Methane and nitrous oxide emission from paddy field under different fertilization treatments

The effects of various long-term fertilization treatments(NPKS, CK, NPK and NKM) on CH₄ and N₂O emission from rice fields were observed by using the static chamber-GC theory with manual method. The seasonal variations of CH₄ and N₂O emission is disparate, a negative correlation of CH₄ flux with N₂O flux was perceivable. The mixture of organic fertilizer with nitrogenous fertilizer would lead large CH₄ flux, while there was only a few CH₄ emission from the treatment with only chemical fertilizer and CK. The NPKS treatment has the largest CH₄ emission: 526.68 kg/hm² in early rice and 1072.92 kg/hm² in late rice. The effects of different fertilizers on N₂O emission from early and late rice were dissimilar. The maximum of the N₂O emission occurs in the NPK from early rice(no significance of difference), but it is NPKS from late rice(p<0.01). NPK treatment has the largest N₂O emission from early rice: 1.48 kg/hm², the NPKS also has the largest N₂O emission from late rice: 1.40 kg/hm². Correlation analysis demonstrated that CH₄ flux was significantly correlated with soil temperature in 10 cm depth and soil pH value during late rice period(p<0.01), the exponential relationship between CH₄ emission and them was also detected. There are many factors which affect CH₄ and N₂O emission from rice fields, the fertilization is one of the most important factors. The GWP of CH₄ from rice fields is much larger than N₂O, the NPKS treatment has the largest GWP among all the treatments, but the NPK has the least.