Recently, the Innovation Team of Fertilizer and Fertilization Technology of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS), uncovered the microbial mechanism of how Chinese milk vetch combined with phosphate-solubilizing bacteria promotes soil phosphorus turnover. The related findings were published under the title "Planting Chinese milk vetch with phosphate-solubilizing bacteria inoculation enhances phosphorus turnover by altering the structure of the phoD-harboring bacteria community" in the international journal "European Journal of Soil Biology."

Phosphate-solubilizing bacteria are commonly used as biofertilizers to improve phosphorus utilization efficiency, while planting Chinese milk vetch can enhance phosphorus turnover and utilization in red soil. The root exudates of Chinese milk vetch affect the growth of phosphate-solubilizing bacteria, whose metabolic byproducts influence the reproduction of microorganisms involved in phosphorus cycling. Inoculating phosphate-solubilizing bacteria when planting Chinese milk vetch can activate insoluble phosphorus in red soil, reduce phosphate fertilizer usage, increase phosphorus supply in the Chinese milk vetch-rice rotation system, and achieve phosphorus reduction and efficiency enhancement. The effects and mechanisms of Chinese milk vetch combined with phosphate-solubilizing bacteria in activating insoluble phosphorus are worth exploring.

The study found that planting Chinese milk vetch with inoculating phosphate-solubilizing bacteria increased the soil active phosphorus content while reducing moderate and stable phosphorus content. Compared to non-inoculated , the average soil active phosphorus pool content increased by 9.2%, while the average content of moderate active and stable phosphorus pools decreased by 6.9% and 5.4%, respectively. On one hand, the combination increased the content of small molecular organic acids and phosphatase activity, activating insoluble inorganic phosphorus and organic phosphorus. On the other hand, the combination increased the relative abundance of alkaline phosphatase gene microbes, altering their community structure, promoting the mineralization of insoluble organic phosphorus. Planting Chinese milk vetch with phosphate-solubilizing bacteria inoculation can serve as an effective measure to improve phosphorus utilization efficiency in red soil and increase phosphorus supply for subsequent rice crops.

Figure 5: Mechanism of increased soil phosphorus turnover by planting Chinese milk vetch with phosphate-solubilizing bacteria inoculation

The first authors of the paper are Assistant Researcher Chang Danna from IARRP, and Master's graduate Song Yarong from Lanzhou University. Researcher Cao Weidong from IARRP, is the corresponding author. The research was supported by the National Key Laboratory for Efficient Utilization of Farmland in Northern Arid and Semi-Arid Areas, the 14th Five-Year National Key Research and Development Program (2021YFD1700200), and the National Green Manure Industry Technology System (CARS-22).

[Citation]:

Chang, D., Song, R., Liang, H., Liu, R., Cai, C., Lv, S., Liao, Y., Nie, J; Duan, T; Cao, W*. 2024. Planting Chinese milk vetch with phosphate-solubilizing bacteria inoculation enhances phosphorus turnover by altering the structure of the phoD-harboring bacteria community. European Journal of Soil Biology, 123: 103678.

Original Paper Link: https://doi.org/10.1016/j.ejsobi.2024.103678