Abstract: Slag is one of the important materials for soil reconstruction in mining areas. We investigated the nutrient characteristics of typical limestone slag and its improvement strategies across six representative limestone mines in North China. We compared the nutrient content and enzyme activity between limestone slag of these sites and conventional greening soil. The potential application of organic waste compost for slag amendment was also explored. The results showed that most limestone slag had a favorable particle size distribution and suitable physical structure, indicating that nutrient recombination was the key to soil reconstruction. The cation exchange capacity, available nitrogen, available phosphorus, available potassium, and organic matter content of limestone slag were all significantly lower than those of conventional soil. The activities of catalase, alkaline phosphatase, sucrase, and urease were lower, suggesting that the limited nutrient release capacity was a key constraint on vegetation restoration. The soil enzyme activity of limestone slag was significantly correlated with the nutrient characteristics. The application of organic waste can effectively improve the pH of limestone slag and enhance nutrient availability. Peat, sewage sludge, composted green waste, fermented chicken manure, and fermented pig manure are suitable materials for ameliorating limestone slag. Our findings will provide a theoretical basis and scientific support for soil reconstruction and ecological restoration projects in limestone mining areas.

Key words: limestone, slag, organic waste, soil reconstruction