Understanding the accumulation rule of nutrients is crucial to promote the production of Camellia Oleifera. The stoichiometry of soil microelements is more critical than their content in affecting the growth and yield of plants. However, research on C. Oleifera in these aspects is limited. In this study, we examined microelement content in soil and various parts of the C. oleifera plant and analysed the relationship between the bioaccumulation, distribution, and production of plant trace elements with the stoichiometry of soil trace elements. Our findings indicated that high-yield plants transported more Ca, Mg, and B to the shoot, while low-yield plants stored higher Fe, Zn, and Al in the root. The significantly lower bioaccumulation factor and translocation factor of B and Mg in the high-yield plants highlighted the importance of nutrient storage in promoting C. Oleifera yield. Multiple regression analysis and the Mantel test demonstrated that plant yield and bioaccumulation and transportation of trace elements were more closely correlated with the stoichiometry of trace elements than their content. The significantly different stoichiometry of trace elements in soil of different yields revealed that the stoichiometry of trace elements was more sensitive and reliable in reflecting the balance in soil nutrients of C. oleifera and regulating its growth. This study provides a comprehensive understanding of the balance in soil trace elements and their relationship with the growth of C. oleifera and highlights the critical role of the stoichiometry of soil trace elements in promoting high and stable production of C. Oleifera.

Camellia oleifera is a high quality woody oilseed crop that produces a low yield in the central subtropics of China. Although fertilization can efficiently increase C. oleifera yield in these areas, the influences of fertilization continuously on soil microbiota and soil fertility remain poorly understood. The purpose of this study was to determine the influences of the type and amount of fertilizer on the soil properties of C. oleifera. Here, we compared the effects of organic fertilizer, organic–inorganic compost, no fertilizer control, and low (F1), medium (F2), and high (F3) amounts of continuously applied organic–inorganic compost at the sapling stage All chemical indicators and copiotropic bacteria measured were significantly lower in organic fertilizer and without fertilizer. Successive fertilization over two years with organic-inorganic compost significantly altered the relative abundance of the dominant bacterial groups at the phylum levels. the abundance of these phyla was the same in F2 and F3 treatments which was higher than their abundance in the other treatments. The relative abundance of kopiotrophic bacteria, especially proteobacteria and gemmatimonadetes, increased significantly and similarly with F2 and F3 treatments. With successive fertilizations, the levels of total nitrogen (TN), total phosphorus (TP) and organic matter (OM) were the vital factors affecting bacterial communities, which was confirmed by structural equation models, redundant analyzes and random forest models. These results suggest that the continuous application of moderate amounts of organic-inorganic compost is the main driver for the improvement of soil bacterial communities, and this was mainly achieved by altering the levels of OM, TN and TP, thus affecting the copiotropic bacterial abundance. This study provides a scientific basis for optimal fertilization of C. oleifera forest.