Chemical Fertilizer Substitution Effect Of The Nitrogen In Environment And Its Ecological Environmental Impact Study

Agricultural non-point source pollution has been one of the main causes of water eutrophication in the Tai Lake region.Reusing the nitrogen(N)in the wastewater with the agriculture system is an effective way to reduce the pollution load.In this study,five treatments with three replicates were designed including tap water with normal N fertilizer treatment(SF),eutraphicated river water with reduced N fertilizer treatment(RW),domestic sewage tail water with reduced N fertilizer treatment(DS),biogas slurry with reduced N fertilizer treatment(BS)and tap water without N fertilizer treatment(NF).1)The results showed that all the low pollution water treatments can ensure the rice growth and yield.Only the domestic sewage treatment promoted the aboveground biomass and the yield of rice significantly.In rice field in 2014 and 2015,the plant nitrogen accumulation quantity of biogas slurry treatment was always lower than the normal N fertilizer treatment.However,the domestic sewage treatment was slightly higher than the normal N fertilizer treatment,but there were significant differences between the wastewater treatments and tap water without N fertilizer treatment.Low pollution water irrigation treatments all improved the utilization rate of nitrogen of rice,and the domestic sewage treatment and biogas slurry treatment were significantly higher than the tap water with normal N fertilizer treatment in rice field in 2015.2)The domestic sewage treatment,the eutraphicated river water,and the biogas slurry treatment could keep the soil fertility,and improve the soil alkali-hydrolysable nitrogen content in the two years.In rice field in 2014 and 2015,all the wastewater treatments improved soil microbial biomass carbon and nitrogen,especially the domestic sewage treatment and biogas slurry treatment.Rice season in 2014 and 2015,all the wastewater treatments improved soil microbial metabolic activity,and the ability of the soil microbial community using carbon source was significantly higher than the tap water with normal N fertilizer treatment,especially the domestic sewage treatment and biogas slurry treatment,which significantly changed the amount and type of soil microbial community,significantly improved the soil microbial diversity of carbon source utilization.3)In rice field in 2014,the domestic sewage treatment,the eutraphicated river water,and the biogas slurry treatment,especially the domestic sewage treatment,compared to the tap water with normal N fertilizer treatment,decreased the total nitrogen concentration of surface water in paddy fields before the tillering N fertilization,thus,reduced the runoff loss risk at the early stage of the rice fertility.But the domestic sewage treatment increased after panicle fertilization,might increase the runoff loss risk at the late growth stage.However,in rice field in 2015,the wastewater treatments especially the domestic sewage treatment and the domestic sewage treatment,decreased the total nitrogen concentration of surface water in paddy fields after the tillering N fertilization,and reduced the nutrient loss risk.In rice field in 2014,the total ammonia volatilization loss ranged from 41.58 and 45.45 kg N·hm-2,and the difference between the treatments was not significant.In rice field in 2015,the domestic sewage treatment,the eutraphicated river water,and the biogas slurry treatment all decreased soil ammonia volatilization flux significantly,and the domestic sewage treatment was the best.4)In rice field in 2015,the domestic sewage treatment significantly reduced the paddy fields N2O emission for 20.9%compared with the tap water with normal N fertilizer treatment.While,the eutraphicated river water,and the biogas slurry treatment significantly improved the paddy fields N2O emission.The eutraphicated river water,and the biogas slurry treatment significantly reduced the paddy fields CH4 emission for 57.3%and 55.5%,but the domestic sewage treatment significantly improved the paddy fields CH4 emission.The eutraphicated river water treatment significantly reduced the paddy net greenhouse effect,the domestic sewage treatment significantly increased the paddy net greenhouse effect.5)In this experiment,Soil heavy metal content of all the wastewater treatments after harvesting accorded with national standard GB 15618-1995?Environmental quality standard for soils?limited requirement.Heavy metal concentration of the grain in paddy field of all the wastewater treatments after harvesting accorded with national standard GB 2762-2012?standard of national food safety in food contaminants limited?limited requirement.6)4858-5441 m3·hm-2low polluted water was consumed and 31.4,106.6 and 132.9 kg N hm-2 was reused in the whole rice season from the eutraphicated river water treatment,the domestic sewage treatment,and the biogas slurry treatment irrigation,and 12.83%,44.41%and 55.11%chemical N fertilizer can be reduced,respectively.Comprehensive consideration of yield and environmental benefits,paddy fields irrigation with domestic sewage tail water is promising for maintaining the high yield of rice with less chemical N fertilizer input while reducing the pollution to waterbody caused by the direct discharge of domestic sewage tail water in TaiLake Region.