Amelioration of Saline Alkali–Soil and Improvement of Soybean Performance by Organically Modified Coal Gangue

Growing global concern over soil salinization has drawn considerable attention to the remediation and amelioration of saline–alkali soils. Coal gangue (M) can be applied to improve saline–alkali soils; nevertheless, its amelioration performance is subject to certain limitations. Organically modified coal gangue (GM) was prepared using alcohol ethoxylate-7 (AEO-7) as the primary modifier, and both M and GM were mixed with a saline–alkali soil at 10%, 20%, 30% and 40% (w/w) in a 28-day incubation and a 28-day soybean pot experiment. At 28 d, compared with the CK group, the GM40% treatment significantly increased the available potassium and alkali-hydrolyzable nitrogen in the saline–alkali soil by 49.91% and 97.10%, respectively, and increased soil organic matter by 10% compared with M40%. The GM groups decreased soil pH relative to CK, alleviated M-induced available phosphorus deficiency, and increased soil urease, peroxidase and catalase activities by 467.77%, 140.37% and 76.29%, respectively. Plant height, shoot dry weight and root dry weight increased by 23.24%, 102.22% and 208.05%. Amplicon sequencing showed that the modified material increased bacterial richness and shifted bacterial community composition. Thus, the organically modified gangue improved soil nutrient pools and soybean performance relative to raw gangue.