肥际是肥料与土壤接触后肥料养分浓度很高、肥料与土壤组分相互作用强烈的区域。P肥肥际反应尤为强烈,其过程对肥料P在土壤中迁移及生物有效性可能起着至关重要的作用。本文以肥际为切入点,通过土柱培养试验,研究了磷酸二氢钙(MCP)在石灰性潮土肥际的形态转化及肥料P的迁移。结果表明,MCP施肥31天后,肥料P的迁移距离达45mm。MCP异成分溶解导致约30%的肥料P残留在原施肥点;另有约70%进入土壤。无机P形态分级结果显示,进入土壤的肥料P仍保持较高的有效性,且主要以磷酸钙盐存在。其中,近10%仍以水溶态(WE-P)存在,近35%转化为Ca2-P,近35%转化为Ca8-P,近15%转化为Al-P,约5%转化为Fe-P,仅不足1%转化成O-P,而Ca10-P没有明显变化。肥际(0~2mm)新增各形态含P矿物中,Ca8-P所占比例显著增加,O-P的比例略有增加,其他形态P的比例相应减少。MCP施肥后土壤WE-P和Ca2-P的分布呈明显的分段特征,即由自施肥点开始的快速线性下降阶段和随后的缓慢线性下降阶段构成,其他形态的P的分布也有肥际集中分布特性,使得进入土壤的肥料P90%左右集中在不足一半的扩散距离内。MCP施肥引起肥际土壤pH显著下降,对肥际碳酸盐及铁、铝矿物溶解破坏作用极为显著,特别是2mm内碳酸盐被完全分解。土壤CaCO3溶解释放的Ca2+是进入土壤的肥料P转化固定的主要因素,其次是施肥伴随的Ca2+,肥际铁、铝矿物溶解释放出的Fe3+、Al3+对P的固定也有重要贡献。MCP对土壤矿物的溶解破坏及其异成分溶解作用是石灰性土壤中该肥料有效性的主要限制因素。 Fertilizers are fertilizers in contact with the soil after fertilizer nutrient concentration is high, fertilizers and soil components interact strongly with the area. Fertilizer P response is particularly intense, and its process may play a crucial role in the migration and bioavailability of fertilizer P in soils. In this paper, we take the fatty soil as the starting point and study the morphological transformation of the calcium dihydrogen phosphate (MCP) in the calcareous soil and soil and the migration of the fertilizer P through soil column culture experiment. The results showed that after 31 days of MCP fertilization, the migration distance of fertilizer P was 45mm. Dissolution of MCP iso-components results in about 30% of fertilizer P remaining at the original fertilization point; another about 70% entering the soil. Inorganic P-type grading results show that fertilizer P entering the soil remains highly effective, and is mainly present as calcium phosphate salts. Nearly 10% of them are still in water-soluble state (WE-P), nearly 35% are converted to Ca2-P, nearly 35% are converted to Ca8-P, nearly 15% are converted to Al-P and about 5% P, less than 1% converted to OP, while Ca10-P did not change significantly. The proportion of Ca8-P increased significantly, the proportion of O-P increased slightly and the proportion of other forms P decreased correspondingly. The distributions of WE-P and Ca2-P in soil after MCP fertilization were obviously segmented, that is, the rapid linear decrease from the beginning of fertilization and the subsequent slow linear decrease, and the distribution of other forms of P were also concentrated Distribution characteristics, making fertilizer P90% into the soil concentrated in less than half of the diffusion distance. MCP fertilization caused a significant decrease in pH of the fertilizers soil, which had a significant effect on the dissolution of fertilizers and iron and aluminum minerals. In particular, the carbonate within 2 mm was completely decomposed. Ca2 + dissolved by soil CaCO3 release is the main factor of fertilizer P conversion into soil, followed by Ca2 + accompanying fertilization. Fe3 + and Al3 + released by the dissolution of Fe and Al minerals also contribute to the fixation of P, too. The dissolution and destruction of soil minerals by MCP and their dissolution of the different components are the main limiting factors for the effectiveness of this fertilizer in calcareous soils.