Effects Of Irrigation Methods And Nitrogen-Application Rate On Distribution Of Nitrate Nitrogen And Yield Of Cucumber In Greenhouse

The experiment was conducted in Dawei village's greenhouse of Zhengzhou Xinmi in October 2014-July 2016.In this experiment,cucumber was used as the research object.Though the district test,we set up two kinds of irrigation?drip irrigation DF,border irrigation BF?and three facilities nitrogen treatment?high nitrogen 100%,medium nitrogen 75% and low nitrogen 50%?.Using incomplete combination,we set up a total of4 treatments,respectively as DF100,DF75 and DF50,BF100.The effects of irrigation methods and nitrogen application on the distribution of soil water,the distribution of soil nitrate nitrogen and the growth and yield of cucumber were studied in order to ensure the stability of cucumber and high economic efficiency while reducing the pollution in soil environment.And it provides the theoretical basis for the sustainable development of the vegetable.The main conclusions are as follows:Under the same irrigation and nitrogen application rates,drip irrigation treatment was less than border irrigation in the mass water content at 20-140 cm soil layer,volume content of soil at 0-50 cm soil layer,surface soil water potential and nitrate nitrogen content in the 0-200 cm soil layer.Nitrate-nitrogen accumulation was occurred both drip irrigation and border irrigation in the 40-100 cm soil layer.Through the determination of15 N isotope,Cl^-and NO₃^-,the border irrigation treatment was deeper and more severe than the drip irrigation treatment.With the loss of water,the fertilizer is also leached.Drip irrigation has a small and multiple of characteristics,which can stabilize the distribution of soil moisture and reduce nitrate residue.As compared with border irrigation treatment,the drip irrigation treatment was bolder at coarse,greater the number of green leaves and better growth,so that the yield was increased by 8.7%-14%,the economic benefit increased 5.7%-13.9%,the water use efficiency increased 14.2%-19.5%.Therefore,the fruit quality of drip irrigation is better than that of border irrigation.In the actual production process,the use of sub-drip irrigation and fertilization technology can improve the number of cucumber,combining with cucumber price,farmers can timely increase water and fertilizer to achieve the best economic benefits.Under the same irrigation amount and drip irrigation condition,there are same trends in mass water content and surface soil water potential of different nitrogen treatments.The content of Nitrate nitrogen in DF100 treated soil was significantly higher than that of DF75 and DF50,and the nitrate accumulation in 40-80 cm soil layer was significantly accumulated.Excessive nitrogen application can lead to increase nitrate nitrogen residuesin soil and leach more severe,which can not be absorbed by crop roots and deepen the pollution to the soil environment.And the results also showed that the diameter and SPAD,amount of leaf of DF100 and DF75 was higher than that of DF50 treatment.Compared to DF50 treatment,the yield and economic efficiency of DF100 increase respectively5.3%-23%,2.6%-18% and yield of DF75 increase respectively 2.6%-7.9%,1.3%-6.3%.The content of VC,soluble sugar,soluble protein and TSS were the highest,to some extents,so the quality of DF75 was better.Increasing the amount of nitrogen can increase the growth of cucumber,and thus increase the number of cucumber,yield growth,economic benefits.However,excessive nitrogen application will reduce the quality and yield of cucumber fruit,so we need to balance the nitrogen fertilizer and yield with the goals of maximum efficiency.In summary,DF75 treatment?drip irrigation and moderate nitrogen fertilizer?can ensure good growth,stable yield,fruit quality of cucumber and high economic efficiency,while irrigation water use efficiency is higher,soil water distribution is more stable.Also it reduces soil water leakage,nitrate residues and deep leaching.Our experimental result can provide a standard cultivation mode for the sustainable development of agricultural cultivation in local areas.