Turning poultry waste into smarter soil: How biochar production conditions shape radish growth

In greenhouse tests, biochar made at a lower pyrolysis temperature of 300 °C and added at 2% by weight promoted larger leaf area, higher biomass, longer roots, and more root tips, all without causing phytotoxic effects. By contrast, a 5% application rate raised soil electrical conductivity and disturbed nutrient balance, which suppressed plant performance.

Poultry production generates huge volumes of litter, creating both a nutrient resource and an environmental management problem. In regions such as the Delmarva Peninsula, where poultry farming is highly concentrated, repeated land application of raw poultry litter can lead to phosphorus buildup, nutrient runoff, and water-quality risks. Converting poultry litter into biochar through pyrolysis has emerged as a promising alternative because it can stabilize nutrients, improve soil properties, and support circular agriculture. Yet the agronomic value of poultry litter biochar is not fixed: it depends strongly on pyrolysis temperature, feedstock composition, and application rate. Concerns also remain about salinity, nutrient imbalance, and possible phytotoxicity, making it necessary to identify conditions under which this waste-derived amendment is both safe and effective for crop growth.

A study (DOI:10.48130/bchax-0026-0009) published in Biochar X on 20 March 2026 by Dong Hee Kang’s team, Morgan State University, suggests that properly engineered poultry litter biochar could become a practical tool for recycling livestock waste, improving soil quality, and supporting more sustainable crop production in poultry-intensive agricultural regions.

To test how production conditions shape agricultural performance, the researchers produced six poultry litter biochars using two pyrolysis temperatures, 300 and 500 °C, and three feedstock compositions: no bedding, 10% pine shavings, and 10% rice hulls. These materials were then incorporated into a sandy loam soil collected from Maryland’s Delmarva Peninsula at two rates, 2% and 5% by weight. Radish was selected as the indicator crop because of its sensitivity to soil physical and chemical conditions. The team conducted both seed germination tests and six-week greenhouse pot experiments, while also measuring soil pH, electrical conductivity, nutrient availability, leaf area, biomass, chlorophyll-related indices, root length, and root tip number. The results showed a clear pattern. Seed germination remained high across all treatments, indicating that none of the tested biochars caused acute toxicity during early establishment. However, plant growth responses diverged sharply after emergence. Biochar produced at 300 °C supported better leaf growth and biomass than biochar produced at 500 °C, likely because lower-temperature material retained more plant-available nutrients and reactive surface groups. Application rate proved even more important. At 2%, the amendment improved soil fertility while keeping electrical conductivity within a range suitable for radish, which translated into stronger leaves and more developed root systems. At 5%, however, the soil became more saline, with much higher nitrogen, phosphorus, and potassium levels. That excess nutrient loading, combined with osmotic stress and cation antagonism, reduced root biomass, shortened total root length, and limited root tip formation despite the greater nutrient supply. The addition of bedding materials further improved outcomes by lowering sodium concentrations and increasing the potassium-to-sodium ratio, helping plants better tolerate salt-related stress. Overall, the optimal treatment was biochar produced at 300 °C, especially with bedding material, and applied at no more than 2%.

Taken together, the study shows that poultry litter biochar is not simply beneficial or harmful on its own; its value depends on how it is made and how much is applied. The work offers practical guidance for transforming poultry waste into a safer and more effective soil amendment, while also highlighting the need for future field-scale studies on long-term nutrient dynamics, microbial interactions, and repeated applications under real farming conditions.

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References

DOI

10.48130/bchax-0026-0009

Original Source URL

https://doi.org/10.48130/bchax-0026-0009

Funding information

This research was supported and funded by the National Science Foundation's Excellence in Research Program, Division of Chemical, Bioengineering, Environmental and Transport Systems (CBET), Directorate for Engineering (ENG), grant under award number 2200616.

About Biochar X

Biochar X is an open access, online-only journal aims to transcend traditional disciplinary boundaries by providing a multidisciplinary platform for the exchange of cutting-edge research in both fundamental and applied aspects of biochar. The journal is dedicated to supporting the global biochar research community by offering an innovative, efficient, and professional outlet for sharing new findings and perspectives. Its core focus lies in the discovery of novel insights and the development of emerging applications in the rapidly growing field of biochar science.