| Facilities vegetable soil is the use of sheds,shading nets,hotbeds,plastic film and other facilities to form a vegetable field.In this paper,the soil of facility vegetable in three different northern regions of Shanxi Province,Inner Mongolia and Tianjin was selected as the research object.Through sampling,processing,measurement,analysis,the statistical contents of different forms of carbon and nitrogen in the three study areas were calculated and the variation of soil carbon and nitrogen in different regions and the difference of soil carbon and nitrogen between different regions were studied.The correlation analysis between soil physical and chemical parameters and different forms of carbon and nitrogen was done at the same time.The main conclusions are as follows:(1)In Shanxi research area,in open-field soil,the average of ammonia nitrogen,nitrate nitrogen,nitrite nitrogen,organic nitrogen,organic carbon concentrations are12.54mg/kg?4.83mg/kg?6.21mg/kg?0.04%?0.2%;in facility soil,the average of ammonia nitrogen,nitrate nitrogen,nitrite nitrogen,organic nitrogen,organic carbon concentrations are 5.62mg/kg?34.9mg/kg?9.09mg/kg?0.12%?0.66%.As the years of planting increase,ammonia nitrogen and organic nitrogen changed little,nitrate nitrogen and nitrite nitrogen increased,organic carbon decreased;as the depth of planting increases,all Forms of nitrogen and organic carbon content will be reduced.Through the correlation analysis,the content of nitrogen was significantly correlated with p H,available potassium and organic carbon;the content of carbon element was significantly correlated with organic nitrogen,p H and available potassium.Through the path analysis,the nitrate nitrogen was the largest positive contribution to the total organic nitrogen and organic carbon has the largest negative total contribution;the total effect of positive contribution to organic carbon is the largest nitrate nitrogen and the total effect of negative contribution is the largest nitrite nitrogen.Cluster analysis identified the index that had the greatest effect on carbon and nitrogen content as:available phosphorus,ammonia nitrogen(2)In Inner Mongolia research area,the average of ammonia nitrogen,nitrate nitrogen,nitrite nitrogen,organic nitrogen,organic carbon concentrations are17.78mg/kg?19.77mg/kg?22.2mg/kg?0.13%?0.89%;in facility soil,the average of ammonia nitrogen,nitrate nitrogen,nitrite nitrogen,organic nitrogen,organic carbon concentrations are 12.46mg/kg?7.20mg/kg?8.95mg/kg?0.15%?0.37%.As the years of planting increase,various forms of nitrogen increased gradually,while organic carbon increased first and then decreased;as the depth of planting increases,ammonia nitrogen gradually increased,nitrate nitrogen,nitrite nitrogen first increased and then decreased,organic nitrogen first decreased and then increased.Through the correlation analysis,the correlation between nitrogen content and organic carbon was significant;the content of carbon element was significantly correlated with organic nitrogen,nitrite nitrogen,nitrate nitrogen and p H.Through the path analysis,the total effect of positive contribution to organic nitrogen is nitrate nitrogen,the total effect of negative contribution is organic carbon,the total effect of positive contribution to organic carbon is conductivity,and the total effect of negative contribution is p H.Cluster analysis identified the index that had the greatest effect on carbon and nitrogen content as:nitrite nitrogen,organic carbon,ammonia nitrogen,nitrate nitrogen and organic nitrogen.(3)In Tianjin research area,the average of ammonia nitrogen,nitrate nitrogen,nitrite nitrogen,organic nitrogen,organic carbon concentrations are 17.70mg/kg ?8.79mg/kg?9.35mg/kg?0.11%?1.04%;in facility soil,the average of ammonia nitrogen,nitrate nitrogen,nitrite nitrogen,organic nitrogen,organic carbon concentrations are17.54mg/kg ? 6.73mg/kg ? 6.96mg/kg ? 0.08% ? 0.48%.As the years of planting increase,ammonia nitrogen decreased gradually,other forms of nitrogen first decreased and then increased,organic carbon first decreased and then increased and then decreased;as the depth of planting increases,ammonia nitrogen,nitrate nitrogen,organic carbon gradually decreased,nitrite nitrogen,organic nitrogen first decreased and then increased.Through the correlation analysis,the content of nitrogen was significantly correlated with p H,EC available potassium and organic carbon,and the content of carbon was significantly correlated with organic nitrogen,nitrate nitrogen,nitrite nitrogen,EC and available potassium.Through the path analysis,the total effect of positive contribution to organic nitrogen content is organic carbon,and the total effect of negative contribution is EC;the total effect of positive contribution to organic carbon content is nitrite nitrogen,and the total effect of negative contribution is nitrate nitrogen.Cluster analysis identified the index that had the greatest effect on carbon and nitrogen content as organic nitrogen,organic carbon,EC.(4)In the three study areas,the content of carbon and nitrogen is Shanxi Province< Inner Mongolia < Tianjin City,the main factors affecting the change of carbon and nitrogen in Shanxi Province are available potassium,organic carbon,nitrate nitrogen and organic nitrogen The main factors affecting the change of carbon and nitrogen in Inner Mongolia are available potassium,organic carbon,p H,EC and organic nitrogen,and the main factors affecting the change of carbon and nitrogen in Tianjin are p H,EC,nitrate nitrogen,organic carbon,organic nitrogen and nitrite nitrogen.As a result of human intervention,the amount of nitrogen and organic fertilizer used in facility vegetable fields in different areas will lead to great changes in soil carbon and nitrogen.The reasonable carbon and nitrogen content is the guarantee of the yield and quality of vegetables grown in the facility soil.Therefore,it is necessary to plan and supervise the input of carbon and nitrogen in the greenhouse,ensure the low-cost input,high-efficiency output and sustainable development of the facility vegetable plot. |
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