Effects Of Different Conditioners On Greenhouse Gases And Soil Physicochemical Properties Of Vegetable Fields

Nitrous oxide(N2O),carbon dioxide(CO2)and methane(CH4)are three important greenhouse gases.Environmental problems caused by high nitrogen application and irrigation are more and more prominent.To explore the characteristics of soil greenhouse gas emissions and emission reduction measures has become the demand of agricultural sustainable development.Rape and lettuce were taken as research objects.There were six treatments: control(CK),nitrogen(N),dicyandiamide with nitrogen(ND),biochar with nitrogen(NB),wood vinegar with nitrogen(NM)and bacterial fertilizer with nitrogen(NBi).Static chamber gas chromatography was used to collect N2 O,CO2and CH4 in situ.The effects of four conditioners on greenhouse gas emission characteristics,soil physical and chemical properties and vegetable nutrient content were determined.The main results are as follows:(1)Compared with CK,fertilization significantly increased N2 O and CO2 emissions and global warming potential(GWP)of vegetable soil.Compared with N,ND could significantly reduce the N2 O emission of two crops of vegetables caused by nitrogen fertilizer application by 11.6% and 58.5%.Compared with N,ND decreased N2 O emission coefficient by 10% and 64.3% during the growth period of two crops of vegetables.Compared with N,the cumulative emission of N2 O increased by 31.9% in rape and decreased by 7.3% in lettuce.NB could reduce CH4 cumulative emissions by 50% and 38% compared with N.Compared with N,NB increased CO2 emission by 49% and 5.1% in two crops of vegetables,respectively.GWP caused by N2 O emission was dominant in two crops of vegetables.ND could reduce the GWP and GHGI caused by nitrogen application in lettuce.Compared with N,NB had no significant effect on GWP and GHGI.The N2 O cumulative emission fluxes of NM and NBi were higher than N in two crops of vegetables,and had no significant effect on CO2 and CH4.(2)Compared with N,ND significantly increased soil ammonium nitrogen content and decreased soil nitrate nitrogen content.Compared with N,NB could significantly increased the content of total N and alkali hydrolyzed N in soil.The content of soil organic matter increased with the increase of biochar.There was no significant effect on p H,K content and P content of two crops of vegetable soil.(3)Compared with N,ND increased the nitrogen use efficiency by 4.9% and 5.9% in rape and lettuce,respectively.Fertilization significantly increased the yield of two crop vegetables by 58.18% and36.06%.The contents of total nitrogen and total potassium were also increased.Compared with N,ND and NB significantly increased the total nitrogen content of vegetables in lettuce.There was no significant difference in vegetable yield among the four conditioners.In conclusion,dicyandiamide can reduce the GWP significantly caused by N2 O emissions and improve the fertilizer utilization.Biochar can reduce GWP of vegetable soil.NM and NBi can increase N2 O emissions,but these had no significant effect on CH4 and CO2.Fertilization can increase vegetable yield and nutrient content significantly.However,there was no significant difference in vegetable yield and nutrient content between the conditioners.In this study,the emission characteristics of greenhouse gases and effects on the physical and chemical properties of vegetable soil and vegetable nutrient content were studied.It can provide theoretical basis for greenhouse gas emission reduction and farmland management optimization.