Tuyển tập các báo cáo nghiên cứu về sinh học được đăng trên tạp chí lâm nghiệp đề tài: Available nitrogen in the surface mineral layer of Serbian forest soils. | JOURNAL OF FOREST SCIENCE 57 2011 4 131-140 Available nitrogen in the surface mineral layer of Serbian forest soils z. S. Dzeletovic1 R. N. Pivic2 N. L. J. Djurovic3 1INEP - Institute for the Application for Nuclear Energy University of Belgrade Zemun Serbia institute of Soil Science Belgrade Serbia 3Faculty of Agriculture University of Belgrade Zemun Serbia ABSTRACT Based on a greenhouse experiment we evaluated nitrogen availability in the surface mineral layer of soil under various deciduous forest stands by analysing the following soil characteristics total organic C total N initial content of easily available N inorganic forms mineralized N content obtained by aerobic and anaerobic incubations and A-value. The experiment was performed on a test plant and through the application of urea enriched with 15N. The studied forest soils are characterized by high mineralization intensity and high N availability indices. Aerobic incubation appears to be the most appropriate method for evaluating the available N content. The amounts of mineralized and nitrified N obtained by aerobic incubation with subtraction of the initial content of available mineral N forms are in correlation P with total organic C content r and total soil N r while the correlation with the C N ratio is poor r . Keywords A-value C N ratio total organic C total soil N An adequate supply of nitrogen is essential for successful establishment and sustainable productivity of forest stands. The long lasting reserves of available forms of this element cannot be formed in the soil. Potentially available N is released during the vegetation season through mineralization of organic compounds in soil under the influence of microorganisms. Although N availability in soils has been the subject of many studies there is not a generally accepted and completely reliable method for its assessment. Namely N availability indices developed for one mode of utilization of the soil surface . for
