THE OXIDATION OF IRON SULPHIDES IN SOILS IN RELATION TO THE FORMATION OF ACID SULPHATE SOILS, AND OF OCHRE DEPOSITS IN FIELD DRAINS

Aerating pyritic soils causes acidification and the forrnation of acid sulphate soils, or cat-clay. The Oxidation of pyrite in soils is associated with the deposition in tile drains of a form of ochre quite distinct from that formed by the action of filamentous iron bacteria. Pyrite-derived ochre results from the action of Thiobacillus ferrooxidans, which, below pH 3.5–4.0, catalyses the Oxidation of Fe²⁺ and pyrite. In soils less acid than c. pH 4, pyrite oxidizes relatively slowly by chemical reactions to Fe²⁺ and SO²₄^?. Under these conditions iron enters the drains as Fe²⁺ and is there oxidized by T. ferrooicidans and deposited as hydrated ferric oxide. Once the soil becomes acid enough for T. ferrooxidans to multiply, the rate at which pyrite oxidizes increases several-fold, and at c. pH 3 iron appears in the drainage water in the ferric form. Liming seems to decrease the rate of Oxidation.     

我国灌淤土的形成和分类

本文从全国范围内全国地研究了灌淤土的形成特点，主要表现在：（１）地面的抬升和耕层的加厚；（２）有机质及Ｎ、Ｐ、Ｋ等养分的增加；（３）土体含水量的提高；（４）可溶盐和石膏的淋洗；（５）碳酸盐和石膏的淋溶与补充；（６）灌淤层理的消失和土壤物理性状的改善等。总结了灌淤土的诊断层－灌淤表层的特点，阐明了灌淤土在土壤系统分类中的位置：灌淤土作为人为土壤，它与干旱土、潮湿土、始成土和新成土等其它土壤具有很大的     

QUANTITY-INTENSITY RELATIONSHIPS FOR LABILE SODIUM IN FIELD SOILS1

Exchange isotherms for Na with Ca+Mg in ten unfertilized soils show smaller buffer capacities for Na than K, larger Na than K activity ratios at equilibrium, and curvatures of the graphs at small Na activity ratios that could indicate larger exchange energies on about 0.5 per cent of the exchange sites. Since equilibrium Na activity ratios in the soils were similar to those in rain, the latter ratios could be most important in controlling Na activity ratios in soils and the percentage saturation of exchange complex with Na. The geochemical significance of these ratios is discussed.     

山西大同盆地的盐漬土及其苏打累积和碱化問題

大同盆地位于山西省北部,地带性土壤为淡栗鈣土。这种土壤与內蒙古的集宁和呼和浩特等地的淡栗鈣土相类似,属于同一发生类型;唯只見于大同盆地北部。至于盆地南部地区如渾源一带的土壤,就很少具有淡栗鈣土特征;而和雁門关以南的土壤性状差不多。从这些土壤特性来看,大同盆地正好位于干草原向南部干早灌丛草原过渡的地带。     

不同利用方式下红壤结构的形成

本文应用顺序脱胶法,对砖红壤、赤红壤和红壤在不同利用方式下的水稳性团聚体的有机和无机胶结物组成进行了分析研究。水稳性团聚体共分>5,3-1,1-0.5和<0.25毫米四级。结果表明,红壤开垦后随着粘粒活度的增加和无机胶结物含量的降低,土壤团聚体的水稳性和土壤结构系数逐渐降低。但是,一旦采用合理的施肥和管理方法,这些物理参数又会逐步恢复和增加。此外,还研究了土壤结构稳定性与土壤地带性的关系。作者认为在中亚热带的红壤上施用有机物料以增强它的结构稳定性比热带砖红壤上施用更为重要。     

利用方式对红壤水稳定性团聚体形成的影响

本文研究了五种利用方式对红壤水性团聚体形成的影响。结果表明，＞稳定性团聚体含量：林地＞旱地＞荒地＞茶园＞果园。水稳定性团聚体数量以及团聚的水稳定性均与有机质的含量呈正相关。红壤开垦后，有机抽分解加快或补充减少是导致团聚体稳定性下降和水稳定稳定团聚体减少的主要原因。同理，恢复和改良红壤结构性及结构稳定性的关键是增加有机质的投入。     

PROCESSES OF HUMUS FORMATION AND TRANSFORMATION IN SOILS OF THE CANADIAN GREAT PLAINS

A study of the A horizons of cultivated soils from Saskatchewan, Canada showed that the organic carbon contents were in the sequence semi-arid Dark Brown soils (1.7 per cent), < Black soils (2.55–2.8 per cent), < sub-humid Dark Gray soils (4.5 per cent). The relative proportions of humic acids and the ratios of humic acid: fulvic acid increased in a similar sequence. There were accompanying increases in extinction values at 280 nm, and in levels of nonhydrolyzable nitrogen suggesting more extensive polycondensation of humic materials. These observations are discussed in terms of a working hypothesis for humus formation and transformations, that gives particular emphasis to the soil environment and to interactions between organic and inorganic components.     

THE DETERMINATION OF IONIC DIFFUSION COEFFICIENTS IN FIELD SOILS. I. DIFFUSION COEFFICIENTS IN SIEVED SOILS IN RELATION TO WATER CONTENT AND BULK DENSITY

A method for measuring diffusion coefficients in large cores of structured field soils has been developed and tested, in the first instance using sieved soil. Bromide-chloride and bromide-nitrate counter diffusion coefficients have been determined using ion exchange membranes as sinks for the diffusing ions. The effects of membrane selectivity, soil surface preparation, solution concentration, water content and bulk density have been investigated. The organic colloid content appears to have a considerable influence on the impedance factor-water content relationship of a soil. Increasing the bulk density at constant volumetric water content linearly reduced the impedance factor by up to 30 per cent. The relationship between impedance factor and bulk density is discussed.     

鄂西山地的酸性棕壤和灰棕壤形成条件及理化性质

根据鄂西山地的自然成土条件，分析了酸性棕壤、灰棕壤诊断层和诊断特性，主要理化性质和粘土矿物组成，结果表明：酸性棕壤和灰棕壤同属于亚热带中山上部或亚高山中上部冷湿条件下形成的森林土壤。其理化性质与我国北方同类土壤又有较大差别。     

黄土区土壤腐殖物质的化学性质及其与成土条件的关系

土壤腐殖质是土壤发生、发育的结果,是土壤区别于成土母质的主要标志。特定的生物气候条件(以及其它成土条件)形成特定的土壤类型,也形成具有特定性质的土壤腐殖质。因此,研究土壤中腐殖物质的组成、特性可以在一定程度上估计土壤生物活动的强弱与成土过程的趋向,从而为土壤分类提供重要的依据。     

我国北部草原系列土壤中成土作用对微量元素含量影响的经向分异

根据我国北部草原系列土壤中１０种微量元素的实测结果，用方差分析和多重比较方法研究了母质和土类因素对该地区土壤微量元素含量的影响。并以主成分得分的调整独立方差为依据，探讨了成土作用对土壤微量元素含量影响的方向，强度及地域分异特征。研究结果证实，不同母质和土类单元草原土壤中微量元素含量有明显差异，其中母质单元间的差别尤为显著，影响草原土壤表层微量元素含量的主要成土因素包括两种类型：导致元素含量下降的淋     

苏北滨海盐渍土的形成和演化

为了加速滨海盐渍土的垦殖和改良利用,建设高产稳产的农业生产基地,必须弄清滨海盐渍土的形成演化规律,提高我们认识自然,改造自然的自觉性,减少片面性和盲目性.     

A METHOD OF PREDICTING BULK DENSITY CHANGES IN FIELD SOILS RESULTING FROM COMPACTION BY AGRICULTURAL TRAFFIC

A simplified soil mechanical model was constructed to predict compaction beneath agricultural wheels when running on soils of certain characteristics. Soil strength functions were developed from in situ measurements of field soils and some laboratory measurements. Soil strain was measured by surface sinkage and changes of dry bulk density by gamma-ray transmission methods. Soil stresses were measured by deformable spherical transducers and compared to predicted stresses using equations developed by Söhne. A method of analysis was devised to identify a form of the virgin compression line from field data. Changes of the slope and intercept of this line were monitored over a range of moisture contents for two soils and used in the prediction model. The prediction model was tested against compaction measured during independent experiments at different sites. Good prediction was found for soils of initial dry bulk density greater than 1.1 g cm^?3 and cone resistance greater than 500 kPa, using a 30°, 12.9mm diameter cone. On looser and weaker soils the predicted compaction was often less than measured values. Using the model for simulation of compaction beneath a range of wheels revealed that contact pressure alone can be a misleading guide to compaction. Increases of bulk density below 10cm are considerably influenced by wheel load. The most effective way of reducing compaction requires the use of both a minimum load and a maximum contact area.     

珠江三角洲水稻土的形成发育

珠江三角洲是华南最大的三角洲平原,全国著名的水稻生产基地,其土壤的形成发育是与.三角洲的形成发展密切相关,并随其演变而不断演化。即泥滩生草或长红树林后,围垦种稻初期,形成沼泽型或酸性盐渍型、盐渍型水稻土,随着种稻时间的延伸,脱沼泽化、脱酸化、脱盐化作用的不断进行,发育成潜育型和潴育型水稻土。在此发育过程,肥力自然趋于下降,但人为的耕作、施肥水平是影响其肥力和发育方向的关键因素。     

江西地区红壤性水稻土形成的特点

红壤性水稻土是我国中亚热带地区的主要水稻土类型。根据江西省土壤普查的初步统计资料(1960),总面积约占全省水稻土的50%以上。红壤性水稻土基本性质的研究,已经累积了许多资料^[1]。侯光炯和马溶之首先从形态发生的角度、研究了江西南昌地区某些红壤性水稻土的特性,以及形成过程中物质移动的淀积特征^[2]。     

不同类型菜田和农田土壤磷素状况研究

以西北地区有代表性的灌淤土为供试土壤,研究不同类型菜田(露地菜田和蔬菜保护地)及农田土壤的P素状况,以及蔬菜保护地土壤P素的空间分布特性。结果表明,露地菜田、蔬菜保护地土壤全P、无机P、有机P、Olsen-P的平均含量是一般农田土壤的1.43~8.30倍,土壤Olsen-P占全P的比率显著高于一般农田。蔬菜保护地土壤各形态P素主要积累在0~30cm土层,并随土层深度的增加各形态P素的含量逐渐降低,各土层Olsen-P、Ca2-P、Ca8-P、Al-P含量降低幅度明显高于Fe-P、O-P、Ca10-P。     

南极半岛海洋气候区的土壤Ⅷ.鸟成土

以强烈生物活动参与和外源有机质输入为发生学基础、以鸟粪矿化与下部岩石层磷化作用为主要发生学过程的鸟成土在南极海洋气候区广泛分布,形成独特的海岸带土壤景观。本文对南极海洋气候区内鸟成土的发生学特点、剖面形态特征、新成矿物主要类型及其发生机制进行了论述;对鸟成土随栖息地遗弃向残积鸟成土演变的过程进行了阐述。在上述基础上,论述了本区内鸟成土在发生、发育与演化过程中相对于南极其他地区鸟成土所表现的特殊性。