Li, et al (2024) Long-term effects 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 application on biological nitrogen fixationNitrogen is a crucial nutrient for plant growth, but plants can’t directly absorb it from the air. Nitrogen fixation is a process where certain bacteria convert atmospheric nitrogen into a form that plants can use. Biochar can provide a home for these nitrogen-fixing bacteria, enhancing More of acacia species and soil carbon and nitrogen pools in an Australian subtropical native forest. Journal of Soils and Sediments. https://doi.org/10.1007/s11368-024-03816-8

This study investigates how acacia species and biochar application rates affect biological nitrogen fixation (BNF) and soil mineral nitrogen (N) in a suburban native forest in subtropical Australia, particularly following prescribed burns. The focus is on comparing the effects of biochar at rates of 0, 5, and 10 t ha−1 on Acacia leiocalyx and A. disparimma over 4-5 years.

Key findings reveal that applying 10 t ha−1 of biochar significantly improved the growth of acacia species and reduced nitrate nitrogen (NO3−-N) loss in the soil. Acacia leiocalyx demonstrated superior BNF abilities (%N derived from the atmosphere or %Ndfa: 91.3%) compared to A. disparimma (%Ndfa: 78.2%). This species also showed better growth metrics, including height, diameter, basal area, and volume. Enhanced growth of A. leiocalyx was linked to improved organic matter mineralization, leading to the accumulation of ammonium nitrogen (NH4+-N), which was then transformed into NO3−-N through nitrification.

Further, A. leiocalyx efficiently absorbed NH4+-N, mitigating its leachingLeaching is the process where nutrients are dissolved and carried away from the soil by water. This can lead to nutrient depletion and environmental pollution. Biochar can help reduce leaching by improving nutrient retention in the soil.   More and resulting in lower δ15N values, indicating better nitrogen retention in the soil. This species also had lower NO3−-N concentrations at soil depths of 0-5 cm and 5-10 cm compared to A. disparimma.

The study concludes that biochar, especially at higher application rates, is an effective soil amendmentA soil amendment is any material added to the soil to enhance its physical or chemical properties, improving its suitability for plant growth. Biochar is considered a soil amendment as it can improve soil structure, water retention, nutrient availability, and microbial activity.   More that can reduce mineral N loss and stimulate plant growth over the long term. The findings highlight A. leiocalyx’s potential as a key species for restoring forest soils due to its higher BNF capacity and greater growth efficiency.