Phosphorus-mineralizing Communities Reflect Nutrient-Rich Characteristics in Japanese Arable Andisols

Elucidating the soil phosphorus cycle driven by soil microbes is a vital question in soil microbial ecology. The Japanese arable Andisols, occupying half of the Japanese cropland, are known for their high phosphorus sorption capacity. However, limited information is currently available on microbially driven phosphorus mineralization in arable Andisols. We herein report that the phosphorus-mineralizing community in the Japanese arable Andisols showed characteristic distribution and composition patterns, from those in other types of soils. We performed a chemical analysis and microbial community analysis of 43 arable Andisols along the Japanese archipelago. Soil phosphomonoesterase activities measured at pH 11 were approximately 70% of those at pH 6.5, which indicates that alkaline phosphatase contributes to phosphorus cycling, although most soil samples were acidic. Functional gene predictions based on 16S rRNA gene sequencing indicated that the alkaline phosphatase gene phoD was more abundant than other alkaline phosphatase genes and, thus, plays major roles. Hence, amplicon sequencing targeting phoD was performed and the results obtained showed that alphaproteobacterial phoD was dominant. This is in contrast to previously reported phoD compositions in other soils and may be attributed to the nutrient conditions in arable Andisols, which favor copiotrophic Alphaproteobacteria. Furthermore, the composition of phoD correlated with soil pH and bioavailable phosphorus concentrations rather than carbon or nitrogen concentrations. These results were partly different from previous findings, varying in the soil types and geographic ranges of sampling sites. Collectively, the present results indicate that the phosphorus-mineralizing community in the Japanese arable Andisols is regulated differently from those in other soil types.