Saiano Filippo, Scalenghe Riccardo
Dipartimento Scienze Agrarie, Alimentari e Forestali, Università degli studi di Palermo, Italy.
Heliyon. 2024 Nov 6;10(23):e40160. doi: 10.1016/j.heliyon.2024.e40160. eCollection 2024 Dec 15.
Phosphorus (P), crucial for plant nutrition, is unevenly distributed in the Earth's crust, necessitating its supplementation in agriculture through fertilizers. However, excessive use can lead to water pollution. Our research focuses on the P adsorbing complex, investigating P release due to flooding, using 12 well-characterized soils with contrasting properties. Our research measures directly the P-adsorbing complex using adsorption/desorption isotherms. We observed that the P concentration in the solution -sufficient to prevent desorption yet low enough to avoid further sorption by the soil- decreases when the soil undergoes complete reduction (anoxia). When grouped by similarity, calcareous soils exhibit higher maximum P adsorption capacities (X) under alternating reducing conditions (ARC) compared to continuous reducing conditions (CRC). In slightly acidic soils, CRC leads to a wider spread in X values than ARC. For acidic, organic matter-rich soils, ARC results in the highest X values (123 mmol P kg soil) compared to CRC, whereas in acidic, light-textured soils, CRC shows significantly higher mean X values than ARC. Nevertheless, we were unable to develop a predictive model for soil P desorption based on key intrinsic properties and climate. When an environmental or anthropogenic transformation induces anoxia, the P released does not follow a predictable pattern.
磷（P）对植物营养至关重要，在地壳中分布不均，因此农业上需要通过肥料进行补充。然而，过度使用会导致水污染。我们的研究聚焦于磷吸附复合体，利用12种特性各异的典型土壤，研究洪水引发的磷释放情况。我们的研究通过吸附/解吸等温线直接测量磷吸附复合体。我们观察到，当土壤完全还原（缺氧）时，溶液中的磷浓度（足以防止解吸但又低到足以避免土壤进一步吸附）会降低。按相似性分组时，与持续还原条件（CRC）相比，石灰性土壤在交替还原条件（ARC）下表现出更高的最大磷吸附容量（X）。在微酸性土壤中，CRC导致X值的分布范围比ARC更广。对于酸性、富含有机质的土壤，与CRC相比，ARC导致最高的X值（123 mmol P/kg土壤），而在酸性、质地较轻的土壤中，CRC的平均X值显著高于ARC。然而，我们无法基于关键内在特性和气候建立土壤磷解吸的预测模型。当环境或人为转变导致缺氧时，释放的磷并不遵循可预测的模式。
