[Effect of Phosphorus Addition on N₂O Emissions from Rice-Rapeseed Rotation Soils]

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.