The N recovery from 15N‐labeled swine manure compost and rice bran with or without simultaneous application of unlabeled cattle manure compost was examined in a paddy field with direct‐seeded rice during a 1‐year period (1 crop season). In all the 15N‐labeled materials including (15NH4)2SO4, the processes of N recovery from the 15N materials by rice plants were different between the plots with and without application of cattle manure compost. At the tillering stage, the N recovery rates from the 15N materials in the plots with application of cattle manure compost were significantly lower than those in the plots without application of cattle manure compost. These recovery rates, however, became close and no significant differences were observed at the maturity stage. Thus, simultaneous application of cattle manure compost could impede the N recovery from swine manure compost, rice bran as well as (NH4)2SO4.

Colors of plinian pumices were measured by spectrocolorimetry, and their quantitative color parameters in the L*a*b* color space were determined. A series of heating experiments of obsidian was conducted to simulate the colorchange processes of rhyolitic glasses. In these experiments, following three stages of color-change processes were observed. Stage I showed a rapid b* (yellowishness) increase associated with fast dehydration controlled by water diffusivity (D water ). In stage II, a* (reddishness) increase was accompanied by Fe 2+ decrease. Both a* increase and Fe 2+ decrease can be simulated by a diffusion model. Obtained diffusivity D oxidation were about two orders of magnitude smaller than D water . The a*-value increase after the oxidation in stage III appeared to be quasi-linear with time, indicating the zeroth order reaction corresponding to the formation of hematite-like structures in rhyolitic glasses. The diffusionlimited a* increase model in stage II was applied to a natural plinian pumice fall unit to evaluate time periods of colorchange processes through oxidation by air of fragmented rhyolitic materials.

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The formation processes of humic-like substances have been simulated by heating a glycine and ribose mixed solution (0.1 mol L) at 80 ℃ using the Maillard reaction. Ultraviolet-visible (UV-Vis), three-dimensional excitation emission spectroscopy and size exclusion liquid chromatography succeeded in quantitatively tracing increases of the products during the heating of glycine and ribose mixed solution (0.1 mol L). Two-dimensional correlation spectroscopic analyses suggested that a band area around 280 nm ( UV) and 254 nm absorbance ( UV) can be used as measures of the formation of furfural-like intermediates and humic-like products, respectively. They were monitored using in situ UV-Vis spectroscopy with the original heatable liquid cell at 60-80 ℃. Kinetic analyses of the obtained data gave activation energies of 91.4-96.6 kJ mol. These nondestructive measurements by an in situ spectroscopic method did not require any additional procedures including drying or extracting the solution and they can be effectively used for direct tracing of the reaction progress and/or decomposition.

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