贵州喀斯特山区典型土壤氧化铁特征及其与土壤类型分异关系

以贵州省喀斯特山区30个典型土壤剖面为研究对象,采集土样,测定不同形态的氧化铁含量、计算相应的风化度指标,通过分析不同形态氧化铁含量、风化度指标与土壤类型分异的关系,探讨了氧化铁特征对喀斯特山区典型土壤类型分异的指示作用.结果 表明:游离氧化铁是区内土壤氧化铁的主要存在形态(26.62～75.99 g kg-1);绝大...     

基于地形因子和随机森林的丘陵区农田土壤有效铁空间分布预测

为了掌握丘陵地区农田土壤有效铁含量及其空间分布,本文以重庆市江津区永兴镇内同源成土母质的典型丘陵(2 km2)为研究区,采集309个土壤样点,利用普通克里格(Ordinary Kriging,OK)、多元线性回归(Multiple Linear Regression,MLR)、随机森林(Random Forest,RF)模型,结合高程、坡度、坡向、谷深、平面曲率、剖面曲率、汇聚指数、相对坡位指数、地形湿度指数等地形因子对土壤有效铁进行空间分布预测,并通过85个验证点评价、筛选预测模型。结果表明:1)土壤有效铁与谷深、地形湿度指数存在极显著水平正相关关系,与坡度、平面曲率、剖面曲率、汇聚指数、相对坡位指数存在极显著水平负相关关系。2)随机森林模型的预测精度明显高于多元线性回归和普通克里格插值,其平均绝对误差为22.33 mg·kg-1、均方根误差为27.98 mg·kg-1、决定系数为0.76,是研究区土壤有效铁含量空间分布的最适预测模型。3)地形湿度指数和坡度是影响该区域土壤有效铁含量空间分布的主要地形因子。土壤有效铁与坡度、谷深、平面曲率、剖面曲率、汇聚指数、相对坡位指数、地形湿度指数均达到极显著水平相关关系。4)研究区土壤有效铁含量范围为3.00~276.97 mg?kg-1,水田有效铁含量大于旱地;土壤有效铁具有较强的空间相关性,土壤有效铁含量空间变异主要受到结构性因素的影响。可见,基于地形因子的随机森林预测模型可以较好地解释丘陵区农田土壤有效铁含量的空间变异,研究结果为丘陵区土壤中、微量元素含量及空间分布预测提供方法借鉴和理论依据。     

四川盆地西部漂洗土壤区水体铁元素的分布特征

铁是水质监测的重要指标。为了弄清四川盆地西部漂洗土壤区不同水环境中铁的形态和含量、浅层潜水的季节动态及其形成原因,为该区土、水资源合理利用提供一定参考,于不同时期在四川省名山县漂洗土壤区采集潜水、池塘水、稻田和茶园沟渠地表水、土壤孔隙水及相应的土壤样品,分析了其铁的形态和含量及相应的理化性质。结果表明,从潜水和土壤孔隙水来看,潜水总铁和亚铁含量（分别为0.30、0.08mg·L^-1）均为最低,稻田孔隙水总铁和亚铁含量（分别为2.92、1.13mg·L^-1）均为最高,茶园孔隙水总铁和亚铁含量（3a生以下茶园分别为1.25、0.92mg·L^-1,6a生以上茶园分别为2.66、0.65mg·L^-1）居中;就稻田和茶园的土壤孔隙水与沟渠地表水比较而言,孔隙水总铁和亚铁含量总体上高于沟渠地表水相应的总铁和亚铁含量;潜水总铁和亚铁含量分别变动在0~0.86mg·L^-1和0~0.36mg·L^-1之间,其季节动态在不同区域间存在一定差异,与其所处地形部位及地表径流条件、离居民房屋和畜禽圈舍远近、土壤pH、有机质和铁元素的形态和含量、土地利用方式及作物种植年限、天气状况及水井自身氧化还原电位等条件有关。     

基于组合模型的庐山森林土壤有效铁光谱间接反演研究

铁是植物生长的重要微量营养元素之一,土壤有效铁含量对林地环境起着重要的影响,利用土壤光谱预测技术获取土壤有效铁含量信息具有重要意义。而要通过土壤光谱直接预测土壤有效铁含量是难以实现的,因此提出利用土壤有机质含量与有效铁含量之间的相关性,探讨间接估算土壤有效铁含量的可行性。以庐山森林土壤样本为研究对象,研究基于偏最小二乘回归(PLSR)和径向基函数(RBF)神经网络的组合模型预测土壤有机质含量的适用性,并且通过构建有机质含量与有效铁含量的二项式线性模型,对土壤有效铁含量进行间接反演,探讨不同权重下的最优组合模型。结果表明,组合模型的预测效果优于偏最小二乘回归和RBF神经网络单个模型,并且熵值组合为最优组合模型,其中,土壤有机质的反演模型验证的决定系数(R~2)为0.81,均方根误差(RMSE_p)为11.54 g kg~(-1),测定值标准差与标准预测误差的比值(RPD)为2.18;有效铁的间接反演模型R~2为0.70,RMSE_p为21.60 mg kg~(-1),RPD为1.77。通过土壤有机质构建土壤有效铁含量的光谱反演间接模型,在光谱反演模型中,组合模型能较大限度地利用各种预测样本信息,能有效减少单个预测模型中随机因素的影响,增强预测稳定性,提高模型的预测能力。因此,组合模型可对土壤有机质含量的光谱预测及土壤有效铁的间接预测发挥更好的作用。     

Pre-lysis washing improves DNA extraction from a forest soil

A pre-lysis buffer washing procedure was introduced to DNA extraction from a forest soil with high organic matter and iron oxide contents. Sodium phosphate of 0.1 M (pH 7.5) was used as a buffer to wash soil samples when subsequent lysis buffer was phosphate, and 20 mM EDTA (pH 7.5) was used when subsequent lysis buffer included EDTA. Initial experiments were not successful because the DNA extracts could not be amplified by polymerase chain reaction (PCR). The consideration of introducing a pre-lysis washing procedure was based on the idea that the washing should promote soil dispersion and homogeneity, decrease DNA adsorption by soil components (e.g. iron oxides), and remove covalent cations and those easily-dissolving organic compounds from the soil samples. Results revealed that humic substance content decreased by 31%, but DNA yield increased by 24% in the DNA extracts of the pre-lysis washing procedures, compared to the non-washing procedures. DNA extracted by the pre-washing procedure needed less purification for subsequent 18S and 16S rDNA PCR amplifications. It was recommended that the pre-lysis buffer washing should be used for DNA extraction from those difficult environmental samples, such as the forest soil with high contents of organic matter and iron oxides.     

A technique for the correction of measurements of iron in alfalfa tops contaminated with soil

Abstract

A technique is described for the correction of abnormally high iron concentrations measured by X‐ray fluorescence spectrometry in alfalfa tops contaminated with soil. By adding to alfalfa samples, known amounts of different soils representative of the textural types occurring in the sampling area, the concentration of iron and aluminium in the contaminating soil was determined by subtracting the concentrations of the elements in the uncontaminated controls. A single regression equation relating concentrations of iron in the contaminating soil as a function of soil aluminium was suitable for correcting iron concentrations measured in all plants contaminated with soils of a loamy texture. Another regression equation was derived to correct values of iron in plants contaminated with sandy soils.     

温度对酸性草酸-草酸铵溶液浸提土壤无定形铁的影响

以下蜀黄土为试材,研究温度对酸性草酸-草酸铵缓冲溶液浸提土壤无定形铁的影响。结果表明:随着浸提温度的升高,铁的浸提量明显增加。30℃浸提出的铁约为20℃的1.57倍;而50℃浸提出的铁约为20℃的4.43倍。随温度的升高,浸提后土壤残渣的磁化率迅速降低。20℃浸提后残渣的磁化率值比原样略有减少;30℃浸提后残渣的磁化率约为原样的93.6%;50℃浸提后残渣的磁化率只有原样的65.3%。这说明随着温度的升高,以磁性矿物为代表的结晶态铁也被溶解,浸提出的铁其实已不仅是无定形铁。因此,用酸性草酸铵浸提无定形铁时,严格控制20℃的反应温度十分关键。     

长期施肥对棕壤铁形态及其有效性的影响

【目的】利用沈阳农业大学棕壤肥料长期定位试验,研究不同施肥处理对耕层土壤酸碱度（pH）、氧化还原电位（Eh）和有机质的影响,探讨不同施肥条件下土壤游离态氧化铁、无定形氧化铁、亚铁总量和有效铁含量的变化以及与pH、Eh和有机质的关系。 【方法】本文选取试验处理为CK（不施肥）、N（氮肥）、NP（氮磷肥配施）、NPK（氮磷钾肥配施）、M（有机肥）、MN（有机肥与氮肥配施）、MNP（有机肥与氮磷肥配施）、MNPK（有机肥与氮磷钾肥配施）。在2014年大豆收获期,采集了不同施肥处理0-20 cm耕层土壤样品,分析了土壤pH、Eh、有机质含量以及游离态氧化铁、无定形氧化铁、亚铁和有效铁含量。 【结果】与1979年原始土壤相比,所有处理土壤pH显著降低了0.6~1.4个单位。不施肥处理土壤有机质下降了11.5%,化肥处理有机质略有下降,而有机肥处理有机质含量显著增加。所有处理有效铁含量显著增加,化肥有机肥配施增加幅度更大;与2014年不施肥处理相比,施用氮肥处理土壤pH最低,而氮肥配施磷、钾和有机肥中的一种或几种pH又有所上升,其中配施有机肥效果最明显;施用化肥处理土壤Eh增加,而施用有机肥处理Eh则下降。施用化肥土壤游离态氧化铁和有效铁含量增加,亚铁含量下降,而施用有机肥土壤游离态氧化铁降低,亚铁总量及有效铁含量增加。 【结论】经过长期耕作和施肥,土壤pH显著下降,有效铁含量显著增加。长期不施肥土壤有机质显著下降。施用氮肥土壤酸化趋势明显,磷、钾和有机肥配施能够缓解氮肥引起的酸化现象。施用有机肥显著降低土壤氧化还原电位,有利于氧化态铁向还原态铁转化,更有利于增加土壤有效性铁的含量。     

Ecology of Arthrobacter JG-9-detectable hydroxamate siderophores in soils

Arthrobacter JG-9-detectable hydroxamate siderophores were monitored in a series of soils subjected to different treatments in the laboratory and in a series of field soils subjected to different regimes. Concentrations of soil siderophores were found to be strongly related to the quantity of organic substrates available for microbial growth in the soil. It was possible to specifically stimulate siderophore production using L-ornithine as a precursor. Soil pH, water activity and iron availability also influenced the production of siderophores in soil. For two series of field samples, siderophores concentration in soil was correlated with grass production. A model is proposed in which the rhizosphere constitutes the most important microsite in soil for siderophore production. Siderophores are thereby conceived as vehicles for iron, increasing the mass flow of iron from the soil-humus complex to the growing microbial, particularly fungal, biomass.     

Effects of fertilizer and soil components on pesticide photolysis

An environmental fate study was performed analyzing the effects of soil composition on the soil photolysis of a chemical. The study was conducted in two phases in which both moist and air-dried soils were fortified with either the common fertilizer sodium nitrate or the natural soil components iron or humic acid and dosed with niclosamide. The soils were photolyzed under a xenon lamp for 7 days. Increasing concentration of sodium nitrate did not affect the degradation pattern but did produce a lower concentration of aminoniclosamide. Soils fortified with iron displayed an unknown, which was not observed in other experiments, and the degradation of niclosamide from these soils was slower than from the sodium nitrate-fortified soils. There were no extractable degradates from any of the soils fortified with humic acid. In irradiated moist soils, the half-life of niclosamide increased when sodium nitrate was present at 20 ppm, and the half-lives of niclosamide in iron- and humic acid-fortified soil were increased slightly over that in unfortified soil. The effect of the nitrate and iron on the half-lives in dark control moist soils was minimal, but humic acid increased the dark control half-life from 420 to 611 h. No transformation of niclosamide was observed in the dark control air-dried soils. Soils with higher organic or iron contents or exposed to fertilizers do not affect as dramatically the half-life of pesticides as does the presence of moisture in the soil. Soil photolysis samples that were not maintained with moisture exhibited differences in half-life and degradation pattern. The maintenance of moisture was found to be more crucial to the reliability of soil photolysis studies than soil composition.     

Potential Iron and Phosphate Mobilization During Flooding of Soil Material

This study shows that mobilization of phosphate from soils under anaerobic conditions can be intimately coupled with reductive dissolution of iron from iron oxides. Among four soil samples from the reclaimed Skjernå estuary in Denmark incubated anaerobically and amended with glucose, 28–39% of the dithionite-citrate-bicarbonate-extractable iron and 10–25% of the oxalate-extractable phosphorus (P_ox) were released to the soil solution after 31 days. Significant correlation (r = 0.992**) between the molar ratio P_ox/(Fe_ox + Al_ox) for the aerobic samples and (P_{P sol}/Fe_sol) (the molar ratio between phosphate and iron in solution during anaerobic incubation), indicates that the phosphate saturation status of the soil is an important determinant of the amount of phosphate released during flooding of moderately acid soils.     

Soil micro- and mesopores studied by N2 adsorption and Xe NMR of adsorbed xenon

N₂ adsorption (77 K) was combined with ¹²⁹Xe nuclear magnetic resonance spectroscopy of adsorbed xenon to characterise soil meso- (2–50 nm) and microporosity (<2 nm). Materials from the Alh and Bt horizons of a Luvisol, the Go horizon of a Gleysol and the Bvs horizon of a Podzol were analysed. Additionally, we examined samples obtained by mixing of H₂O₂-treated soil fractions with organic soil material (“soil + organic matter” samples). N₂- specific surface areas (S_BET) and micropore volumes (V_micro) and areas (S_micro) were markedly affected by the presence of iron oxides in soils. Their removal with dithionite-citrate-bicarbonate (DCB) treatment was accompanied by a significant decrease in S_BET and almost complete disappearance of the micropores. The organic carbon (OC) content decreased by 10–35% after the DCB-procedure showing that a certain proportion of the soil organic matter was extracted together with iron oxides. This may point to a close association between carbon compounds and iron oxides, possibly by incorporation of low molecular weight organic compounds into the phase of iron oxides. Such interactions are expected to contribute to the stabilisation of organic carbon in soils. Indeed, as compared to the top horizon (Alh of Luvisol), a higher proportion of organic matter was co-extracted with iron oxides from the subsurface horizons (Bt of Luvisol, Go of Gleysol) characterised by higher amounts of organic carbon resisting oxidation with H₂O₂. Examination of the mixed “soil + organic matter” samples supports that after addition, organic molecules occupy micropores (evidenced by N₂ adsorption) and narrower mesopores of the mineral matter (evidenced by ¹²⁹Xe NMR).     

土壤中氧化铁的转化及其对土壤结构的影响

氧化铁虽是土壤粘粒中的次要矿质成分,但它具有较高的活性,对土壤性质有重要的影响。作为胶结物质之一,氧化铁的形态及其含量,对土壤团聚体的形成,亦起重要作用^[4,8]。某些水稻土中细孔隙增多,土块趋向紧实等问题^[1,2],似乎与土壤中氧化铁存在形态有关。     

Organic Carbon and Total Iron Effect on Soil Vis-SWNIR Spectraand Quantification of Their Contents Using PLS R Models

ABSTRACT

Many factors could influence simultaneously soil spectra. We aimed to study the single effect of organic carbon and total iron in soil visible and short-wave near-infrared spectra and to quantify their contents. Two datasets of soil mixture samples were prepared by mixing, in various fractions, an organic carbon-rich material with a total iron-rich material and then with a total iron-poor material. For these two datasets, contents in organic carbon are quite similar but contents in total iron are significantly different. Results show that samples of the same dataset have the same overall spectral shape. Organic carbon has a decreasing effect that affects the whole spectral range without showing any specific absorption peaks. By contrast, total iron has specific absorption peaks. Spectra of the second dataset characterized by soil mixtures with higher total iron contents were more compact within the spectral bands 400–440 and 920–950 nm. Besides, continuum removal enables to exaggerate absorption peaks of wavelengths linked to total iron content. Partial Least Squares Regression (PLS R) models of both total organic carbon and total iron assign high coefficients to the wavelengths that are considered relevant and conversely low coefficients to those that are considered irrelevant. Both organic carbon content and total iron content were well predicted. For these models, coefficients of determination were superior to 0.9 and RMSE was closed to zero. The global models calibrated on all the samples demonstrated that PLS R was able to integrate sample heterogeneity.     

聚合氨基酸对北方水稻土中氧化铁存在形态的影响

为了解不同类型水稻土中氧化铁含量特征,探明添加外源聚合氨基酸对水稻土中氧化铁形态变化的影响,本研究以中国北方不同类型水稻土(棕壤型、草甸土型和滨海盐渍型)为研究对象,设置添加占供试土壤干重0.05%的γ-聚谷氨酸和聚天冬氨酸处理,以不添加氨基酸作为对照。通过室内恒温厌氧培养30 d后,测定各水稻土全铁、游离氧化铁、无定形氧化铁和络合态铁含量及氧化铁的活化和络合程度。结果表明:供试的北方3种典型水稻土中,游离氧化铁含量为滨海盐渍型草甸土型≥棕壤型,络合态铁含量为棕壤型滨海盐渍型≥草甸土型,而无定形氧化铁含量为棕壤型滨海盐渍型草甸土型。两种外源聚合氨基酸对不同类型水稻土氧化铁形态转化能力影响存在差异,与不添加氨基酸的对照相比,添加γ-聚谷氨酸的棕壤型水稻土无定形氧化铁和络合态铁含量分别增加27.72%和32.25%,聚天冬氨酸对无定形氧化铁和络合态铁含量无显著促进作用;在草甸土型水稻土中,γ-聚谷氨酸和聚天冬氨酸均能显著增加无定形氧化铁含量,且与对照相比,络合态铁含量分别增加136.24%和12.00%;γ-聚谷氨酸能有效促进滨海盐渍型水稻土中无定形氧化铁和络合态铁的生成。总之,添加γ-聚谷氨酸和聚天冬氨酸对水稻土游离氧化铁的含量没有明显影响;而添加γ-聚谷氨酸能有效增加水稻土中无定形氧化铁和络合态铁含量,降低晶胶率,有利于提高土壤中有效铁含量,显著活化铁氧化物,抑制各类型水稻土中铁的结晶老化;而聚天冬氨酸对水稻土无定形氧化铁和络合态铁没有明显的激发效应。     

Influence of iron oxides on cobalt adsorption by soils

Eleven soils from Denmark and Tanzania were extracted with ammonium acetate (controls), EDTA, and dithionite-EDTA (DE) to fractionate iron (and manganese) oxides. The amounts of cobalt adsorbed and acidity desorbed by the extracted soils as well as by two synthetic iron oxides were determined, using 0.85 mM cobalt in 0.2 m NaNO₃.
No significant correlations were found between cobalt adsorption and the contents of extractable manganese or organic matter, presumably because of their low contents. The major part of the cobalt adsorption (by DE-extracted samples) was due to the clay fraction and was associated with the release of approximately one proton per adsorbed Co. The remaining cobalt adsorption was attributed to the iron oxides. This portion of adsorbed cobalt was well described by considering soil iron oxides composed of only two fractions, an EDTA-extractable fraction of high reactivity and a less reactive fraction corresponding to the difference between DE-extractable iron and EDTA-extractable iron. Approximately 1.7 protons were released per Co adsorbed by these iron oxide fractions and by the synthetic iron oxides.
The amounts of cobalt adsorbed by the soil iron oxides were well predicted from the contents and specific surfaces of the two iron oxide fractions together with the specific cobalt adsorption of synthetic iron oxides.     

Adsorption of cobalt by soil iron oxides at low solution concentration

Abstract

Eleven selected soils from Denmark and Tanzania were treated with ammonium acetate (controls), EDTA, and dithionite‐EDTA (DE) to fractionate iron and (manganese) oxides. The amounts of cobalt adsorbed were determined from a 3 μM equilibrium cobalt solution, corresponding to the cobalt level in natural soil solutions using sodium nitrate (0.2 M) to suppress non‐specific adsorption, by the extracted soils as well as by two synthetic iron oxides.

No significant correlations were found between cobalt adsorption and the contents of organic matter and extractable manganese, presumably due to their low contents in the soils investigated. Close correlations were, however, found between the amounts of cobalt adsorbed, especially fractions thereof, and the contents of iron oxides.

The amounts of cobalt adsorbed by the DE‐ex‐tracted soils, void of iron (and manganese) oxides, were attributed to the clay silicates. The remaining cobalt adsorption, i.e. the difference between cobalt adsorbed by acetate‐extracted and DE‐extracted samples, was attributed to the iron oxides. This portion of adsorbed cobalt was well described by considering soil iron oxides composed of only two fractions, an EDTA‐extractable fraction of high reactivity and a less reactive fraction corresponding to the difference between DE‐extractable iron and EDTA‐extractable iron.

The amounts of cobalt adsorbed by the soil iron oxides were well predicted from the contents and specific surface of the two iron oxide fractions in soil together with the amount of cobalt adsorbed by the synthetic iron oxides.     

Interaction of Different Iron Chelates with an Alkaline and Calcareous Soil: A Complementary Methodology to Evaluate the Performance of Iron Compounds in the Correction of Iron Chlorosis

Abstract

A great number of studies have shown that the stability of iron chelates as a function of pH is not the unique parameter that must be considered in order to evaluate the potential effectiveness of Fe‐chelates to correct iron chlorosis in plants cultivated in alkaline and calcareous soils. In fact, other factors, such as soil sorption on soil components or the competition among Fe and other metallic cations for the chelating agent in soil solution, have a considerable influence on the capacity of iron chelates to maintain iron in soil solution available to plants. In this context, the aim of this work is to study the variation in concentration of the main iron chelates employed by farmers under field conditions—Fe‐EDDHA (HA), Fe‐EDDHMA (MA), Fe‐EDDHSA (SA), Fe‐EDDCHA (CA), Fe‐EDTA (EDTA), and Fe‐DTPA (DTPA)—in the soil solution of a calcareous soil over time. To this end, soil incubations were carried out using a soil:Fe solution ratio corresponding to soil field capacity, at a temperature of 23°C. The soil used in the experiments was a calcareous soil with a very low organic matter content. The variation in concentration of Fe and Fe‐chelates in soil solution over time were obtained by measuring the evolution in soil solution of both the concentration of total Fe (measured by AAS), and the concentration of the ortho‐ortho isomers for Fe‐EDDHA and analogs or chelated Fe for Fe‐EDTA and Fe‐DTPA (measured by HPLC). The following chelate samples were used: a HA standard prepared in the laboratory and samples of HA, MA, SA, CA, Fe‐EDTA, and Fe‐DTPA obtained from commercial formulations present in the market. The percentage of iron chelated as ortho‐ortho isomers for HAs was: HA standard (100%); HA (51.78%); MA (60.06%); SA (22.50%); and CA (27.28%). In the case of Fe‐EDTA and Fe‐DTPA the percentages of chelated iron were 96.09 and 99.12, respectively. Results show that it is possible to classify the potential effectiveness of the different types of iron chelates used in our experiments as a function of two practical approaches: (i) considering the variation of total iron in soil solution over time, MA is the best performing product, followed by HA, CA, SA, DTPA, EDTA, and ferrous sulfate in the order listed and (ii) considering the capacity of the different iron chelates to maintain the fraction of chelated iron (ortho‐ortho isomers for HA, MA, SA, and CA and total chelated iron for EDTA and DTPA) in soil solution, the order is: SA > CA > HA > MA > EDTA ≈ DTPA. This result, that is related to the nature of the chelate and does not depend on the degree of chelated Fe in the products, indicates that SA and CA might be very efficient products to correct iron chlorosis. Finally, our results also indicate the suitability of this soil incubation methodology to evaluate the potential efficiency of iron compounds to correct iron chlorosis.     

毕节烟区土壤pH值分布状况及与土壤养分的关系

分析了贵州省毕节市植烟土壤pH的分布状况及与土壤养分的关系。研究表明,毕节市植烟土壤pH平均值为6.39,变异系数为11.87%,pH值处于最适宜范围(5.5~6.5)的土壤样本数占总样本数的44.83%;各县(市)pH最适宜的土壤样本数占各地总样本的比例由高到低顺序为:金沙(67.44%)>织金(64.29%)>大方(54.84%)>七星关(47.54%)>黔西(36.59%)>威宁(35.19%)>赫章(24.24%)>纳雍(15.38%)。不同土壤类型pH平均值高低顺序为:石灰土>紫色土>潮土>黄壤>黄棕壤;毕节烟区土壤pH与全氮含量呈极显著正相关,与有效硼和有效锌的含量呈显著正相关,而与铵态氮、有效锰、有效铁的含量呈现极显著负相关。毕节市植烟土壤的有机质、全氮、有效硫、铜、锰、铁的含量丰富,但全磷、有效硼、水溶性氯的含量偏低或极低。     

黄土高原淋溶土黏粒、氧化铁与颜色的关系及发生学解释 ——以山西土系调查的31个黏化层为例

以黄土高原山西省14个淋溶土剖面的31个偏红的黏化层(Bt)为研究对象,分析了其全铁、游离氧化铁、无定形态氧化铁的含量与土壤颜色参数、黏粒含量之间的相关性,并建立了定量关系模型.结果表明:Bt的黏粒含量与氧化铁含量之间呈极显著正相关(P<0.01);颜色的红度与全铁、游离氧化铁和无定形氧化铁含量之间均呈极显著正相关(P...