Toyoaki Ito

Properties Of Nonallophanic Andosols From Japan

We studied various properties of nonallophanic Andosols in Japan. Our results showed that, despite many similarities between nonallophanic and allophanic Andosols, significant dissimilarities also exist between the two groups of soils. The nonallophanic Andosols used for our study formed from rhyolitic, dacitic, or andesitic volcanic ash in a humid temperature climate. They had distinctive morphological properties common to allophanic Andosols in Japan: (1) very dark, thick humus horizons, (2) granular structure in the humus horizons, (3) friable to very friable consistence, and (4) abrupt or clear smooth boundaries between humus and nonhumus horizons. The clay mineralogy of the nonallophanic Andosols was very different from that of the allophanic Andosols. In nonallophanic Andosols the clay fractions are mostly dominated by chloritized 2:1 minerals and the active Al (acid-oxalate-ex-tractable Al) consists largely or wholly of Al complexed with humus (pyrophosphate-extractable Al). The nonallophanic Andosols had mostly medium to fine textures and considerable high water retention at 15 bars. We noted that these soils have characteristically low bulk density, which is closely correlated with the organic carbon content. A remarkable accumulation of humus took place in the nonallophanic Andosols and was closely correlated with the formation of Al-humus complex. The high CEC of these soils was ascribed to the high humus content. We noted that nonallophanic Andosols are strongly acid to very strongly acid, reflecting the abundance of chloritized 2:1 minerals and the very low base saturation. Therefore, they had high Al saturation and large amounts of KCl-exchangeable Al, which is a major deterrent to plant growth in the soils. The average values of Al saturation and KC1-ex-changeable Al were 74.4% and 5.51 meq/ 100 g for humus horizon soils and 59.8% and 3.50 meq/100 g for nonhumus horizon soils, respectively. Almost all the nonallophanic Andosol samples had pH (NaF) >10 and phosphate retention > 85%. These values were significantly correlated with the acid-oxalate-extractable Al (Alo). Soils containing > 1% Alo have pH (NaF) > 9.4 and phosphate retention >85%. Therefore, we noted that Al complexed with humus has a significant amount of OH groups and is highly reactive. The analysis of pyro-phosphate-soluble components indicated that the humus associating with Al and Fe consists largely or wholly of humic acid with the highest degree of humification.

Extensive Chromosome Homoeology among Brassiceae Species Were Revealed by Comparative Genetic Mapping with High-Density EST-Based SNP Markers in Radish (Raphanus sativus L.)

A linkage map of expressed sequence tag (EST)-based markers in radish (Raphanus sativus L.) was constructed using a low-cost and high-efficiency single-nucleotide polymorphism (SNP) genotyping method named multiplex polymerase chain reaction–mixed probe dot-blot analysis developed in this study. Seven hundred and forty-six SNP markers derived from EST sequences of R. sativus were assigned to nine linkage groups with a total length of 806.7 cM. By BLASTN, 726 markers were found to have homologous genes in Arabidopsis thaliana, and 72 syntenic regions, which have great potential for utilizing genomic information of the model species A. thaliana in basic and applied genetics of R. sativus, were identified. By construction and analysis of the genome structures of R. sativus based on the 24 genomic blocks within the Brassicaceae ancestral karyotype, 23 of the 24 genomic blocks were detected in the genome of R. sativus, and half of them were found to be triplicated. Comparison of the genome structure of R. sativus with those of the A, B, and C genomes of Brassica species and that of Sinapis alba L. revealed extensive chromosome homoeology among Brassiceae species, which would facilitate transfer of the genomic information from one Brassiceae species to another.

Radiocesium sorption in relation to clay mineralogy of paddy soils in Fukushima, Japan.

Relationships between Radiocesium Interception Potential (RIP) and mineralogical characteristics of the clay fraction isolated from 97 paddy soils (Hama-dori, n = 25; Naka-dori, n = 36; Aizu, n = 36) in Fukushima Prefecture, Japan were investigated to clarify the mineralogical factors controlling the (137)Cs retention ability of soils (half-life 30.1 y). Of all the fission products released by the Fukushima accident, (137)Cs is the most important long-term contributor to the environmental contamination. The RIP, a quantitative index of the (137)Cs retention ability, was determined for the soil clays. The composition of clay minerals in the soil clays was estimated from peak areas obtained using X-ray diffraction (XRD) analyses. The predominant clay mineral was smectite in soils from Hama-dori and Aizu, while this was variable for those from Naka-dori. Native K content of the soil clays was found to be an indicator of the amount of micaceous minerals. The average RIP for the 97 soil clays was 7.8 mol kg(-1), and ranged from 2.4 mol kg(-1) to 19.4 mol kg(-1). The RIP was significantly and positively correlated with native K content for each of the geographical regions, Hama-dori (r = 0.76, p < 0.001), Naka-dori (r = 0.43, p < 0.05), and Aizu (r = 0.76, P < 0.001), while it was not related to the relative abundance of smectite. The linear relationship between RIP and native K content not only indicate a large contribution of micaceous minerals to the (137)Cs retention ability of the soil clays, but also could be used to predict the (137)Cs retention ability of soil clays for other paddy fields in Fukushima and other areas.

CHARACTERISTICS AND CLASSIFICATION OF VOLCANIC-ASH-DERIVED SOILS IN ALASKA

Twenty pedons of volcanic ash soils from southern Alaska used in this study have a cryic temperature regime and udic to perudic moisture regimes. They have distinctive morphological properties common to Andisols in many other parts of the world: (1) multisequum with abrupt or clear boundaries, (2) very friable granular structure in A horizons and friable subangular blocky structure in B horizons, and (3) loamy texture with a smeary consistency. They also have distinctive morphological properties common to Spodosols: (1) an organic horizon in all the pedons, (2) an albic or E horizon in most pedons, (3) underlying the E horizon, one or more horizons with hue redder than 10 YR in most pedons, and (4) a placic horizon below the spodiclike horizons in some pedons. The physical and chemical properties of the 13 pedons are presented and discussed. The properties of 7 pedons presented in previous studies are reviewed. All 20 pedons were found to meet the criteria of andic properties, and 19 of them also meet the chemical criteria of a spodic horizon. The pedons were classified according to both Soil Taxonomy and the Andisol proposal. Andisols were proposed to be keyed out after Histosols, but before Spodosols (Leamy 1988). Those Andisols having chemical properties of spodic horizon are differentiated from Spodosols by not having an albic-spodic sequum within the required thickness of horizons with andic properties. A comparison of the two classifications and the implication for soil survey and interpretation are also discussed.

Chemical Kinetics Of Weathering In Young Andisols From Northeastern Japan Using Soil Age Normalized To 10°c

We studied chemical kinetics of weathering in the humus horizons of young Andisols from northeastern Japan. Since there is no idealized chronosequence of Andisols, we selected eight pedons that have many similarities in the properties of parent material, soil moisture regime, vegetation, drainage, etc., but show significant differences in soil age and soil temperature. We introduced “soil age normalized to 10°C,” which was defined as the number of years a soil has been subjected to pedogenesis under mean monthly soil temperature (MMST) of 10°C throughout the year. For this calculation, temperature dependency coefficient (Q10) of Al release from volcanic glass was determined to be 1.5 by the laboratory dissolution experiment using separated glass samples. Mean monthly air temperature (MMAT) plus 1°C was employed as MMST based both on the comparison between MMST and MMAT and the determination of diurnal variations of soil temperature. Of the various elements contained in volcanic ash, Al was found to be most reliable for evaluating chemical weathering of the bulk soils, and released Al was determined by the acid oxalate method. The correlation between the soil age normalized to 10°C and acid oxalate extractable Al (Alo) showed that the chemical weathering is expressed as zero-order kinetics.

Seasonal increase of methane in sediment decreases δ13C of larval chironomids in a eutrophic shallow lake

Recent studies have shown that larval chironomids assimilate 13C-depleted carbon derived from biogenic methane by feeding on methane-oxidizing bacteria (MOB). The dietary contribution of MOB is known to be maximized in the autumn overturn period or winter in eutrophic dimictic lakes due to the increase of MOB biomass following the supply of oxygenated water, but in polymictic lakes, such seasonal variability has not been revealed. We investigated the seasonal patterns of larval δ13C and methane concentrations in the sediment of a eutrophic polymictic lake, Izunuma, Japan. Larval δ13C decreased in late summer and autumn. Methane concentrations above a 6 cm depth peaked in late summer or autumn, while those in the 10–11- and 20–21-cm layers peaked in October. Negative correlations between methane concentrations in the 5–6/10–11-cm layers and larval δ13C were found. This suggests that an increase in the supply of methane stimulated the activity of MOB in a polymictic lake, where water above the lake bottom rarely became anoxic because of frequent overturn, thus increasing the dietary contribution of MOB to larval chironomids.

Relationships between Paddy Soil Radiocesium Interception Potentials and Physicochemical Properties in Fukushima, Japan.

The radiocesium interception potential (RIP) of bulk soil (RIP) can reliably be used to predict the magnitude of soil-to-plant radiocesium transfer. There has been some controversy about which soil properties control the RIP, although the RIP is theoretically proportional to the amount of frayed edge sites in micaceous clay minerals. The RIP was determined for 97 paddy soils in three regions (Hama-dori, Naka-dori, and Aizu) in Fukushima Prefecture, Japan, and the relationships between selected physicochemical properties and the RIP were analyzed. The mean (± standard deviation) of the RIP for the 97 soils was 1.67 (±0.87) mol kg, and the range was 0.34 to 5.36 mol kg. Pearson correlation analysis revealed that the RIP positively correlated best ( < 0.01) with the clay fraction K content as a mass fraction of the bulk soil (clay-K) and negatively correlated with the total C content and the phosphate absorption coefficient ( < 0.05). Therefore, clay-K, an indicator of the amount of micaceous clay minerals in a soil, was confirmed as being useful for estimating the magnitude of the RIP for paddy soils in Fukushima. The RIP was invariably low if either the total C content exceeded 6.0% or the phosphate absorption coefficient exceeded 1500 mg kg, suggesting that these parameters could be useful for screening soils with particularly low RIP values.

Microbial community profiles in intercellular fluid of rice

Plants harbor microorganisms that are thought to stimulate plant defense systems or promote plant growth. Individual species in these intercellular microbial communities are often not sufficiently abundant to be easily described, although some endophytic microorganisms amenable to culture have been characterized. To better understand the microbial population of plants, we collected intercellular fluid (IF) from leaf blades and sheaths of rice and subsequently isolated DNA from the IF. Denaturing gradient gel electrophoresis (DGGE) analysis of 16S and 18S rDNA fragments amplified from IF DNA by PCR indicated that these band patterns were distinguishable from those of a leaf surface-wash fluid (SF). Analysis of a set of rDNA fragments amplified from IF DNA of rice with different genotypes, paddies or growth stages for the primary survey of overall microbial community in the IF suggested that this approach is suitable for analyzing microbial diversity in the IF from various plant samples. Actually, comparative analysis of amplified rDNA fragments of rice and other five plant species indicated that the microbial diversity in IF is likely to vary substantially among plant species. We can also use sequence analysis of 16S rDNA fragments amplified from rice IF DNA to identify species including unculturable bacteria and proteobacteria and Xanthomonas and 18S rDNA fragments to identify Tilletiaria anomala, Tilletia iowensis, Ustilago maydis and unculturable eukaryotes. Thus, IF DNA analysis seems to be a good tool to further study the microbial ecology of plants.

Measurement of total phosphorus and organic phosphorus contents of animal manure composts by the dry combustion method

Abstract The objective of this paper was to determine the optimum ignition temperature to measure precisely the total and organic P contents of animal manure composts by the dry combustion method. Total P content of the composts was measured by the wet digestion method and the dry combustion method, while the organic P content was measured by the fractionation method and the dry combustion method. Total P content of the composts ranged from 4.43 to 48.6 g kg−1 and there were significant correlations between the total P content measured by the wet digestion method and that measured by the dry combustion method at 550°C. Organic P content measured by the fractionation method ranged from 0.44 to 8.62 g kg−1. Organic P content measured by the dry combustion method ranged from 0.10 to 8.63 g kg−1, and there were significant correlations (r = 0.951) between the data obtained by the fractionation method and those obtained by the dry combustion method at 550°C. Ignition at 240 and 350°C was insufficient to completely decompose the organic matter, and resulted in the underestimation of the total and organic P contents of the composts. The proportion of organic P in all the compost samples ranged from 0.54 to 46%. Based on these results, we concluded that 550°C was the optimum ignition temperature for a precise determination of the total and organic P contents of animal manure composts by the dry combustion method.

Production and utilisation of iron and steelmaking slag in Japan and the application of steelmaking slag for the recovery of paddy fields damaged by Tsunami

Abstract In Japan, about 40 million tonnes of slag is generated annually during the iron and steelmaking process. This large amount of byproduct warrants investigation on its disposal. In this study, the production, chemical characteristics, and use of iron and steel slag in Japan, especially converter slag, have been reviewed. Then, the necessity for sodium removal and nutrient supply for the recovery of the paddy fields damaged by the Tsunami, which resulted from the great east Japan earthquake, has been explained. Since converter slag can serve the above two requirements simultaneously, owing to its chemical properties, investigations on efficient utilisation of converter slag have been carried out. With the perspective of both agriculture and engineering science, the positive effects of converter slag on desalting, pH improvement, and supply of nutrients such as silicon have been found.