Low molecular weight organic acids (LMWOAs) are common and abundant compounds in the environment, responsible for the release of the nutrients from rhizosphere into the soil solution and, therefore, facilitating the availability of these nutrients for plants. Sewage sludge biochar (SSB) is considered to be a potential source of phosphorus (P) in soil. In this context, the efficacy of twelve LMWOAs in releasing SSB-bearing P was tested in a laboratory extraction experiment. Moreover, the potential effects of (i) biochar pyrolysis temperature (varying from 220°C to 620°C) and (ii) other elements in SS, to estimate the P bonds attacked predominantly by the LMWOAs, were also assessed. The results revealed citric acid was the most effective extraction agent enhancing the mobility of the SSB-derived P. P release was strongly affected by biochar pyrolysis temperature (the highest P release was from the 320°C biochar, significant at p < 0.05). Moreover, the results showed that P was released preferably from Fe-P bearing compounds in SS. Citric acid was recorded as less effective at releasing other nutrients, such as Ca, Mg, K, indicating the exceptional performance of citric acid in P release from biochar without substantial effect on the other nutrients.

低分子量有机酸 (LMWOA) 是环境中常见且含量丰富的化合物，负责将营养物质从根际释放到土壤溶液中，从而促进植物对这些营养物质的利用。污水污泥生物炭（SSB）被认为是土壤中磷（P）的潜在来源。在这种情况下，在实验室提取实验中测试了 12 种 LMWOA 在释放含 SSB 的磷方面的功效。此外，还评估了 (i) 生物炭热解温度（从 220°C 到 620°C 不等）和 (ii) SS 中的其他元素的潜在影响，以估计主要受 LMWOA 攻击的 P 键。结果表明，柠檬酸是提高 SSB 衍生的 P 迁移率的最有效提取剂。p  < 0.05)。此外，结果表明，在 SS 中，P 最好从含 Fe-P 的化合物中释放出来。柠檬酸在释放其他养分（如 Ca、Mg、K）方面的效率较低，这表明柠檬酸在从生物炭释放 P 方面表现出色，而对其他养分没有实质性影响。