Long-term biochar use boosts soil health and soybean yields, study finds

A decade-long field study has revealed that biochar, a charcoal-like material made from plant residues, can significantly improve soil quality and boost soybean production in continuous cropping systems. The findings provide new evidence that biochar could be a powerful tool for making agriculture more sustainable.

Researchers from Shenyang Agricultural University tested the effects of biochar applied at two different rates compared with conventional fertilization. Over ten years, plots treated with biochar showed major improvements in soil structure, fertility, and microbial activity. Higher application levels enhanced soil porosity, increased organic carbon by more than 100 percent, and improved pH and nutrient balance while lowering soil compaction.

The study also showed that biochar reshaped soil microbial communities. Beneficial groups such as Firmicutes, Pseudomonas, and Mortierella became more abundant, while potential plant pathogens were suppressed. At the same time, biochar influenced the chemical signals plants release through their roots. These rhizosphere metabolites help regulate plant–microbe interactions. Biochar reduced compounds linked to soil stress and disease while promoting metabolites that strengthen plant defenses and growth.

“These results demonstrate that biochar does more than just improve soil structure. It also acts on the biological and chemical networks around plant roots, helping create a healthier ecosystem for crops,” said lead author Di Wu.

The benefits for farmers were clear. Biochar-treated soybeans grew taller, developed stronger root systems, and produced significantly higher yields. In high-dose plots, yields rose by nearly 46 percent compared to conventional fertilization.

Continuous soybean cultivation is widely practiced but often leads to declining soil fertility and rising disease pressure. Conventional solutions like fertilizers and pesticides can temporarily reduce problems but do not restore soil health. Biochar, by contrast, offers a long-lasting way to rebuild soil quality and resilience.

“Our decade of field data shows that biochar can support both soil restoration and crop productivity,” said co-author Wenfu Chen. “This could be a promising strategy for farmers facing the challenges of continuous cropping.”

The study provides strong evidence that biochar can play a vital role in advancing sustainable agriculture. By simultaneously improving soil physics, chemistry, and biology, it offers a practical solution to help secure global food supplies while protecting the environment.

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Journal Reference: Wu, D., Zhang, Y., Gu, W. et al. Rhizosphere metabolite-mediated soil enhancement: long-term biochar application optimizes continuous soybean production systems. Biochar 7, 95 (2025). https://doi.org/10.1007/s42773-025-00490-y 

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About Biochar

Biochar 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. 

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