Restoring subsided coal mined land to farmland using optimized placement of Yellow River sediment to amend soil

Abstract

Underground coal mining causes land subsidence and large areas of cultivated land are destroyed. The Yellow River interlayer filling reclamation technology is a powerful way to restore cultivated land. Understanding the mechanism of action of interlayers in reconstructed soil filled with Yellow River sediment is essential to achieving sustainable land management in the Yellow River regions. Column experiments and field experiments were conducted to explore optimum interlayer placement in reconstructed soil with Yellow River sediment for restoring subsided land. Our findings show that the inclusion of interlayers in the sediment reduced water leakage and moisture evaporation and improved the water-holding capacity of the material in comparison to a conventional reconstructed soil profile (CK2). The optimal profile with the highest water-holding capacity was constructed using two 30 cm thick interlayers (T6). In comparison to CK2, the migration rate of the wetting front decreases by 32.16%, the cumulative evaporation decreases by 16.29%, the volumetric water content of the filling layer (θ fl ) increases by 121.56%, and the water-holding coefficient (C WR ) increases by 59.47%. The same trend is also demonstrated by field experiments. The wheat and maize yields of T6 improved 45.85% and 60.69%, respectively, as compared with CK2, that more closely resembles undisturbed farmland (CK1). This study provides a valuable framework for subsided land reclamation regarding the method of placing interlayers into Yellow River sediment for enhancing water retention and productivity.

A Study of the Physical and Mechanical Properties of Yellow River Sediments and Their Impact on the Reclamation of Coal-Mined Subsided Land

“…In addition, in terms of physical and mechanical properties, the Yellow River sediment has an inhomogeneity coefficient of 1.75 and a curvature coefficient of 1.36, with more uniform particle sizes and poorer gradation, which is intuitively reflected by the fact that the reclaimed farmland is prone to the leakage of water and fertilizer compared with the control farmland. Zhenqi Hu [26] proposed the principle and method of sandwich-type soil reconstruction, and through the study of multiple profiles, Xiaotong Wang [27] found that the Yellow River sediment sandwich reclamation reduces seepage.…”

“…To address this, Zhenqi Hu [26] proposed a "sandwich-structure" method for the filling reclamation of soil using Yellow River sediment. Further research on multiple profiles have shown that this approach can effectively reduce water seepage when used for reclamation [27]. The sandwich design better retains water by enclosing sediment layers between more conducive materials.…”

Progress of Mine Land Reclamation and Ecological Restoration Research Based on Bibliometric Analysis

“…The publications of the top five countries accounted for 28.26%, 10.82%, 9.63%, 6.07%, and 3.52%, respectively, indicating those countries made the greatest contributions to the research on LRER. For example, in China, there are many studies on LRER in coal mining areas, and the research areas are mainly concentrated in ecologically fragile areas in Northwest China [4,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] and high water level areas in Eastern China [6,[45][46][47][48][49][50][51][52]. The research focuses include reclamation of open-pit coal mines [8,38,39,[53][54][55][56][57][58], reclamation of coal mining subsidence sites [7,51,[59][60][61][62][63][64]…”

Effect of the interlayer on soil temperature and the transformation between phreatic water and soil water under laboratory freeze-thaw action

“…Sandy interlayer structures are common in the field soil profile because of external forces, such as wind and sand, hydrology, and geology (Xue et al, 2020). In layered soil, the movement of moisture is closely related to the nature, thickness, texture, soil-layer order and groundwater table depth of the soil layer (Pillai et al, 2009;Shokri et al, 2010;Li et al, 2014;Hu et al, 2022;Wu et al, 2022). At the interface of different soil layers, the hydraulic characteristics of soil are discontinuous, which leads to the difference of hydraulic characteristics between homogeneous soil and heterogeneous soil.…”