Research On Atmospheric Nitrogen Deposition And Nitrogen Use Efficiency In Several Plants

Increased nitrogen utilization by human resulted from incremental food production increases the amounts of atmospheric nitrogen deposition globally, consequently, changes in N can affect environmental activities and the response of ecosystems to N. Atmospheric concentrations and fluxes of major reactive nitrogen species from June 2007 to May 2009 were studied. 3 Poaceae plants of ryegrass (Lolium perenne L.), barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) were planted to determine the absorption and utilization of N. The results were as followes:(1) Total fluxes of atmospheric total inorganic nitrogen were 10.68kg/ha in this observation station the whole year of 2008, 7.48-8.88 kg/ha or 233%-493% more than the value of 1.8-3.2kg/ha/yr without human disturbance, which showed the effects of human disturbance on atmospheric nitrogen, and the trend of atmospheric nitrogen pollution.(2) The main components of rainfall shifted from NH₄⁺-N to NO₃^--N. The fluxes of NH₄⁺-N were 23.44% more than NO₃^--N during the period of June 2007 to March 2008 while were 19.92% less than the latter from April 2008 to May 2009.(3) The total biomass, under the treatment applied with NO₃^--N, was the largest among the 4 treatments of rainfall, NH₄⁺-N, NO₃^--N and control.In pot experiment, treatment applied with NO₃^--N had the largest biomass and the highest nitrogen concentration in soil among the 4 treatments of rainfall, NH₄⁺-N, NO₃^--N and control. The total biomass under the NO₃^--N treatment was 66.95% more than the rainfall treatment, 19.05% than the NH₄⁺-N treatment and 166.77% than the control.In field experiment, treatment applied with NO₃^--N had the largest biomass and the lowest nitrogen concentration in soil among the 3 treatments of NH₄⁺-N, NO₃^--N and control. The total biomass under the NO₃^--N treatment was 23.09% more than the NH₄⁺-N treatment and 70.49% than the control while the nitrogen concentration in soil under the NO₃^--N treatment was 1.43% less than the NH₄⁺-N treatment and 3.66% than the control.(4) The barley had the largest biomass among the 3 plants of ryegrass, wheat and barley.In pot experiment, the barley had relative larger biomass and lower nitrogen concentration in soil than the ryegrass, which led to the best ecological benefit. The total biomass of barley was 18.81% more than and the nitrogen concentration in soil was 3.37% less than the ryegrass.In field experiment, the barley had relative larger biomass and higher nitrogen concentration in soil than the wheat. The total biomass of barley was 15.93% and the nitrogen concentration in soil was 8.88% more than the wheat.In conclusion, barley should be considered to be planted in agricultural production in Dalian area, so as to make better use of NO₃^--N in atmospheric deposition which based on the follow 2 reasons: the main components of rainfall shifted from NH₄⁺-N to NO₃^--N and barley had better absorption in NO₃^--N than ryegrass and wheat.Where there is not enough nitrogen, soil fertility declines, serious land degradation may occur, and agricultural productivity is reduced, as a consequence, populations that rely directly on these agricultural systems cannot produce enough food to survive. Where there is excessive nitrogen is likely to result in significant losses of that nitrogen to the surrounding environment, with the attendant environmental, economic and human health consequences for society. Further study on how to avoid excessive nitrogen to surroundings is suggested.