长期施磷的土壤中新生磷矿物鉴定及形态转化机制研究

The phosphorus is easily fixed with soil constituents when phosphate fertilizer applied into soils，which results in phosphorus unavailable to plants and relatively low use efficiency of phosphate fertilizer in the whole life of plants. It is always a hot reseach hotspot to enhance the utilization efficiency of phosphate fertilizer, especially accelerate the accumulative phosphorus transforming into available forms to the plants. However, phosphate activities in soils were controlled by the solubility of the insoluble forms of phosphate, especially new formed crystalline phosphate minerals. Because of the low total P content and complexity of phosphate minerals in soils, direct determination of naturally occurring phosphate minerals and clarifying of the mechanisms of phosphorus transformation in soils is generally very difficult and the key problem in science. The simulating incubation, pot, pool and field experiments will be conducted in the laboratory and field; and the methods of high-density separates and P mineral enrichment from the silt fractions of selected soils, the X-ray diffraction (XRD) analysis, micromorphological and ultrastructural analysis analysis, electron probe microanalysis, mass spectral analysis will be used to study the fractionation of soil phosphorus, the solubility and saturation of accumulative phosphorus in the long term repeated heavy application of phosphate fertilizer; to determine and identify the naturally occurring crystalline phosphate minerals in soils with long term repeated application of phosphate fertilizer; to elucidate the mechanism of phosphorus transformation and the control factor of phosphate solubility and activity; to probe up the mechanism of nutrient release rate of controlled-release phosphate and compound fertilizers synchronized with crop requirement, thereby, decreasing the fixation with soil constituents and increasing the phosphorus use efficiency; and to illuminate the theoretical basis for controlled-release fertilizer application on crop yield increment. This project has great realistic significance for us to exploit and utilize the soil accumulative phosphorus, to increase the use efficiency of phosphate fertilizer, to promote prograss of the slow and controlled-release fertilizer industry, and to enrich the theory and knowledge of soil science.

磷肥施入土壤中易被固定，造成作物对磷肥的利用率较低。提高磷肥利用率，特别是促进土壤中积累态磷的有效化，一直是研究的热点。然而，土壤中难溶态磷尤其是新生晶质磷矿物的溶度是控制其有效化的关键，由于磷矿物含量低，结晶程度差，且高度分散，从土壤中分离和鉴定新生磷矿物并阐明其形态转化机制一直是研究的难点和亟待解决的关键科学问题。本研究拟采用室内培养、盆栽、池栽和田间试验，结合磷矿物分选富集、X射线衍射、超微形态分析、电子探针质谱分析等手段，研究长期施磷的土壤中磷素分级形态、积累态磷的溶度和饱和度，确定并鉴定出由于长期施磷而新形成的晶质磷矿物，探明不同条件下控制土壤磷溶度和活度的因素及形态转化机制，明确包膜控释磷复肥磷素释放与作物吸收相同步从而减少土壤固定、提高磷肥利用率的作用机制和在作物上应用的理论基础。对于开发利用土壤磷资源、提高磷肥利用率、推动缓控释肥行业发展、丰富土壤学理论都具有现实意义。

磷肥施入土壤中易被固定，造成作物对磷肥的利用率较低。研究如何提高磷肥利用率，特别是促进土壤中积累态磷的有效化，对于减肥增效和减少面源污染具有重要意义。本研究采用室内培养、盆栽和田间试验，结合土壤颗粒分级、磷矿物分选富集、X射线衍射、超微形态分析等手段，系统研究了长期施磷的土壤中磷素分级形态、积累态磷的溶度和饱和度，已从长期大量施肥的石灰性菜地土壤中分选并鉴定出由于长期大量施磷而新形成的晶质磷矿物，探明了不同条件下控制土壤磷溶度和活度的因素，揭示了不同温度和磷肥施用量对控制土壤磷溶度和有效性的影响及其形态转化机制；探明了包膜磷酸二铵配施黄腐酸对土壤磷素有效性的影响，明确了包膜控释磷复肥磷素释放与作物吸收相同步从而减少土壤固定、提高磷肥利用率的作用机制和在小麦玉米等作物上应用的理论基础。已发表论文36篇，申请/授权专利7项，项目建立的土壤中新生磷酸盐矿物鉴定体系，为土壤学中以往仅从理论推断长期施肥能够生成磷酸盐矿物的基础理论知识提供了实践验证数据的支撑，丰富了土壤学理论和实验测试技术。