Pathways of N2O emission from rice paddy soil

The pathways of nitrous oxide (N2O) emission from a paddy soil were investi gated in a pot experiment. The results indicate that the main pathway of N2 O emission from rice-soil system depends on the soil water status. When the soil was flooded, the emission was predominantly (87.3% on average) throug h the rice plants, while in the absence of floodwater, N2O was emitted main ly through the soil surface, with only 17.5% on the average released throug h the plants. Cutting the rice stems below water surface immediately decrea sed the N2O flux to 55.8% of that before cutting, while the N2O flux from t he pots with intact plants did nor 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 significan tly affect the N2O flux compared with that from the pots with intact plants . (C) 2000 Elsevier Science Ltd. All rights reserved.