Microbiological Activities of Iwatahara Soils, Shizuoka Prefecture (part 4) : Nitrate Reduction

Abstract

Reductions of nitrates and nitrites in Yellow and Ando soil at Iwatahara Shizuoka prefecture, were studied, and the results obtained were as follows : l) Reduction of nitrates under paddy condition in Yellow soils occurs even when no addition of glucose is made as sources of energy, and it is favored by the application of CaO to correct soil acidity, but in Ando soils it occurs only when glucose is added. 2) Under aerobic condition, this reduction takes place only when glucose is added to Yellow soils. 3) Nitrate reduction occurs so rapidly in soils acidified (below pH 3.5) with H_2S0_4,and also in buffer solution (below pH 3.2). From these resnlts, the nitrate reduction by acid reaction seems to be of chemical mechanisms. 4) Nitrite added to soils is unstable. In the neutral and anaerobic condition the reduction occurs biologically, while in acid condition it occurs chemically under both aerobic and anaerobic conditions. Reduction of nitrite added to soils in the paddy condition is more retarded than when added to those in the field condition.