Pathways of N2O emission from rice paddy soil

The pathways of nitrous oxide (N2O) emission from a paddy soil were investigated in a pot experiment. The results indicate that the main pathway of N2O emission from rice–soil system depends on the soil water status. When the soil was flooded, the emission was predominantly (87.3% on average) through the rice plants, while in the absence of floodwater, N2O was emitted mainly through the soil surface, with only 17.5% on the average released through the plants. Cutting the rice stems below water surface immediately decreased the N2O flux to 55.8% of that before cutting, while the N2O flux from the pots with intact plants did not change. Two days after the cutting, the average N2O flux from the cut pots was 51.1% of that from the intact pots. During the absence of floodwater, cutting the rice stems did not significantly affect the N2O flux compared with that from the pots with intact plants.