Impacts of long-term planting on the microbial community of phosphorus mineralization in citrus orchard soil.

Background: Citrus is one of the most economically significant fruit crops in China, with the largest global planting area and production. However, long-term intensive planting has led to nutrient imbalances and soil-related problems in citrus orchards. Phosphorus (P)-mineralizing microorganisms are crucial for soil P cycling and plant growth. Despite their importance, the impact of long-term citrus planting on these microbial communities of P mineralization and their ecological functions remains poorly understood. This study investigated phosphatase activity, the abundance of P-mineralizing genes and the microbial community structure related to P mineralization in soils from citrus orchards with 5, 15 and 25 years of continuous planting in a typical citrus-producing region of China. We also analyzed the factors that influence changes in microbial composition.

Results: Our results revealed that prolonged citrus planting exacerbated soil acidification and increased P accumulation. The reduced soil pH and enhanced soil P bioavailability negatively impacted the diversity of phoC- and phoD-harboring bacteria, phoD gene abundance and alkaline phosphatase activity. Moreover, we observed an increase in antibiotic-producing bacteria and pathogenic citrus bacteria in the microbial community of P mineralization, particularly in soils with a longer planting year.

Conclusion: This study underscores the detrimental effects of long-term citrus planting on microbial community structure, highlighting the potential risks to soil health and the long-term sustainability of citrus production. These findings provide important insights into how prolonged agricultural practices can disrupt soil microbial dynamics and may inform strategies for mitigating negative impacts in citrus orchards. © 2025 Society of Chemical Industry.