Predicting soil phosphorus (P) bioavailability requires an understanding of organic P mineralization (P_min) but assessing P_min rates is challenging. Recent advances in the use of radioisotopic P labeling enable estimates of P_min rates in soil. However, there is yet no standardization of radioisotopic dilution methods, potentially compromising comparison of results among studies. We conducted a systematic literature search to (1) synthesize the varying procedures among different studies, (2) compare the soil P_min results obtained via two most commonly used approaches, isotopically exchangeable kinetics (IEK) and isotope pool dilution (IPD), and (3) address the methodological advantages and limitations of IEK and IPD. We identified and analyzed 98 studies, and found large discrepancies in study-specific radioisotope spike level, soil incubation period and extraction methods used to estimate the soil available P pool. On average, a spike level of 10-20 kBq g^-1 soil was used among studies but empirical assessments are required to confirm that this assumed range of spike level is sufficient to measure exchangeable P. We found that incubation duration should be ≤14 d because there is an increasing possibility of measuring declining cumulative gross P_min values beyond 14 d, even though reduced cumulative rate with additional time is theoretically impossible. Gross P_min rates were lower by IPD compared to IEK. However, 18 studies reported undetectable gross P_min, possibly due to the unverified but widely made assumption that biotic and abiotic process rates are additive. The complexity of the methodological issues necessitated a more nuanced approach via an advanced statistical approach (e.g., decision tree) to select a method based on trade-offs. To address the methodological issues identified in this review, a greater quantity and quality of observations need to be collected (e.g., well-designed experiments, data quality assurance such as quenching correction).

中文翻译：

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追求土壤 P 矿化：放射性同位素标记技术的综述和综合


预测土壤磷 （P） 生物利用度需要了解有机磷矿化 （P _min ），但评估 P _min 速率具有挑战性。使用放射性同位素 P 标记的最新进展可以估计土壤中的 P _min 含量。然而，放射性同位素稀释方法尚无标准化，可能会影响研究之间的结果比较。我们进行了系统的文献检索，以 （1） 综合不同研究之间的不同程序，（2） 比较通过两种最常用的方法获得的土壤 P _min 结果，同位素交换动力学 （IEK） 和同位素池稀释 （IPD），以及 （3） 解决 IEK 和 IPD 的方法学优势和局限性。我们确定并分析了 98 项研究，发现研究特异性放射性同位素加标水平、土壤潜伏期和用于估计土壤可用 P 库的提取方法存在很大差异。平均而言，研究中使用了 10-20 kBq g ^-1 土壤的加标水平，但需要实证评估来确认这个假设的加标水平范围足以测量可交换的 P。我们发现孵育持续时间应为 ≤14 d，因为在 14 d 之后测量累积总 P _min 值下降的可能性越来越大，即使理论上不可能随着时间的增加而降低累积速率。与 IEK 相比，IPD 的总 P _min 率较低。然而，18 项研究报告了检测不到的总 P _min ，可能是由于未经证实但被广泛做出的假设，即生物和非生物过程速率是相加的。方法论问题的复杂性需要通过先进的统计方法（例如、决策树）以根据权衡选择方法。为了解决本综述中确定的方法学问题，需要收集更多数量和质量的观察结果（例如，精心设计的实验、数据质量保证，如淬灭校正）。