乌拉盖水库工程天然建筑材料调查与评价

水利水电工程一般多因地制宜、就地取材,有的当地天然建筑材料甚至成为决定建筑物类型和工程造价的决定性因素。本文分析了区域地形、地貌、地层、岩性等,通过地质调查、钻探、坑探等勘察手段,在前人工作程度很低的地区寻找到了设计需要的建造土坝的各种材料。同时,使用野外和室内土工实验方法,研究了这些建材的物理、力学性质。在此基础上根据平均厚度法和设计、规范标准对各料场建材进行了计算和评价,其质量和数量均满足要求,为本工程设计和施工提供了可靠的建材依据。     

Interaction of Bradyrhizobium sp. with an antagonistic actinomycete in culture medium and in soil

Summary Experiments were conducted to determine the extent to which populations of Bradyrhizobium sp. strain Tal 209SR were suppressed by the antagonistic activity of a Streptomyces sp. isolated from a highly weathered tropical soil. The activity of the actinomycete was evaluated in culture medium in the presence or absence of clay minerals and in the soil from which the actinomycete was isolated after sterilization by gamma-irradiation. The presence of the actinomycete in culture medium was associated with a significant reduction in the density of Bradyrhizobium sp. (Tal 209SR). Nevertheless, the density of the Bradyrhizobium sp. surviving in the medium in the presence of the actinomycete was much higher than that normally observed when comparable densities of rhizobia are introduced into non-sterile soils. The presence of the antagonistic actinomycete in culture medium was associated with a drastic decrease in the optical density of the medium. This decrease was accompanied by a significant decrease in the insoluble exopolysaccharide content of the medium in addition to the significant decrease in bradyrhizobial cells. The actinomycete did not appear to significantly influence the growth and survival of the test Bradyrhizobium sp. in sterile soil. The inability of the actinomycete to significantly antagonize the test bacterium in sterile soil was not adequately explained by the presence of clay minerals.Hawaii Institute of Tropical Agriculture and Human Resources Journal Series No. 3129     

Water-dispersible clay after wetting and drying cycles in four Brazilian oxisols

Widespread intensive land use in the seasonal tropics can damage the physical stability of aggregates. Similar damage can be expected from wetting and drying cycles causing aggregate fragmentation and, consequently, leading to an increase in their specific area and exposure of internal electric charges. Thus, we hypothetised that the influence of wetting and drying cycles is dependent on the mineralogical composition of oxisols (latosols) and it is higher in soils with low aggregate stability. A greenhouse experiment was carried out to test this hypothesis in highly weathered soils from Brazil, all with variable-charge clays and highly stable aggregates. Wetting and drying cycles were defined from the quantity of water available between field capacity and the permanent wilting point. Soil columns were submitted to 0, 2, 6, 9, 12, 15 and 18 wetting and drying cycles. After each number of wetting and drying defined physical and chemical properties were determined. Statistical analysis, such as simple and multiple linear regression and Pearson's correlation were performed, showing significantly correlated WDC contents with wetting and drying cycles. The obtained results led to the conclusion that there was a close interdependence among mineralogical composition, aggregate stability and WDC influenced by wetting and drying cycles. Soils of reduced aggregate stability like kaolinitcs made them more susceptible to the action of wetting and drying on the WDC. Changes in the WDC with wetting and drying cycles showed correlated with eletrochemical properties.     

海南岛土壤粘粒矿物特征与土壤系统分类

研究了海南岛不同母质土壤的粘粒矿物特征:都含有较多的高岭石,其中玄武岩发育土壤粘粒中高岭石最多,但其结晶最差。片岩和紫色砂岩发育土壤含相当多的水云母,粘粒部分水云母含量高达40％～45％,石灰岩发育土壤水云母含量亦较高,达20％～37％,此类水云母属二八面体型的水化白云母。玄武岩和花岗岩发育的“湿润”土壤粘粒中针铁矿与赤铁矿的含量之比为（3～4）:1,而花岗岩发育的“常湿”土壤粘粒中只有针铁矿,不见赤铁矿存在,证明土壤中氧化铁矿物的类型是土壤湿润状况的反应,在中国土壤系统分类中可以用来区分“湿润”和“常湿”土壤的一个指标。     

我国变性土粘土矿物组成和土壤系统分类

对淮北变性土和长江下游变性型新成土的粘土矿物半定量研究表明,变性土胶粒和粘拉以蒙皂石占优势,粘料中蒙皂石占41.1％～56.5％,次为水化云母、高岭石。新成土胶拉以蒙皂石为多,粘粒则以水化云母为主,占43.6％～51.0％,次为高岭石,尚存蒙皂石及混层矿物。二地区土壤粘拉中含蛭石,但均未发现绿泥石。粉砂中矿物类型甚多,但几无蒙皂石。作者认为大量膨胀性粘土矿物存在,是土壤产生变性诊断特征的物质基础,因而是变性土鉴定主要依据之一。文中对上述土壤作了土属的系统分类和命名。     

Variations in soil characteristics affecting the occurrence of Aphanomyces root rot of sugar beet - Risk evaluation and disease control

Damping off and chronic root rot of sugar beet caused by Aphanomyces cochlioides is a major constraint in cultivation of sugar beet, with occurrence of the disease in Sweden being concentrated to specific areas. This study examined soil factors that can be used for risk assessment of Aphanomyces root rot. Soils from 134 field plots were assessed over three years for Aphanomyces root rot potential in bioassays and analysed for easily measured soil factors such as soluble nutrients, pH and soil electrical conductivity (EC). Classification of the field plots into four groups with increasing disease severity index (DSI) according to the bioassay revealed that the group with the lowest DSI (<39) had an average soil calcium (Ca) content of 430 mg/100 g and a soil EC of 1.12 mS/cm, which were significantly higher than in the groups with DSI >40. From these results, we concluded that soil Ca concentration is an easily measured factor that can be used to identify soils with an increased risk of Aphanomyces root rot. We suggest that the Ca content should be above 250 mg Ca/100 g soil to avoid problems with Aphanomyces root rot in sugar beet. To gain a more thorough understanding of the geographical variation in Aphanomyces root rot and its connection to the geological origin of the soils, a number of other soil factors were analysed in the field plots, including clay mineralogy, CEC, and particle size distribution. Aphanomyces root rot was very rare in soils with a high proportion of smectite and vermiculite relative to illite and kaolin minerals, here predominantly calcareous soils developed on clay till in south-western Scania.     

绰墩遗址古今水稻土黏土矿物特征比较研究

在江苏绰墩山遗址考古发掘中,发现了在剖面不同深度埋藏的距今约6000年的史前水稻土层、距今约3 000年的商周史前的古水稻土层和现代水稻土层.本研究为了比较古今水稻土黏土矿物特征的差异,以土壤剖面P01(包含史前古水稻土、商周史古水稻土和现代水稻土)与P03(仅含商周时期古水稻土和现代水稻土)为对象,测定其各种形态铁锰...     

Impact of rainfall and topography on the distribution of clays and major cations in granitic catenas of southern Africa

Soil catenas integrate and amplify gravity transfer and differentiation processes of eluviation and illuviation in soil profiles. We quantified differences in these redistribution processes along granitic catenas across an arid to sub-humid climate gradient in Kruger National Park, South Africa. We measured soil properties in nine catenas sampled from three areas receiving annual rainfall of 470 mm (arid zone), 550 mm (semi-arid zone) and 730 mm (sub-humid zone). As rainfall increased, kaolinite replaced smectite as the dominant clay mineral in all landscape positions across the catenas. Toeslopes showed the strongest evidence of this transition with an excess of smectite in the arid catenas but complete prevalence of kaolinite in toeslopes of sub-humid catenas. The concentration and distribution of clay along the catenas were dependent on landscape position as well — soil profiles at and near the crests were clay depleted (as low as 1%) while those at the toeslopes had much more clay (up to 60%). Clay redistribution along catenas was sensitive to climate with the least amount of redistribution occurring in the dry sites and the most occurring in the wet sites. As a consequence, the sub-humid catenas had clay accumulation only in a small part of the toeslopes while the bulk of their length was represented by highly leached soils. In contrast, arid zone catenas showed little clay redistribution and semi-arid sites displayed the greatest within-catena clay redistribution and preservation. Clay movement and storage conditioned other soil properties such as CEC, base cation distribution, base saturation and pH.     

Comparative Ammonium and Potassium Fixation by some Wetland Rice Soil Clays as Affected by Mineralogical Composition and Treatment Sequence

Comparative fixation of NH₄ and K by wetland rice soils in relation to clay mineral composition and treatment sequence is of agronomic interest, but information on the subject is scanty. An attempt has been made to clarify this relationship by employing the normally recommended doses of fertilizers, 3 application sequences, and 5 soil clays of divergent mineralogies. The results show that montmorillonitic clay is the greatest fixer of NH₄, but least of K. X-ray amorphous clay also prefers NH₄ over K. Vermiculitic and beidellitic clays strongly fix both NH₄ and K. Soil clay consisting of hydrous mica, chlorite, and halloysite fixes low proportions of applied NH₄ and K. The sequence in which NH₄ and K are applied does not appear to affect the relative amounts that are fixed.     

黄土高原淋溶土黏粒、氧化铁与颜色的关系及发生学解释——以山西土系调查的31个黏化层为例

以黄土高原山西省14个淋溶土剖面的31个偏红的黏化层(Bt)为研究对象,分析了其全铁、游离氧化铁、无定形态氧化铁的含量与土壤颜色参数、黏粒含量之间的相关性,并建立了定量关系模型。结果表明:Bt的黏粒含量与氧化铁含量之间呈极显著正相关(P0.01);颜色的红度与全铁、游离氧化铁和无定形氧化铁含量之间均呈极显著正相关(P0.01),其中游离氧化铁是最直接的土壤红色"染色剂";其他色调、明度与彩度等颜色参数与土壤全铁、游离氧化铁含量之间亦呈现出显著的相关性,这也间接说明了黏粒含量与土壤颜色具有一定相关性。野外观测发现,某些黏化层结构体表面颜色较结构体内基质颜色更红,证实了在土壤结构体表面氧化铁随着黏粒在土壤空隙中的迁移淀积。黄土高原淋溶土偏红的黏化层多是来自由于土壤侵蚀而出露地表或接近地表的第三纪保德红土和第四纪红黏土,其黏粒含量、土壤颜色等指标均表明第三纪的古气候条件较第四纪更为湿热。