The Study On Loss Of Nitrogen And Phosphorous From Paddy Field And Construction Of Ecological Ditch

The problem of exacerbating agricultural nonpoint source pollution is a serious cause for nitrogen(N)and phosphorus(P)losses of paddy fields in the suburbs of Shanghai,by building monitoring field for N and P losses and ecological blocking system,respectively to research the use of different fertilization means,ecological ditches and paddy fields of the two different technical means to control N and P losses,to decrease loss problems of nitrogen and phosphorus in the paddies,to reduce the exacerbation of the water,to decrease the load of the enclosing environment.The main research results are as follows:(1)The variation of nitrogen and phosphorus concentrations in paddy field surface water was closely related to the amount of fertilizer application and the type of fertilizer in different fertilization treatments.The results of monitoring the field test showed that the nitrogen in the paddy field was the most likely to be caused by conventional fertilization treatment(CT).In different fertilization treatments,the total nitrogen loss(runoff loss,leakage loss)of conventional treatment in the standard test field was the highest in the same period,and it could reach 37.33kg/hm2.Compared with the conventional treatment,the majorization treatment(MT)can reduce the total loss of 19.31% of the nitrogen element,while the organic fertilizer treatment(OT)can reduce the total loss of 32.15% of the total nitrogen loss load.Organic fertilizer treatment(OT)of the most likely to cause a large amount of phosphorus in rice fields with the loss of water.In different fertilization treatments,the total phosphorus loss(runoff loss,leakage loss)of organic fertilizer treatment was the highest,and it could reach 5.45kg/hm2.Compared with the organic fertilizer treatment,the majorization treatment(MT)could reduce the total loss of phosphorus by 16.51%,while organic fertilizer treatment(OT)could reduce the total loss of phosphorus by 31.92%.The experimental results of standardized monitoring field show that the loss of runoff from paddy field is an important way for the loss of Inada and phosphorus,and the key factor to reduce the loss of N and P.(2)The experimental results show that the ammonia volatilization from rice field is closely related with the type of fertilization from rice field.Compared with the conventional treatment,the majorization treatment(MT)can reduce the total loss of 19.35% of ammonia volatilization loss,while the organic fertilizer treatment(OT)can reduce the total loss of 16.29% of ammonia volatilization loss,which is used to measure the ammonia volatilization from rice field.The total loss amount of ammonia volatilization from majorization fertilization treatment(MT)and organic fertilizer treatment(OT)was similar,but in the time of loss,it had significant difference.In the base fertilization period,ammonia volatilization of organic fertilizer treatment(OT)is about two times of the majorization fertilization treatment(MT).(3)In order to explore different types of ditch interception effect and mechanism of nitrogen and phosphorus in drainage from farmland,experiment on 3 types of ditch(ecological intercepting ditch?soil ditch ?concrete ditch)had been designed.The results showed that the ecological intercepting ditch can significantly reduce the content of nitrogen and phosphorus in runoff water,the declined ratio of nitrogen and phosphorus in eco-ditch was 54.18% and 58.21%,which was significantly stronger than soil ditch(31.91%,38.46%)and concrete ditch(11.03%,15.38%).It was found that the effectiveness of the eco-ditch removing nitrogen and phosphorus from drainage was mainly through plant absorption and the sediment adsorption.etc.In general,the ecological intercepting ditch has better purification effect on nitrogen and phosphorus pollution,which can reduce the pollution load of surrounding environment for receiving farmland runoff water.