【Objective】Soil aggregates in the soil are important media capable of storing, transforming and activating soil phosphorus(P), and distribution and stability of soil aggregates is influenced by long-term fertilization. However, little has been reported on release pattern and adsorption capacity of P across various soil aggregates and their relationships in red soils as affected by long-term fertilization,which are essential to sustainable management of P sources in agricultural fields. The objectives of this study are to: (i) investigate changes in TP, available P, CaCl₂-P, PSI and DPS, in soil aggregates of different particle-size fractions in a red soil under long-term fertilization; (ii) to explore relationships between CaCl₂-P, available P, DPS; and (iii) to study how DPS andAvailable P affect P loss potential.【Method】A long-term fertilization experiment was established in 1988 and soil samples were collected from the 7 fertilization treatments, designed in the experiment as follows: NPK, NK, Control (CK), CK + peanut straw (PS), CK + rice straw (RS), CK + fresh radish (FR) and CK + pig manure (PM). The soil samples were fractionated, using the wet sieving method,into aggregates of different particle sizes (> 2.0 mm, 2.0 ~ 1.0 mm, 1.0 ~ 0.25 mm and 0.25 ~ 0.053 mm). Then the various fractions of aggregateswere analyzed for total P (TP), available P, CaCl₂-P, P sorption index (PSI) and degree of P saturation (DPS) and relationships between the parameters.【Result】Results show that Treatment NK was the lowest in TP, and DPS but the highest in PSI in all the aggregates, regardless of particle size fraction in the red soil. Compared with Treatment CK, TreatmentsPS, RS and FR were quite similar in effect on soil TP, PSI, Available P and DPS; but Treatment PM significantlydecreased soil P retention capacity with the highest TP and lowest PSI, and increased P release or loss potential in all the fractions of aggregates with the highest DPS, Available P and CaCl₂-P. All the fertilization treatments, irrespective of their pattern, significantly increased P content in the > 2.0 mm fraction of aggregates with PEC (P enrichment coefficient) >1, but in Treatment NPK + PM soil P was more easily enriched in macro-aggregates (> 0.25 mm). 【Conclusion】Correlation analysis indicates that the P accumulated in the soil may be subject to potential loss to the safety of water quality when available P was range in 168 ~ 260 mg kg^-1 or DPS < 28% in the red soil; otherwise P loss would be significant. Therefore, new strategies of using both commercial fertilizers and animal manures must be established and implemented to prevent P build up in the soil and to minimize P loss to water bodies in the red soil region.