Effects Of Different Measures Of Reducing Fertilizer On Growth Of Pakchoi And Soil Properties In Continuous Cropping Facilities

The excessive application of fertilizer in facility vegetables has caused a series of problems in the protected soil.For example,soil acidification,secondary salinization,etc.Reducing the input of fertilizers and finding other ways to replace or reduce fertilizers has become a hot point in sustainable agriculture.In this study,more than 5 years greenhouse was selected for single experiment,and 7 treatments were set up,including 2 controls(blank control and conventional fertilization control),1 only reducing fertilizer measure,and 4 measures to replace fertilizer:soil mulching with solarization,foliar fertilizer,double organic fertilizer,bio-organic fertilizer.We evaluated these measures from four aspects(soil physical and chemical properties,soil enzyme activity,soil microorganism and yield and qualities of pakchoi).Integration test setup 7 treatments:blank control,conventional fertilization control,soil mulching with solarization+bio-organic fertilizer,soil mulching with solarization+double organic fertilizer,soil mulching with solarization+double organic fertilizer+foliar fertilizer,soil mulching with solarization+bio-organic fertilizer+foliar fertilizer,soil mulching with solarization+ foliar fertilizer.The above is for screening the efficent measures of reducing fertilizer for facility vegetables.The mian results of study are as follows:First,in this study,the yield and qualities of pakchoi(nitrate content,Vc,soluble sugar and protein)were analyzed.The results showed that soil muiching with solarization significantly increased the yield of pakchoi and decreased the nitrate nitrogen content of pakchoi;Foliar fertilizer can significantly increased Vc content.Double organic fertilizer increased the soluble sugar and protein content of pakchoi.Bio-organic fertilizer also reduced the nitrate content and increased the Vc and soluble sugar content of pakchoi.Second,in order to study the effects of different measures on soil physical and chemical properties,this study analyzed soil nitrate nitrogen,ammonium nitrogen,available phosphorus,available potassium,pH,EC and the composition of soil water soluble salt ions.The results showed that soil nitrate nitrogen was accumulated heavily,accounting for the main part of water-soluble salt ions,and becomes the most main ion caused salinization;The content of available phosphorus and available potassium is high,and soil nutritionalization is obvious;The soil EC value far exceeds the critical value of vegetable growth;the conventional fertilization method significantly reduces the pH of the soil.The application of reducing fertilizer measures has different effects on the soil physical and chemical properties.The treatment of soil mulching with solarization significantly reduced soil nitrate nitrogen content and soil EC value and water soluble salt ion content.Bio-organic fertilizer significantly increased the soil ammonium nitrogen content.Double organic fertilizer significantly increased the soil available potassium content.Third,this study analyzed soil urease,acid phosphatase,catalase,sucrase and the bacterial diversity of rhizospheric soil of pakchoi.The results showed that fertilization reduced soil urease,catalase and sucrase activities.Among treatments,the urease activity was the lowest in the soil muiching with solarization.Except for the soil muiching with solarization,the urease activity of foliar fertilizer and conventional fertilization decreased obviously.Catalase and sucrase activities have the lowest activity in Conventional fertilization and foliar fertilizer.Double organic fertilizer and bio-organic fertilizer can improved soil urease,catalase and sucrase activities by reducing the negetive effect of fertilization on these three enzymes activities;Phosphate fertilizer can increases the activity of acid phosphatase,and acid phosphatase activity of conventional fertilization is the highest.For the bacterial diversity of rhizospheric soil of pakchoi.Fertilization had a great influence on the composition and structure of soil bacterial community.No fertilization,soil muiching with solarization and double organic fertilizer was benifits to the growth of bacteria at lower taxa levels;The effects of soil muiching with solarization,conventional fertilization and bio-organic fertilizer are more significant than other treatments on the bacterial community structure of rhizospheric soil;Double organic fertilizer and bio-organic fertilizer increased the bacterial diversity and uniformity compared to the treatment of reducing fertilizer alone.Finally,this study conducted a combanition of several reducing fertilizer measures.The result showed,the treatment of soil mulching with solarization+double organic fertilizer+foliar fertilizer significantly increased the yield of pakchoi.The difference in yield between soil mulching with solarization+foliar fertilizer,soil mulching with solarization+double organic fertilizer and soil mulching with solarization+bio-organic fertilizer is not significant;All combined treatments reduced the nitrate content of pakchoi compared with conventional fertilization and the treatment of soil mulching with solarization+double organic fertilizer+foliar fertilizer was best.Soil mulching with solarization+foliar fertilizer,soil mulching with solarization+double organic fertilizer+foliar fertilizer,soil mulching with solarization+bio-organic fertilizer+foliar fertilizer,both significantly promoted the soluble sugar of pakchoi,soil mulching with solarization+double organic fertilizer+foliar fertilizer also promoted the Vc of pakchoi.Considering all the indicators comprehensively,soil mulching with solarization+double organic fertilizer+foliar fertilizer integrated measures is the best.