基于磷酸盐氧同位素的典型设施土壤遗留磷循环机制与供给潜力研究

The large accumulation of surplus phosphorus (P) in greenhouse soils due to the excessive and intensive application of chemical fertilizers and manures, termed soil legacy P, which has threatened the sustainable development and water environmental quality of greenhouse agriculture. Legacy P could substitute manufactured fertilizers, help preserving critical reserves of finite phosphate rock to ensure future food and bioenergy supply, and gradually improve water quality. However, the greenhouse soils have more complicated P cyclical process due to special semi-closed environment with high temperature, high humidity, high evaporation, no rainfall and no sedimentation. So far, the supply potential of legacy P has not be clearly assessed for greenhouse soils in China. Therefore, it is of great significance to study the cycling mechanism of legacy P and further to evaluate its supply potentiality in order to alleviate and prevent further accumulation of legacy P in greenhouse soils. . Using phosphate stable oxygen isotope technique, this study focuses on the investigation of P speciation and its transformation processes in Shouguang, Shandong province, one of the representative greenhouse areas of China. Based on legacy P speciation and its phosphate stable oxygen isotope ratios (δ18OP), the cycling mechanism of legacy P was identified and its supply potentiality was also assessed. The results of the study can provide deeper insights into P forms, pool size, transfers and fluxes, and P cycling in greenhouse soils. And the scientific evidence was also provided for sustainable development of greenhouse agriculture and reasonable utilization of legacy P resources.

过量施肥造成的设施农业土壤遗留磷大量积累，对设施农业的可持续发展及水环境质量造成严重威胁。土壤遗留磷储量可以替代部分磷肥来保护有限的磷矿资源并保障全球粮食安全。然而，设施土壤常处于高温、高湿、高蒸发的特殊环境中，其磷素循环复杂，遗留磷的供给潜力仍不清楚。因此，研究设施土壤遗留磷的循环机制，并进一步评估其供磷潜力对于开展减量施肥，促进土壤遗留磷的作物利用并减缓其继续累积，具有重要意义。. 本研究以我国典型设施农业区域山东寿光市设施土壤为研究对象，利用国际前沿的磷酸盐氧同位素技术，从探究设施土壤遗留磷的赋存形态及其循环周转过程入手，对设施农业土壤遗留磷循环过程及供给潜力进行研究。探明设施土壤遗留磷赋存形态及其磷酸盐氧同位素特征与差异，阐明设施土壤遗留磷的循环机制并估算其潜在供磷能力，以期为实现土壤遗留磷的资源化和有效管控，为减肥增效及设施农业可持续发展提供科学依据。

过量施肥造成了设施农业土壤遗留磷大量积累。土壤遗留磷的再利用可以降低对水环境的威胁，同时保护有限的磷矿资源并保障全球粮食安全。. 本研究以山东寿光设施农业土壤为研究对象，利用磷酸盐氧同位素技术，从探究设施土壤遗留磷的赋存形态及其循环周转过程入手，明确了设施农业土壤遗留磷循环过程及供给潜力。结果表明，种植年限越长，设施农业土壤磷累积越严重，尤其是日光温室土壤更加突出。塑料大棚土壤磷累积主要发生在耕作层，而日光温室土壤中，磷不仅在表层累积，还在土壤剖面上发生了迁移，在底层土壤中也有较高的累积。日光温室和塑料大棚的NaHCO3提取态δ18OP均处在同位素平衡分馏范围内。同位素的结果证明了底层的NaHCO3提取态磷是从表层迁移来，且较常规含量研究更能说明磷的淋溶和累积程度。日光温室0-90cm的TP储量为18.72 t hm-2，是塑料大棚的3.15倍。日光温室土壤HCl-Pi比例较塑料大棚低，而活性磷的比例偏高，日光温室土壤的磷储量具有较高比例的活性磷。底层土壤遗留高含量的磷主要来源于上层土壤活性磷的迁移和固定，日光温室底层土壤高含量的活性磷，具有为作物生长提供磷潜力，但是对水环境安全存在隐患。