Native AMF colonization and microbial enzyme-mediated phosphorus mineralization are decoupled in organically fertilized jambu (Acmella oleracea (L.) R. K. Jansen)

The application of organic fertilizers is a fundamental practice in organic farming. However, its effects on the interaction between colonization by native arbuscular mycorrhizal fungi (AMF; referred to here as those originating from non-isolated field soil inoculum) and microbial enzyme-mediated phosphorus mineralization, two key strategies for plant phosphorus acquisition, are largely unknown in the cultivation of jambu ( Acmella oleracea (L.) R. K. Jansen). Here, using two genetic accessions of jambu (“Yellow Flower” and “Purple Flower”) and three commonly employed organic fertilizers (cattle manure, vermicompost, and poultry litter), we show that the application of these inputs did not affect native AMF colonization (%MC) in “Yellow Flower” plants but reduced it in “Purple Flower” plants - possibly due to differences in mycorrhizal plasticity associated with accession-specific traits. In contrast, organic fertilizers increased acid phosphatase activity (A-PHO), easily extractable glomalin-related soil proteins (EE-GRSP) and plant yield, although the effect size varied by source and plant access. Notably, we found a decoupling between %MC and A-PHO driven by “Yellow Flower” jambu, suggesting a potential functional trade-off between these phosphorus acquisition strategies. Together, our findings indicate that organic fertilizers (especially vermicompost and poultry litter) can enhance soil biological attributes and improve jambu yield, while also providing evidence for a potential decoupling between AMF colonization and microbial enzyme-mediated phosphorus mineralization.