Abstract
The author studied the change of oxidation-reduction potential of both paddy and dry field soils which were dressed with various nitrogenous manures. The results are summarized as follows : 1. Paddy field soil. Potential dropped markedly in the first stage and Eh attained to the lowest value after 2-7 weeks, and then it increased gradually to initial value. Plots of organic manures, especially of Genge (Astragalus sinicus) and of sardine cake, showed much lower value than the others, and those of ammonium sulphate and of no manure, much higher value. Subsoil (about 15cm depth) showed also the same tendency, but had somewhat higher Eh value and later Eh drop than surface soil. 2. Dry field soil. Potential dropped slightly in the early stage. But no marked difference was found among plots with the exception of calcium cyanamide plot, which showed lower value throughout the experiment. The above was true with subsoil potential. It was also experimented that lower Eh value of calcium cyanamide plot was partly due to higher pH value of the plot.
