Tree Genetics and Molecular Breeding 2024, Vol.14, No.5, 256-268 http://genbreedpublisher.com/index.php/tgmb 258 to be fine-textured with silt clay, while Indian soils are more coarse with sandy clay loam (Thapa et al., 2022). These soil types are crucial as they influence the availability of nutrients and the overall health of the tea plants. The physical properties of the soil, such as bulk density and porosity, also play a significant role in tea cultivation. In China, tea soils have been found to have higher bulk density and lower total porosity compared to Indian soils, which can affect root penetration and water retention (Thapa et al., 2022). Additionally, volcanic ash soils, like those in southern Kyushu, Japan, are known for their unique properties that enhance moisture retention and permeability, making them suitable for tea cultivation (Maehara et al., 1965). These soils also benefit from the accumulation of organic residues, which improve the cation exchange capacity and nutrient availability. 3.2 pH and nutrient availability The pH of the soil is a critical factor in tea cultivation, as it directly affects nutrient availability and plant health. Tea plants prefer acidic soils, with an optimal pH range of 4.5 to 5.5, which supports their unique nutrient uptake mechanisms (Yan et al., 2020; Ding et al., 2021). In China, a significant portion of tea-growing soils have been found to be too acidic, with pH levels below 4.5, which can hinder growth unless managed properly (Yan et al., 2020). The acidity of the soil is often exacerbated by the use of chemical fertilizers, which can lead to further soil degradation. Nutrient availability in tea soils is influenced by the soil's chemical properties, including the presence of essential elements like nitrogen (N), phosphorus (P), and potassium (K). Studies in India have shown that tea soils are generally rich in plant-available potassium, which is crucial for tea yield (Karak et al., 2015). However, the availability of other nutrients can vary significantly, necessitating balanced fertilization practices to maintain soil fertility and support sustainable tea production (Karak et al., 2015; Malakar et al., 2022). The use of organic fertilizers has been shown to improve soil pH and enhance the availability of nutrients, thereby supporting better tea growth (Li et al., 2022). 3.3 Organic matter content and soil structure Organic matter content is vital for maintaining soil structure and fertility in tea plantations. The presence of organic matter enhances the soil's ability to retain moisture and nutrients, which are essential for the growth of tea plants. In regions like Southwest China, long-term tea cultivation has been shown to increase the content of soil organic carbon (SOC) and humic substances, which improve the quality of soil humus and enhance nutrient cycling (He et al., 2021). This increase in organic matter is beneficial for maintaining the structure and fertility of tea plantation soils. The structure of the soil is also influenced by the accumulation of organic residues, which can improve the cation exchange capacity and nutrient availability. In volcanic ash soils, for example, the accumulation of organic matter in the surface layer has been observed, which contributes to better soil structure and fertility (Maehara et al., 1965). The integration of organic and inorganic fertilizers can further enhance soil organo-mineral associations, supporting the sequestration of soil organic matter and improving soil fertility (Li et al., 2022). These practices are crucial for sustaining the productivity and health of tea plantations over the long term. 3.4 Role of microbial communities in soil health Microbial communities play a crucial role in maintaining soil health and fertility in tea plantations. These communities are involved in the decomposition of organic matter, nutrient cycling, and the suppression of soil-borne diseases. The presence of diverse microbial populations can enhance the availability of nutrients like nitrogen and phosphorus, which are essential for tea plant growth (Ruan et al., 2023). In degraded soils, the selection of tea plant varieties with high nutrient efficiency can influence microbial activity and improve soil health by reducing nutrient heterogeneity and soil acidification (Figure 1). The interaction between microbial communities and soil organic matter is also significant in enhancing soil fertility. Organic fertilization practices have been shown to support microbial activity, leading to improved soil structure and nutrient availability (Li et al., 2022). These practices can increase the concentration of beneficial soil
RkJQdWJsaXNoZXIy MjQ4ODYzMg==