Improving on the Prediction of Cation Exchange Capacity for Highly Weathered and Structurally Contrasting Tropical Soils from Their Fine-Earth Fractions

The roles of fine-earth materials in the cation exchange capacity (CEC) of especially homogenous units of the kaolinitic and oxyhydroxidic tropical soils are still unclear. The CEC (pH 7) of some coarse-textured soils from southeastern Nigeria were related to their total sand, coarse sand (CS), fine sand (FS), silt, clay, and organic-matter (OM) contents before and after partitioning the dataset into topsoils and subsoils and into very-low-, low-, and moderate-/high-stability soils. The soil-layer categories showed similar CEC values; the stability categories did not. The CEC increased with decreasing CS but with increasing FS. Silt correlated negatively with the CEC, except in the moderate- to high-stability soils. Conversely, clay and OM generally impacted positively on the CEC. The best-fitting linear CEC function (R², 68%) was attained with FS, clay, and OM with relative contributions of 26, 38, and 36%, respectively. However, more reliable models were attained after partitioning by soil layer (R², 71–76%) and by soil stability (R², 81–86%). Notably FS's contribution to CEC increased while clay's decreased with increasing soil stability. Clay alone satisfactorily modeled the CEC for the very-low-stability soils, whereas silt contributed more than OM to the CEC of the moderate- to high-stability soils. These results provide new evidence about the cation exchange behavior of FS, silt, and clay in structurally contrasting tropical soils.     

不同肥力土壤各级微团聚体中主要营养元素含量的变化

为了探讨不同肥力土壤团聚体中主要营养元素含量的变化情况,以我国东部3种地带性土壤（黑土、棕壤和红壤）为研究对象,分别测定了其全量营养元素的含量,并进行了比较分析。结果发现,各营养元素在不同类型土壤中呈地带性分布。由北向南,有机碳、全氮、全磷、全钾、全钙、全镁的含量呈逐渐降低的趋势,全铁、全铝的变化趋势则相反;施用有机肥能明显增加土壤中各种营养元素的含量。无论哪个粒级的微团聚体,有机碳、全氮含量呈北高南低的趋势;钾素的变化呈北高南低分布。除了硅素外,其余营养元素在〈2μm粒级内富集。对于不同肥力的土壤而言,各营养元素在高肥力土壤中含量较高;在不同肥力的各级团聚体中,也是主要分布在〈2μm粒级范围内。     

不同肥力土壤各级微团聚体中主要营养元素含量的变化

为了探讨不同肥力土壤团聚体中主要营养元素含量的变化情况,以我国东部3种地带性土壤(黑土、棕壤和红壤)为研究对象,分别测定了其全量营养元素的含量,并进行了比较分析.结果发现,各营养元素在不同类型土壤中呈地带性分布.由北向南,有机碳、全氮、全磷、全钾、全钙、全镁的含量呈逐渐降低的趋势,全铁、全铝的变化趋势则相反;施用有机肥能明显增加土壤中各种营养元素的含量.无论哪个粒级的微团聚体,有机碳、全氮含量呈北高南低的趋势;钾素的变化呈北高南低分布.除了硅素外,其余营养元素在＜2 μm粒级内富集.对于不同肥力的土壤而言,各营养元素在高肥力土壤中含量较高;在不同肥力的各级团聚体中,也是主要分布在＜2 μm粒级范围内.     

日光温室栽培对土壤养分累积及交换性养分含量和比例的影响

研究了日光温室栽培下陕西关中地区不同土壤养分累积及交换性养分含量及比例的变化,结果表明：日光温室栽培下土壤有机质、硝态氮、有效磷和速效钾等养分显著累积,土壤阳离子交换量明显增加,而土壤pH却出现下降趋势。日光温室土壤交换性K^＋含量显著增加;日光温室和大田土壤交换性Ca^2＋含量相比无明显差异,而日光温室土壤交换性Mg^2＋的含量及其离子饱和度有所提高。日光温室土壤钙饱和度、Ca/K和M g/K均明显低于大田土壤。认为日光温室栽培下大量施用钾肥,是土壤钙离子饱和度及Ca/K和M g/K比例降低的主要原因,建议在评价日光温室土壤养分有效性时,应综合考虑交换性养分的含量、饱和度及离子间的比例关系。     

Examination into the Accuracy of Exchangeable Cation Measurement in Saline Soils

Abstract

Despite the increasing prevalence of salinity worldwide, the measurement of exchangeable cation concentrations in saline soils remains problematic. Two soil types (Mollisol and Vertisol) were equilibrated with a range of sodium adsorption ratio (SAR) solutions at various ionic strengths. The concentrations of exchangeable cations were then determined using several different types of methods, and the measured exchangeable cation concentrations were compared to reference values. At low ionic strength (low salinity), the concentration of exchangeable cations can be accurately estimated from the total soil extractable cations. In saline soils, however, the presence of soluble salts in the soil solution precludes the use of this method. Leaching of the soil with a prewash solution (such as alcohol) was found to effectively remove the soluble salts from the soil, thus allowing the accurate measurement of the effective cation exchange capacity (ECEC). However, the dilution associated with this prewashing increased the exchangeable calcium (Ca) concentrations while simultaneously decreasing exchangeable sodium (Na). In contrast, when calculated as the difference between the total extractable cations and the soil solution cations, good correlations were found between the calculated exchangeable cation concentrations and the reference values for both Na (Mollisol: y=0.873x and Vertisol: y=0.960x) and Ca (Mollisol: y=0.901x and Vertisol: y=1.05x). Therefore, for soils with a soil solution ionic strength greater than 50 mM (electrical conductivity of 4 dS/m) (in which exchangeable cation concentrations are overestimated by the assumption they can be estimated as the total extractable cations), concentrations can be calculated as the difference between total extractable cations and soluble cations.     

Evaluation of Coconut Wastes as an Amendment to Acidic Soils in Low-Input Agricultural System

The effectiveness of plantation wastes along with locally available organic materials in ameliorating acidic soil was studied by conducting an experiment with coconut husk, poultry manure, vermicompost, and compared with limestone. Application of organic amendments significantly increased the soil pH, and it was greatest in poultry manure–amended soils followed by vermicompost and coconut husk + poultry manure treatments. The relative liming efficiency was greatest for poultry manure through out the observation period of 180 days. The coconut husk alone showed the least liming effect and its liming efficiency had increased when applied in combination with poultry manure and or vermicompost. This increase in soil pH was mirrored by significant reductions in exchange acidity, exchangeable aluminum (Al³⁺), diethylenetriaminepentaacetic acid (DTPA)–extractable iron (Fe²⁺), and manganese (Mn²⁺) and increases in cation exchange capacity, exchangeable bases, especially calcium (Ca), and Olsen-extractable phosphorus (P) by addition of organic amendments and lime. This study indicated the potential of using coconut husk along with poultry manure for managing acidic soils in low-input agricultural systems, especially in tropical islands.     

西北石灰性土壤阳离子交换量测定方法比较

阳离子交换量是评价土壤保肥性能和缓冲性能的重要指标,也是改良土壤和合理施肥的重要依据之一。为了给西北石灰性土壤阳离子交换量的测定提供科学依据,通过平行性实验、标准物质检测、实际样品检测,分析比较了目前普遍采用的测定方法乙酸钙交换法和三氯化六氨合钴浸提-分光光度法的优劣。结果表明,2种分析方法均具有较好的精密度和准确度,均适合西北地区石灰性土壤阳离子交换量的测定。从测定结果来看,三氯化六氨合钴浸提-分光光度法的土壤阳离子交换量测定值略高于乙酸钙交换法,在实际样品检测中相对标准偏差介于3.47%～9.46%。但相比之下乙酸钙交换法具有试剂成本较低的优势,而三氯化六氨合钴浸提-分光光度法具有节省时间的优势,检测人员可根据实际情况灵活选择使用。     

Factors Affecting Sampling Error of Nutrient Element Contents of Arable Fields

A sampling proficiency test is evaluated to analyze the influence of soil heterogeneity and sampling parameters on sampling error of nutrient contents. The influence of parameters on sampling error was assessed by multiple linear regression, regression tree analysis, and variance component analysis (VCA). Error was governed mainly by heterogeneity. Among sampling parameters, the number of increment samples had the largest influence. VCA revealed that the component between sampling repetitions was larger than the component between samplers. This suggests a predominance of heterogeneity for the influence on sampling error, increasing with field-scale heterogeneity. Sampling patterns of low complexity seemed sufficient for the homogeneous field, whereas sampling performance was enhanced by more complex sampling pattern on fields of intermediate and high heterogeneity. Overall, the results suggest that sampling error on arable fields sampled with simplified sampling schemes is often determined by soil heterogeneity and to a lesser degree by sampling parameters.     

Soil Acidity and Exchange Properties of Cryogenic Soils in Arctic Alaska

The physical and chemical properties of Arctic tundra soils were studied along a 250-km latitudinal transect in northern Alaska. The transect includes the nonacidic tundra of the Arctic Coastal Plain, the moist nonacidic tundra of the northern Arctic Foothills, and moist acidic tundra of the southern Arctic Foothills. The parent material of the coastal plain consists of carbonate-rich alluvium. The northern foothills have a mantle of calcareous loess. Further south the parent materials are moraines of late Quaternary. Vegetation changes from sedges on the coastal plain, to grasses on the northern foothills, and tussock and shrub tundra in southern foothills. Following the same order, soil pH and base saturation decrease and soil acidity increases. Most of the soil exchangeable acidity and cation exchange capacity are from soil organic matter.     

Comparative Evaluation of Animal Manures and Their Ashes on Soil pH and Electrical Conductivity in some Southwestern Nigerian Soils

To promote the use of animal waste in agriculture and prevent environmental pollution, an alternative product from the waste should be appraised. This necessitated the study to characterize animal manure ashes and determine its effect on soil pH and electrical conductivity (EC) dynamics. Dried manures of cattle, goat, and poultry, their ashes, and nitrogen (N)–phosphorus?–potassium were applied to soil at 120 kg N ha^?1.? Soils collected fortnightly were analyzed for pH and EC. Results indicated that nutrients in manure ashes were comparable to that of dried manures. Changes in pH and EC were not predictable, application of manure ash increased pH by 12% and 13%, 23% and 14%, 20% and 3% while EC increased by 616% and 109%, 1274% and 156%, 2992% and 458%, relative to dried manures and control during incubation, screenhouse, and field experiments, respectively. It was concluded that incorporation of manure ashes increased soil pH and EC although dynamics were unpredictable.     

曲靖植烟土壤pH和主要养分空间变异特征及其影响因素

2017—2020年用GPS定位采集云南省曲靖市9个县区核心烟田耕层(0～20 cm)土壤样品6685个,测定pH、有机质、水解性氮、有效磷和速效钾,运用地统计学和地理信息系统(GIS)分析上述指标的空间分布特征及其变异主控因素.结果表明:土壤pH、有机质、水解性氮、有效磷和速效钾变幅分别介于4.16～8.50、2.2...     

小流域尺度土壤养分的空间分布特征及其与土地利用的关系

以四川省资阳市松涛镇的响水村小流域为研究背景,以地理信息系统为技术手段,研究了小流域尺度土壤养分的空间分布特征,并结合数理统计的分析方法,进一步探讨了土地利用对土壤养分的影响。结果表明:研究区域土壤表层养分含量均呈现较明显的空间分布格局,总趋势大都具有条带状和斑块状的特点,旱地、果园、裸地的土壤全氮、有机质普遍缺乏,特别是处于坡顶的裸地,应成为今后的控制重点,此外,旱地、果园的水溶态养分高值分布区也应给予高度重视。方差分析与均值比较表明:土地利用对全氮、有机质、全磷、水溶性磷含量都有显著影响(P<0.01),其影响程度为有机质>全氮>全磷>水溶性磷,而全钾、硝态氮则不受土地利用的显著影响,究其原因可能是紫色土钾素含量更倾向于土壤母质中所含矿物的控制,而土壤硝态氮的情况比较复杂,可能有更为重要的因素(如施肥、降雨、径流)制约着硝态氮的含量。     

河南三种土壤阳离子交换量相关性及预测模型研究

土壤阳离子交换量是一项重要的土壤理化性质,它是衡量土壤肥力和作物养分有效性的一个重要指标。通过对河南3种土壤1177个数据的相关性及回归分析来研究阳离子交换量与土壤有机质、pH值、粘粒含量、粉粒含量和砂粒含量的关系。结果表明:(1)对于阳离子交换量来说,砂姜黑土>水稻土>褐土;3种土壤的上层土>下层土;3种土壤的阳离子交换量比第二次土壤普查分别降低15.7%,12.7%,6.5%;(2)对与砂姜黑土和褐土来说,其阳离子交换量与pH值和0.02~2 mm砂粒含量成显著负相关,褐土与粘粒含量成显著正相关;对于水稻土来说,其阳离子交换量与有机质含量和粘粒含量成显著正相关,与砂粒含量成显著负相关;(3)利用这些数据做出的这三个土壤类型的6个回归模型是有科学依据的。总的来说,土壤有机质、pH值、粘粒含量与砂粒含量与CEC有着紧密联系,但还有其他因素影响着预测模型的准确性。     

Nitrogen Fractions in Arable Soils in Relation to Nitrogen Mineralization and Plant Uptake

Abstract

Nitrogen (N) as a major constituent of all plants is one of the most important nutrients. Minimizing input of mineral nitrogen fertilizer is needed to avoid harm to the environment. Optimal input of mineral nitrogen should take the nitrogen supply of the soil into account. Many different soil tests have been proposed for determining soil nitrogen availability. In this article we present a new approach that is based on the measurement of nitrate, ammonium, and dissolved organic nitrogen (DON) in a 0.01 M CaCl₂ soil extract. Eighteen agricultural soils, differing widely in the availability of nitrogen were used, fertilized and unfertilized. It is shown that the nitrogen uptake by maize plants (Zea Mays L.) in both “N‐fertilized” and “N‐unfertilized” soils as measured in a pot experiment can be described with a simple model using the measured nitrogen fractions in the extract. The main source of nitrogen uptake by the plants is the mineralized organic nitrogen during the growing period. It is shown that the initial measured DON fraction is a good indicator of the nitrogen mineralized during plant growth.     

云南绿春哈尼梯田湿地水稻土基本养分特征

选取了云南绿春县规东河片区、松东河片区、二号桥河片区为样区,分析了样区未发生土壤冲蚀、发生土壤冲蚀后修复1a,修复8a的梯田湿地水稻土表层土壤pH值、有机质、碱解氮、速效磷和速效钾特征。结果表明,(1)绿春哈尼梯田湿地水稻土pH值在5.21～6.79之间,呈微酸性;土壤有机质含量在3.80～47.14g/kg之间;土壤碱解氮含量在39.51～137.47mg/kg之间;土壤速效磷含量在1.29～13.31mg/kg之间;土壤速效钾含量在33.32～178.90mg/kg之间。从空间上看,绿春哈尼梯田湿地水稻土基本养分在同一地方相同片区较稳定,变异不大,但是不同地方之间有一定差异。(2)未发生土壤冲蚀的梯田水稻土基本养分显著高于发生土壤冲蚀后修复的梯田水稻土基本养分。经过修复和田间管理,梯田湿地水稻土养分含量有所升高,发生土壤冲蚀后修复8a在0.05水平上显著高于发生土壤冲蚀后修复1a。(3)绿春哈尼梯田同一山麓不同海拔高度土壤有机质含量基本稳定,变化较小。土壤速效养分含量在不同海拔高度变化较大,随着海拔高度的升高或者降低,养分并没有表现出明显的垂直变化特征。     

Effect of Clay Minerals and Organic Matter on the Cation Exchange Capacity of Silt Fractions

The cation exchange capacity (CEC) and specific surface properties were investigated in four particle‐size fractions < 50 μm from three loess (one Kastanozem and two Phaeozems), a holocene (Fluvisol) and a basalt soil (Nitisol) before and after destruction of organic matter. Particle‐size fractions were separated by sedimentation after chemical and physical dispersion of the soil samples. Illite, amorphous minerals, mixed layers, smectite and kaolinite were the predominant clay minerals. They were detected in all size fractions. The CEC increased with increasing organic matter contents and this effect was more pronounced in coarser fractions. The organic matter content per unit surface area was two or three times larger in coarse silt than in clay, irrespective of the soil type.     

膨胀珍珠岩对大棚设施土壤养分含量及分布的影响

通过设施栽培实验,研究了膨胀珍珠岩的施入(4m3/亩)对两次种植土壤(一茬和二茬)中碱解氮有效磷速效钾含量变化及分布规律。结果表明:膨胀珍珠岩的施入有效提高了设施土壤中有效养分的含量;其中碱解氮含量可提高14.5%～49.7%,有效磷可提高12.8%～113.3%,速效钾可提高1.3%～25.1%。膨胀珍珠岩施入后第二次种植土壤中,表层土壤的有效养分含量明显低于对照区和珍珠岩施入后的第一次种植土壤,而耕层土壤中的养分含量高于第一次种植土壤及对照区;其中表层中碱解氮的含量比第一次种植土壤降低了34.5%,而耕层中含量却提高了10.5%～13.0%;有效磷含量在表层中降低了42.8%,而耕层中提高了35.0%;表层中的速效钾含量变化不明显,但耕层中速效钾含量由第一次的增加量1.3%～16.3%提高到14.6%～25.1%。     

作物生长与土壤有效养分关系之研究

一、引言观察施用某种肥料,所表现之作物生长状况,及秤其产量而决定某种作物在某种土壤气候及环境下,需要某种肥料概况,此为一般研究肥效之最普通方法。若在田间详细观察作物之生长情况,进而研究生长地土壤内各种肥料有效养分之富缺程度及其他影响因子尚少,著者等认为地面上农作物生长良窳与土壤有效养分之供给有密切之关系,故本此目的在田间详细观察作物生长状况后,即采取土样,加以分析,并施用同样养分量栽培同样作物作对照比较,求其互相关程度,此本研究之目的也。     

河南郑州郊县保护地养分及重金属含量演变趋势

对河南郑州郊县不同种植年限保护地土壤速效氮、磷、钾及重金属铜、锌、镉、铅含量调查表明:随保护地种植年限的增加,速效氮、磷含量有显著的增加,其增加与种植年限呈极显著正相关,速效钾含量增加幅度不大,说明氮、磷、钾肥施用不均衡;重金属铜、锌、铅含量随保护地种植年限的增加有一定的增加,镉含量没有明显的规律性,但这几项重金属含量均比农田含量要高,说明在保护地高强度施肥及人为活动下,引入了重金属;农田及保护地重金属含量较土壤背景值均有一定程度的增加,但未超出国家土壤环境质量标准。     

西藏土壤磷素和钾素养分状况及其影响因素

探讨西藏土壤磷钾养分状况及其影响因素.结果表明西藏土壤全磷和全钾主要决定于母质.此外,土壤全磷与有机质呈正相关,故表层全磷高于底层,表现磷的生物表聚作用;而全钾与有机质呈负相关,故表层全钾低于底层,表现为有机质对钾的"稀释效应".表层速效磷(Olsen-P)＜10 mg/kg 的缺磷土壤面积约占78%,表明下层速效磷更低.土壤速效磷与全磷、有机质的关系复杂,而与pH的关系密切,一般在pH 6.4～7.3的土壤中含量较高.西藏土壤表层速效钾100～150 mg/kg 和＞150 mg/kg 的面积分别占17%和66%;并且速效钾主要决定于CEC,进而决定于有机质,而与粘粒关系不明显,与全钾无关.