Possibility of No-Input Farming in Lowland Rice Fields in Japan from the Viewpoint of Sustaining Soil Fertility

In Japan, the area of low-input rice production is gradually increasing with a growing public interest in the quality and safety of our staple food. In an extreme case, rice has been grown over years without using any chemical fertilizers and agrochemicals. However, it is uncertain how much and how long such no-input farming can sustain rice yield and soil fertility. To better understand the sustainability of no-input rice farming in Japan, I briefly review previous results obtained from the long-term field experiments. The topics are (1) rice yield and soil fertility under no-input farming, (2) the environmental factors affecting rice growth and soil fertility under no-input farming, and (3) the dynamics of soil K under continuous rice cropping. The corresponding conclusions are as follows: (1) rice yield and soil fertility under no-input farming in Japan were influenced by various environmental and management factors operating at regional and field scales; (2) the input of K through irrigation and the high-clay content in soil were considered the key environmental factors that enable to sustain no-input farming; and (3) soil K depletion caused by long-term exhaustive cropping should be assessed by monitoring the decrease of soil nonexchangeable K rather than that of exchangeable K

An Overview of the Effects of Heat Treatments on the Quality of Organic Wastes as a Nitrogen Fertilizer

Sewage sludge is often heat-dried to eliminate water and pathogens. However, heat-drying can also change the form of nitrogen (N). To improve our understanding of this phenomenon, we examined the heat-induced changes in the rate of N mineralization from soils and organic wastes. Published results revealed that the response to the heating temperature differed between soils and organic wastes. As the heating temperature increased to 200°C, the rate of N mineralization increased in soils but decreased in organic wastes. In organic wastes such as sewage sludge, the content of mineralized N tended to decrease sharply when heating temperatures increased to 150–200°C. Furthermore, our results obtained from heat-drying of sewage sludge at 180°C indicated that the rate of carbon (C) mineralization decreased with increasing heating period after the sludge temperature reached 180°C. The C in sewage sludge heated at 180°C for 120 hours after complete drying contained more humin and aromatic C than that in sludge that was heat-dried at 180°C without the additional heating period. These results suggest that the heat-drying treatment can be divided into the drying and denaturing periods and that the temperature of the sludge, not that of the reactor, affects the quality of the end-product

An Overview of the Studies on Biochar Fertilizer Carried Out at the Beginning of the Twentieth Century in Japan

Biochar is a recently coined term for charred organic matter used as a soil amendment. Although the term is relatively new, the substance has been used for a long time throughout the world, including Japan. After we read a Japanese book entitled Nibai Shukaku Tenri Nouhou (How to Double Crop Yield by Almighty Farming System) originally published in 1912, we found that there were conflicting opinions between the author (Mr. Katsugoro Oyaizu) and soil scientists of the time (Dr. Gintaro Daikuhara and others) on the benefits of the use of biochar fertilizer. Previous publications on this topic have been written in Japanese from a sociological viewpoint. By referring to the literature published at the beginning of the twentieth century in Japan, we attempt to shed light on the conflict between traditional knowledge of biochar fertilizer and new concepts of soil science imported from the Western countries. We also describe briefly the socioeconomic impacts on the use of biochar fertilizer in the later generations

Characterisation of human saliva as a platform for oral dissolution medium development

Human saliva is a biological fluid of great importance in the field of dissolution testing. However, until now, no consensus has been reached on its key characteristics relevant to dissolution testing. As a result, it is difficult to select or develop an in vitro dissolution medium to best represent human saliva. In this study, the pH, buffer capacity, surface tension, viscosity and flow rate of both unstimulated (US) and stimulated (SS) human saliva were investigated in order to provide a platform of reference for future dissolution studies using simulated salivary fluids. Age and gender related differences in a sample size of 30 participants for each parameter were investigated. Significant differences were established between US and SS for all characteristics except surface tension. Therefore, the requirement for using two simulated salivary fluids should be considered when developing an oral dissolution model

ニンチショウ コウレイシャ ノ ザイタク セイカツ ケイゾク オ カノウ ニ スル チイキ ホウカツ シエン センター オ チュウシン ト スル センモンショク レンケイ ノ ユウコウセイ ニ カンスル イチコウサツ

認知症高齢者とその家族を最前線で支援する地域包括支援センターにおける，社会福祉士・保健師・看護師を中心とする専門職の実践に注目し，認知症高齢者の在宅生活継続に必要な要件を探ることを目的として，熊本県内の地域包括支援センターを対象にインタビューを実施し，得られたデータを分析した．その結果，地域包括支援センターにはさまざまな相談が寄せられ，地域の包括的相談窓口として認識されつつあること，配置されている専門職がチームアプローチを実践していること，その一方で，地域の諸機関と有効な連携が行われているものの，医師や医療機関との関係については認知症高齢者の在宅生活継続を可能にするほど十分なものではないこと，等が明らかとなった．今後も，住民の組織化による認知症高齢者を支えることのできる地域づくりへの努力が引き続き求められる

Caesium incorporation and retention in illite interlayers

Radioactive caesium (chiefly 137Cs) is a major environmental pollutant. The mobility of Cs in temperate soils is primarily controlled by sorption onto clay minerals, particularly the frayed edges of illite interlayers. This paper investigates the adsorption of Cs to illite at the molecular scale, over both the short and long term. Transmission electron microscopy (TEM) images showed that after initial absorption into the frayed edges, Cs migrated into the illite interlayer becoming incorporated within the mineral structure. Caesium initially exchanged with hydrated Ca at the frayed edges, causing them to collapse. This process was irreversible as Cs held in the collapsed interlayers was not exchangeable with Ca. Over the long term Cs did not remain at the edge of the illite crystals, but diffused into the interlayers by exchange with K. Results from extended X-ray absorption fine structure spectroscopy (EXAFS) and density functional theory modelling confirmed that Cs was incorporated into the illite interlayer and revealed its bonding environment

コンケン ドジョウ ノ ヨウブン ドウタイ ニ カンスル ケンキュウ

京都大学0048新制・課程博士博士(農学)甲第9148号農博第1209号新制||農||831(附属図書館)学位論文||H13||N3579(農学部図書室)UT51-2001-K355京都大学大学院農学研究科地域環境科学専攻(主査)教授 小﨑 隆, 教授 櫻谷 哲夫, 教授 關谷 次郎学位規則第4条第1項該当Doctor of Agricultural ScienceKyoto UniversityDA

Soil color analysis for statistically estimating total carbon, total nitrogen and active iron contents in Japanese agricultural soils

Soil color originates mainly from organic matter, iron mineralogy and moisture content. We aimed to find a suitable method to measure soil color sensitively and to evaluate the extent to which the color parameters can be useful for statistically estimating total carbon (C), total nitrogen (N) and active iron (Fe) contents in Japanese agricultural soils. A soil color reader (SPAD-503) was applied to two sample sets: (1) 100 surface soils collected throughout a 0.5-ha paddy field (field scale) and (2) 147 surface soils collected from agricultural fields in Japan (national scale). For analysis with this instrument, about 2 g of air-dried, finely-ground samples were packed firmly in a plastic cell, and their colors as they appeared on windows in both sides of the cell were measured. A CIE 1976 (L[*], a[*], b[*]) color space was used for color description. For the field-scale samples, the values of the coefficient of variation were around 15% for total C, total N and acid oxalate extractable iron (Feo). The L[*] value (lightness) was negatively correlated with the content of total C and total N (R[2] = 0.18** and 0.26**, respectively), and the b[*] value (yellowness) was positively correlated with the Feo content (R[2] = 0.59[**]). For the national-scale samples, the values of the coefficient of variation were around 60% for total C, total N and Feo. The L[*] value was negatively correlated with the content of total C and total N (R[2] = 0.70** and 0.59[**], respectively), but the b[*] value was not correlated with the content of Feo (R[2] = 0.00). When the analysis was limited to 65 samples frequently used for paddy fields, the b[*] value was positively correlated with the Feo content (R[2] = 0.52[**]). In conclusion, the proposed method enabled us to measure soil color sensitively with a small sample size. The L[*] and b[*] values obtained can be useful for rapid estimation of total C, total N and Feo contents in agricultural surface soils in Japan