Effects Of Different Additives On The Emission Intensity Of N₂O And NH₃ In Facility Vegetable Fields

The ongoing increased concentration of active gaseous nitrogen(N₂O and NH₃)in the atmosphere leads to climate warming,ozone layer destruction and environmental pollution,which is considered as one of the global environmental problems.Because of the characteristics of high nitrogen input,high temperature and high humidity,greenhouse vegetable field has become an important source of active gaseous nitrogen emissions.Nitrification inhibitors can reduce the formation and accumulation of nitrate nitrogen in soil,thus reducing the loss of nitrogen and its impact on the environment;urease inhibitors can inhibit the hydrolysis rate of urea,thus reducing the volatilization and nitrification of ammonium nitrogen;microbial agents can improve soil quality,maintain the balance of rhizosphere microflora and increase crop yield.Therefore,it is of great theoretical and practical significance to comprehensively study the effects of nitrification,urease inhibitors and microbial agents on the active gaseous nitrogen emission,the active gaseous nitrogen emission intensity and vegetable yield in intensive vegetable fields.In this study,the active gaseous nitrogen emission(N₂O and NH₃)emission were monitored in suit in the intensive vegetable fields in Nanjing.The N₂O and NH₃ were stimutaneously measured using the static chamber gas chromatography and ventilation methods,respectively,the vegetable yield was measured during the consectutive two vegetable planting seasons.The effects of nitrification,urease inhibitors and microbial agents on N₂O and NH₃ emission and vegetable yield were explored.Five treatments were set up in the intensive vegetable field experiment: no nitrogen fertilizer(CK),only urea(U),urea combined with nitrification inhibitor(dicyandiamide,UDCD),urea combined with urease inhibitor(Nthiophosphoric triamide,UNBPT)and urea combined with microbial agents(effective micoorganisms,UEM).The main results are as follows:(1)Compared with the treatment without nitrogen fertilizer,the cumulative N₂O emissions were increased by 53.28%(p<0.05)and 82.17% respectively(p<0.05)in the treatments which urea was applied alone and the urea was combined with EM microbial agents (p<0.05),while the N₂O emissions decreased by 26.57%(p<0.05)and 25.00%(p<0.05)respectively,when urea was combined with DCD and NBPT.Compared with the treatment without nitrogen fertilizer,the four treatments with urea fertilizer significantly increased the ammonia volatilization(p<0.05);compared with the treatment with urea fertilizer alone,the treatments with DCD,NBPT and EM microbial agents had no significant effect on the ammonia volatilization.(2)The cumulative emission and emission intensity of soil active gaseous nitrogen were consistent among different treatments.Compared with the treatment without nitrogen fertilizer,the application of urea alone and the combination of urea and EM microbial agents increased gnres and GNRI by 56.86%(p<0.05),85.24%(p<0.05)and4 2.86%(p<0.05)?50.00%(p<0.05)respectively.At the same time,the application of urea combined with DCD and NBPT,respectively,reduced the GNr Es by 23.05% and 24.02% and GNr I by 28.57%(p < 0.05)and 28.57%(p < 0.05)respectively.The results showed that urea combined with DCD or NBPT could alleviate the increase of soil active gaseous nitrogen emission caused by nitrogen application.(3)Combined with the application of urea treatment,urea combined with EM microbial agents could significantly increase the total yield of two crops of vegetables(p<0.05).And the urea combined with DCD and NBPT treatments increased the total yield of two crops of vegetables,however,there was has no significant differences.Compared with urea only treatment,DCD and EM combined with urea significantly increased the agronomic nitrogen use efficiency of protected vegetable field(p<0.05).The results of yield and agronomic use efficiency of nitrogen fertilizer showed that EM combined with urea had good economic benefits for facility vegetables.Compared with urea only treatment,DCD and EM combined with urea significantly increased the agronomic nitrogen use efficiency of protected vegetable field(p<0.05).Overall consideration the yield of vegetable and agronomic use efficiency of nitrogen fertilizer,EM microbial agents combined with urea had good economic benefits for intensive vegetables.Therefore,the application of DCD and NBPT combined with urea can significantly increase the vegetable yield and reduce the active gaseous nitrogen emission intensity in the vegetable field.While the application of EM microbial agents has the best effect of increasing yield,its environmental effects needed to be further evaluated.