Effects Of Organic Fertilizer Application On NH₃ Volatilization And N₂O,CH₄ Emission From Typical Paddy Fields In The Pearl River Delta

Rice field ecosystems is considered to be a crucial source of ammonia?NH₃?,nitrous oxide?N₂O?and methane?CH₄?.NH₃ can promote the formation of atmospheric haze pollution.CH₄ and N₂O are important greenhouse gases.Compared with chemical fertilizer,organic fertilizer can not only meet the needs of crop nutrients,but also improve the soil,increase the capacity of soil water and fertilizer conservation.However,the effects of organic fertilizer application on the ecological environment,especially on the volatilization of NH₃ and the emission of N₂O and CH₄,are not clear.In this paper,a typical double cropping rice field in the Pearl River Delta of China was used as the research object,and the treatments of equal nitrogen fertilization were set up,including six treatments,namely,stack organic fertilizer?SOF?,fresh organic fertilizer?FOF?,composted organic fertilizer?COF?,composted organic and inorganic fertilizer?COIF?,chemical fertilizer?CF?and no fertilizer?CK?,to investigate the effects of applying organic fertilizer on NH₃ volatilization and N₂O,CH₄ emission of rice field.The main results are as follows:NH₃ volatilization mainly concentrated in two weeks after fertilization,and the peak of NH₃ volatilization appeared in three days after fertilization.Compared with the control without fertilization,the application of organic fertilizer and chemical fertilizer increased NH₃ volatilization in paddy field,and NH₃ volatilization in early rice field was lower than that in late rice field.In terms of reducing NH₃ volatilization in paddy field,composted organic fertilizer has a good application prospect.The N₂O emission level of paddy field is very low.The accumulated N₂O emission of paddy field under different fertilization treatments is negative in the whole year,which shows that the paddy field absorbs the N₂O in the atmosphere,but the absorption is very low.Compared with no fertilizer treatment,organic fertilizer treatment and chemical fertilizer treatment had no significant effect on N₂O emission.CH₄ emission from rice field mainly concentrated in two months after transplanting.Applying fertilizer and organic fertilizer increased CH₄ emission in paddy field.Compared with chemical fertilizer treatment,the cumulative CH₄emissions of fresh organic fertilizer,composted organic fertilizer,stack organic fertilizer,composted organic and inorganic fertilizer increased 156.7%,132.1%,124.8%and 36.6%respectively.The N₂O and CH₄ emissions from rice fields showed tradeoff relationship.Soil water condition is the key factor of N₂O and CH₄ emission in rice field.CH₄ is the main greenhouse gas emitted from rice fields,and the emission is far greater than N₂O.The reduction of CH₄ emissions should be the main way to reduce the greenhouse gas emissions from double cropping rice fields in the Pearl River Delta.On the whole,under the premise of stable yield and yield increase of rice,the composted organic and inorganic fertilizer can better balance the relationship between production benefit and environmental benefit.