The ratio of β-1,4-glucosidase activity to phosphomonoesterase activity remains low in phosphorus-fertilized tropical soils: A meta-analysis

The ratio of β-1,4-glucosidase (BG) activity to phosphomonoesterase (PME) activity (BG:PME) in soil is an indicator of microbial phosphorus (P) demand, with lower BG:PME ratios indicating greater P shortages. In this study, I performed a meta-analysis to investigate the impact of P fertilization on the BG:PME ratios of P-poor tropical soils. Linear mixed-effects model analysis demonstrated that the BG:PME ratio was lower in tropical soils than other soils, reflecting higher microbial P demand in P-poor tropical soils compared to those in other regions. P fertilization significantly elevated the BG:PME ratio, indicating microbial P requirement was satisfied to some extent. However, the BG:PME ratios of tropical soils never reached the global average, even under continuous, long-term fertilization, although P fertilization often substantially increased the available P content of tropical soils. This result may indicate that the usage of the BG:PME ratio as an indicator of microbial P demand could overestimate the P shortages in tropical soils. On the other hand, it is also possible that soil available P content, which is often used as an indicator of soil P richness, does not necessarily reflect available P for soil microorganisms. Validating the BG:PME ratio as an indicator of microbial P demand could improve our understanding of microbial P shortage in tropical ecosystems.