Accumulation Characteristics Of Nitrogen And Phosphorus Pollution In Agricultural Facilities In Eastern Facilities

In response to the excessive application of nitrogen and phosphorus fertilizers in the facility agricultural cultivation process,the soil nitrogen and phosphorus accumulation,the physical and chemical properties of the soil deteriorated,and the yield and quality of vegetables decreased.In this study,the soil,irrigation water and groundwater of different planting years in the eastern agricultural facility of Qinghai Province were studied.Through the field investigation,sample collection and indoor test analysis of fertilization in the facility agricultural area,46 soils in the facility agricultural area were studied.The changes of nitrogen and phosphorus in different soil profiles in the sample were analyzed.The spatial and temporal distribution characteristics of nitrogen and phosphorus in the soil of different planting years were analyzed,and the nitrogen was evaluated by analytic hierarchy process,membership function method and natural breakpoint method.The potential pollution risk of phosphorus accumulation on the soil environment in the eastern facility agriculture area,combined with the preliminary investigation of the 19 irrigation water samples in the facility agricultural area and the nitrogen and phosphorus levels in the 21groundwater samples,is important for further guiding the scientific management of nutrient resources in the eastern facility agricultural area.The results of this study are summarized as follows:1.In the eastern facility agricultural area,chemical fertilizer is mainly applied,supplemented by organic fertilizer.The highest input of chemical nitrogen and phosphorus fertilizer is 1489.93kg/hm ² and 1709.06 kg/hm².The average fertilization level of three different types of vegetables?N:P₂O₅:K₂O?was 1:1.51:0.19,the phosphate fertilizer was greater than the nitrogen fertilizer,the potassium fertilizer was seriously insufficient,and the nutrient ratio was not balanced.The soil nitrogen and phosphorus nutrients have a large surplus,and the average surplus is 885.3 kg/hm²and 1231 kg/hm² respectively.The phenomenon of large-scale fertilization by farmers is unreasonable.2.With the increase of planting years,the accumulation of nitrogen and phosphorus in the agricultural soil of the facility is gradually increasing,that is,?3 years<3⁵ years<5¹0years<10¹5 years<15²0 years.The facility agriculture area is continuously planted for 15to 20 years.The cumulative nitrogen and phosphorus accumulations in the 1 meter soil are:nitrate417.55 kg/hm²,ammonium nitrogen 40.98kg/hm²,total nitrogen 19.35t/hm²,quick-acting Phosphorus 659.15kg/hm²,total phosphorus 3.54t/hm²,and the accumulation of nitrogen and phosphorus in the soils of conventionally cultivated fields were:nitrate nitrogen 16.64kg/hm²,ammonium nitrogen 16.63kg/hm²,total nitrogen 7.19t/hm²,available phosphorus 119.10kg/hm²,total phosphorus 3.48t/hm²,respectively,25.10 times,2.46 times,2.69 times,5.53 times,3.54times higher than field soil.In the soil profile,the distribution of nitrogen and phosphorus in the vegetable soil of the facility is hierarchical,and it is distributed from top to bottom along the soil depth from high to low.Soil plough layer?0-20 cm?,the phenomenon of nitrogen and phosphorus accumulation in various forms is strong,and nitrogen and phosphorus in soil are concentrated in0-40 cm soil layer,which can meet the nutrient demand of growth and development of shallow root vegetable crops.In the 80-100 cm soil layer,there is still a large amount of nitrate nitrogen and available phosphorus,and it exceeds the accumulation of the same soil layer in the field soil.3.Combined with AHP and subordinate function to establish a comprehensive system of evaluating the potential risk of contamination of agricultural facilities district of nitrogen and phosphorus,potential contamination risk status was evaluated using the grading evaluation index?IFI?obtained in the agricultural area east of nitrogen and phosphorus facilities The comprehensive potential pollution risk is divided into four levels:no pollution?IFI=0.24⁰.29?,mild potential pollution?IFI=0.30⁰.40?,moderate potential pollution?IFI=0.41⁰.51?,potential potential pollution?IFI=0.52⁰.77?.The results show that the eastern facility agriculture area has been continuously planted for more than 10 years,and the potential risk of soil nitrogen and phosphorus is intensified.The nitrogen and phosphorus accumulation of the agricultural soil in the four regions of the four typical facilities and agricultural areas:Huzhu County,Minhe County and Ping'an District There is a slight potential pollution risk,and there is a moderate potential pollution risk in Ledu District.4.68%of the total sample nitrogen in the irrigation water collected in the facility agricultural area exceeds the national V-class water quality standard,which has exceeded the critical range of agricultural water use.In the groundwater samples,according to the groundwater nitrate nitrogen content of 5¹0 mg/L,but the warning state is the grading standard,33%of the groundwater samples in this study have a warning risk of nitrate nitrogen,the total sample 52%of the groundwater samples have been artificially disturbed.