Soil quality is one of the main factors that affect the growth and quality of tea (Camellia sinensis L.) plantations. The formation of the organo-mineral complex is one of the critical factors that influence the evolution of soil fertility. This study used chemical analyses and spectroscopy to study the effects of inorganic and organic fertilizer on the soil nutrients and organo-mineral complex in tea garden soil. SR-FTIR analysis revealed that clay minerals were connected as nuclei with the capacity to bind carbon, and that this interaction was aided by organic fertilization. Specifically, the O-H has the quickest reaction to aliphatic-C, next by Si-O, Fe-O, and Al-O in OM70. The soil pH of organic and inorganic fertilization treatments are obviously lower than the no fertilization (CK) treatment. Furthermore, OM70 and OM100 had notably higher pH values in fertilized soil. Organic fertilization (OM70) treatment significantly increased Soil organic matter (SOM), total nitrogen (TN), available phosphorous, potassium (AP, AK), as well as the concentration of total and exchangeable Ca²⁺ and Mg²⁺ in soils when compared to no fertilization (CK) and inorganic fertilization (NPK). Together, these results can provide the scientific theoretical basis for the study on the understanding of the sequestration of SOM and confirmed the feasibility of organic fertilization in improving soil fertility and supporting organo-mineral interactions, thereby making a contribution to carbon storage in tea plantation ecosystems.

Changes in the organic carbon fraction and mineralization of soil aggregates play an important role in the improvement of soil quality by organic fertilization. Nevertheless, the effects of organic fertilizer application on the organic carbon fraction and mineralization characteristics of soil aggregates are still unclear. This study carried out a 6-year field trial with five different fertilization treatments, namely, no fertilization (CK), chemical fertilization (CF), rapeseed cake (CR), chicken manure (CM), and a combination of chicken manure with biochar (CMB). The distribution, organic carbon density, and carbon mineralization characteristics in soil aggregate fractions were tested. The results showed that CR significantly increased the contents of large soil macroaggregates and enhanced the stability of soil aggregates of all sizes. CM increased the contents of macroaggregates and microaggregates but decreased the stability of the soil aggregates. CR, CM, and CMB increased the content of soil organic carbon and its components in the tea garden, while the contribution rate of organic carbon to large aggregates was the highest under the CR treatment. Organic fertilizer treatments had a positive effect on enhancing soil microbial biomass and carbon and nitrogen contents. The mineralization rate and accumulation of organic carbon in tea garden soil aggregates were increased under organic fertilizer treatments, of which CMB was the most significant. There was a high increase in tea yield and bud density under the CR treatment. In short, the application of organic fertilizers in tea garden soil is helpful to improve soil nutrients and soil fertility; plant- and animal-derived organic fertilizers are recommended for corporate application in agricultural production.