Soil phosphorus fractions drove nitrous oxide emissions: Based on nitrification inhibitor and phosphate-solubilizing...

Nitrogen and phosphorus are the important factors for improving terrestrial ecosystem productivity, and nitrification inhibitor and phosphate-solubilizing bacterium (PSB) are the sustainable practices to reduce soil nitrous oxide (N₂O) emission while enhancing nitrogen and phosphorus availability, resulting in an environmentally friendly terrestrial ecosystem. However, the effects of combined applications of 3, 4-dimethyl pyrazole phosphate (DMPP) and PSB on N₂O emission reduction and phosphorus fractions transformation, and their correlations in rhizospheric and non-rhizospheric soils are unclear. In this study, soil chemical properties, N₂O emissions and phosphorus fractions, were characterized and analyzed. Although the DMPP inhibited soil N₂O emission rate, this inhibitory effect was gradually weakened by the PSB in rhizospheric and non-rhizospheric soils. Compared to the control, DMPP and PSB increased available phosphorus by 10.09 %-33.25 % in rhizospheric soil, and a significant increase (7.33 %) in available phosphorus was only observed as DMPP application in non-rhizospheric soil at the end of incubation. Additionally, contrary results were detected that accumulation but declination of residual-P in rhizospheric and non-rhizospheric soils, respectively, as combined DMPP and PSB on day 28. Soil pH driven soil N₂O emission rate, which was also positively affected by available phosphorus, water-soluble inorganic phosphorus (H₂O-P), sodium bicarbonate extraction of phosphorus (NaOH-Pi and NaOH-Po). However, positive and negative contributions to the N₂O emission rate were generated by residual-P in rhizospheric and non-rhizospheric soils, respectively. In conclusion, the findings suggested that the PSB accelerated soil phosphorus fractions transformation and improved phosphorus availability but weakened the inhibitory capacity of DMPP on N₂O emissions.