Molecular Soil Biology 2025, Vol.16, No.5, 255-264 http://bioscipublisher.com/index.php/msb 256 2 Soil pH and Nutrient Dynamics 2.1 Macronutrient availability: N, P, K responses to acidic vs. neutral soils The pH of the soil can affect the utilization rate of major elements such as nitrogen (N), phosphorus (P), and potassium (K) in the rhizosphere of the bayberry. Studies have found that the more acidic the soil is, the more difficult these elements are to be absorbed, and the growth and fruit quality of bayberries will deteriorate (Li et al., 2022). In soils with strong acidity, the relationship between N, P, K and some metal elements (such As Cu, Cr, Ni, As, Cd) will change, thereby affecting the nutrient absorption of bayberries (Hong et al., 2023). In addition, the influence of soil pH on microbial communities can also indirectly change the availability of nutrients (Ren et al., 2021; 2022). 2.2 Micronutrient balance: Iron, manganese, aluminum toxicity at low pH In acidic soil, the solubility of iron (Fe) and manganese (Mn) increases, making it easy for plants to absorb excessive amounts, resulting in toxicity (Che et al., 2022). Especially when the pH is lower than 5.0, a large amount of aluminum (Al3+) is released, which will directly hinder the growth of the root system of the bayberry and also reduce the microbial diversity in the rhizosphere, thereby causing atrophy disease. Aluminum toxicity not only harms root tissues, but also interferes with the absorption of nutrients such as Ca, Mg, and P, ultimately affecting the health and yield of plants (Li et al., 2022). 2.3 Soil amendments and buffering capacity To alleviate acidification and nutrient imbalance, people often use some soil conditioners, such as biochar, organic fertilizer and lime. Studies have shown that biochar and humic acid can increase soil pH, enhance organic matter and available nutrients such as N, P, K, Ca, and Mg, and also improve microbial diversity and metabolic activity (Ren et al., 2021; 2022; 2023). Alkaline conditioners such as lime and calcium magnesium phosphate fertilizer can enhance the buffering capacity of the soil, reduce aluminium toxicity, and help maintain nutrient balance (Li et al., 2022). However, different conditioners have different effects and should be selected based on soil conditions and the growth requirements of bayberries (Ng et al., 2022; Arwenyo et al., 2023). 2.4 Interaction with soil microbial community and rhizosphere processes Soil pH can also alter the nutrient cycling in the rhizosphere of the bayberry by influencing the microbial community. In acidified soil, the diversity of bacteria and fungi will decline, and the community structure becomes complex but unstable, which will affect the decomposition of organic matter and nutrient transformation (Hong et al., 2023). Conditioning agents such as biochar and organic fertilizers can promote the growth of beneficial microorganisms (such as Mycobacterium, Fusarium, etc.), enhance the metabolic activity of the rhizoum, and make bayberries more adaptable to adverse conditions (Ren et al., 2021; 2022; 2023). In addition, associated plants, such as ryegrass, can also enhance the quality of bayberry fruits by improving the soil environment and microbial structure (Li et al., 2023). 3 Physiological and Morphological Responses 3.1 Root growth and architecture under varying pH The pH of the soil will directly affect the root system of the bayberry. When the soil is too acidic (with a low pH), the growth of the root system will be suppressed, the types of microorganisms in the rhizosphere will decrease, and the ability of the root system to absorb water and nutrients will also decline. This can easily cause bayberry decay disease (Chen et al., 2022; Hong et al., 2023). In alkaline or saline-alkali soil, if salt-tolerant waxberry is used as the rootstock, the condition of the root system can be significantly improved, making the grafted waxberry grow more normally and the root structure more stable (Saeed et al., 2023). In addition, changes in water pressure and pH often act together, affecting the thickening of the cell walls in the root cortex and the formation of the cork layer. Under drought conditions, the cell walls of the root cortex will be thicker, which helps the root system adapt to adverse conditions (Song et al., 2011).
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