Phosphorus fixation in alkaline calcareous soils severely limits crop productivity. Bacterial inoculants containing plant growth-promoting bacteria aim to improve soil quality and crop yield, but the precise mechanism influencing rhizosphere phosphorus availability remains unclear. 

A research team led by Prof. WANG Ruoyu from the Northwest Institute of Eco-Environment and Resources of the Chinese Academy of Sciences discovered that a high-concentration, low-cost, and sustained-release solid granular bacterial inoculant (GBI) significantly increased available phosphorus (AP) levels, resulting in improved maize growth. 

The study was published in Science of the Total Environment on Dec. 16.  

The researchers showed that GBI alters the rhizosphere microbiome and increases soil AP by altering the abundance of other beneficial bacteria and fungi. 

The recruited strains act as cooperative partners with bacterial inoculants, helping to improve soil AP and promote maize growth. 

In addition, the application of GBI significantly increased AP content, phoD gene abundance, and alkaline phosphatase activity in macroaggregates.  

GBI also affected soil aggregate composition, resulting in substantial changes in fungal and bacterial community composition.  

In the rhizosphere soil of GBI-treated plants, key microbial groups associated with phosphorus cycling, such as Saccharimonadales and Mortierella, were enriched. 

Furthermore, the study provides valuable and timely insight into the mechanism by which P availability in alkaline calcareous soils is increased by a high-concentration, cost-effective, and slow-release GBI. 

"The use of GBI as an alternative to chemical fertilizers to alleviate soil P limitation has the potential to contribute positively to the development of sustainable agriculture on alkaline calcareous soils," said Prof. WANG. 

Contact:    

WANG Ruoyu 

E-mail: wangruoyu@lzb.ac.cn