Nitrogen Conversion And Microbial Response Mechanism Of Vineyard Soil Under Water And Fertilizer Regulation

Aiming at the problems of soil environmental quality decline,resource waste and air pollution caused by low nitrogen utilization rate and serious loss in grape production,the present study adopted the experimental methods of field investigation and indoor aerobic incubation.After using 16SrDNA high-throughput sequencing technology to understand the status of soil microorganisms in the vineyard,a monitoring experiment combining the appearance and the microscopic level was further designed.The characteristics of soil nitrogen conversion and loss under different regulation water and fertilizer measures were explored,the internal microbial mechanism was preliminarily discussed,and the appropriate nitrogen regulation methods were selected,which could provide certain theoretical basis for the rational application of nitrogen fertilizer and the resistance control of the nitrogen losses in grape production.The main results are as follows:(1)Long-term fertilization has a great influence on the soil environmental quality of the vineyard.Compared with the traditional method,under the long-term optimal treatment,the available nutrients in the soil of wine vineyard and fresh food vineyard did not decrease significantly.The pH of the soil of wine vineyard increased significantly and the acidification rate decreased.At the same time,the abundance and diversity of the bacterial community in the vineyard soil have increased,and the soils indexes of Chaol,ACE and Shannon in the wine vineyard increased by 18.80%,18.89%,5.01%respectively.Although the indicators of the fresh food vineyard increased,the analysis of the diversity still showed that there was no significant difference in the soil microbial status between the optimization,mobile water with fertilizer and the traditional treatment.(2)Under different water content,different nitrogen regulation measures have different effects on soil transformation.Under the condition of the WHC60%and WHC80%water contents,the NH4+-N content in the vineyard soil after the single application of urea for 14 days was low,and the nitrogen was mainly existed in the form of NO3--N.When formaldehyde urea were applied into the soil,most of nitrogen was in the form of NO3--N,but the content of NH4+-N was low.There was no significant change in the transformation rule of inorganic nitrogen in urea after 15%was replaced by bio-organic fertilizer.The conversion time of NH4+-N to NO3--N in soil was delayed after DMPP was applied with urea,which could be extended for up to 7 days.(3)Under different regulation measures,soil N2O emission characteristics were different,but NH3 volatilization characteristics are basically the same.Under the condition of WHC60%,nitrogen reduction treatments reduced N2O loss by 46.03%,NH3 loss by 26.82%,and gaseous net loss rate by 24.80%compared with traditional nitrogen application.On this basis,the application of other biochemical control measures can further reduce N2O emissions by 10.52%?43.61%,reduce total gaseous loss by 11.99%?47.19%,and nitrogen losses was lower than that of WHC80%water content.(4)The analysis of soil NH3 volatilization amount and urease activity showed that nitrogen application was an important factor affecting soil urease activity,which determined the peak and cumulative emission levels of NH3 in soil.In addition,DMPP increased urease activity 122.63%?146.12%under the condition of high water content.(5)Under the condition of WHC60%,there was no significant relationship between the amount of nitrogen applied and the abundance of AOA-amoA?AOB-amoA,nirS and nirK in the soil.Application of bio-organic fertilizer can reduce the abundance of AOA-amoA and increase the abundance of nirS.Adding DMPP can simultaneously reduce the abundance of AO A-amoA and AOB-amoA by 57.61%and 32.86%,respectively.(6)The abundance of nitrifying bacteria and denitrifying bacteria in vineyard soil significantly affected the N2O emission.Under the influence of both,N2O emission increases significantly.However,the change of soil environmental factors will change the growth conditions of microorganisms,thus determining the weight of nitrification and denitrification.The number of nitrification and denitrification bacteria was low in the critical period of nitrogen conversion due to the flat supply of nitrogen source substrates in the soil.In conclusion,the application of formaldehyde urea(N,450 kg/hm2)in grape planting can simultaneously reduce the emission of N2O and NH3,and ensure the long-term supply of soil Inorganic nitrogen,which is an effective regulation measure to control the loss of nitrogen in the vineyard soil and improve the utilization rate of nitrogen.