阴山北麓农牧交错带裸露耕地土壤风蚀物垂直分布规律

为了解阴山北麓农牧交错带的土壤风蚀特性,采用SCC-6型集沙仪在野外自然风况下对风蚀物进行实地收集试验并对其粒度组成进行分析研究,得到了阴山北麓农牧交错带裸露耕地土壤在自然风况下风蚀物沿高度的变化规律,揭示了风蚀物沿高度的变化规律和不同跃移颗粒体的粒度组成沿高度的变化特征。并利用室内风洞研究了不同风速作用下,不同风力作用时间内,风蚀物含量沿高度的变化规律和风蚀量与风速的关系。结果表明：阴山北麓农牧交错带土壤风蚀是一种近地表的风沙运动,风蚀物跃移颗粒体主要集中在7.5～43.5 cm高度,风蚀物含量沿高度呈一递减函数,对幂函数、指数函数和对数函数均具有较好的相关性;风蚀物颗粒组成与风蚀强度和地表状况关系密切;风蚀物颗粒组成以某一粒径范围、某一高度为界随高度的变化而表现出明显的规律性;风蚀量沿高度的变化与风力作用时间有关,风蚀量随风速的增大呈指数增加。为研究该区域土壤风蚀规律及提出合理防风固沙措施奠定了基础。     

裸露耕地土壤风蚀物化学组分的分布特征

为研究风蚀引起的土壤营养物质的流失,进一步理清土壤沙化的原因及机理,该文以内蒙古阴山北部的典型农牧交错带耕地为试验区,采用SCC-6型集沙仪收集跃移土壤风蚀物,对收集到的土壤风蚀物进行筛分、称质量,并对表层土壤及收集的土壤风蚀物采用化学滴定及火焰原子吸收分光光度法对土壤营养物质中的主要成分及部分金属元素组成进行测定。通过分析整理,得出了风蚀物各化学组分含量、各化学组分总质量在地面垂直高度的分布规律,以及土壤各化学组分含量、土壤粒径大小与风蚀程度的相关关系;通过化学组分含量的分布规律分析进一步验证了风蚀是使细小颗粒的损失,造成土壤贫瘠的主要因素。     

裸露耕地土壤风蚀跃移颗粒分布特征的试验研究

以内蒙古阴山北部的典型农牧交错带耕地为试验区，利用DEM6型轻便三杯风向风速表和LV50便携式风速仪(可测瞬时风速和任一时段的平均风速)，采用SC—I型沙尘采集器收集跃移沙粒，并对收集到的沙粒进行筛分、称重，详细地分析了不同高度风蚀物百分含量、输沙量等风沙运动主要影响因素的变化特征，得出了耕地土壤在风沙跃移运动中的粒径分布特征，初步了解了该地区土壤风蚀的特点，为今后风沙运动力学理论的深入研究，以及实施保护性耕作和其他土地荒漠化的防治提供依据。     

北方农牧交错带农田风蚀成因与防治

我国北方农牧交错带是指自东北西部科尔沁草原向西南沿长城至兰州附近长2 000多km、宽200~300 km的特殊地带,区内年降水量在400 mm以下,生态环境脆弱,土地生产力的丧失是风蚀对土壤吹蚀累积影响的结果。分析了农牧交错带农田风蚀的成因和风蚀对农田生产力的影响,认为通过实施农田保护性耕作措施控制风蚀是可行的,从植被覆盖及农田耕作时间、措施上对风蚀进行控制应是防治风蚀研究的重点。     

北方农牧交错带不同农作制度对土壤风蚀因子的影响

不合理的农作制度是引发北方农牧交错带土壤风蚀的重要原因。以内蒙古武川旱农试验区为基地,研究了撂荒制、压青休闲制、粗放轮作制、保护性耕作制4种农作制度对风速、土壤紧实度、地表粗糙度、地表覆盖度、土壤有机质含量、表层土壤含水率、土壤风蚀量等因子的影响。结果表明,保护性耕作能够显著降低土壤风蚀,有效防止土地荒漠化。当前,北方农牧交错带应重点推广保护性耕作制,促进农业生产的可持续发展。     

农牧交错带缓坡丘陵区土壤风蚀研究——以内蒙古后山地区为例

土壤风蚀与风、土壤粒径组成和地表植被覆盖度有关,在农牧交错带缓坡丘陵区,风蚀是很严重的自然灾害。通过在有风的天气对丘陵不同坡向和坡位的风速和风蚀量以及土壤粒径进行测定和分析,得出丘陵不同部位受侵蚀大小是坡顶大于北坡、北坡大于南坡。该项研究为控制缓坡丘陵土壤风蚀提供了理论支持。     

土壤风蚀物中沙粒的动力学特性分析

该文以内蒙古阴山北部的典型农牧交错带耕地为试验区,采用SC-I型沙尘采集器收集跃移沙粒,对收集到的土壤风蚀物进行分析整理,得出了沙粒动力学计算的各重要参数,并从单颗粒土壤在气流中所受的作用力出发,紧密联系野外实验测得的数据,采用4/5阶RKF算法,对沙粒不同受力状况下的运动轨迹和运动特征进行分析。研究表明沙粒粒径愈小发生漂浮所需要的条件愈低,随粒径的增大要求达到的旋转角速度ω、垂直起跳初速度v0越来越大,而小于0.075 mm的颗粒容易在脱离地面后,浮在空中从而成为悬移的主体;同时得到了沙粒最大跃移高度Hm关于风蚀物粒径D和垂直起跳初速度v0的通用双因子预测模型。研究为今后风沙运动力学理论的深入研究及土地荒漠化的防治提供依据。     

农牧交错带不同农田耕作模式土壤风蚀的风洞实验研究

在农牧交错带——内蒙古自治区太仆寺旗采集的土壤样品的风洞实验研究结果表明:耕作模式的不同导致土壤风蚀状况的差异。在深松、翻耕、翻耕碾碎、小麦茬10 cm、荞麦茬10 cm、胡麻茬10 cm与无残茬等7种耕作模式的风洞实验中,翻耕碾碎风蚀速率均值最大,达到124.8 g m-2 min-1,胡麻茬最小,为15.14 g m-2 min-1,前者是后者风蚀速率的8.24倍。7种耕作模式风蚀速率均值的大小顺序为:翻耕碾碎>无残茬>深松>荞麦茬>翻耕>小麦茬>胡麻茬。结合对不同耕作模式土壤风蚀速率与风速关系的进一步分析可定量揭示出:翻耕碾碎、无残茬模式防风蚀效果最差,胡麻茬、小麦茬、翻耕模式防风蚀效果最好,深松、荞麦茬防风蚀效果居中。本文结论对农牧交错带旱作农业增强农田防风抗蚀能力有借鉴意义。     

农牧交错带不同利用方式下草原土壤的变化

以半干旱农牧交错带的典型土壤类型－具有过渡特性的，质地较砂，肥力一般的栗钙土为代表，从轻度放牧疏林草地，轻度放牧草地和重度放牧草地，以及耕地的不同利用方式下，土壤物理性质，化学性质和生物学性质的角度，阐明了草原土壤的变化。进而指出，在半干旱农牧交错带生态环境脆弱背景下，人为的滥垦和不合理的管理，以及过度放牧是引起土壤紧实度增加，土壤风蚀沙化和土壤养分丧失的主导因素。     

开垦对农牧交错带地带性和非地带性草地土壤性质的影响

该文以农牧交错带由地带性和非地带性草地开垦的农田及其相应的草地类型为研究对象,采用野外取样与实验室分析相结合的方法研究了开垦对农牧交错带草地土壤理化性质的影响,以期为农牧交错带土地的合理利用提供参考。结果表明,草地开垦后,其土壤特性出现颗粒组成粗化,体积质量增加,土壤毛管持水力降低,土壤有机碳、可溶性有机碳全氮、有效磷、有效钾和土壤有效态微量元素质量分数降低的现象;开垦导致了地带性草地土壤中有效铁、有效锰质量分数不能够满足农作物生长发育之需要。基于对地带性和非地带性两类草地开垦后土壤性质变化的分析及对比,提出了在农牧交错带秋季收获时应该对作物进行高留茬处理并适当延后春季翻耕时间,以减少风蚀作用的负面影响;应该通过秸秆还田和增施有机肥等方法来改善土壤性质,建议研究区应严格贯彻执行禁止对地带性草地的开垦,对已开垦的地带性草地应尽快实施国家提出的退耕还草政策;对于非地带性草地开垦的农田,应注重科学管理,合理利用。     

碳酸钙对石灰性土壤颗粒组成测定的影响

采取化学分析和Tessier连续提取法,对西宁市6个功能区城市土壤重金属Cu、Zn、Pb和Cd的含量及形态进行研究。结果表明:西宁市各功能区土壤的Cu、Zn、Pb和Cd的全量分别是全国土壤相应重金属几何平均值的1.9~5.2,1.9~6.9,0.8~4.0,7.4~11.1倍,4种重金属污染比较严重。6个功能区的重金属Cu、Zn、Pb和Cd含量进行差异显著性分析,结果是广场区Cu的含量与风景区的差异不显著(P>0.05),但与其他4个功能区差异显著(P<0.05);风景区与开发区差异显著(P<0.05),但与其他4个功能区差异不显著(P>0.05);开发区Zn的含量与商业区和居民区的差异显著(P<0.05),而其他各功能区间差异均不显著(P>0.05);各功能区Pb和Cd的含量均无显著差异(P>0.05)。研究土壤中重金属的化学形态有较大的差异,Cu以残渣态和有机结合态为主;Zn以残渣态和铁锰氧化物结合态为主;Pb和Cd以残渣态为主。Cu活性相对较高的土壤出现在风景区、矿冶区和居民区,Zn活性相对较高的土壤出现在风景区和广场区,Pb活性相对较高的土壤出现在风景区和居民区,Cd活性相对较高的土壤出现在矿冶区和开发区,研究土壤中4种重金属均具有一定的生物有效性和潜在的生态危害性。     

激光粒度仪与沉降一吸管法测定褐土颗粒组成的比较

土壤颗粒组成是土壤的基本物理属性之一,沉降—吸管法是传统土壤颗粒分析的主要方法,激光粒度仪法是近年来新兴的粒度分析方法。为了研究二者的差异,选取了23个黏粒含量差异较大的褐土样品,采用上述两种方法对土样进行了分析。结果表明:激光粒度仪检测<0.002mm颗粒含量低于吸管法,但二者有较好的相关性,决定系数为0.97;在检测<0.02mm颗粒含量时两者比较接近,并且相关性很好,决定系数为0.99;检测<0.05mm颗粒含量时两者也比较接近,决定系数为0.91。激光粒度仪检测结果通过转换模型修正后,可以较好地反映褐土土壤颗粒组成情况。     

不同粒径黄绵土的溅蚀规律及表土结皮发育研究

溅蚀是土壤侵蚀过程的开始,为侵蚀发展提供了物质来源。因此,对其进行研究有助于对侵蚀过程的深入了解。本文选择了广泛分布于黄土高原地区的黄绵土,通过对不同粒径的土样进行模拟降雨试验,分析了土壤颗粒的溅蚀规律和表土结皮的形成过程,以及溅蚀率变化趋势。结果表明,不同粒径土样的溅蚀量差异明显,粒径在0.15mm附近的土壤颗粒最易被溅蚀;在一定的降雨历时内不同粒径土样的表土结皮发育完善程度不同,据此可以很好地解释溅蚀率的变化。     

Soil profile distribution of total C content and natural abundance of 13C in two volcanic soils subjected to crop residue burning versus crop residue retention

Abstract

Soil organic carbon (SOC) plays a key role in crop productivity and soil quality. Conservation agriculture has a positive effect on SOC accumulation in the surface soil horizons, but little information is available regarding the effect of the removal of crop residues by burning. This study aimed to assess the impact of different types of crop residue management practices on the total C distribution and natural abundance of ¹³C (‰, δ¹³C). Two volcanic soils, located in the Mediterranean temperate zone of Southern Chile, were studied: an Ultisol (Collipulli Series, CPL) and an Andisol (Santa Bárbara Series, SBA). Both soils had been cultivated under direct-drilling and a typical annual crop rotation system for a long period of time. Two different types of crop residue management practices were imposed in both soils: (i) crop residue burning (CPL-B; SBA-B) and (ii) crop residue retention over the soil (CPL-R; SBA-R), corresponding to treatments B and R, respectively. Soil profile distribution of the C content and natural abundance of ¹³C were analysed for bulk soils (down to 100 cm depth) and three particle-size fractions of the soils (down to 20 cm of soil depth): (a) ≤ 53 µm, (b) 53-212 µm and (c) ≥ 212 µm. It was found that the effect of crop residue management can be observed in the variations of C content and δ¹³C in the soil profile in both volcanic soils. Crop residue burning (B treatment) increased the C content in bulk soil and the particle-size fractions. On the other hand, soil organic matter of crop residue retention (R treatment) showed higher natural abundance of ¹³C (δ¹³C) compared with residue burning (B treatment) in the two volcanic soils. R treatment enriched the particle-size fractions (except ≥ 212 µm fraction of CPL soil) with ¹³C. Factors that could account for these findings are also discussed here.     

The particle-size distribution in soils: Problems of the methods of study,interpretation of the results,and classification

The analysis of literature sources and a database on soil physical properties collected by the Department of Soil Physics and Amelioration of Soils of the Faculty of Soil Science of Moscow State University made it possible to compare three major constituents of the particle-size distribution analysis (PSDA): (a) the classification of soil separates with respect to their sizes and the classification of soil textures, (b) the procedures used to prepare soil samples for the PSDA, and (c) the specificity of the determination of the particle-size distribution by different methods. It was shown that there are good physical and statistical grounds for the conversion of data on the particle-size distribution from the Russian classification system into other systems. Much larger problems are related to the pretreatment of soil samples for the PSDA. The diversity of existing methods, classification schemes, and technical devices based on different physical principles (sedimentation and laser diffractometry) should be taken into account in the analysis and quantitative conversion of particle-size distribution data from a given classification system into another system. The Russian classification of soil textures and soil particle-size groups developed by N.A. Kachinskii has certain advantages and can be easily converted into other systems. In the choice of a particular system, it is important to take into account the goals of the study. Agreement between soil scientists concerning the major constituents of the PSDA has to be reached.     

Genesis of a So-called Ferrolysed Soil of Bangladesh

It was postulated by Brinkman (1970) that low clay contents in the surface horizon of paddy soils (Planosols) are caused by clay destruction through ferrolysis. In an effort to test this, a rice profile from the site of Brinkman's Eutric Planosol (Salna, Bangladesh) and a neighbouring forest soil (Dystric Cambisol) of the same parent material and particle-size distribution (Bhawal National Park) were investigated. The micro-structure, particle-size distribution, mineral contents, pedogenic oxides, contents of Zr, Ti and K of the fine earth and individual fractions and also the exchangeable ions were studied. The clay fraction of both soils were chloritised by interlaying of hydroxy-Al in the smectite interlayers in the surface horizons and got stabilized. As a result CEC showed some decrease. The forest profile has a loose and uniform brown-yellow surface horizon and is relatively rich in coarse sand at 62–75 cm depth which might be caused by a strong termite activity as observed during sampling. On the contrary, the frequent and alternate reducing and oxidizing conditions have resulted in gleying the top soil and forming iron-oxide films on the surface of aggregates during dry periods in the paddy soil. An evaluation of all results shows that a little clay destruction and an enrichment of silt in the top soil through vertisol formation and also through primary parent material stratification were the reasons for low clay content in epipedons. In forest soil there was a little clay migration, while the epipedon of the paddy soil had low clay in addition, because of selective erosion during heavy rains following the destruction of structure by puddling. The ferrolysis as a dominant factor for a clay-low epipedon is improbable, because the clay loss of the neighbouring forest soil can not be explained by ferrolysis.     

Automorphic taiga soils of the Sredneobskaya Lowland

The morphology of the profile, some chemical properties, and particle-size distribution of the automorphic soils developed from lacustrine-alluvial loamy-clayey deposits in the Sredneobskaya Lowland are considered. The soils of the West Siberian middle taiga zone remain poorly studied. A comparison of our data with data on podzolic soils in the northeastern part of European Russia and with diagnostic characteristics of the soil type of svetlozems included in the new classification system of Russian soils (2004) allows to argue that the studied soils cannot be classified as podzolic soils; most of them also do not fit the diagnostic criteria of svetlozems. The obtained data on the particle-size distribution in the studied soils do not agree with the concept of the sedimentation zonality in the West Siberian Plain.     

鲁中山区小流域不同土地利用类型的土壤分形及水分入渗特征

为探讨坡耕地土壤入渗性能退化特征与分形机制,对鲁中山区选择典型小流域,运用土壤分形和水文学原理与方法,通过测定坡耕地、弃耕地、生态林地和经济林地4种土地利用类型的土壤分形特征与入渗性能,探讨土壤人渗速率与土壤颗粒分维及孔隙分维的定量关系。结果表明：1）不同土地利用类型土壤稳渗速率表现为坡耕地〉弃耕地〉生态林地〉经济林地,土壤颗粒分维数与孔隙分维数表现为生态林地〉经济林地〉弃耕地〉坡耕地;2）研究区土壤颗粒分维与孔隙分维数之间显著正相关,二者与土壤黏粒及粉粒体积分数显著正相关、与土壤入渗速率显著负相关;3）霍顿入渗模型和幂函数模型比较适用于拟合研究区土壤入渗过程与入渗速率,而菲利浦模型的适用性较差。因此,研究区土壤具有粗骨性砂土的物理特性,坡耕地耕作会加剧土壤中粉粒和黏粒等细粒物质流失,降低土壤颗粒分布与孔隙分布的均匀性及其分维数,导致土壤入渗性能增强但水肥保蓄性能降低。     

花岗岩风化土物理特征曲线间的相关性研究

花岗岩风化壳水分及收缩特性的研究是花岗岩土体稳定性评价及侵蚀机理研究的基础。通过Van Genuchten(VG)模型对不同风化程度的花岗岩土壤的颗粒累积分布、土水特征曲线和收缩特征曲线进行拟合,分析曲线拟合参数间以及这些参数与基本物理性质间的线性及非线性相关关系。结果表明:VG模型可以很好地用于不同风化程度花岗岩风化土的颗粒组成、土水特征与收缩特征的拟合与预测;曲线拟合参数间具有一定的线性相关关系;曲线拟合参数与基本物理性质间具有一定的线性相关关系,其中土水特征曲线参数与土壤质地以及容重线性相关性较高,收缩特征曲线物理参数与基本物理性质间的线性相关性较收缩特征曲线其他参数高。此外,曲线拟合参数间以及这些参数与基本物理性质间具有一定的非线性相关关系,而关系多为二次、三次非线性相关。根据花岗岩风化土颗粒组成状况及其基本物理性质对其水分特征曲线及收缩特征曲线进行预测具有一定的可行性。     

Evaluation of different procedures to interpolate particle-size distributions to achieve compatibility within soil databases

Many environmental and agricultural problems are not restricted to national boundaries and therefore require international cooperation if solutions are to be found. Often, these solutions require the ability to use soil data as input in simulation models, however, despite a number of recognised international standards, soil data are rarely compatible across national frontiers. This problem was encountered when creating the draulic operties of uropean oils (HYPRES) database. The data, which includes particle-size distributions, were collected from 20 institutions in 12 countries. Only a few of these institutions adhered strictly to a recognised international system. Therefore, interpolation of the cumulative particle-size distribution was required to achieve compatibility of particle-size distributions within the HYPRES database. In this study, four different interpolation procedures were evaluated. The accuracy of the different procedures was found to vary with size intervals between measured points of the particle-size distribution. The loglinear interpolation of the cumulative particle-size distribution has previously been used in various studies but was found to give the least accurate estimation of the four procedures. Fitting the Gompertz curve, which is a special asymmetric type of curve described by a closed-form equation, showed less sensitivity to size intervals between measured points. However, interpolation within some of the particle-size distributions was not sufficiently accurate and this procedure could not be applied to particle-size distributions where the number of measured size fractions was less than the number of model parameters. Fitting a nonparametric spline function to the particle-size distributions showed a considerable increase in accuracy of the interpolation with decreasing size intervals between measured points. As a novel approach, the similarity procedure was introduced which does not use any mathematical interpolation functions. It uses an external source of soil information from which soils are selected with particle-size distributions that match the distribution of the soil under investigation. This similarity procedure was capable of giving the most accurate interpolations. Once an extensive external reference data set with well-quantified particle-size distributions is available, the similarity procedure becomes a very powerful tool for interpolations. Based on the number and distribution of measured points on the particle-size distributions, a general rule was formulated to decide whether to fit a spline function or use the novel similarity procedure to estimate missing values. Results of this study were used to classify all soils in the HYPRES database into the same soil texture classes used in the 1:1.000.000 scale Soil Geographical Database of Europe.