A three-year field study shows that pairing biochar with arbuscular mycorrhizal fungi can improve soil health, nutrient supply, microbial diversity, and maize productivity in reclaimed mining land
Coal mining can leave behind more than empty pits. It can strip land of vegetation, weaken soil structure, reduce organic matter, and make it difficult for crops and ecosystems to recover. A new three-year field study suggests that two nature-based tools, biochar and arbuscular mycorrhizal fungi, may work together to help bring degraded mining soils back to life.
The study, published in Biochar, investigated how maize straw biochar and the beneficial fungus Funneliformis mosseae affected reclaimed coal-mining soil in Shanxi Province, China. The researchers compared four treatments: traditional planting without biochar or fungi, fungi alone, biochar alone, and a combined biochar plus fungi treatment.
Their results show that the combined treatment improved soil structure, increased nutrient availability, stimulated soil enzymes, reshaped microbial communities, and enhanced overall soil multifunctionality. The findings point to a practical strategy for restoring land that has been disturbed by mining and reused for agriculture.
"Mining reclamation is not only about covering disturbed land with soil. The real challenge is rebuilding a living soil system that can retain water, cycle nutrients, support microbes, and sustain crop growth," said corresponding author Wei Wang. "Our study shows that biochar and arbuscular mycorrhizal fungi can act together to accelerate that recovery."
Biochar is a carbon-rich material produced by heating biomass under low-oxygen conditions. Because it is porous and chemically active, it can help soils hold water, improve aeration, and provide surfaces where nutrients and microbes can accumulate. Arbuscular mycorrhizal fungi, or AMF, form symbiotic relationships with plant roots, helping plants obtain nutrients and water while receiving carbon from the host plant.
In the field experiment, biochar was added to reclaimed soil and AMF was introduced around maize roots. The researchers found that the biochar plus AMF treatment reduced soil bulk density and increased soil porosity, creating a better physical environment for root growth. It also increased mycorrhizal colonization, fine root development, and soil pore volume.
The biological response was also striking. The combined treatment increased the activity of key soil enzymes involved in carbon, nitrogen, and phosphorus cycling. Compared with untreated soil, the biochar plus AMF treatment increased sucrase, β-glucosidase, urease, cellulase, and other enzyme activities, indicating a more active soil biochemical environment.
The treatment also changed the soil microbiome. Bacterial and fungal diversity increased, and microbial groups associated with nutrient cycling became more abundant. These changes were closely linked with improvements in soil water content, porosity, organic carbon, available phosphorus, and enzyme activity.
Most importantly, the combined treatment produced the strongest gains in soil multifunctionality, a measure that integrates several soil functions such as productivity, structure, nutrient supply, microbial community performance, and enzyme activity. A random forest analysis showed that nutrient supply was the main driver of soil multifunctionality, while enzyme activity was the strongest contributor to maize productivity.
"Biochar creates a better habitat, while mycorrhizal fungi expand the plant's ability to access nutrients," said co-corresponding author Dongsheng Jin. "Together, they appear to build a stronger plant-soil-microbe network in reclaimed mining land."
The authors note that coal gangue reclamation areas often face poor fertility, compacted soil, and unstable microbial communities. By combining biochar with AMF inoculation, land managers may be able to improve both crop production and ecological restoration.
The study provides evidence that integrated biochar and microbial approaches can serve as a sustainable, nature-based strategy for restoring degraded soils in mining regions.
===
Journal Reference: Dong, Y., Yang, L., He, X. et al. Synergistic enhancement of soil multifunctionality by biochar and arbuscular mycorrhizal fungi via improved nutrient supply in coal mining reclaimed soils. Biochar 8, 104 (2026).
https://doi.org/10.1007/s42773-026-00618-8
===
About Biochar
Biochar (e-ISSN: 2524-7867) is the first journal dedicated exclusively to biochar research, spanning agronomy, environmental science, and materials science. It publishes original studies on biochar production, processing, and applications—such as bioenergy, environmental remediation, soil enhancement, climate mitigation, water treatment, and sustainability analysis. The journal serves as an innovative and professional platform for global researchers to share advances in this rapidly expanding field.
