Nitrogen Mineralization Experiment under Fir Stand with Different Measurement Methods

Abstract

Within the current study nitrogen mineralization under East Black Sea Fir (Abies nordmanniana (Steven) Spach) stand at Ataturk Arboretum has been investigated. Closed top solid cylinder, buried bag, laboratory incubation and ground samples were taken from a 30 x 30 m 2 sampling area during a year. Soil samplings were carried out from April 2013 to 2014 for field and laboratory incubation. We tested (i) to what extend is the method efficient on the amount of mineralization, (ii) to what extend mineralization amount differs seasonally and (iii) is there any correlation between nitrogen pool of soil and mineralization rates under in situ and in vitro conditions. Our results revealed that both seasonality and incubation methods were efficient on mineral N amounts. Ammonium-N accumulation values with tube incubation samples were significantly higher at summer incubation periods while opposite at samples incubated at laboratory conditions. We found significant difference in terms of incubation method (Closed top cylinder and buried bags) at August and December periods for Nitrate-N (mg-N/kg/day) values. The lack of correlation between total nitrogen and/or initial total mineral nitrogen and ammonium mineralization or nitrification implies unimportance of mineral N pool instead, furthermore possible addition or removal of organic and mineral nitrogen fluxes takes accounts to a more determinant factor.