暗洞在粘质淤土中的排水效益

安徽霍邱县城西湖农场,是1966年围湖造田建成的一座大型机械化农场.该场地势低湿,土壤粘重,种植作物以旱作三麦为主.场內建有完整的排灌渠系,日降雨100毫米所形成的地面迳流可在一昼夜之内排除.但因土壤内排水性能甚差,田块又大,根层内饱和水长久不得消失,因而造成土壤湿害,既影响作物正常生长,又给田间机械化作业造成许多困.     

THE EFFECT OF SOIL COMPOSITION AND ENVIRONMENTAL FACTORS ON THE SHRINKAGE OF SOME CLAYEY BRITISH SOILS

The shrinkage potential of natural clods from a variety of clayey soils was measured and related to their physical, chemical and mineralogical properties. It is shown that the most important factors affecting shrinkage are initial bulk density, clay content, organic carbon content and cation exchange capacity of the peroxidised clay, and mica-smectite content on a whole soil basis. Multiple regression equations involving the initial bulk density, clay content, organic carbon and cation exchange capacity accounted for 87 and 82 per cent of the variation in total shrinkage of topsoils and subsoils respectively. Because of restrictions on shrinkage imposed by factors such as climate, crops, ground-water and moisture release characteristics of soils, soils with a high shrinkage potential may not behave very differently to soils with a much lower potential. On these grounds it is concluded that the shrinkage criteria used in US Taxonomy are not applicable in Britain.     

湖北省宜昌地区土壤有效锌含量分布及施锌肥效益分区

宜昌地区位于湖北省西南部,地跨江汉平原和鄂西山地,过渡性的位置和复杂的自然条件,导致土壤有效锌含量变化很大。在全区430万亩耕地中,严重缺锌土壤达208万亩,占总耕地面积48%,是粮食生产上新台阶的限制因素之一。     

DETECTION OF CLAY IN SOIL SOLUTION WITH METHYLENE-BLUE PAPER AND THE ASSESSMENT OF CLAY MOBILITY IN SOILS

The adsorption of methylene blue and the accompanying colour change appears to be a fairly specific and sensitive reaction for colloidal soil clay, especially when used with chromatography paper as a supporting medium. Thus minute amounts of clay in migrating soil solutions can be detected, and stability and electro-phoretic mobility of very dilute suspensions evaluated.     

旱改水对砂姜黑土中锌含量的影响研究

本文用连续分级浸提法,研究了旱改水对砂姜黑土中锌的含量、赋存形态和有效性的影响。砂姜黑土中的锌绝大部分以残留态存在,晶态铁结合态约占１０％,其余形态锌一般小于＃％。这些形态锌可以分为三类;一类为土壤锌的强度因子,即代换态锌,另一类是土壤锌的容量因子,即有机态、无定形铁结合态的晶形铁结合态锌;第三类为残留态 有效态锌主要来自代换态。旱改水后,晶形铁结合态锌向有机态和无定形铁结合态锌转化,使得土壤中锌     

几种土壤和粘土矿物上磷的解吸

用0.5NHOAc、0.5NNH₄F和0.1NNaOH浸提的方法,研究了几种土壤和粘土矿物上磷的解吸与矿物组成和时间的关系,以及追加吸附及其解吸状况,结果表明,全部供试样品磷的解吸量都随吸磷量的增加而增加;解吸平衡的时间除红壤需要1天外,其余样品均在1小时内基本上达到平衡,同时可见缓慢解吸作用的存在;追加吸附中可见到从吸附正值到吸附负值的转变,以及0.1NNaOH解吸磷量的明显变化。     

中国土壤胶体研究 Ⅵ.西藏高原几种主要土壤的粘土矿物组成和演变

西藏高原突起于我国西南,绝大部分地面的海拔高度在4000米以上,为世界上最高的大高原。它大致在第三纪开始形成,后来曾受第四纪冰川的深刻作用,高山顶部至今仍是冰川的活动场所^[1,2]。高原为昆仑山、唐古拉山、喜马拉雅山和横断山等大山脉所盘踞。     

STUDIES OF SOME CRACKING CLAY SOILS IN THE LAKE CHAD BASIN OF NORTH EAST NIGERIA

The pedological characteristics, and physical, chemical and mineralogical properties are investigated for soils developed in a 1 m to 1.5 m layer of lacustrine clay material deposited on a former sand plain in the Lake Chad basin in north east Nigeria. (These soils are being developed for intensive production of rice, wheat and other crops under irrigation.) The surface layer of these soils has about 60 per cent clay, a pH of about 7.9, and a coarse, strong prismatic structure. The sub-soil is often notably higher in clay content, pH and exch. Na. The smectite content of the clay fraction (surface soil) is 35 to 45 per cent and the CEC 350 meq kg^-1. The levels of montmorillonite and CEC, and the size of the cracks in dry soil, although the latter are appreciable, are all notably less than the values reported for the clay soils of the Sudan Gezira. The Lake Chad basin clay soils are not considered to be vertisols according to the FAO Soil Map of the World, on grounds of profile morphology, though it seems the French pedologists would regard them as paravertisols.     

MICROMORPHOLOGY OF SOME TROPICAL ALLUVIAL CLAY SOILS

The micromorphological properties of some marine and estuarine tropical clays from Holocene coastal plain soils of Surinam and Thailand have been explained against the background of sedimentation and initial soil formation. During geogenesis stratified sediments are formed, above which are sediments with slightly disturbed stratification, with or without matric faecal pellets. Pedogenesis during the sedimentation phase included development of channels in the sediment, formation of channel neostrians, biological homogenization, possibly pyrite accumulation, and partial oxidation and precipitation of iron as ferric hydroxide. During the brackish water phase pyrite accumulates in various amounts, mass illuviation may occur, part of the iron may oxidize and precipitate and part of the pyrite may be oxidized. During and after the swamp phase further oxidation and precipitation of iron as ferric hydroxide occurs, ferric hydroxide crystallizes into goethite. Pyrite becomes oxidized, resulting in the formation of jarosite, gypsum, silica, and ferric hydroxide.     

THE ORIGIN OF THE RED MEDITERRANEAN SOILS IN EPIRUS, GREECE

To determine the contribution of limestone weathering to soil formation the insoluble residues of six samples of the Pantokraton limestone were separated by treatment with 2M acetic acid at pH 3. The mean insoluble residue content is only 0.15% and to produce a soil depth of 40 cm it has been calculated that about 130 m of limestone would have to be weathered. No correspondence was found between the particle size distribution of the residues and of the overlying red soils, and the high siltrclay ratios of the soils do not indicate prolonged subtropical weathering. The particle size distribution of the soils is akin to that of aerosolic dusts. The dust loading of the atmosphere in the eastern Mediterranean is among the highest recorded, and it is proposed that the soils have developed on dust blown by sirocco winds from the deserts of N. Africa.     

EFFECTS OF CULTIVATION ON SOIL WATER RETENTION AND WATER USE BY CEREALS IN CLAY SOILS

The effects are repotted of direct drilling and mouldboard ploughing on soil water retention and extraction in three soils over two to four years. In the years 1972–75 when winter rainfall was close to or greater than the long-term average the maximum soil water content of the upper 100 cm differed little between the cultivation treatments. In contrast, after the dry winter of 1975–76, about 10 per cent more water was stored in the direct-drilled soil, especially below 50 cm. In the following dry summer, winter wheat extracted up to 22 mm more water from uncultivated soil and this was associated with better growth of the crop than after ploughing. When simulated rain was applied, water infiltrated rapidly to a depth of 50–100 cm in direct-drilled soil, whereas on ploughed land its movement was retarded below the plough sole even when cultivation had been carried out under conditions which minimized smearing. Water storage at depth was consequently greater under dry conditions in the direct-drilled soil while excess water reached drain depth more rapidly in wet conditions.     

SOIL DEFORMATION AND SHEAR STRENGTH CHARACTERISTICS OF SOME CLAY SOILS AT DIFFERENT MOISTURE CONTENTS

The soil deformation and shear strength characteristics of three clay soils were determined at different moisture contents and spherical pressures, using a quick un-drained triaxial compression test. The soils were found to deform either in a compressive way or by brittle fissuring, depending upon the relative values of moisture content, dry density and spherical pressure. The critical state concept of soil deformation can explain qualitatively the behaviour of these spils at high moisture contents but not at low. The Bridgman concept for fracture in brittle materials describes the soil behaviour at low moisture contents. The shear strength of the clay soils tested was more closely related to the soil moisture suction and to the amount of shrinkage which occurred on drying than to the absolute dry bulk density. The influence of moisture content and spherical pressure on the effectiveness of certain cultivation operations are considered.     

几种土壤组分对原有土壤中锌的富集能力的研究

本文研究了我国部分自然土壤中氧化铁、氧化锰及有机质三种组分对原有土壤中锌的富集能力。并比较了不同土壤类型中各组分对锌的富集能力,探讨了土壤环境条件主要为pH对组分富集能力的影响。结果表明,土壤中这三种组分其单位含量对锌的富集能力为:氧化锰>氧化铁>有机质;三:种组分对锌的富集能力在土壤间的变化以氧化铁最为明显,其顺序为石灰性土壤>中性土壤>酸性土壤;土壤pH对土壤氧化铁富集锌能力的影响也很明显。氧化铁对锌的富集分配比例为:酸性土壤<5,中性土壤5—15,石灰性土壤≥15,各土壤组分对锌的富集容量次序为:氧化铁>有机质>氧化锰,氧化铁中,晶形铁>无定形铁。     

粘土夹层对地下水上升运行的影响

我国华北平原土壤质地情况比较复杂,壤土剖面中,在不同部位上往往有不同厚度的粘土层^[6]。土壤中水盐运行的情况密切受土壤质地和地下水位的影响^[5]。如土壤剖面中有粘土夹层,它将在很大程度上影响剖面中水分的分布和运行。     

土壤理化性质对铝电极电位的影响

本文系统研究了土壤的某些主要理化性质对铝电极电位的影响。结果表明，土壤水分，土壤松紧度，土壤盐分及土壤ｐＨ对铝电极电位都有明显影响。在土壤饱和水后和饱和水前的一定含水量范围内，则出现一个很大的电位突降。在同一含水量情况下，电位与土壤容重呈明显的线性反相关。土壤盐分浓度的增高能导致电位的负偏。同时在不同土壤中，盐分的作用也各相同。可变电荷土壤盐分的加入对电位的影响比较明显，从土壤ｐＨ的影响可以区分出