Effects Of Different Fertilizer Treatments On Nitrogen Loss From Paddy Fields

Paddy field is an important type of cultivated land in China.The traditional fertilization method used in rice production has a low nitrogen utilization rate.Nitrogen easily enters the surface and groundwater with runoff and leaching water,resulting in serious agricultural non-point source pollution.In view of a large amount of nitrogen loss in paddy fields and the high risk of water pollution in China,the treatments consisted of control（CK）,conventional chemical fertilizer（CT）,50%organic fertilizer+50%chemical fertilizer（BS）,and carbon-based fertilizer（CB）were performed to study the effects of different fertilizer treatments on rice yield and nitrogen loss.The following results were the main results of this study were as follows:（1）BS and CB treatments on reducing nitrogen runoff loss in paddy fields had significant effects（p<0.05）.The total loss of ammonium nitrogen decreased in the following order:CT>BS>CB>CK;the total loss of nitrate decreases in the following order:CT>CB>BS>CK.Ammonium nitrogen was the main form of nitrogen runoff loss.The risk of nitrogen runoff loss of BS was greater in the early stage,whereas the risk of nitrogen runoff loss of CT and BS was greater in the mid-term.（2）The effects of BS and CB on reducing nitrogen leaching loss in paddy fields was limited.Hydrus-1D model was used to simulate the leaching water in paddy field,and the amounts of nitrogen leaching loss were calculated.The total amount of ammonium nitrogen leaching loss decreases in the following order:BS>CB>CT>CK,and the nitrate leaching loss ranged from 0.14 to 0.17 kghm^-2.and there was no significant difference among the different treatments for the leaching loss of ammonium nitrogen and nitrate.The concentrations of ammonium nitrogen in the leaching water at different depths for each treatment increased first and then decreased,and the concentrations of nitrate decreased first,then increased and then decreased.（3）The total runoff loss of inorganic nitrogen loss in the CT,BS,and CB treatments accounted for 5.3-8.3%of the nitrogen application,and the total amount of leaching losses accounted for 0.21-0.27%of the nitrogen application,which indicating that runoff loss was the main form of nitrogen loss.The treatments of CT,BS,and CB increased rice yields by 18.34,28.40,and 24.85%（p<0.05）,respectively,compared with no nitrogen treatment（CK）.However,there was no significant differences among them（p>0.05）.