Evaluation of Soil Quality and Maize Growth in Different Profiles of Reclaimed Land with Coal Gangue Filling

Abstract

Reclaiming subsidence and waterlogged zones caused by coal mining to maintain food and feed supplies is an urgent issue in China. Utilizing coal gangue (CG) as a filling matrix to construct different profiles of reclaimed land in coal mining subsidence has downsides, e.g., due to its low conservative capability of water-fertilizer and crop yield, its lack of quantitative evaluation of soil quality, and its limiting factors of crop growth. Quantifying the soil quality by principal component analysis (PCA), obtaining key soil indicators, and a scoring system can clarify the influence of the profile structure on soil quality and limiting productive factors of soil and ascertain the optimal profile. Soil quality was evaluated by the minimum data set (MDS) of soil quality index (SQI) obtained by PCA in seven different profiles of reclaimed plots constructed in a field with maize planting experiments. The agronomic traits of maize were analyzed and compared. The result shows that the pH value contributed highest in surface SQI value. Maximal and minimal SQI value is 0.57 and 0.18, respectively, the variation of SQI between different profiles reveals it increases with the increase in thickness of overburdens and decreases with the increase in soil interlayer depth of reclaimed land. SQI based on MDS has a correlation coefficient of 0.4280 with maize yield and the same sequence with comprehensive growth of maize in reclaimed plots. Agronomic traits of maize are positively correlated with the nutrient index and SM of the surface soil, and negatively correlated with pH, electrical conductivity (EC), and total salt content (TS). Choosing a thicker surface overburden and control pH of CG preceding filling can effectively augment soil quality and maize growth. This study provides the exploratory means and a scientific basis for the management and improvement of filling reclamation.

Are Iron Tailings Suitable for Constructing the Soil Profile Configuration of Reclaimed Farmland? A Soil Quality Evaluation Based on Chronosequences

“…The traditional filling reclamation materials such as fly ash and gangue usually contain harmful heavy metal elements such as Cd, Pb, and Hg, and the reclaimed soil has potential ecological harm [ 26 ]. In addition, if these heavy metals diffuse with runoff, they will also pollute a wider range of soil [ 51 ].…”

“…For variables with significant correlation, a variable with a high Norm value was selected for soil quality evaluation, and the rest were excluded. If the highly weighted variables are not correlated, each variable can be used for soil quality evaluation [ 26 ].…”

“…Therefore, the quality status of mine soil after reclamation should be focused on. In addition, farmland is a three-dimensional system [ 25 ]; the reasonable degree of soil profile configuration of reclaimed farmland plays a decisive role in the migration of soil water, fertilizer, gas, and heat and has significant effects on soil water infiltration, nutrient transfer, and solute transport, and will affect the material and energy cycle of the farmland system [ 26 ]. Soil reconstruction should pay attention to building a reasonable profile configuration while increasing farmland area to realize a healthy and sustainable farmland system.…”

“…Soil quality evaluation can evaluate the progress and success of reclamation, which is one of the important indicators to appraise the quality of reclamation farmland [ 26 ]. However, inferring soil quality by merely measuring single or specific soil property is insufficient [ 27 ].…”

Corn Cropping Systems in Agricultural Soils from the Bajio Region of Guanajuato: Soil Quality Indexes (SQIs)

“…Other researchers have created several SQIs for corn cultivation in different regions of the world by considering a variety of environmental conditions and soil types. Hu et al [57] developed a PCA-based SQI by using a minimum data set of reclaimed marsh soils using coal mining residues and evaluated its performance under corn-growing conditions. This SQI was based on texture, pH, EC and TOC indicators.…”