Ocimum basilicum L. growth and nutrient status as influenced by biochar and potassium-nano chelate fertilizers

In sustainable agriculture, the protection of environment against pollution is the main goal for consumers. Nowadays, the overuse of pesticides and chemical fertilizers, are one of the main causes of environmental pollution. It is claimed that incorporation of organic compound into soil enhances nutrient availability and plant productivity. A greenhouse experiment was conducted to determine the effects of 0%, 1.5% and 3% cattle manure biochar and 0, 300 and 600 mg K-nano chelate kg^?1 soil on agronomic properties and nutrient status of Ocimum basilicum L. Biochar increased leaf area and plant height, significantly. Application of 1.5% and 3% biochar increased fresh weight by 40% and 42% and dry weight by 50% and 49%, respectively. Addition of 3% biochar increased P, K and Mn concentrations by 45%, 17% and 109%, respectively. Biochar increased N, P, K, Zn and Mn uptake, significantly. Addition of 300 mg K increased dry weight by 15%; while application of 600 mg K decreased it. Application of 300 and 600 mg K-nano chelate increased K and Zn concentration and K uptake significantly. Furthermore, 300 mg K increased Cu and Zn uptake. In order to achieve sustainable agricultural productions, biochar application is recommended especially in the soils of arid and semiarid regions.     

施用有机物料对土壤镉形态的影响

采用室内培养试验,研究作物新鲜秸秆和腐熟猪粪对模拟镉（Cd）污染的土壤中Cd形态转化的动态影响。结果表明,各处理土壤交换态Cd含量随培养时间均逐渐降低。碳酸盐结合态和铁锰氧化物结合态Cd含量先增加后降低, 而有机质结合态和残渣态Cd含量则逐渐增加。添加秸秆可增加土壤交换态Cd含量,但随时间延长,增幅逐渐降低, 猪粪则可降低土壤交换态Cd含量。添加有机物后土壤交换态Cd含量的变化主要是由有机质结合态或残渣态Cd含量的变化而引起。秸秆和猪粪对土壤Cd形态的转化与土壤胡敏酸（HA）和富里酸（FA）的变化有关。秸秆对能活化土壤Cd的FA增加幅度大于对能钝化土壤Cd的HA增加幅度,降低HA/FA比,但降幅随时间逐渐减少; 猪粪在整个培养阶段对HA增加幅度均大于FA的增加幅度,增加HA/FA比。秸秆和猪粪均可降低潮土pH而提高红壤pH,但只有猪粪可通过提高红壤pH降低Cd向交换态转化。添加秸秆和猪粪后,Cd由低活性态向交换态转化与HA/FA呈显著负相关。     

大豆和小麦对土壤中镉的吸收与富集研究

在温室条件下,采用盆栽方法研究了大豆和小麦在全镉含量为0.211~2.011 mg/kg的土壤中生长状况以及对镉的吸收与富集特征。结果表明,试验所设土壤镉含量对两种作物的株高和单盆籽粒数没有影响。随土壤镉含量的增加,两者单盆产量呈先增加后降低的趋势。大豆籽粒在土壤全镉含量为0.211~0.811 mg/kg时,小麦籽粒在土壤全镉含量为1.411~2.011 mg/kg时更容易积累镉。添加镉能明显增加两种作物植株各部分镉含量。外源添加镉对大豆的转移系数影响不明显,但能增加小麦的转移系数。两种作物的富集系数基本表现为根>茎叶>籽粒。在土壤全镉含量低于0.511 mg/kg时,大豆根和茎的富集系数接近或大于1.0,对镉的吸收较强。在土壤全镉含量高于0.811 mg/kg时,小麦茎叶的富集系数接近或大于1.0,对镉的吸收较强。小麦根的富集系数均高于大豆,且大于1.0,前者具有更高的镉富集能力。     

Cadmium adsorption on hydroxyaluminosilicate-montmorillonite complex as influenced by oxalate and citrate

The hydroxyaluminosilicate (HAS)-montmorillonite (Mt) and hydroxyaluminum (HyA)-Mt complexes are important constituents of soil colloidal complexes in acidic environments. Oxalate and citrate are dominant organic acids in the root exudates of many plants. These acids, among other factors, strongly influence the adsorption behavior of HAS-Mt and HyA-Mt complexes. In this study, we investigated the adsorption phenomena of Cd on the HAS-Mt and HyA-Mt complexes as influenced by oxalate and citrate. Without addition of oxalate and citrate, the adsorption of Cd on Mt was easy. However, in the presence of oxalate and citrate, the adsorption was strongly inhibited. In contrast, the HAS-Mt and HyA-Mt complexes in the absence of oxalate and citrate hardly adsorbed Cd. In the presence of oxalate, the HAS-Mt and HyA-Mt complexes were able to adsorb Cd. Thus, optimal concentration of oxalate for Cd adsorption on both complexes could be determined. Similarly, the HyA-Mt complex showed an optimal concentration of citrate for Cd adsorption. However, the HAS-Mt complex did not adsorb Cd in the presence of citrate. We concluded that the optimal concentrations of oxalate and citrate for Cd adsorption depended on the form of Cd ions and their proportion in the solution. Based on the amount of Cd adsorbed and the distribution of Cd species in the solution, the adsorption of Cd on the HAS-Mt and HyA-Mt complexes took place in various chemical forms.     

Formula fertilization of nitrogen and potassium fertilizers reduces cadmium accumulation in Panax notoginseng

ABSTRACT

This study investigated the effect of nitrogen (N) and potassium (K) formula fertilization on cadmium (Cd) accumulation in P. notoginseng. Field investigations as well as formulated N and K fertilizers application experiments were conducted. Field investigations showed that Cd accumulation decreased PNS content in the main roots of P. notoginseng, while PNS content was promoted by soil available potassium (AK) and K in the main roots. The Cd content in P. notoginseng and the bioavailable Cd content in the soil decreased with the increasing of total K (TK) and AK in the soil. The increase of soil pH, total organic matter (TOM) and cation exchange capacity (CEC) values can reduce the bioavailable Cd content in soil, thus reducing the Cd accumulation in P. notoginseng. Under current fertilization in P. notoginseng cultivation, decreased N fertilization can alleviate the deterioration of soil physical and chemical properties. Under identical N fertilization, increasing K fertilization promoted the PNS accumulation (0.3–38.3%), also improved soil physical and chemical properties. Formulated N and K fertilizers application (1:2) experiments showed that reducing application of N and increasing K fertilization could reduce the bioavailable Cd content in soil, and the Cd content also decreased by 0.5–69.6% in P. notoginseng.

Abbreviation: PNS: P. notoginseng saponins; F(EXC): Exchangeable fraction; F(Carb): Bound to carbonates fraction; F(Fe-MnOX): Bound to iron and manganese oxides fraction; F(OM): Bound to organic matter fraction; F(RES): Residual fraction; AK: Available potassium; TK: Total potassium; CEC: Cation exchange capacity; TOM: Total organic matter     

配施硫基肥对夏玉米镉铅累积的阻控效应

该文以府河流域污灌区农田为研究对象,通过田间小区试验研究了5种施肥措施对土壤重金属镉(Cd)、铅(Pb)有效性以及夏玉米(Zea mays L.)对Cd、Pb富集和转运能力的影响。结果表明:与农民常规施肥(CK)相比,尿素、磷酸二铵和氯化钾配施(N-P-K)以及腐殖酸复合肥、尿素和磷酸二铵配施(HA-N-P)的表层土壤Cd、Pb有效性以及夏玉米对Cd、Pb的富集和迁移能力差异均不显著(P0.05)。然而,腐殖酸复合肥、硫酸铵和磷酸二铵配施(HA-S-P)以及硫酸铵、磷酸二铵和硫酸钾配施(S-P-K)2种施肥措施的表层土壤有效Cd含量分别比CK降低了10.60%和6.36%,表层土壤有效Pb含量分别比CK降低了11.49%和6.00%。此外,HA-S-P处理和S-P-K处理夏玉米Pb转运系数分别比CK降低了50.33%和77.10%,且夏玉米籽粒Pb含量分别比CK降低了59.75%和80.43%(P0.05),但各处理间夏玉米对Cd的转运和富集能力差异并不显著,这说明施用硫基肥可有效抑制夏玉米对Pb的富集和转运,但并未影响其对Cd的富集和转运。综上所述,该污灌区轻度Cd、Pb复合污染农田土壤种植夏玉米建议硫酸铵、磷酸二铵和硫酸钾配施,或者腐殖酸复合肥、硫酸铵和磷酸二铵配施。     

Magnesium accumulation and mineral balance in sudangrass as influenced by potassium,calcium and sodium

Abstract

Sudangrass (Sorghum sudanense, ‘Piper’ Stapf) was grown in the greenhouse in a slightly calcareous sample of Shano silt loam. The purpose of the study was to evaluate plant response to Mg and to determine any changes in Mg nutrition following individual or composite application of Mg, Ca, K and Na as nitrate compounds. The concentration of Mg in plant tissue decreased following K application and increased with each increment of Mg applied irrespective of variations in the proportions of Ca and Na included in the treatments. A base treatment including Ca, Na, and K applied with or without Mg showed a significant yield response to Mg. The Mg response was attributed to a more favorable ionic balance in the growth medium with respect to Mg because the soil was not particularly Mg deficient. Application of Mg in this case lowered the plant K concentration significantly, increased the concentration of Mg, and gave a lower K/(Ca+Mg) ratio in the foliage than was obtained without Mg. Results suggest that high levels of other nutrient cations may adversely affect the Mg nutrition of crops growing on alkaline soils not abundantly supplied with available Mg.     

Stimulation in the movement and uptake of phosphorus in response to magnetic P solution and arbuscular mycorrhizal fungi in Ocimum basilicum

A greenhouse experiment was conducted to assess the effects of magnetic field, arbuscular mycorrhizal fungi (AMF), and phosphorus (P) concentration in the nutrient solution (0, 5, 10, 20, or 40 mg L^?1) on the mobility and accumulation of P in soil and plant tissues of basil (Ocimum basilicum L.). The experiment was designed as a factorial combination and treatments were arranged in a completely randomized design with four replicates. Magnetic field increased water-soluble P in the soil and P concentration in plant shoot by 30.0% and 13.0%, respectively, in comparison to the control. The application of magnetic field and inoculation of AMF at 10 mg P L^?1 increased the P translocation efficiency by 23.3% and 17.8%, respectively. Overall, our results demonstrated that the use of magnetic field and AMF could be an effective tool for enhancing of uptake and movement efficiency of P even at low concentrations.     

不同氮磷钾肥对土壤pH和镉有效性的影响

采用土壤培养方法研究了不同氮、磷、钾肥对土壤pH和镉有效性的影响。结果表明,在培养60 d时,所有氮肥处理均降低了土壤pH,增加了Cd的提取量;但高量尿素和氯化铵处理土壤pH降低最多,提取的Cd也最多;硫酸铵提取的Cd较对照增加最小。所有磷肥处理均引起土壤pH小幅降低,但对土壤Cd提取量的影响以普钙稍大。3种钾肥处理均降低了土壤pH,其中氯化钾在0 d时提取的Cd在所有钾肥处理中为最高,其提取能力15 d后逐渐消失,试验结束时所有钾肥处理对Cd提取量均低于对照。本研究进一步表明,在土壤Cd含量处于污染临界值附近或已受Cd污染的土壤上,应避免施用高量的酸性肥料如尿素、氯化铵、普钙,以及其他酸性物料。在常用磷、钾肥中,磷酸二铵和硫酸钾在Cd污染土壤上施用更为适合。     

Translocation and accumulation of heavy metals in Ocimum basilicum L. plants grown in a mining-contaminated soil

Purpose

The evaluation of the ecotoxicity effects of some heavy metals on the plant growth and metal accumulation in Ocimum basilicum L. cultivated on unpolluted and polluted soils represented the objective of the present study.

Materials and methods

The basil aromatic herb was evaluated in a laboratory experiment using soil contaminated with Cd, Co, Cr, Cu, Ni, Pb, and Zn, similar to the one from a mining area. The soils and different organs of the basil plants were analyzed, the total contents of the added elements being determined using inductively coupled plasma optical emission spectrometry. The ability of basil plants to accumulate metals from soil and to translocate them in their organs was evaluated by transfer coefficient, translocation factor, enrichment factor, and geo-accumulation index determinations.

Results and discussion

The basil plants grown in the metal-polluted soil showed stimulation effects comparing with the plants from the control soil. At the end of the exposure period, the plants had a visible increase of biomass and presented inflorescences and the leaves’ green pigment was intensified. The metals gathered differently in plant organs: Cd, Co, Cr, and Pb were accumulated in roots, while Cu, Ni, and Zn in flowers. Cr and Pb exceeded the toxic levels in roots. Also, the heavy metal intake depends on the plant development stages; thus, Cd, Cr, and Pb were accumulated more in mature plant leaves. The Cd and Pb contents were higher than the World Health Organization and European Commission permissible limits.

Conclusions

The experimental results revealed that the basil plants exposed to a mixture of heavy metals have the potential to reduce the metal mobility from soil to plants. Translocation process from roots to flowers and to leaves was observed for Cu, Ni, and Zn, emphasizing a competition between metals. The calculated bioaccumulation factors were insignificant, but Cd and Pb concentrations exceeded the legal limits in the mature plants, being restricted for human or animal consumption.

     

柴达木农田土壤Cd的积累影响及风险预测

【目的】土壤重金属空间结构特征是土壤环境质量评价及重金属污染评价的基础。本文用地质统计学方法研究了柴达木盆地原生地和耕种50年的农田土壤镉的空间分布特征,对土壤镉进行质量评价,同时分析了农业耕种对土壤镉积累的影响,调查统计了灌溉水、肥料、农药等农业源土壤镉的输入量,为农田镉积累的风险预测提供参考。【方法】以柴达木盆地诺木洪农场的一块原生地（从未耕种过的土地,可以认为无化肥污染）和一块耕种地（已种植了50年的农田）为研究对象,从原生地采集22个土壤样本,耕种地采集50个土壤样本进行镉含量的测定,同时检测灌溉水、农药、化肥中的镉含量,并进行每年农田输入量的统计。用Excel软件进行数据处理,反比权重法（IDW,Inverse Distance Weighting）插值,GIS9.3进行空间分析和图像处理;以单项污染指数法评价土壤镉质量,评价模式为Pi=Ci/Si（Pi为污染物镉的单项污染指数,Ci为污染物镉的实测数据,Si为污染物的评价标准）。评价标准分别以农业部公布的行业标准《无公害食品 枸杞生产技术规程》（NY/T 5249-2004）和《绿色食品 枸杞》（NY/T1051-2006）产地环境标准要求下的《绿色食品 产地环境技术条件》（NY/T 391-2000）为依据。依据农业源土壤镉输入量,以土壤现状值为起点,以绿色食品标准限量值为终点,测算输入量积累突破两端差值的年限。【结果】原生地22个土壤样品的镉平均含量为0.30 mg/kg,是土壤背景值的两倍（0.14 mg/kg）,达到无公害食品（0.60 mg/kg）和绿色食品（0.40 mg/kg）标准;种植50年农田的50个土壤样品的镉平均含量为0.43 mg/kg,是土壤背景值的3倍,达到无公害食品标准,但超过绿色食品标准。用于灌溉的河水的镉含量为0.0036 ng/kg。检测生产中使用的15种农药和7种肥料,其中的镉导致每年土壤镉增加3444 mg/hm2。最严重的污染源是鸡粪,施入土壤后每年导致土壤镉增加2025 mg/hm2,其次依次为复合肥（使土壤镉增加576 mg/hm2）,磷酸二铵（增加432 mg/hm2）,有机肥（增加360 mg/hm2）。【结论】以小尺度空间分布和全量统计研究的诺木洪农场土壤镉含量这一单一指标衡量,可以看出诺木洪原生地土壤是清洁的,能够满足无公害、绿色食品的生产;但是研究选择的多年耕种田已经遭到重金属镉的污染,只能达到无公害食品标准,而达不到绿色食品标准。现行生产中的施肥措施是导致诺木洪土壤重金属镉污染的一个重要因素,其中鸡粪对镉污染的贡献最大,其次是复合肥、磷酸二铵和有机肥。如果继续现在这种耕种方式,以现有的原生地镉含量均值为0.30 mg/kg进行计算,76.3年后该土地镉含量将超过0.40 mg/kg的绿色标准上限。     

Effect of cadmium toxicity on micronutrient concentration,uptake and partitioning in seven rice cultivars

Heavy metal uptake, translocation and partitioning differ greatly among plant cultivars and plant parts. A pot experiment was conducted to determine the effect of cadmium (Cd) levels (0, 45 and 90 mg kg^?1 soil) on dry matter yield, and concentration, uptake and translocation of Cd, Fe, Zn, Mn and Cu in seven rice cultivars. Application of 45 mg Cd kg^?1 soil decreased root and shoot dry weight. On average, shoot and root Cd concentrations and uptake increased in all cultivars, but micronutrients uptake decreased following the application of 45 mg Cd kg^?1. No significant differences were observed between 45 and 90 mg kg^?1 Cd levels. On average, Cd treatments resulted in a decrease in Zn, Fe and Mn concentrations in shoots and Zn, Cu and Mn concentrations in roots. Differences were observed in Cd and micronutrient concentrations and uptake among rice cultivars. Translocation factor, defined as the shoot/root concentration ratio indicated that Cu and Fe contents in roots were higher than in shoots. The Mn concentration was much higher in shoots. Zinc concentrations were almost similar in the two organs of rice at 0 and 45 mg Cd kg^?1. A higher Cd level, however, led to a decrease in the Zn concentration in shoots.     

不同基因型番茄幼苗对镉胁迫的生理响应及镉吸收差异

采用盆栽试验,通过研究不同浓度镉（1、5、10mg·kg-1）胁迫下4种基因型番茄圣粉1号、东圣1号、农城906和宝冠1号幼苗地上部及根部生物量、镉吸收量、活性氧含量（ROS）及其他生理指标,筛选出镉低积累基因型番茄品种。结果表明,不同基因型番茄对镉胁迫响应存在差异。随镉处理浓度增加,4个品种番茄幼苗地上部生物量显著下降（P〈0.05）。地上部Cd吸收量呈增加趋势,在中浓度（5mg·kg-1）镉处理下达到峰值,品种间为宝冠1号〉圣粉1号、农城906〉东圣1号。4个品种番茄幼苗Cd转移率随镉处理浓度增加显著降低,其中东圣1号Cd转移率较低,根部Cd滞留较多,向地上部转移较少。4个品种番茄幼苗生理活性存在差异,宝冠1号番茄幼苗ROS含量及抗氧化酶（POD,CAT）活性随镉处理浓度增加变化幅度较大,东圣1号变化幅度相对较小。综合各项指标,4个基因型番茄中东圣1号为镉低积累品种。     

Effects of soil amendments, foliar sprayings of silicon and selenium and their combinations on the reduction of cadmium accumulation in rice

Agricultural soil contamination by cadmium (Cd) is becoming one of the most serious environmental issues and public concerns. In this study, factorial arrangements of treatments were designed to explore the effects of two soil amendments, sodium sulfide-biofuel ash (SSBA) and lime (0.1%), and three foliar applications, silicon (Si, 2.5 mmol L^-1), selenium (Se, 40 mg L^-1), and their combination (SS), on Cd reduction in rice (Oryza sativa L.) in a pot experiment, which were then verified in a field experiment. Compared with the control without amendment but with spraying of deionized water, both SSBA and lime significantly reduced concentrations of CaCl₂-extractable Cd in soil by 30%-39% and 31%-40% and Cd in brown rice by 44%-63% and 53%-72% in the pot and field experiments, respectively. Foliar Si, Se, and SS applications significantly reduced Cd accumulation in brown rice by 62%-64%, 72%-83%, and 39%-73%, respectively, increased rice grain yield, and improved antioxidant enzyme activities in rice leaves but with different trends in the pot and field experiments. Combinations of SSBA and lime with Si, Se, and SS had a non-significant synergistic effect on Cd reduction in brown rice compared to only foliar spraying or soil amendment in both pot and field experiments, although SSBA + Se and SSBA + Si reduced Cd concentration in brown rice by 16%-34% and 14%-24% compared to only foliar Si and Se and soil SSBA applications, respectively. Soil lime application and foliar Si spraying were the most cost-effective strategies to reduce Cd accumulation in brown rice in the field and pot experiments, respectively. Although soil amendments and foliar treatments were individually effective, their combinations failed to generate a significant synergistic reduction of Cd concentration in brown rice.     

Growth and flowering of tuberose (Polianthes tuberosa L.) as influenced by foliar application of organic fertilizers

Foliar application effects of two commercial organic fertilizers: Drin and Algaren on growth and flowering of two cultivars (‘Mahallati’ and ‘Dezfuli’) of tuberose (Polianthes tuberosa L.) were examined. This research was carried out in a complete randomized design with factorial arrangements including two factors (cultivars and organic fertilizers), each treatment with three replications. Drin and Algaren improved vegetative growth in tuberose and concentration of 0.4–0.6 mL L^?1 Drin and concentration of 0.6 and 0.8 mL L^?1 of Algaren could be recommended for foliar application on tuberose. This is the first report on using new types of organic fertilizers on ornamental bulbous plants. Further experiments are needed to clarify more the effects of these organic fertilizers on bulbous plants.     

Effects of Exogenous Nitric Oxide and 24-Epibrassinolide on the Physiological Characteristics of Peanut Seedlings Under Cadmium Stress

Cadmium(Cd) is highly toxic to plants, animals, and humans. Limited information is available on the role of nitric oxide(NO)and/or 24-epibrassinolide(EBR) in response of plants to Cd stress. In this study, a hydroponic experiment was performed to investigate the effects of NO and/or EBR on peanut plants subjected to Cd stress(200 μmol L~(-1)) with sodium nitroprusside(SNP, an exogenous NO donor)(250 μmol L~(-1)) and/or EBR(0.1 μmol L~(-1)) addition. The results showed that Cd exposure inhibited plant growth, and this stress was alleviated by exogenous NO or EBR, and especially the combination of the two. Treatment with Cd inhibited the growth of peanut seedlings, decreased chlorophyll content, and significantly increased the Cd concentration in plants. Furthermore, the concentration of reactive oxygen species(ROS) markedly increased in peanut seedlings under Cd stress, resulting in the accumulation of malondialdehyde(MDA) and proline in leaves and roots. Under Cd stress, applications of SNP, EBR, and especially the two in combination significantly reduced the translocation of Cd from roots to leaves, increased the chlorophyll content, decreased the concentrations of ROS, MDA, and proline, and significantly enhanced the activities of superoxide dismutase(SOD), peroxidase(POD), and catalase(CAT) in peanut seedlings. Exogenous NO and/or EBR also stimulated the activities of nitrate reductase(NR)and nitric oxide synthase(NOS) and increased the contents of antioxidants, such as ascorbic acid(AsA) and reduced glutathione(GSH). Furthermore, exogenous NO and/or EBR enhanced Cd accumulation in the cell wall and thus decreased Cd distribution in the organelles in the roots. The concentrations of calcium(Ca), iron(Fe), magnesium(Mg), and zinc(Zn) were also regulated by exogenous NO or EBR, and especially by the two in combination. These results indicated that SNP and EBR, alone and particularly in combination, can mitigate the negative effects of Cd stress in peanut plants.     

Nitrous oxide concentrations in an Andisol profile and emissions to the atmosphere as influenced by the application of nitrogen fertilizers and manure

A field experiment was conducted to determine N₂O concentrations in the soil profile and emissions as influenced by the application of N fertilizers and manure in a typical Japanese Andisol, which had been under a rotation of oat and carrot for the previous 3 years. The treatments include ammonium sulphate (AS), controlled-release fertilizer (CRF) and cattle manure (CM) in addition to a control; all the fertilizers were applied either at 150 kg N ha^-1 or 300 kg N ha^-1 at the time of sowing carrot. N₂O emissions from the soil surface were measured with closed-chamber techniques, while N₂O concentrations in the soil profile were measured using stainless steel sampling probes inserted into the soil at depths of 10, 20, 40, 60, 80 and 100 cm. Moreover, soil water potential, soil temperature and rainfall data were also recorded. The results indicated that N₂O concentrations in the soil profile were always greater than in the atmosphere, ranging from 0.36 µl N₂O-N l^-1 to 5.3 µl N₂O-N l^-1. The relatively large accumulation of N₂O in the lower profiles may be a significant source for N₂O flux. Taking the changes of soil mineral N into consideration, most emissions of N₂O were probably produced from nitrification. The accumulation of N₂O in the soil profile and emissions to the atmosphere were differently influenced by the amendments of N fertilizers and manure, being consistently higher in CRF than in CM and AS treatments at the corresponding application rates, but no significant difference existed with respect to the various N sources.     

Cadmium and zinc accumulation by the hyperaccumulator Thlaspi caerulescens from soils enriched with insoluble metal compounds

Abstract

The clay mineralogy of seven Dystrandepts developed on basalts in Northland (New Zealand), the French Massif Central and Western Oregon (U.S.A.) was determined by selective dissolution—differential infrared spectroscopy in combination with chemical, X-ray diffrac tion, electron microscopic and thermogravimetric analyses. Of 14 soil samples, 6 from Northland and Cantal (French Massif Central) contained allophane and imogolite, whereas the remaining 8 did not. Allophane-like constituents and/or “alumina” were found in all the samples, and opaline silica was present in three A₁ horizons. The contents of 2 : 1–2 : 1 : 1 layer silicates and their intergrades varied somewhat among the samples. Predominant volcanic glass shards in the Northland Dystrandepts and quartz in the Western Oregon Dystrandepts indicated that their parent materials were not restricted to basalt.     

Cadmium and zinc accumulation in willow and poplar species grown on polluted soils

Woody plant species that produce high biomass have been proposed for use in phytoremediation technology. We investigated the accumulation of cadmium (Cd) and zinc (Zn) in Salix babylonica, S. caprea, S. dasyclados, S. matsudana × alba, S. purpurea, S. smithiana, Populus tremula, and P. nigra clones grown in a pot experiment on a Calcaric and a Eutric Cambisol (pH 7.2 and 6.4) of different levels of contamination (total metal concentrations in mg kg^–1 in soil A: 32.7 Cd, 1760 Zn; soil B: 4.34 Cd, 220 Zn). Generally, the tested clones tolerated large metal concentrations in soils and had larger Cd and Zn concentrations in leaves compared to the roots. The largest Cd concentrations in leaves were found in two clones of S. smithiana (440 mg kg^–1 on soil A; 70 mg kg^–1 on soil B). One of the S. smithiana clones had also the largest Zn concentrations (870 mg kg^–1) on soil B but accumulated slightly less Zn than a S. matsudana × alba clone (2430 mg kg^–1) on soil A. The Cd concentrations in leaves of both S. smithiana clones on soil A are the largest ever reported for soil‐grown willows. The bioconcentration factors of the best performing clone reached 15.9 for Cd and 3.93 for Zn on the less contaminated soil B. Also based on the metal contents in leaves, this clone was identified as the most promising for phytoextraction. The metal concentrations in leaves observed in the pot experiment do not reflect those found in a previous hydroponic study and the leaf‐to‐root ratios are clearly underestimated in hydroponic conditions. This demonstrates the need for testing candidates for phytoextraction crops on soils rather than in hydroponics. Our data also show that the phytoextraction potential should be tested on different soils to avoid misleading conclusions.