Shozo Kuwatsuka

Behavior of phenolic substances in the decaying process of plants: I. Identification and Quantitative Determination of Phenolic Acids in Rice Straw and Its Decayed Product by Gas Chromatography

Abstract Phenolic acids in rice straw and its decayed product were surveyed and quantitatively analyzed by gas chromatography. 1) Thirteen kinds of phenolic acids in rice straw and its decayed product were identified. Besides p-hydroxybenzoic, vanillic, P-coumaric, and ferulic acids which had been already reported, nine phenolic acids were newly identified; these were benzoic, salicylic, syringic, protocatechuic, β-resorcylic, caffeic, sinapic, gallic, and gentisic acids. 2) A gas chromatographic analysis was applied to the micro-determination of major phenolic acids in rice straw and . the decayed products. The methanolic alkaline extracts from them were washed with ether, acidified, transferred into ether, trimethylsilylated, and injected into a gas chromatograph equipped with a silicon SE-30 column. The recoveries of p-coumaric, p-hydroxybenzoic, vanillic, and syringic acids were more than 90%, and ferulic and syringic acids were recovered at about 70%. 3) The content of each of the above described maj...

Comparison of two methods of preparation of humic and fulvic acids, IHSS method and NAGOYA method

Abstract Two methods for preparing soil humus samples, NAGOYA (Nagoya University) method and IHSS (International Humic Substances Society) method, were compared using A-horizons of an acid brown forest soil and an ando soil. Alkali-extractable humus was recovered more effectively by the NAGOYA method, while the IHSS method recovered only 80 and 26% of the maximum yield by extraction with 0.1 N NaOH from both soils, respectively. The recoveries of fulvic acids (FAs) by the IHSS method in which XAD-8 was used as adsorbent to obtain only humic substances in the FA fraction from the brown forest soil and the ando soil were only 1/5 and 1/40, respectively, of those by the NAGOYA method in which the whole FA fraction was recovered. The FAs obtained by the NAGOYA method were further fractionated into adsorbed and non-adsorbed fractions with XAD-8 or insoluble polyvinylpyr-rolidone (PVP). The recoveries of the XAD-8-adsorbed fraction increased 3.8 and 26 times by changing the volumes of the extractant and adsorbe...

Chemical studies on soil humic acids: II. Composition of oxygen-containing functional groups of humic acids

The levels of alcoholic and phenolic hydroxyl, methoxyl, carboxyl, and carbonyl groups of 33 to 38 humic acids obtained from various types of soils were determined to analyze the relationships between the amounts of these functional groups and the degree of humification or the types of soils. The amounts of various oxygen-containing functional groups examined were all proven to be significantly different among the various types of humic acids by analyses of variance. During humification. generally, the carboxyl and carbonyl groups increased while alcoholic and phenolic hydroxyl and methoxyl groups decreased. Linear and logarithmic regression analyses of carboxyl group contents on RF values (optical density of the alkaline solution of humic acids at 600 nm) gave very significant positive correlations. The carboxyl group contents of Rp type humic acids and humic acids from calcareous soils were largely distributed in the upper side of the regression curve. The carbonyl group contents showed a very ...

Methane Production and Its Fate in Paddy Fields : I. Effects of Rice Straw Application and Percolation Rate on the Leaching of Methane and Other Soil Components into the Subsoil

Abstract Oxidation of methane and total water soluble organic carbon (TOC) in the subsoil, which percolated from the plow layer, was investigated in a column experiment. The amounts of both methane and TOC in the leachate decreased by percolation in the subsoil. Fe2+ percolated from the plow layer was nearly completely retained in the subsoil. The decomposition of methane and TOC in the subsoil was considered to result in the coupling with the formation of Fe2+. Methane was estimated to contribute ca. 19–21% to the total amount of Fe2+ formed in the subsoil by the organic materials in the leachate.

Molecular size distribution of humic acids as affected by the ionic strength and the degree of humification

Molecular size distribution of soil humic acids was investigated by permeation chromatography on porous silica (µBondagel) and porous glass (Controlled Pore Glass, CPG) which enabled rapid analysis. Humic acid molecule was fully expanded at low ionic strength at pH 7.5, but it shrank considerably with increasing ionic strength. This behavior of humic acid molecule was analogous to that of linear polyelectrolyte molecule. Molecular size of humic acids decreased with increasing RF value and carboxyl group content and with decreasing 41og K value (namely with the increasing degree of humification). This phenomenon was attributed to oxidative depolymerization and intramolecular condensation during the process of humification. Based on the fractionation experiments on CPG, the fraction with the highest RF value and the lowest Δlog K value had an intermediate molecular size among the fractions. The excluded large molecular size fraction contained both highly humified components and a large amount of non-colored...

Degradation of PCP in soils

Abstract In laboratory experiments, the degradation of PCP in soil with regard to the relationship to soil properties was studied under upland and flooded conditions using gas-chromatographic techniques. The degradation products and their behavior were elucidated by using 10 diCferent soils collected from rice fields and adjacent upland fields and one sample of a subsoil from the forest. The results are as follows: 1) The degradation of PCP in soils was faster under flooded conditions than upland conditions. 2) The degradation under flooded conditiont was more rapid in soils collected from rice fields than in those from adjacent upland fields, Tbe reverse was true under upland conditions. 3) The degradation rate was highly correlated with the organic matter content of the soil. Almost 100% of the PCP remained in the subsoil sample even after 50 days of incubation. The rate was slightly correlated with the clay mineral composition, free iron content, phosphate absorption coefficient and C.E.C., but hardly ...

Comparison of the composition of humic and fulvic acids prepared by the IHSS method and NAGOYA method

Abstract The composition of humic acids (HAs) and fulvic acids (FAs) prepared by the NAGOYA (Nagoya University) method and the IHSS (International Humic Substances Society) method was investigated using an an do soil and a brown forest soil. Extraction with a smaller volume of 0.1 N NaOH in the IHSS method yielded HAs containing larger amounts of 0, carboxyl groups, alcoholic hydroxyl groups, hexoses, and uronic acids than those prepared by the NAGOYA method. The contents of C, carbonyl groups, and amino acids were higher in the HAs obtained by the NAGOYA method. The relative content of aromatic C was higher in the HAs prepared by the NAGOYA method, especially in the ando soil. The FAs prepared by the IHSS method contained smaller amounts of H, N, alcoholic hydroxyl groups, saccharides, and amino acids than the F As obtained by the N AGOY A method, mainly due to the XAD-8 treatment in the IHSS method. The saccharide and amino acid contents in the XAD-8-adsorbed fractions obtained from the FAs prepared by ...

Chemical characteristics of soil fulvic acids fractionated using polyvinylpyrrolidone (PVP)

Abstract Elementary composition, IR spectra, 13C-NMR spectra and molecular size distribution were determined for fulvic acids (FAs), polyvinylpyrrolidone (PVP)-adsorbed and non-adsorbed fractions of FAs and humic acids (HAs). The analytical data showed that the properties were distinctly different between the PVP-adsorbed and the non-adsorbed fractions. Atomic ratio, IR spectra and 13C-NMR spectra indicated that the PVP-adsorbed fractions contained a larger number of aromatic rings and carboxyl groups including ester than the non-adsorbed fractions. On the other hand, carbohydrates and N-containing compounds such as peptides or amino acids were concentrated in the PVP-non-adsorbed fractions. Weight average molecular weights (Mw ) of the adsorbed fractions were lower and the range of molecular size distribution was narrower than those of the non-adsorbed fractions. Chemical characteristics of HAs varied depending on the types of soils, while the characteristics of the PVP-adsorbed and non-adsorbed fraction...

Suppression of methane fluxes from flooded paddy soil with rice plants by foliar spray of nitrogen fertilizers

Abstract A pot experiment was conducted to evaluate the effects of the kind of ammonium fertilizers (ammonium sulfate, ammonium chloride, and urea) and method of topdressing (broadcasting and foliar spray) on the methane fluxes from paddy fields. Among the broadcasted plots, the methane flux from the ammonium sulfate plot to the atmosphere was the lowest, followed by the ammonium chloride and urea plots, in this order. Topdressing by foliar spray reduced the methane fluxes in each fertilizer plot compared with the respective broadcasted plots, with a reduction of 45, 60, and 20% in the ammonium sulfate plot, the ammonium chloride plot, and the urea plot, respectively. Topdressing by foliar spray decreased the grain yield. Among the three kinds of nitrogen fertilizers, the methane flux rate for the production of a unit weight grain was the lowest in the (NH4)2SO4 plot in both methods of topdressing. Topdressing of (NH4)2SO4 fertilizer by broadcasting was the most appropriate method in this experiment, when...

Monosaccharide composition of four humus fractions in an Andosol and a Cambisol

Abstract The composition of seven neutral monosaccharides (glucose, galactose, mannose, xylose, arabinose, fucose and rhamnose) released by acid hydrolysis with 0.5 mol L−1 H2SO4 was compared among four humus fractions, including humic acids (HAs), fulvic acids (FAs), water-soluble non-humic substances (WS-NHS; XAD-8-non-adsorbed fraction of the FA fraction) and humin, for two representative types of Japanese soils, an Umbric Andosol (ando soil) and a Dystric Cambisol (brown forest soil). Although more than 58% of the hexoses and pentoses in the soil were recovered in humin, 29–57% of fucose and rhamnose were found in WS-NHS. In the principal component analysis, humin was separated from the other three fractions because of larger proportions of glucose and xylose and smaller proportions of fucose and rhamnose. The HAs contained a larger proportion of arabinose than the other fractions. The monosaccharide composition of the FAs and WS-NHS was similar in each soil type. As deoxyhexoses and pentoses in soil are known to originate mainly from microorganisms and higher plants, respectively, the contribution of microorganism-derived saccharides to total neutral saccharides was considered to be greater in the order of WS-NHS and FAs > HAs > humin.