Study on the ammonia volatilization from paddy field in irrigation area of the Yellow River

The batch-type airflow enclosure method was adopted to measure the ammonia volatilization (AV) from paddy field under different fertilization rates in irrigation area of the Yellow River .The results indicated that，total amount of AV loss generally increased with the urea application rate in paddy field. During the whole rice growing season，AV loss varied from N 27.6 to 94.1 kg /ha，which accounted for 16.4%22.2% of applied N. The AV lasted for 10 days and the peak of AV occurred 23 days after fertilization. Most of the AV loss occurred at the tillering dressing stage，which accounted for 27.1%37.0% of the total AV loss throughout the rice growing season. The AV in irrigation area of the Yellow River was affected mainly by temperature，light and pH value. The AV loss has a significant positive linear relationship with the ammonium concentrations in surface water of paddy field. Compared with the local fertilizer application (N300)，optimizing N application (N240) and N fertilizer application amended with organic manure (N240-1/2OM) could obviously reduce the AV loss from the field，meanwhile, get a desirable yield. Based on our experiment, the optimum fertilization formula for the paddy field in irrigation area of the Yellow River is N240 and N240-1/2OM.