The red soils in southern China are generally classified as phosphorus-deficient, and therefore planting crops in these regions usually requires high applications of phosphate fertilizer. However, the effect of phosphorus addition on N2O emissions in rice-rapeseed rotation soils is not clear. We carried out an incubation experiment with the rice-rapeseed rotation soil from Qianjiang and Xianning to explore the effect of different concentrations of phosphorus (0, 15, and 30 mg·kg-1) and different concentrations of nitrogen (0 and 100 mg·kg-1) on N2O emission. Studies have shown that the addition of phosphorus has a significant effect on soil N2O emissions, but the pathways of impact are varied:in the case of low nitrogen soil, the addition of phosphorus promotes the fixation of nitrogen in the soil by microorganisms and thus reduces N2O emissions; in case of sufficient nitrogen content in soil, adding less phosphorus promotes the activity of nitrifies and thereby promotes the emission of N2O, while adding more phosphorus also promotes fixation by microorganisms in the soil; when there is a high content of available phosphorus in the soil, whether the nitrogen is sufficient or not, the addition of phosphorus will inhibit the emission of N2O.
Keywords: N2O; nitrification; nitrification rate; phosphorus; rice-rapeseed rotation soil.