Soil phosphorus partitioning and bacterial communities vary with prolonged Camellia oleifera cultivation.

INTRODUCTION

Camellia oleifera (C. oleifera) is a valuable plant whose seeds produce tea seed oil, with potential applications in food, cosmetics, and agriculture. In the allitic soils of southern China, the complexity of soil phosphorus (P) fractions and influencing factors significantly restricts plant growth, especially for C. oleifera.

METHODS

This study examined soil samples from C. oleifera. plantations with cultivation periods of 2, 10, and 40 years, focusing on variations in P bioavailability among different soil aggregate sizes and the underlying regulatory mechanisms.

RESULTS

Soil P availability and its fractions changed significantly with cultivation period and aggregate size. Generally, as the cultivation period extended, soil available P (AP) declined by approximately 78.3%, while the root P accumulation factor increased by 657.91%, 687.01%, and 283.16% in large macroaggregates (LM), small macroaggregates (SM), and microaggregates (Mi), respectively. Maximum P adsorption capacity was highest in SM in the 2-year plantation but shifted to the Mi fraction in the 10- and 40-year plantations. Iron-bound phosphorus (Fe-P) was the predominant inorganic P fraction and showed a consistent distribution pattern across aggregate sizes. With increasing cultivation time, calcium-bound phosphorus (Ca-P) and occluded phosphorus (O-P) decreased, whereas aluminum-bound phosphorus (Al-P) increased in larger aggregates. AP and P fractions were negatively associated with bulk soil organic matter (SOM) content, while individual P fractions showed contrasting relationships with non-hydrophilic and hydrophilic SOM functional groups. Additionally, O-P, Al-P and Fe-P were positively correlated with bacterial ɑ-diversity in LM but negatively correlated in SM and Mi. Specific bacterial taxa were associated with different P forms.

DISCUSSION: Overall, the results show that aggregate specific P partitioning, SOM composition, P adsorption characteristics and bacterial community patterns are closely associated with soil P availability during prolonged C. oleifera. cultivation.