Studies on Polder Soils in Japan. : XVI. Rapid Method for Determining Oxidizable Sulfur and Change of Soil Reaction of Sea Muds and Polder Soils.

Sea muds and saline polder soils frequently contain appreciable amounts of sulfur in various forms, and in polder soils and transported soils derived from sea muds acid condition sometimes develops through aeration of anaerobic soil. A description is given of practical rapid methods of determining the oxidizable sulfur and change of soil reaction of these soils. Recommended experimental procedures are as follows: A weighed quantity of soil (about 1 - 2 g) is mixed with 10 ml of 30 % H2O2, adjusting the pH to 6.0 - 6.5 with N/10 NaOH and removing the sulfuric acid when contained with Ba (OH)2, and heated for about 1 hour on water bath. After cooling, the contents are filled up to 100 ml and filtered. Soil pH value is determined in this soil suspension by means of the pH meter and glass electrode. Titrable acidity is determined by titrating 50 ml of this filtrate with N/10 NaOH and the result is given in terms of ml N/10 NaOH per 100 g soil. Active oxidizable sulfur is calculated from sulfuric acid equivalent to titrable acidity and given in terms of S mg per 100 g soil. Easily oxidizable sulfur is determined from the difference between the water soluble sulfate of the H2O2-treated soil and that of original soil and given in terms of S mg per 100 g soil. Sulfate is determined volumetrically by Benzidine sulfate method. The reliability of this method was examined with sea muds collected from sea bottom, saline pond soils, transported soils derived from sea muds and saline polder soils. The data obtained showed that saline pond soils and some of polder soils contained appreciable amounts of easily oxidizable sulfur and the pH values of these soils became extremely acid after oxidation with H2O2 and easily oxidizable sulfur of fresh soils amounted to over 80 % of total sulfur determined from the difference between the sulfate content of the aqua regia extract and that of the water extract of the soils. (See Table 1 and 2) A considerable difference was frequently found between active oxidizable sulfur and easily oxidizable sulfur and it was shown that the relative amounts of oxidizable sulfur and easily soluble base compounds determine titrable acidity, active oxidizable sulfur and soil pH value of H2O2-treated soil. (See Table 3) The pH values of transported soils derived from sea muds were found to gradually approach in natural fields to the pH values determined by H2O2-treatment. (See Table 4

A Study on Salpeter and Soda Produced in Saline and Alkali Soils in Northern Honan, China.

河南省開封を中心として硝石の製造が,又旧黄河河床に沿うアルカリ地帯に於ては曹達の製造が広く行はれている.著者は硝石及び曹達の生成過程と関連して原料土,浸出液及び製品の分析を行い,次の結果を得た. 1 硝石の製造には主として都市,村落附近の含窒素有機物に富む表土を掻き集めたものを原料土に用い,曹達の製造には地中及び地下水中より毛管力によつて地表に集積された塩皮殻を採取して原料に供試している. 2 製硝原土は全窒素として0.5～0.6%,硝酸態窒素として0.3～0.4%を含有し,アンモニア態窒素は僅少にすぎない.全固形物量は約8%に達する. 3 製硝原液は約1.5%の硝酸態窒素駈含有し,全固形物量も28%を示し,硝酸塩の外塩化物・硫酸塩の多量を含有している. 4 硝石の組成産みるに粗硝石はKNO3として77%で可なりの不純物を含有しているが,精製硝石はKNO3として92～95%を含有し,製品の純度は可なり高い. 5 曹達原料土の採取地の土壌を層位別に比較するに表土程アルカリ性が強く,且つ多量の可溶性炭酸塩を含有している. 6 曹達製造原料土の全固形物量は約8.5%,炭酸(CO3)として約0.8%にして,此外塩化物及び硫酸塩の多量を含有し,pH価10.1を示している

Studies on Polder Soils in Japan. : XVII. Nature of Salted Soil Formed by Flooding of Sea Water at the Typhoon "Isewan".

This study was conducted to determine some characteristics of salted soil formed by flooding of sea water at the typhoon "Isewan", occurred on Sept. 26, 1959, with special reference to the effect of salinity and sulfide on growth of rice plant. A survey was carried out on May 1960, on Mie Prefecture and soil samples were collected and investigated. By this survey and investigation, the following points were made clear: 1. A considerable difference in chloride content and electric conductivity was found among soil samples. It was observed that, in general, the surface soil before leaching contained a large amount of soluble salt but most of surface soil in which the leaching was accomplished showed a marked reduction of salinity, with less than 4 millimhos/cm electric conductivity. 2. The texture of sea-mud deposits was very fine, containing more than 30% of silt and 10% of clay, and an appreciable amount of H2S was produced when incubated in water-logged condition. 3. Most of the soil of this region had the common characteristic of halogenetic soil, containing relatively large amounts of exchangeable mono-valent cations and magnesium. 4. Some of the salted soil contained appreciable amounts of oxidizable sulfur and the pH values of the soil became extremely acid after oxidation with H2O2. 5. A considerable difference in content of H2S and readily soluble and HCl soluble sulfide was found among these samples of soil. The experiments have indicated that an addition of rice-straw to salted soil in water-logged condition enhanced the rate of formation of H2S and sulfides in soil greatly

Forms and Distribution of Phosphorus in the Profiles of Soils in Okayama Prefecture

岡山県下に分布する急傾斜地土壌,果樹園土壌,腐植質火山灰土壌及び老朽化水田土壌を供試して土壌燐酸の形態別の分別定量法を検討する一方,その層位別の分布を究明し,次の結果を得た. 1) 可吸態P含量は鉱質土壌及び腐植質火山灰土壌の何れにおいても未耕土は10ppm.以下で,とくに､"くろぼく",では殆んどが痕跡量にすぎなかつた.然るに熟畑化の進行に伴い可吸態P含量は次第に増加し,とくに施用燐酸の影響が顕著に認められた. 2) 鉱質土壌においては熟畑土壌では全P,酸性弗化物可溶P,酸可溶P及び有機態Pの各含量は何れも未耕土に比べて増加するが,就中吸收態Pと有機態Pの各含量の増加が著るしい, 3) 腐植質火山灰土壌においては未耕土の全P含量も可なり多く,その約80%が有機燐として存在している.且つ"くろぼく",に於ては燐酸肥料の施用により有機燐の増加及び吸收態Pと同程度,又はそれ以上の酸可溶Pの増加を結果する一方可吸態Pの増加は鉱質土壌に比べて遙かに僅少に止る

Studies on the Characteristics of Bottom Sediments, with Special Reference to the Nature of the so-called Hedoro in Japan : (I) Types of Oxidizable Sulfur Compounds in Muddy Sediments

水底の底質,とくにヘドロの特性を解明する目的で,まず本研究においては,児島湖,中海,八郎潟および岡山県下の瀬戸内海沿いの湾内の底質など,各地の徴粒質の堆積泥を供試して,所含酸化性イオウ含量と形態に重点をおいて,その実態を解明した. なお比較の対照として,徳島市内を流れる今切川の粗粒質の底質を供試して,前記堆積泥との比較を試み,次の結果をえた. 1.H2O,処理によって,堆積泥のpH価は顕著に低下し,PH4以下の強酸性に転じた試料も約半数に達した. これに対して,今切川底質の場合は,H2O2処理によるPH価の低下は,前者に比べて少なかった. 2.堆積泥試料の易酸化性イオウ含量は,337.0～2200.5mg S/100gと,試料間で大差を生じたが,全試料とも,かなり多量の酸化性イオウを含有することが判った. これに対して今切川底質は,14.0～225.8㎎S/100gの範囲にあり,前者に比べて明らかに少なく,酸化性イオウの生成量と底質の粒度組成,とくに粘土含量との問に密接な関係の存在することが判った. 3.堆積泥,今切川底質ともに,酸化性イオウとしてはFeS2が主要部分を構成すること,また児島湖その他数種の底質中には,かなりの量のFeSの存在することを認めた. これに対して酸化性イオウの絶対盤は異常に多いにもかかわらずFeSおよび単体・有機態イオウ含量はきわめて少なく,その大部分がFeS2より成る堆積泥も存在した. 4.酸化性イオウの形態別分析成績から,児島湖の底質中では,有機物の供給が豊富なため,硫酸還元菌の作用によるFeSの生成,さらには単体および有機態イオウを経てのFeS2の生成が現在も活発に進行していること,これに対して中海および波根湖の底質においては,過去に多量に生成したFeSが,現在では安定なFeS2に転化して,平衡状態を保持していることが推察された. これを要するに,嫌気的条件下にあるヘドロ中には,各種のイオウ化合物,主として硫化物が生成集積し,その生成過程および生成物はきわめて複雑であり,さらに硫化物の生成と好気的条件下での変化も,徴生物的および化学的の両作用の総合結果として進行し,かかる反応それ自体が底質の環境条件を左右する重要因子であることが判明した

Studies of Sendos of Mat Rushes. : IV. The Effect of Bentonite and Chemicals on Dispersiveness of Sendos in Preparing Mud Water.

Previous studies showed that there is a marked difference among the dispersion characteristics of sendo samples, and the coating work with sendo seems to be highly lessened by their dispersiveness in water. Therefore, in this study the effects of bentonite and chemicals on dispersiveness of sendos in preparing mud suspension were studied by the authors. The results obtained are summarized as follows: 1)Two kinds of bentonite samples produced in Gunma and Shimane prefectures are used in this study. The former may be classified as alkali bentonite and the latter as alkaline-earth bentonite according to their chemical and physical characteristics. 2)Sendo samples contained 10 percent of Gunma bentonite were prepared with Akashi, Awaji, Hiroshima, Kyushu and Okayama Sendos, and dispersion characteristics of these samples were compared with that of a non-treated sample. It is found that pH value and dispersiveness are more or less increased by the addition of bentonite and its effect has been exhibited strongly upon sendos which coagulate markedly in water. And the effect of Shimane bentonite is much less than that of Gunma bentonite. 3)Kyu-Akashi sendo samples contained 0.5 percent of sodium carbonate or 0.25 percent of sodium silicate are also highly dispersive in water, while non-treated samples coagulate completely in water. A combination of bentonite with chemicals is superior to bentonite and chemicals used singly for the increase of dispersiveness of sendos

A Study on Polder Soils in Japan : XII. On the Young Polder Soils of the East Fukuda Polder in Okayama Prefecture.

The purpose of this paper was to study the effects of iron sulfides which had been formed in marine deposits under an anaerobic condition on the chemical compositions and the soil forming processes of soils in East Fukuda Polder. These polder soils examined contained a large amount of soluble salts; especially chlorides constituted the dominant salt among them. Sulfates content was also high and soluble salts appeared to accumulate in surface layers. Air-dried surface soils showed fairly strong acidities, due to the presence of soluble acid compounds formed in the course of oxidation of iron sulfides contained in these soils. The content of FeS2 was found to be between 0.305% and 1.682% as SO3 in the original soils ; and 10% HCl sol. CaO contents were very poor. Soil reactions and soluble salts were determined after the incubation of soils during several weeks at 30℃ under the condition of the moisture content of field capacity. Consequently, in all soils, the pH value became extremely acid, and total solids and water soluble sulfates were greatly increased in the incubated soils; and a relatively good correlation was found between decreased pH values and increased sulfates contents in the incubated soils. It has been concluded that iron sulfides had a marked influence on the chemical compositions of soils and on the prospective soil forming processes of these polder soils

Studies of Sendos of Mat Rushes. : 1. On the Effect of Sendos for Coating the Stems of Mat Rushes.

イ草の品質は使用する染土の種類によつて変化するが,現段階においては染土のイ草に及ぼす作用そのものが未だ十分には解明されていない状態にある点に鑑み,本研究の第1段階として泥染のイ草に及ぼす機作の解明を試みた.その結果,染土作業の目的はコロイド粘土のゲル状皮膜で茎の表面を被覆する点にあること,またこのことが次の諸作用を通じて製品の品質,色調などに重要な影響を及ぼすことを明らかにした.すなわち1)乾燥過程中における効果粘土皮膜の存在によつて間接乾燥の状態となるため,乾燥は徐々に,かつ均一に進行し,このことがしわ,よぢれの生ずることを抑制し,更に葉緑素の酸化を抑えて褪色を減退させる.かつ乾燥促進の効果も若干は認められる.2)糊付の効果乾燥イに特有の直立性,柔軟性,弾力性を附与する.3)貯蔵中における効果過度の乾燥を抑制し,適温を保つ.4)色調に及ぼす効果製品の色調はイ草固有の色と附着している染土の色の綜合結果として示されることから染土の色調は製品の品質に著しい影響を与える

Studies on Polder Soils in Japan. : XVIII. Changes of Chemical Properties of Soil in Relation to Age of Polder Cultivated Under Paddy-Field Condition.

It is the purpose of this report to study changes of chemical properties of the soil in a halogenetic young polder, developed along the seacoast of inner Kojima Bay, in relation to the length of time which has elapsed since these polder being diked and cultivated under paddy-field condition. Soil samples used in this study were collected from Kojima 7 Polder B Section, A Section and Kojima 3・5 Polder. 7 Polder B Section is located in a recently empoldered virgin region. Ages of 7 Polder A Section and 3・5 Polder under paddy cultivation are 5 years and about 10 years, respectively. The results obtained are to be summarized as follows: (1)Ground water contains a large amount of soluble salts and its table is very high in a recently empoldered region. As paddy cultivation proceeds, a continuous decrease in salinity and lowering of water table are observed in well drained fields. On the contrary, salinity and water table remain unchanged in poorly drained fields along the dike. (2)The content of soluble salt in recently empoldered soils is also very high in all the horizons. A considerable part of soluble salt has been washed cut from the upper layer during 5 year cultivation by rain or irrigation water, and most of surface soils show the electric conductivity of less than 7 millimhos/cm, but salinity of subsoils remains unchanged, having 7 millimhos/cm or more. After about 10 year cultivation, all of the first horizon and most of the second horizon show a marked reduction of salinity, having the electric conductivity of less than 4 millimhos/cm and 7 millimhos/cm, respectively. (3)The reaction of all the horizons of just empoldered soils lies within the range pH 7.0 to 8.1 but that of most surface soils becomes slightly acid, after 5 year cultivation, and considerably acid after about 10 year cultivation, showing the pH of 6.0-6.9 and below 5.9, respectively. (4)Of exchangeable bases, mono-valent cations and Mg are more prominent than others, and the base-exchange complex is nearly saturated with bases in just empoldered soils. It is shown that the V values and exchangeable mono-valent cations are decreased slightly in surface soils but remain unchanged in subsoils during 5 year cultivation. After about 10 year cultivation, mono-valent cations and Mg are replaced by hydrogen, and V values decrease greatly in surface soils and the composition of the exchangeable bases gradually approaches to that of normal acid soil. (5)A large amount of oxidizable sulfur is found in all the horizons of just empoldered soils and a considerable decrease of oxidizable sulfur in surface soils is found after 5 year cultivation, but a marked decrease of oxidizable sulfure in all the horizons is found after about ten year cultivation. It is shown that oxidizable sulfur is rapidly oxidized in a field condition and its product is easily leached out. A relatively close correlation is also found to exist between the degree of desalting and the decrease of oxidizable sulfur