolia

Abstract

The purpose of this study was to reveal that reconstructed soil composed of different types and proportions of materials has different effects on the growth of Melilotus officinalis, and to determine the most suitable formula of reconstructed soil materials to use for soil replacement. Using topsoil, coal gangue, fly ash, and rock and soil stripping materials from Shengli Mining Area of Inner Mongolia as raw materials, stratified and mixed pot experiments were carried out in a greenhouse using different proportions of each material. The differences in the aboveground biomass, leaf width, plant height, and root length of Melilotus officinalis plants in pot experiments were then compared using analysis of variance. The results showed that using different combinations of materials in different proportions affected the growth status of Melilotus officinalis, and their effects on biomass were greater than their effects on plant height, root length, and leaf width. When topsoil, coal gangue, and rock and soil stripping materials were mixed at a ratio of 3:3:4, respectively, the biomass of Melilotus officinalis increased by nearly 30% compared with that of plants potted in pure topsoil. When the content of coal gangue was controlled to be 30%, the content of fly ash was below 10%, and the content of rock and soil stripping materials was below 40%, the reconstructed soil conditions clearly promoted the growth of Melilotus officinalis. Coal gangue, rock and soil stripping materials, and fly ash can thus be used as substitutes for topsoil. Mixing soil reconstruction materials in the optimal proportion can solve the scarcity of topsoil in the grassland mining areas in the study region and, at the same time, can effectively improve the utilization of solid waste in this mining area.

Sludge amendment accelerating reclamation process of reconstructed mining substrates

“…The ecological restoration of coal mining areas is strongly limited by soil nutrient deficiencies, unstable soil structures, and slow growth rates of the vegetation. Soil reconstruction is the core component of land reclamation, and thus the quality of reconstructed soil directly determines the quality of land reclamation 1 . Coal gangue and fly ash are produced during coal mining, processing, and use.…”

Influence of coal gangue mulching with various thicknesses and particle sizes on soil water characteristics

“…The greatest challenges for the ecological reconstruction of mine lands are derived from scarce fertile soil 31 , 32 . The reconstructed soil, which mainly comprises raw soil and is similar to the soil parent material used in the reclamation of coal gangue dump land, was characterized by a lack of organic matter, weak soil structure, and an elevated salt content 31 , 33 . Mixing coal gangue with soil to reconstruct degraded soil can influence soil infiltration rates and saturated hydraulic conductivity 34 , 35 .…”

Influence of Coal Gangue Mulching With Various Thicknesses and Particle Sizes on Soil Water Characteristics

“…The greatest challenges for the ecological reconstruction of mine lands are derived from scarce fertile soil [34][35]. The reconstructed soil, which mainly comprises raw soil and is similar to the soil parent material used in the reclamation of coal gangue dump land, was characterized by a lack of organic matter, weak soil structure, and an elevated salt content [34,[36][37]. Mixing coal gangue with soil to reconstruct degraded soil can in uence soil in ltration rates and saturated hydraulic conductivity [38][39].…”

“…Previous research has demonstrated that coal gangue is a material that can be used in fertilizer production. Furthermore, as the concentration levels of trace elements are below permissible limits, coal gangue can also be used as a substitute for soil replacement because of its low transportation cost [36,[43][44]. More critically, granular coal gangue has a morphology similar to that of the gravel currently used and contains mineral elements similar to those in soil.…”