Simple correlations between certain mineral and organic components of common beans,peanuts, and cowpeas

Abstract

Selected organic and mineral analyses of common beans, peanut kernels, and cowpeas were determined. Simple correlations were computed between organic and mineral components to investigate possible linear relationships that might be useful. Most correlations between mineral and organic components were negative, and relatively low coefficients of determination (r²) indicated little merit in attempting to predict organic components from inorganic compositions and sample linear models. A positive correlation between stachyose and the N content of common beans was observed.     

The chemistry of pedogenic thresholds

Pedogenesis can be slow or fast depending on the internal chemical response to environmental forcing factors. When a shift in the external environment does not produce any pedogenic change even though one is expected, the soil is said to be in a state of pedogenic inertia. In contrast, soil properties sometimes change suddenly and irreversibly in a threshold response to external stimuli or internal change in soil processes. Significant progress has been made in understanding the thermodynamics and kinetics of soil-property change. Even in the open soil system, the direction of change can be determined from measures of disequilibrium. Favorable reactions may proceed in parallel, but the most prevalent and rapid ones have the greatest impact on product formation. Simultaneous acid–base, ion exchange, redox and mineral-transformation reactions interact to determine the direction and rate of change. The nature of the governing reactions is such that soils are well buffered to pH change in the alkaline and strongly acid regions but far less so in the neutral to slightly acid zones. Organic matter inputs may drive oxidation–reduction processes through a stepwise consumption of electron acceptors (thereby producing thresholds) but disequilibrium among redox couples and regeneration of redox buffer capacity may attenuate this response. Synthesis of secondary minerals, ranging from carbonates and smectites to kaolinite and oxides, forms a basis for many of the reported cases of pedogenic inertia and thresholds. Mineralogical change tends to occur in a serial, irreversible fashion that, under favorable environmental conditions, can lead to large accumulations of specific minerals whose crystallinity evolves over time. These accumulations and associated “ripening” processes can channel soil processes along existing pathways or they can force thresholds by causing changes in water flux and kinetic pathways.     

试论中国淋溶土的成土过程与基本特性

淋溶土是我国的一类重要土壤,总面积约１２．５万ｋｍ＾２。在我国现行的土壤分类系统中,有几个土类－暗棕壤、棕壤、酸性棕壤、白浆土以及部分褐土可归属于淋溶土＾１）。这些土壤大都是温带针阔叶混交林下的森林土壤,生物地球化学循环别具特征。据３０个剖面的统计分析,其Ｂ／Ａ层粘粒含量比值,从暗中壤－棕壤－黄棕壤,为１．４７－１．８８－２．５３,经统计土壤发育过程中粘粒的生成量（或损失量）相差七倍。上述几种土壤     

不同粒径土粒表面性质的纬度地带性变化

土壤的发生、演化和分布在空间上与生物气候条件的变化相适应而呈现地带性特点,土壤矿物、有机组成也呈现一定的地带性变化规律,而土壤矿物演化定会伴随土壤表面性质变化。为揭示不同粒径范围土壤颗粒表面性质的地带性变化规律,研究了主要纬度地带性土壤中0~500、500~1 000、1 000~2 000以及大于2 000 nm不同粒径土壤颗粒的表面性质。结果发现：（1）小于2 000 nm颗粒对土壤有机质、次生矿物、比表面积和表面电荷量的贡献起主要作用,而其中小于500 nm土壤颗粒是土壤比表面积和表面电荷量的最大贡献者;（2）土壤颗粒的粒径分布、有机质与矿物含量、表面化学性质等均表现出纬度分布特征,随着纬度降低,0~500 nm极细颗粒含量和次生矿物含量增加,而有机质含量、比表面积、表面电荷量降低;（3）以黄壤分布区为界的高纬度地区土壤（黑土、暗棕壤、黄棕壤）的有机质含量、蒙脱石含量、比表面积以及表面电荷量均远高于低纬度地区土壤（黄壤、红壤、赤红壤、砖红壤）;（4）高纬度地区土壤的比表面积和表面电荷量主要受蒙脱石和有机质含量的影响,而低纬度地区土壤的比表面积和表面电荷量则主要受伊利石和有机质含量的影响。     

雷琼地区玄武岩发育时间序列土壤中植硅体特征及其发生学意义

对雷琼地区发育于玄武岩跨度为0.01~6.12 M a时间序列土壤中植硅体的含量和形态进行了研究。结果表明:(1)土壤中植硅体的含量为1.54~21.95 g kg-1,其随着土壤深度的增加而降低;从新成土到富铁土阶段急剧降低,从富铁土到铁铝土阶段降幅明显减少,进入铁铝土阶段则基本趋于稳定。(2)植硅体主要源于禾本科、棕榈科植物,大小在5~130μm之间,形态包括刺球型、哑铃型、扇型、长方型、方型、鞍型、帽型、棒型、尖型、齿型、圆型和其他12种植硅体类型。所有样品中的温暖指数值均大于0.5,说明6.12 M a以来研究区域基本以温暖气候为主。     

安徽凤阳石英岩发育土壤的磁学性质及环境磁学意义

通过对安徽凤阳石英岩发育土壤典型剖面的磁学参数测量,结果表明,A层和B层中的磁性矿物含量明显高于C层,且A层和B层中磁性矿物的粒度明显比C层细.C层的磁学性质由磁铁矿主导,A层和B层的磁学性质由磁赤铁矿主导.磁赤铁矿是石英岩在成土过程中形成的次生矿物.土壤中磁赤铁矿的出现及含量的变化指示成土作用的强弱.石英岩的磁性对土壤的磁性影响甚小,而成土作用和生物作用对土壤磁性增强起到了主要作用.     

红壤表土团聚体稳定性对坡面侵蚀的影响

通过野外人工模拟降雨试验,研究了第四纪红粘土、泥质页岩和花岗岩三种母质发育的红壤团聚体稳定性对土壤坡面侵蚀和侵蚀泥沙特性的影响.结果表明：坡面土壤侵蚀量和径流强度与土壤团聚体稳定性存在显著负相关关系,且不同团聚体稳定性指标与二者相关程度存在差异,其中湿筛团聚体平均重量直径（MWD）和》0.25 mm水稳性团聚体含量（WSA0.25）与侵蚀量和径流强度相关程度最高,快速湿润中1～0.5 mm团聚体和湿润振荡中2～1 mm团聚体标准化平均重量直径（NMWD）与二者的相关性也达到了显著;泥沙粒径与湿筛MWD和WSA0.25之间相关关系（偏相关分析）呈显著正相关（r=0.8283^＊,r=0.8209^＊）;快速湿润中1～0.5 mm团聚体和湿润振荡中2～1 mm团聚体的NMWD与泥沙粒径也存在较好正相关关系（r=0.7458,r=0.6859）.泥沙粒径和水流功率在本研究中未表现出较好相关性（r=-0.1852）.     

Lithological effects in soil formation and soil slips on weathering-limited slopes underlain by granitic bedrocks in Japan

Soil slips occur every few years due to heavy rains on biotite granite (Gb) and hornblende biotite granite (Ghb) slopes in the Taga Mountains, Ibaraki Prefecture, Japan. The occurrence density of soil slips per unit area is 2.7 times greater in the Gb slopes than that in Ghb slopes. We examined the chemical, mineral, physical, and mechanical properties of two soil profiles on soil-slip scars in these slopes to study the effect of bedrock mineral composition on the density of soil slips. For a given size of mineral grain, the amount of biotite (which is susceptible to chemical weathering) in granitic bedrocks strongly influenced the density of soil slips. In the Gb slope the soil layer becomes thinner because of the smaller proportion of biotite in the bedrock; this restricts the downward movement of soil water into the material below the slip plane. During heavy rainfall the water surface then rises toward the slope surface above the slip plane. This promotes soil slips, increasing the density of soil-slip scars. In contrast, in the Ghb slope, with more biotite in the bedrock, the soil layer becomes thicker, so that soil water moves easily into the material beneath the slip plane. This limits the rise of water surface toward the slope surface above the slip plane even during heavy rainfalls. There are consequently fewer soil slips and density of soil-slip scars.     

Mineral magnetic properties of a weathering sequence of soils derived from basalt in Eastern China

The magnetic properties and magnetic mineralogy of a weathering sequence of soils developed on basalt parent material from eastern China, were studied by rock magnetism, X-ray diffraction and soil chemical analyses to establish the connection between mineral magnetic properties and pedogenic development in a subtropical region. The magnetic susceptibility of soils formed on basalt varied greatly and did not increase with the degree of pedogenic development. The frequency-dependent susceptibility (χfd) values of soils ranged from 1.0 to 11.1% and increased with the pedogenic development. Highly significant linear relationship was found between the frequency-dependent susceptibility and the Fe_d content (R² = 0.683) and Fe_d/Fe_t ratio (R² = 0.780) in soils, indicating that pedogenic SP ferrimagnetic grains were associated with enrichment of the secondary iron oxide minerals in the weathering process of soil. Rock magnetism analysis showed that the major magnetic carriers in the weakly weathered soil profiles are magnetite and/or maghemite, and the highly developed soil profiles are generally enriched in magnetite/maghemite grains of pedogenic origin and the magnetically hard haematite, indicating that the magnetic component was transformed from a ferrimagnetic phase (magnetite) to antiferromagnetic phase (hematite) during pedogenic development. Results indicated that some of the magnetic parameters of soils, in this case χfd, can be useful for pedogenic comparisons and age correlations in the weathering sequence of soil. It is thus suggested that multiparameter rock magnetic investigations represent a more powerful approach for pedogenesis.     

岷江上游杂谷脑河谷土壤发生特征与系统分类研究

为了解岷江上游杂谷脑河谷的土壤发生特征及类型归属,以位于四川阿坝藏族羌族自治州理县杂谷脑河谷的8个典型土壤剖面为研究对象,通过野外成土因素调查与土壤形态特征观测及室内土壤物理、化学性质分析,依据《中国土壤系统分类检索(第三版)》(简称系统分类)与《中国土壤(1998)》(简称发生分类)鉴定其类型。研究表明,8个剖面均为温性土壤温度状况、半干润土壤水分状况;土壤色调为7.5YR和10YR,部分剖面表层明度和彩度均低于3.5,达到暗沃表层的颜色要求;土壤颗粒组成以粉粒含量最高、砂粒次之、黏粒最低,质地为壤土或粉质壤土;土壤结构主要为亚角块状,部分剖面表层为团粒结构;部分剖面中具有腐殖质、黏粒胶膜及假菌丝体等新生体,形成黏化层和钙积层;均具石灰性,主要为碱性到强碱性反应;有机碳含量范围1.64～61.45 g/kg,部分剖面含量自上而下逐渐降低,具有均腐质特性;游离铁含量为10.78～19.57 g/kg,个别剖面B层均在14 g/kg以上,具有铁质特性;有效磷含量为1.2～43.1 mg/kg,个别符合肥熟表层和磷质耕作淀积层的有效磷含量要求。供试土壤在中国土壤系统分类中归属于人为土、均腐...     

亚热带花岗岩坡地富铁土铁氧化物相分配对团聚体稳定性的影响

铁氧化物是环境敏感矿物,也是土壤团聚体的重要胶结物。自然铁氧化物相存在多尺度分异现象,可能影响团聚体的形成与稳定。本文以闽中丘陵区花岗岩坡地上发育的富铁土序列为研究对象,通过湿筛法和吸管法分离团聚体;运用土壤化学和漫反射光谱(Diffuse reflectance spectroscopy,DRS)方法测定了全铁(Fet)、游离铁(Fe_d)、无定形铁(Fe_o)、赤铁矿(Hm)和针铁矿(Gt)含量,并系统探讨了坡地、剖面和团聚体尺度铁氧化物相分异特征及其对团聚体稳定性的影响。研究表明,坡地尺度上,沿坡面向下,全样Fe_d与游离度(Fe_d/Fet)减小,Fe_o与活化度(Fe_o/Fe_d)增加,Hm与Hm/(Hm+Gt)明显降低,Gt变化不明显;剖面尺度上,上层土壤的Fe_d、Gt多高于下部,Fe_o和Hm则多低于下部;团聚体尺度上,Fe_d、Fe_o和Gt趋向微团...     

Parent material and chemical weathering in alpine soils on Mt. Mansfield,Vermont, USA

We compared the elemental composition of soil and bedrock samples to determine the extent of chemical weathering and the nature of the soil parent material in alpine soils on Vermont's highest summit. Previously it was unclear whether these soils formed through weathering of bedrock, glacial till, or eolian sediment, or solely through the accumulation of organic matter. In eighteen profiles, no evidence was found to indicate that soils have developed in glacial till, despite evidence that the mountain was completely inundated by the Laurentide Ice Sheet. In contrast, results strongly support the theory that pedogenesis in this environment involves in situ bedrock weathering under a thickening blanket of acidic organic litter. Weathering indices reveal an increase in weathering intensity upwards from the bedrock, and trends of normalized rare earth elements demonstrate a strong similarity between bedrock and soil samples. Leaching has concentrated less mobile elements such as Al, Cr, La, P, Pb, and Ti in soil horizons and removed mobile elements such as Co, Fe, K, Mg, Mn, Si, and Zn. X-ray diffraction reveals that chlorite, which is present in all bedrock samples and some saprolites, has weathered completely from upper soil horizons, and that hydrobiotite, vermiculite, kaolinite, gibbsite, and goethite have formed in the soil. Ratios of immobile elements (Ce, Cr, Nb, Ta, Ti, Y, and Zr) in soil and bedrock samples are, however, notably different. Furthermore, the moderately mobile trace elements Cu, Mo, and Sr are actually more abundant in soil than in bedrock, and soil concentrations of Zr are up to an order-of-magnitude greater than in bedrock samples. Together these data argue for at least a modest eolian influx, which may have arrived during the regression of Lake Vermont during the latest Pleistocene or from an outwash source in the immediate post-glacial period. Similarly, increased Ca and Na concentrations in soil samples may signify modern deposition of dust bearing Ca (from agricultural fields) and Na (from roads).     

Erodibility and runoff-infiltration characteristics of volcanic ash soils along an altitudinal climosequence in the Ecuadorian Andes

Soil erosion is a widespread phenomenon in Andean South America, where many regions are covered with soils derived from volcanic parent materials. Climate-induced differences in the genesis of these soils have been demonstrated along toposequences on volcanic slopes. This research was conducted to study the impact of such differential pedogenesis on erodibility and runoff-infiltration characteristics along an altitudinal Entisols–Inceptisols–Andisols sequence in the Andes of northern Ecuador. Surface soils were packed into small pans and placed on a 9% slope, and a simulated rainstorm with varying intensities was applied for a duration of 30 min. The runoff-erosion behaviour of the studied volcanic ash soils is strongly affected by their pedological development. Accumulation of organic matter and precipitation of active amorphous materials at high elevations have led to the formation of well-developed Andisols with very stable aggregate structure. These soils remain wettable when air-dried, show very high infiltration capacity and, consequently, low potential for runoff generation and soil erosion. Low organic matter contents and absence of active amorphous materials at low elevations have led to the formation of weakly aggregated Entisols and Inceptisols. These soils are susceptible to surface crusting, which lowers their infiltration capacity and increases their erodibility. However, in comparison with other soils of different origin and composition, the interrill erodibilities determined for these more erodible low-elevation soils are classified as low. The findings of this study suggest that upland soil erosion is not a major threat to sustainability in the studied volcanic landscape, which is generally confirmed by field observations.     

热带地区玄武岩发育土壤中的生物硅及其发生学意义

运用重液分离法对海南岛北部不同喷发期玄武岩发育的7个土壤剖面生物硅进行了分离和测定,发现生物硅的含量变幅为2.9～54.0 g kg-1,其中最小值出现在发育时间较长的HE11剖面的B2层,最大值出现在发育时间较短的HE09剖面的表层。生物硅的剖面分布特征和有机碳、总氮比较相似,呈现出随土壤深度的增加含量逐渐降低的趋势,在0～40 cm范围之内这种现象更明显。生物硅和总硅之间极显著相关性表明生物硅土壤硅循环中起着主要作用。随着风化强度的提高,黏粒含量的增加,土壤pH逐渐降低,土壤中的生物硅含量有逐渐下降的趋势。初步认为:在土壤发育的初期阶段,来自原生矿物的直接风化释放的溶解硅有利于生物硅在土壤中保存和积聚。而随着土壤的进一步发育,原生矿物的逐渐被分解,土壤的pH下降和黏粒含量进一步增加,土壤中的生物硅也会被溶解、利用,结果是其含量逐渐下降。至发育的高级阶段,土壤中的硅进一步淋失,pH和黏粒含量逐渐趋于稳定。在陆地生物\"泵\"作用下,生物成因硅会被植物循环利用并维持在一个含量相对稳定的状态。     

三江平原白浆土发生学特性

本文对三江平原三个典型白浆土剖面的理化性质、土壤微形态和矿物学性质的研究,探讨了白浆土的发生学特性。土体中Ｚｒ／Ｓｒ和Ｔｉ／Ｚｒ比率的变异系数表明,所研究的土壤剖面其成土母质岩性是连续的。典型白浆土具有一个松软的表土层、一个漂白层和一个相当厚的粘化淀积层。研究还表明,粘粒的悬浮迁移是白浆土的主要成土过程。表层和白浆层在成土过程中有Ｆｅ－Ｍｎ结核形成,且是原地形成的,其Ｆｅ、Ｍｎ明显源于原生矿物的风