Dynamic change of ammonia volatilization and rice yield during double-rice growing seasons in red paddy soil under different long-term fertilizing systerms

Ammonia volatilization under different long-term fertilizer systems of double rice field was monitored with a continuous airflow enclosure method,and its main affecting factors were investigated,meanwhile,the relationship between ammonia volatilization and rice yield was analyzed.The results showed that there were no significant differences in rice yield between combined inorganic/organic fertilizers at reduced rate(JF)and full rate(OM),and chemical fertilizer(NPK)treatments,all higher in rice yield than phosphorus deficient(NK)treatment.The agronomic nitrogen use efficiency(NUEA)of JF treatment was the highest in both early-and late-rice growing seasons.NUEA in JF treatment were 17.4 and 8.9 kg·kg-1,respectively,which were significantly higher than in NK treatment.The cumulative amounts of ammonia volatilization in OM treatment during the double rice seasons(86.2 kg·hm-2) was the highest,and NK treatment(78.2 kg·hm-2) was the second,which was higher than JF treatment(60.7 kg·hm-2).Ammonia volatilization rate was mainly dependent on NH4+-N concentration in surface water.Because of lower air temperature and rainfull after basal fertilizer application,the rate of ammonia volatilization in early rice after tiller fertilizer application was higher than after basal fertilizer application,while they were no difference in late rice.In conclusion,JF system could maintain a constant higher rice yield,not only with low ammonia volatilization,but also for a high soil organic and N content.