Intercropping Improves Tea Quantity and Quality with Enhanced Soil Nutrients, Soil Enzyme Activity, and Bacterial Community Structure

The tea plant (Camellia sinensis L.) is a beverage crop with significant commercial importance in China. The soil ecological environment in tea plantations, including the soil nutrients and biological community is susceptible to the stress of long-term monoculture. Intercropping in tea gardens is expected to improve soil fertility and benefit the soil microbial community, increasing tea quality and yield. The present study comparably investigated the impact of clover (Trifolium repens L.) or peanut (Arachis hypogaea L.) intercropping on the physical and biotic factors of the tea garden, including soil nutrients, enzymes, and bacterial community by contrasting with the system of tea monoculture. The soil nutrient factors, namely the soil moisture content (MC), pH, organic matter (OM), total nitrogen (TN), total phosphorus (TP), total potassium (TP), and soil peroxidase, acid phosphatase(ACP), and sucrase were significantly increased in the intercropping pattern. The soil bacterial diversity was beneficially increased. The abundance and composition of predominant bacteria were changed dynamically in different stages (D1-D3). Proteobacteria, Acidobacteria, Chloroflexi, Bacteroidota, and Gemmmatimonates were found predominant in different cropping patterns but with a significantly different abundance. Mantel test correlation analysis showed that the dominant differential bacteria matrix is significantly correlated to the matrix of physicochemical factors such as MC, TN, catalase, and urease (p<0.05). The predicted metabolic function analysis showed that carbohydrate metabolism, amino acid metabolism, biosynthesis of other secondary metabolites, and cell growth/death were the main metabolic functional pathways. Further, tea quality and yield in intercropping practices were all promoted in different intercropping stages. The results indicated that these two leguminous plants had compatibility with tea plants and can benefit soil microorganisms and nutritional function hence promoting tea growth. This report provides evidence that leguminous crops are beneficial for the long-term sustainable management and efficient production of tea plantations and are of great potential to raise the incomes of tea farmers and producers.