Elbana Tamer A, Bakr Noura, Shahin Sahar A, Azab Nahed A A, El-Ashry Soad M
Soils and Water Use Department, Agricultural and Biological Research Institute, National Research Centre, Cairo, Egypt.
Sci Rep. 2025 Aug 20;15(1):30504. doi: 10.1038/s41598-025-16247-3.
Biochar application is recommended to enhance soil fertility, particularly in arid and semi-arid regions. In alkaline soils, acidifying biochar can help overcome high pH constraints and improve phosphorus (P) and potassium (K) availability. This study evaluated the effects of acidified palm frond (PF) and guava branch (GB) biochars on P and K availability in alkaline sandy soil through a controlled batch incubation experiment. Biochars were acidified using acetic or phosphoric acid and characterized for their chemical properties, surface morphology, and functional groups. A 15-week incubation was conducted using sandy alkaline soil pre-treated with 0.48 Mg ha of superphosphate fertilizer. Acidified and unacidified PF and GB biochars were applied at rates of 2.4 and 4.8 Mg ha. PF biochar showed a higher cation exchange capacity (CEC: 37.9 cmol kg) and greater K enrichment than GB biochar (CEC: 17.6 cmol kg). Phosphoric acid significantly increased the CEC of both biochars, while acetic acid had minimal impact. Application of 4.8 Mg ha phosphoric acid-treated GB biochar significantly improved soil P availability, reaching 104.02 mg kg after one week, with no evidence of P fixation over 15 weeks. PF biochar, regardless of acidification, significantly enhanced exchangeable K levels, particularly at the higher application rate. Acidification improved P and K availability in the studied alkaline sandy soil, but such influence depended on biochar type, chemical composition, and incubation time. Selecting the appropriate acid for biochar modification is crucial to optimizing nutrient availability in alkaline soils.
建议施用生物炭以提高土壤肥力，特别是在干旱和半干旱地区。在碱性土壤中，酸化生物炭有助于克服高pH值的限制，并提高磷（P）和钾（K）的有效性。本研究通过控制批量培养试验，评估了酸化棕榈叶（PF）和番石榴枝（GB）生物炭对碱性砂土中P和K有效性的影响。使用乙酸或磷酸对生物炭进行酸化，并对其化学性质、表面形态和官能团进行了表征。使用预先用0.48 Mg/ha过磷酸钙肥料处理的砂质碱性土壤进行了为期15周的培养。以2.4和4.8 Mg/ha的施用量施用酸化和未酸化的PF和GB生物炭。PF生物炭显示出比GB生物炭更高的阳离子交换容量（CEC：37.9 cmol/kg）和更大的K富集（CEC：17.6 cmol/kg）。磷酸显著提高了两种生物炭的CEC，而乙酸的影响最小。施用4.8 Mg/ha磷酸处理的GB生物炭显著提高了土壤P的有效性，一周后达到104.02 mg/kg，在15周内没有P固定的迹象。无论是否酸化，PF生物炭都显著提高了可交换K水平，特别是在较高施用量时。酸化提高了所研究的碱性砂土中P和K的有效性，但这种影响取决于生物炭类型、化学成分和培养时间。选择合适的酸对生物炭进行改性对于优化碱性土壤中的养分有效性至关重要。
