Abstract
We carried out experiments to compare the composition of the extractable organic substances between the heated (50, 100 and 150℃) and fumigated soils in order to clarify the origin of the nitrogen mineralized by soil heating treatment. The soils in order to clarify the origin of the nitrogen mineralized by soil heating treatment. The soils used were Dark Red soils (Kamogawa soil) and Andosols (chiba soil). The extractable total organic C and N, the extractable saccharides (hexose and pentose) and the various forms of the extractable N (amino acid N, amino sugar N, amide N and ammonium N) were measured. In the Kamogawa and chiba soils, the composition of the extractable organic substances in the soil heated at all temperatures was out of accord with that in the fumigated soil, suggesting that the extractable organic substances in the heated soil in the two soils were derived from both biomass and non-biomass fraction. The difference in the extractability between hexose and pentose in the heated soil was observed. The amount of extractable amino sugar N in heated soil was more than that of extractable amino acid N, suggesting that amino sugar N would be a key compound as a source of nitrogen mineralized by heating treatment. Large amount of the ammonium N in the soil heated at 150℃ was observed. We considered that this phenomenon could be attributed to the deamination of organic N, especially amino sugar N by the heating treatment at high temperature.
