Liu, T., Shao, T., Jiang, J. et al. Influence of potassium addition on phosphorus availabilityPhosphorus is another essential nutrient for plant growth, but it can sometimes be locked up in the soil and unavailable to plants. Biochar can help release phosphorus from the soil and make it more accessible to plants, reducing the need for chemical fertilizers.   More and heavy metals immobility of biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More derived from swine manure. Sci Rep 14, 21069 (2024). https://doi.org/10.1038/s41598-024-69761-1

Biochar, a byproduct of pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More, has been widely studied for its potential to recycle nutrients like phosphorus (P) from organic wastes such as animal manure. However, while the process effectively immobilizes heavy metals, the resulting biochar often has low levels of available phosphorus, making it less suitable as a fertilizer.

A recent study explored whether adding different potassium (K) compounds—both organic (CH₃COOK and C₆H₅K₃O₇) and inorganic (KOH and K₂CO₃)—to swine manure before pyrolysis could improve the biochar’s P availability while maintaining its ability to immobilize heavy metals. The results showed that all K additions increased P availability compared to untreated biochar, with organic K sources performing slightly better. Notably, water-extractable P levels remained low, but extractable P in ammonium citrate and formic acid, which is critical for plant use, improved significantly.

Additionally, the study found that K compounds affected the biochar’s silica content and facilitated the transformation of heavy metals like copper and zinc into more stable forms, reducing their environmental risks.

Overall, the co-pyrolysis of swine manure with potassium additives could be a promising method for producing biochar that offers higher P availability and lower heavy metal risks, making it more effective as a sustainable fertilizer for agricultural use. Further field trials are needed to validate these laboratory findings.