Haruo Shindo

Elementary composition, humus composition, and decomposition in soil of charred grassland plants

Abstract Charred plant residues collected after the burning of grassland vegetation in which Susuki plants predominated (Eulalia, Miscanthus sinensis A.), were divided into 5 particle size fractions of >2, 1-2, 0.5-1.0, 0.25-0.5, and <0.25 mm using sieves. 1) The percentage distribution of organic matter in the charred plant residues was higher in the larger particle size fractions, and the reverse was true for the distribution of ash. 2) The contents of carbon, hydrogen, and oxygen of each fraction on an oven-dried basis decreased with decreasing particle size, but the ash content showed an inverse relationship. No regular trend was found between the nitrogen content and the particle size. 3) The atomic H/C and O/C ratios of each fraction and other data suggested that dehydrative condensation took place during the burning of the grassland vegetation studied. 4) The amounts of NaOH-extractable materials from each fraction which were very small significantly increased after the HNO3 treatment of the fracti...

Carbon source of humic substances in some Japanese volcanic ash soils determined by carbon stable isotopic ratio, δ13C

Abstract Volcanic ash soils (including Andisols) have been known to accumulate extremely large amounts of humic acids in their thick surface horizons, and their accumulation mechanism is of interest. Two mechanisms have been proposed: (1) active metals like Al and Fe, supplied from weathered volcanic materials, stabilize humic acids through complexation reactions; (2) cultivated Japanese pampas grasses ( Miscanthus sinensis A.) and its charred materials are the major carbon source of humic acids. In the present study, contribution ratio of the pampas grass (C4-plant) on the carbons of the humic acids was determined by measuring their stable isotopic ratio of carbon (δ 13 C). In Japanese volcanic ash soils, humic acids were originated from both C3- and C4-plants, and the contribution ratio of C4-plants (mostly pampas grass) ranged from 18% to 52%. Highly humified (dark-colored) humic acids tended to show higher contribution ratio of C4-plants among volcanic ash soils, although the major part of the carbon had originated from C3-plants. It was also clarified that the δ 13 C values of crude soil samples correlated well with those of humic and fulvic acids. Therefore, reported δ 13 C values of crude soil samples in the literature would be useful for estimating the carbon source of soil humic substances. Literature survey of the δ 13 C values of crude soil samples also indicated that a large part of the carbon in humic substances has originated from C3-plants rather than C4-plants, implying the importance of the active metals (such as Al and Fe) on the formation and accumulation of the humic acids in volcanic ash soils.

A Possible Source Of Humic Acids In Volcanic Ash Soils In Japan—charred Residue Of Miscanthus sinensis

We compared the physicochemical and spectroscopic properties of humic acids obtained from the charred residue of Miscanthus sinensis Anderss and the A horizons of volcanic ash soils in Japan. The elementary composition, Δlog K and RF values, UV, visible, and IR absorption spectra, and x-ray diffraction pattern of the acids are similar to those of the soils. The findings indicate that the charred residue of Miscanthus sinensis deserves attention as a possible source of humic acids with a high degree of darkening in volcanic ash soils in Japan.

Comparison of Humic Acids from Charred Residues of Susuki (Eulalia, Miscanthus sinensis A.) and from the a Horizons of Volcanic Ash Soils

The physico-chemical and spectroscopic properties of humic acids from the charred residues of Susuki (Eulalia, Miscanthus sinensis A.) and from the A horizons of volcanic ash soils were compared. The humic acid (M-HA) of charred Susuki residues belonged to Type A. The elementary composition (C: 61.0%. H: 3.1%. N: 1.5%.0: 34.4%), δlog K (0.57), and RF (97) values of M-HA, except for N content, fell Within the ranges of those of the Type A humic acids in the A horizons of volcanic ash soils. The UV, visible, and IR absorption spectra of M-HA were similar to those of the Type A soil humic acids. Like the Type A soil humic acids, the X-ray diffraction pattern of the M-HA revealed the presence of two peaks at d=3.5 and 2.1A, corresponding to the (002)- and (10)-bands of graphite, respectively. The Fourier transformation method of (002)-band enabled to show that the M-HA mainly consisted of stacked fractions of two and three layers, as in the case of the Type A soil humic acids.

Humus Composition of Charred Plant Residues

Japan is a typical volcanic country. Volcanic ash soils which develop in deposits of volcanic ash are widely distributed in Japan. Studies have shown that an important feature of humus in the A horizons of volcanic ash soils is the predominance of Type A humic acids with a high degree of humification (1, 2). The formation of Type A humic acids may proceed with the mediation of soil enzymes and inorganic components, since they are capable of accelerating the conversion of phenolic compounds to humic polymers with a high degree of darkening (3–5). As another possible mode, the authors suggested that the charring process of plants might contribute to the formation of Type A humic acids, because the abundant accumulation of humus in volcanic ash soils may be attributed to the presence of a dense grass vegetation and to the burning of these materials (6). Furthermore, carbonaceous materials such as charcoal and cinder are considered to be one of the possible sources of soil humus (7). In the present study, to ...

Adsorption, activities and kinetics of acid phosphatase as influenced by montmorillonite with different interlayer material

The effects of montmorillonite (Osage, Wyoming) with different interlayers on the adsorption, activities, and kinetic properties of acid phosphatase were examined. Hydroxy polymers of aluminum or chromium (200 cmol kg−1 clay) were intercalated in montmorillonite in the absence or presence of citric acid (citrate/Al or Cr = 0.1 and 0.5). The activities of acid phosphatase in the presence of different amounts of clay at three pH values (5.0, 5.5, and 6.0) were determined, and the Michaelis-Menten kinetic parameters were calculated. The amount of enzyme adsorbed by interlayered montmorillonite was considerably lower than that by pure montmorillonite and increased as the citrate/Al or Cr ratio increased. The type of interlayer (Al or Cr) influenced the ease with which enzymes could be removed by washing. Complete adsorption of the enzyme led to the formation of clay-enzyme complexes, which had lower activities than the free enzyme. The order of activity of enzymes following adsorption was Cr-montmorillonite > Al-montmorillonite > montmorillonite. The effect of citrate on enzyme activity in the clay-enzyme complexes was significant only at the higher ratio. Factors that caused a reduction in enzyme activity were adsorption by clay, amount of clay, and increase in pH. These effects were modified by the type of interlayers (Al or Cr), the citrate/Al or Cr molar ratio, and the strength of adsorption. In the presence of clay, the Michaelis-Menten affinity constant (Km), increased, whereas the maximum enzyme reaction velocity (Vmax), decreased compared with the free enzyme. The change of the enzyme kinetics by Al- and Cr-interlayered montmorillonite can be described as partial noncompetitive inhibition.

Adsorption, Activity, and Kinetics of Acid Phosphatase as Influenced by Selected Oxides and Clay Minerals

Abstrac The effects of 3 oxides (Fe, Al, and Mn oxides) and 3 clay minerals (kaolin, montmorillonite, and allophane) on the adsorption and subsequent kinetic properties of acid phosphatase were compared. The amount of enzyme adsorbed by the oxides and clay minerals followed the order: montmorillonite ≫ kaolin > Mn oxide > Fe oxide > Al oxide ≫ allophane. The adsorption isotherms of the enzyme on the oxides and clay minerals, except for montmorillonite and allophane, fitted the Langmuir equation. The activity of the enzyme immobilized by the inorganic components studied was in the order of allophane > kaolin > Fe oxide > montmorillonite > Al oxide ≒ Mn oxide. Compared to the free enzyme, the V max, Km, and V max / K m values of the immobilized enzyme decreased, increased, and decreased, respectively. Among the oxides or clay minerals, the higher the ability of the inorganic components to adsorb the enzyme, the lower the value of the V max / K m ratio of the immobilized enzyme. These findings suggest that the catalytic efficiency of the enzyme complexes formed is determined by the adsorbability of the inorganic components for the enzyme.

BEHAVIOR OF PHENOLIC SUBSTANCES IN THE DECAYING PROCESS OF PLANTS : III. Degradation Pathway of Phenolic Acids

p-Coumaric, ferulic, vanillic, and p-hydroxybenzoic acids, the main phenolics in rice straw and its decayed products, were incubated at 50°C at concentrations of 30 ppm in dilute water-extract solu...

Mineralization and microbial biomass formation in upland soil amended with some tropical plant residues at different temperatures

Abstract A model experiment was carried out at 15, 25, and 35°C to investigate the changes in microbial biomass and the pattern of mineralization in upland soil during 8 weeks following the addition of 8 organic materials including 6 tropical plant residues, ipil ipil (Leucaena leucocephala), azolla (Azolla pinnata), water hyacinth (Eichhornia crassipes), dhaincha (Sesbania rostrata), cowpea (Vigna unguiculata), and sunhemp (Crotalaria juncea). The amounts of CO2-C evolved and inorganic N produced at 35°C were about 2 times larger than those at 15°C. At any temperature, the flush decomposition of C was observed within the first week and thereafter the rate of mineralization became relatively slow. A negative correlation was observed between inorganic N and C/N ratios of the added organic materials. The relationships between the amounts of cellulose or cellulose plus hemicellulose and the amount of mineralized N of the added organic materials were also negative. The changes in the microbial biomass were af...

δ13C values of organic constituents and possible source of humic substances in Japanese volcanic ash soils

To gain a better understanding about the δ13C values of organic constituents and possible source of humic substances in Japanese volcanic ash soils, we determined the δ13C values of charred plant fragments, humic and fulvic acids, and whole soils, using 10 volcanic ash soil samples. Furthermore, the characteristics of the humic acid obtained from the dil. H2O2-treated residues of charred plant materials, which were produced during the burning of a grassland, were compared with those of black (type A) humic acids in volcanic ash soils. The δ13C values of the charred plant fragments, humic and fulvic acids, and whole soils studied ranged from −25 to −17‰, −25 to −17‰, −23 to −15‰, and −24 to −17‰, respectively. The δ13C values of the whole soils were highly correlated with those of the charred plant fragments (r = 0.968, significant at 0.1% level), humic acids (r = 0.947, significant at 0.1% level) or fulvic acids (r = 0.900, significant at 0.1% level), suggesting that in Japanese volcanic ash soils, the δ13C data of whole soils are valuable for discussing and estimating the origin of carbon of charred plant fragments as well as humic and fulvic acids. The δ13C values of the charred plant fragments were highly correlated with those of the fulvic acids (r = 0.792, significant at 1% level) and especially humic acids (r = 0.951, significant at 0.1% level). The contribution ratios of C4-plant-derived carbon on the carbon in the charred plant fragments, humic and fulvic acids, and whole soils ranged from 15 to 69%, 16 to 65%, 29 to 86%, and 24 to 66%, respectively. The 13C-NMR spectrum and X-ray diffraction pattern of the humic acid obtained from the oxidative degradation products of the charred plant materials were similar to those of type A humic acids reported previously. Based on these findings, it was assumed that both charred C3- and C4-plant materials merit close attention as an important source of humic substances in Japanese volcanic ash soils.