Innovative manure via hyper-thermophilic fermentation coupled with heat-resistant phosphate-solubilizing Bacillus inoculation promotes phosphorus transformation by assembling keystone taxa in the oat rhizosphere

Phosphorus forms and distribution in organic manures vary under different treatment conditions, thereby exerting distinct effects on the soil microbiome and soil phosphorus transformation process. This study examined the effects of a novel manure treated with hyper-thermophilic fermentation combined with Bacillus strain inoculation, compared with raw and composted manure, on the oat rhizosphere microbiome and phosphorus transformation across different soil types in a controlled pot experiment. Our findings demonstrate that hyper-thermophilic fermentation with Bacillus inoculation not only promotes the survival and abundance of the bacterial genus Bacillus but also selectively enriches the hyper-thermophilic bacterial genus Thermobifida in the fermented manure. Notably, the application of hyper-thermophilic fermented manure led to a significant enrichment of keystone species like Bacillus and Thermobifida across both soil types, relative to other manure applications. These genera emerged as key drivers of available phosphorus, phosphatase activity, and differential metabolites in the rhizosphere, exhibiting a synergistic effect on soil phosphorus transformation. Fermented manure exhibited superior performance relative to conventional composted manure, as it increased the phosphorus uptake rate of oats by 35.5% in black soil and 27.9% meadow soil, respectively, over a single growing season. Additionally, among all organic manures, the application of fermented manure significantly enhanced the sequestration of phosphorus from manure in the soils, with 78.0% in black soil and 56.9% in meadow soil. This consequently reduced P loss to 13.6% and 34.4% in the respective soil types.

Phosphate-solubilizing microorganisms (PSMs) are frequently proposed as catalysts for promoting phosphorus recycling; however, their performance is often inefficient or ineffective in the context of a circular bioeconomy within agricultural systems. This study introduces innovative concepts and methodologies by integrating hyper-thermophilic fermentation with heat-resistant phosphate-solubilizing Bacillus inoculation, thereby enhancing the effective phosphorus recovery and utilization from manure waste in sustainable agricultural practices.