Nutritional status of Washington Navel orange orchards in arid lands of southern Iran

Nutrient deficiency may be a reason for citrus decline in many countries. In the current investigation, soil and leaf samples of 63 Washington Navel orange orchards in arid lands of southern Iran (Darab region) were analyzed to study the nutritional status of orange orchards and to find relationships between soil properties and nutrients content of soils and orange leaves. The soils differed widely in clay content (3–37%), pH value (7.04–7.95), calcium carbonate equivalent (18–86%), and organic matter content (0.3–12%). These soils represented a wide range of plant nutrients concentration. Majority of the studied soils had sufficient concentrations of all nutrients (except Fe). Results indicated that pH, organic matter, clay, and calcium carbonate contents are the most important characteristics that control the soil nutrients availability. The mean contents of N, K, P, Fe, Mn, Zn, and Cu in leaves were 2.59, 0.84, and 0.14% and 66, 44, 17, and 12?mg?kg^?1, respectively. Most orchards showed K, Fe, and Zn deficiencies. We found no relationships between nutrients content in leaf and soil (except for K, Mn, and Zn); and this indicated that soil analysis may not be a reliable method for most nutrient deficiency diagnosis.     

干旱区绿洲土壤Cd-Zn复合污染下重金属形态及其生物有效性的研究

通过模拟基于Cd-Zn复合污染下干旱区绿洲土壤的胡萝卜盆栽试验,用Tessier连续提取法对胡萝卜土壤中Cd、Zn的形态分布进行分析,同时就生物利用性形态的变化研究了Cd、Zn的生物有效性。结果表明:1)原状土壤中Cd和Zn主要以残渣态存在,随着复合胁迫浓度的增加,Cd的主要赋存形态逐步转变为碳酸盐结合态和可交换态,Zn主要赋存形态逐步转变为以铁锰氧化态和残渣态,但有效态和潜在有效态的比例大大增加。2)胡萝卜对Cd、Zn的富集作用均为地上部分大于地下部分,对Cd的富集能力远远大于Zn。3)胡萝卜吸收的Cd和Zn不仅包括可交换态和碳酸盐结合态,还包括了在一定条件下释放出来的铁锰氧化态和有机结合态。     

Influence of Dissolved Organic Carbon and Initial Moisture on Zinc Sorption by Two Arid Soils

Sorption of added zinc to irrigated soils in arid regions is an important process that may control the availability of zinc to growing plants . Two soil surface samples varying in clay , organic matter , and calcium carbonate content were selected from central and southwestern regions of Saudi Arabia and prepared in order to give different initial moisture contents ranging from air dried to 100 % of field capacity . The sorption experiment was conducted using Zn concentrations ranging from 5 to 25 mg L 1, prepared from ZnSO4 either in distilled water or in solutions containing 75 mg L 1 dissolved organic carbon (DOC). Results indicate that the amount of Zn sorbed in the presence of DOC was relatively high compared with the absence of DOC and Zn retention was strongly affected by the initial soil moisture content . Also , equilibrium Zn concentrations were quite low , while Zn retentions were high in all treatments . Data of Zn sorption were described by the Freundlich isotherm , and two linear portions were found in most cases . In the absence of DOC , retentions of added Zn were controlled by the available exchange sites and / or the precipitation of Zn as sparingly soluble forms. Zn ions in the presence of DOC were able to form soluble - Zn organic complexes that adsorb on the soil surfaces . The extent of such behavior was related to the variations in clay , organic matter , and calcium carbonate contents as well as the initial moisture of the soil . Results indicate that addition of DOC reduces the amount of extractable Zn from either soil Zn or the sorbed Zn by ammonium bicarbonate diethylenetriamine pentaacetic acid ( AB DTPA ). More than 80 % of the sorbed Zn was extracted by AB-DTPA , and the percentage of extracted / sorbed Zn decreased with the increase in sorbed Zn . The obtained results give evidence that initial moisture content and addition of DOC reduce the extractability of applied inorganic Zn by AB-DTPA extract in arid soils.     

不同形态氧化铁对黄土性土壤吸附铅的影响

针对土壤含氧化铁的普遍性以及氧化铁对土壤理化性质的重要影响,探求氧化铁对土壤吸附重金属离子的作用与影响。采用了化学选择性溶提技术,分别去除黄土性母质上发育的古土壤、淋溶褐土和黄褐土中不同形态的氧化铁,采用了等温吸附试验,并以Langmuir和Freundlich方程拟合参数为指标,分析去除不同形态氧化铁前后土壤对Pb~(2+)的吸附特征。结果表明:原土壤对Pb~(2+)的吸附曲线逐渐递增,并无明显阶段特征,且更符合Freundlich方程;而去除不同形态氧化铁后的3类土壤对Pb~(2+)的吸附曲线均为L型,阶段特征显著,更加符合Langmuir方程,且土壤对Pb~(2+)的亲和力(KL)成倍增加;去除络合态铁和无定形氧化铁后,土壤对Pb~(2+)的最大吸附量均有不同程度增加,其中去除无定形氧化铁之后,古土壤对Pb~(2+)的最大吸附量增幅最大,增加了14.71 mg·g-1;去除游离态氧化铁后古土壤、淋溶褐土对Pb~(2+)的吸附量分别下降了5.95、3.10 mg·g-1,黄褐土对Pb~(2+)的吸附量则增加了2.98 mg·g-1。土壤中氧化铁对Pb~(2+)吸附能力与吸附容量的影响不完全依赖于氧化铁的含量,在很大程度上依赖于土壤中氧化铁的形态。对于不同氧化铁形态的土壤采用相应的化学溶提技术,能够获得具有较高吸附性能的粘土矿物环境材料。     

新乡小冀工业区周边土壤重金属污染评价与形态分析

通过实地调查和实验分析,对小冀工业区周边土壤中六种重金属(Cd、Cr、Cu、Ni、Pb和Zn)进行了总量测定。参照GB15618-1995二级标准,采用单因子指数法和内梅罗综合污染指数法对土壤质量进行了现状评价,并采用Tessier五步连续萃取法对超标重金属Cd、Ni和Zn进行了形态分析及生物活性分析。结果表明:1)Cr、Cu和Pb含量均未超过国标二级标准,Cd、Ni和Zn三种重金属含量均超标,工业区综合污染非常严重,主要污染元素是Cd;2)Cd、Ni和Zn在土壤中的形态分布差异性较大,Cd主要以铁锰氧化物结合态存在,Ni和Zn主要以残渣态和铁锰氧化物结合态存在;3)金属生物活性系数大小顺序为Cd>Zn>Ni,迁移系数的大小顺序是Cd>Zn>Ni,其中Cd的生态风险很大。     

不同增施微肥方式对马铃薯块茎产量和Zn、Fe含量的影响

本研究的目的在于揭示土施和喷施两种增施微肥方式对马铃薯块茎产量和Zn、Fe含量的影响。试验选取定薯1号为试材,进行田间试验,设13个处理,依次为:硫酸锌、硫酸亚铁、硫酸锰分别作基肥施入(D1、D2、D3),在现蕾期、开花期和块茎膨大期喷施0.2%水溶液(A1、A2、A3、B1、B2、B3、C1、C2、C3),不喷施为对照(CK)。结果表明:增施微肥能使株高降低0.9~3.9 cm,茎粗增粗0.02~0.13 cm,单株结薯数增加0.13~0.86个,也能使单株产量增加0.002~0.18 kg,平均单薯重增加7.48~12.04 g,使生育期延长1~8 d,在现蕾期、开花期、块茎膨大期喷施硫酸锌和现蕾期喷施硫酸锰能使产量增加18.4%~25.7%;现蕾期喷施硫酸锌可提高块茎Zn含量(提高2.2 mg·kg~(-1)),而在现蕾期喷施硫酸锌、硫酸亚铁、硫酸锰,开花期喷施硫酸亚铁,硫酸锰作基肥施入可提高块茎Fe含量(提高2.0~9.0 mg·kg~(-1))。     

Micronutrient Distribution in Different Physiographic Units of the Siwalik Hills of the Semiarid Tract of Punjab,India

We investigated the profile distribution of total and diethylenetriamine pentaacetic acid ( DTPA )- extractable micronutrients ( Zn , Mn , Cu , Fe ) in soils developed on six physiographic units of the semiarid Siwalik hills of Punjab in northwest India . The soils showed a gradual fining of texture from shoulder slopes to toe slopes . All soils were alkaline and calcareous . In general , total and DTPA-extractable micro nutrients were higher in surface horizons and decreased in subsurface horizons . However , none of the micronutrients exhibited any consistent pattern of distribution with depth on different geomorphic surfaces . Physiography had a strong influence on the spatial distribution of total and available micronutrients . Contents of all micronutrients and their forms were higher in fine-textured and uneroded soils than in coarse-textured eroded soils . Soil pH , calcium carbonate , organic matter , and size fractions had strong influence on the distribution of total and extractable micronutrients . Based on linear coefficients of correlation , total content of micro nutrients increased with increase in clay content , whereas DTPA - extractable micronutrient content increased with increase in organic carbon and decreased with increase in pH and CaCO3 content . Except for Cu , no other micronutrient showed influence of total reserves on availability of the respective micronutrient . Among the various micronutrients , deficiency of Zn was found to be widespread , followed by Fe and Cu in the cultivated soils on foot slopes , toe slopes , and floodplains .     

甲磺隆污染土壤生物修复的初步探索

以14C-甲磺隆为例,通过投加优选菌株青霉(Penicillium sp.)和发酵有机肥,研究了污染土壤中甲磺隆除草剂的生物修复。结果显示,加入优选菌株Penicillium sp.或有机肥对甲磺隆污染土壤进行生物修复是可行的,Penicillium sp.或有机肥的引入,显著提高了土壤中甲磺隆残留物的降解速率,并大大减少了土壤中结合态甲磺隆残留物的形成,甲磺隆的降解半衰期由162.3 d降至42.5~51.6 d,56 d时其结合残留率仅为1.1%~4.6%,而对照土壤中结合残留率仍达到35.6%。     

Reduced severity and impact of Fusarium wilt on strawberry by manipulation of soil pH, soil organic amendments and crop rotation

Strawberry (Fragaria?×?ananassa) is one of the most important berry crops worldwide. Fusarium wilt poses a serious threat to commercial strawberry production worldwide and causes severe economic losses. Our previous surveys suggested that soil pH, soil amendment with organic matter and/or crop rotation could offer opportunities for improved management of strawberry disease. Studies were conducted for the first time to determine the effects of soil pH, soil amendments with manure compost and crop residue, and crop rotation on the severity and impact of Fusarium wilt on strawberry. At soil pH 6.7, plants showed the least severe disease and the lowest reductions in shoot and root dry weight (DW) of plants from disease, significantly lower than those of plants in acidic soil at pH 5.2 or 5.8. In soil amendment with manure compost at 5.0?%, plants showed the least severe disease and the lowest reductions in shoot and root DW of plants from disease, significantly lower than those of plants in the other three levels of manure compost. In soil amendment with crop residue at 2.5?% or 5.0?%, shoot and root disease of plants and reductions in shoot and root DW of plants from disease were significantly lower than those of plants in soil without crop residue or excessive crop residue amendment at 10.0?%. Plants in soil rotated with tomato not only showed the least severe disease but also showed the lowest reductions in shoot and root DW of plants from disease, significantly lower than those of plants in soil continuously planted with strawberry without rotation or rotated with capsicum. Soil pH, soil amendment with manure compost or crop residue, and crop rotation, all significantly reduced the severity and impact of Fusarium wilt on strawberry. There is great potential for manipulating soil pH, adding soil organic amendments and utilizing crop rotation, not only to successfully manage Fusarium wilt on strawberry, but to do so in a sustainable way without current reliance upon chemical fumigants.     

The extraction and assay of thiabendazole in strongly adsorbing soils

Thiabendazole is strongly adsorbed on soils, and is not readily extracted by conventional solvents. two-phase solvent system consisting of a mixture of aqueous ammonium chloride solution (pH 10), ethanol and chloroform was developed which extracted thiabendazole from a range of soils including high-organic fen peat soils and mushroom compost. Subsequent partition of the extract between organic solvents and acid or alkaline solutions provided sufficient clean-up for assay by ultraviolet or fluorescence spectroscopy, of concentrations of less than 1 mg thiabendazole kg^?1 of soil. Investigation of the adsorption of thiabendazole from aqueous solution by soils indicated the importance of both soil organic and mineral matter and the adsorption of both neutral and protonated molecules.     

不同基因型冬小麦对氮肥与锌铁肥配施的反应

以10种不同基因型冬小麦为材料,采用田间再裂区设计,研究了不同氮肥用量(0,105 kg N/hm2)与锌铁用量(Zn:0,6.8 kg/hm2;Fe:0,12.1 kg/hm2)对冬小麦幼苗(返青期)生长及锌铁吸收的影响.结果表明,施氮对10种基因型冬小麦的生物量、分蘖数和叶绿素SPAD值均有显著影响,增幅分别达到15.8%,14.7%,4.6%;施用锌铁肥后生物量增加8.0%,但分蘖数减少5.8%,而对叶绿素SPAD值几乎无影响;10种不同基因型小麦植株的长势有较大差异.施用氮肥后,显著提高了各基因型小麦植株的锌含量与锌携出量,平均提高7.6%和22.9%,而小麦植株铁的含量降低6.4%,但携出量提高7.2%;施用锌铁肥显著增加了小麦的锌含量和携出量,增幅分别11.9%和19.2%,但对铁的含量和携出量影响不显著.10种不同基因型小麦植株锌铁携出量存在一定差异,吸收值较高的三种基因型分别为绵阳31、陕优225、陕优253.     

Response of Cape gooseberry (Physalis peruviana L.) to nitrogen application under sandy soil conditions

The effect of different nitrogen (N) levels on growth and productivity of Cape gooseberry, cultivated in new reclaimed lands (sandy soil) at Nubaria region in Egypt, was investigated. Nitrogen levels were applied at rates of 50, 100, 150 and 200?kg?N?ha^?1 as ammonium sulfate. The amount of??N for each treatment was divided into five applications (after transplanting, seven days later, at the beginning of flowering, during fruit set and after the first harvest). Several growth parameters and yield were recorded in addition to nitrogen content in leaves. The results revealed that Cape gooseberry plants responded positively to nitrogen levels in sandy soils. Yield, number of fruits, and diameter of fruits increased significantly by increasing the nitrogen level up to 200?kg?N?ha^?1. Moreover, plant height, number of leaves, N-content in leaves and N-uptake shows a positive reaction to increased nitrogen supply. The quantitative effects of nitrogen on Cape gooseberry plants and the possible explanations of plant responses are discussed.     

宝鸡某冶炼厂周边土壤铅镉总量及形态空间分布特征

采用克里金插值法对宝鸡某冶炼厂周边农田土壤中铅镉含量及形态空间分布特征进行了研究,并分析了土壤中铅镉总量及各形态含量与小麦中铅镉含量的相关性,目的在于为冶炼厂周边土壤重金属污染的表征提供依据。结果表明,土壤中Pb形态的高低顺序为：残渣态>有机硫结合态>铁锰氧化态>可交换态,Cd形态为：可交换态>残渣态>有机硫结合态>铁锰氧化态。土壤中Pb总量及Pb、Cd铁锰氧化态在距离冶炼厂500 m处含量均显著高于1 500 m和2 500 m处,后两者之间无差异;而Cd总量及Pb、Cd可交换态、有机硫结合态和残渣态在三个采样距离并没有表现出显著性差异。克里金插值分析表明,除Pb可交换态外,Pb和Cd其余形态在一定程度上均显示出与风向的一致性。相关分析表明,土壤中Pb、Cd可交换态、铁锰氧化态与小麦Pb和Cd含量均有显著的相关性,表明冶炼厂周边旱地土壤中,Pb、Cd可交换态和铁锰氧化态都可能作为土壤重金属污染空间分布和有效性表征的指标。     

Copper and Zinc Competitive Adsorption: Desorption in Calcareous Soils

The behavior in competitive adsorption-desorption reactions of Cu and Zn was studied in four calcareous soils. Cu and Zn were added to the soil by Cu, Zn, and Cu+Zn sulfate solutions in a CaSO4 background. Soil sorption of these cations was described by equilibrium isotherms that fitted either Freundlich- or Langmuir type equations, although Cu desorption data fitted only Freundlich isotherms. Cu and Zn competition was quantified by distribution coefficients, Kd, relating cation distribution between soil and solute and by the competitive Langmuir equation. The competitive Langmuir equation was the better suited to describe the Cu-Zn competitive adsorption in these soils. Distribution coefficients presented lower values when both cations were present, decreasing when the Cu and Zn concentration in solution increased (decreasing soil affinity for these cations), thereby increasing their mobility through the soil. However, the distribution coefficient of specifically adsorbed Cu in equilibrium with cations extracted by a Mg (NO) solution increased with Cu concentration. Cu adsorption was more depres 3 se 2 d by Zn than Zn adsorption by Cu. The different behavior of Cu and Zn seems dependent on the percentage Ca (CO) and, to a lesser degree, on Cu and Zn organic matter complexes, free iro 3 n 2 content, and surface precipitation on oxides and carbonates.     

Adsorption and degradation of thiazopyr in compost‐amended and non‐amended soils

Adsorption and degradation of thiazopyr on two unamended soils and a soil amended annually during 8 years with compost were studied under laboratory conditions and compared with the results obtained on soils amended with fresh sewage sludge compost. The adsorption isotherms fitted the Freundlich equation well and a marked sorption increase was found in amended soils. Degradation data followed first‐order kinetics and thiazopyr had a half‐life of about 75 days at 25 °C and 60% water‐holding capacity of soil. The addition of fresh compost markedly decreased the rate of thiazopyr degradation, whereas the compost mineralised in the field after annual additions had only a small influence. Incubation studies with sterile soils showed a very significant decrease of the degradation rate, indicating that degradation by micro‐organisms was the main pathway of thiazopyr degradation in the soils studied. © 2001 Society of Chemical Industry     

Biological control of Fusarium wilt by <Emphasis Type="Italic">Bacillus amyloliquefaciens</Emphasis> IUMC7 isolated from mushroom compost

Bacillus amyloliquefaciens IUMC7 isolated from mushroom compost inhibited growth of Fusarium oxysporum f. sp. lycopersici (FOL) on culture plates, and a culture supernatant of IUMC7 inhibited in vitro germ tube elongation of FOL. When compared with control soils, mushroom compost inoculated with IUMC7 significantly reduced disease severity caused by FOL in tomato plants. PCR tests for expression of PR genes indicated that IUMC7 did not induce resistance in tomato plants. These results suggested that the suppression of disease was mainly caused by antimicrobial compounds produced by IUMC7.     

供锌和添加碳酸钙对不同基因型小麦幼苗生长及锌磷吸收的影响

以Hoagland营养液为介质,在不同Zn与CaCO3用量下,将以下5种基因型冬小麦进行营养液混合培养,探讨小麦幼苗生长及Zn与P吸收的状况。根据生长量及缺Zn症状的严重程度,把S02-8、远丰998判定为缺Zn敏感型,而中育6号、小偃22及西杂1号为缺Zn非敏感型;适量供Zn比高量供Zn更有利于小麦生长;低量Ca-CO3可在一定程度上促进小麦幼苗生长而高量CaCO3会抑制生长,缺Zn敏感型的生长量显著低于非敏感型,且前者的根冠比小于后者。加入CaCO3后对小麦植株Zn、P吸收的影响较小,但地上部P/Zn随CaCO3添加量的增加而递减。根系与地上部含Zn量与吸收量均随供Zn量的增加而增加,而高量供Zn时Zn在根部大量累积,同时高Zn用量在一定程度上抑制小麦植株对P的吸收,P/Zn随Zn用量的增加而降低。与不供Zn相比,高量供Zn显著降低了小麦植株根系及地上部的P/Zn值,而低量供Zn时,地上部的P/Zn仅有轻微的降低。供试的5种基因型小麦的P含量均未超过P中毒临界值,因此小麦幼苗出现的缺Zn症状与P无关。相对于缺Zn非敏感型小麦,缺Zn敏感型更易于在根系中累积Zn,吸P量较低,且地上部P/Zn较高。     

Biofumigation with Fresh Manure or Brassicaceae Residuals could be a Promising Methyl Bromide Alternative in Head Lettuce Production

The current study investigates the natural alternatives of methyl bromide on head lettuce plants grown in greenhouse. Lettuce (Lactuca sativa L.) seedlings (cv. “Big Bell”) were treated with six different MBr alternatives which are, Biofumigation with fresh cow manure, fresh chicken manure, or Brassicaceae residuals plus Bio-Compost application (using disease suppressive compost) in comparison with chemical control with one of MBr chemical alternatives (Basamid) and finally negative control (which is the standard farmer treatment). Despite that chemical control with Basamid recorded the highest survival rate, biofumigation with fresh chicken manure gave the best head length, diameter, fresh weight, dry weight, total and marketable yield. Also, highest head quality characteristics such as TSS, SPAD reading, and nitrogen content were recorded with biofumigation with fresh chicken manure. Regardless of the superiority of Biofumigation with fresh chicken manure, Biofumigation with fresh cow manure or Brassicaceae residuals showed a better vegetative growth and quality parameters than farmer treatment (control), and they had significantly less effect than chemical control treatment. Bio-Compost fortified with Trichoderma harzianum and Bacillus subtilis (disease suppressive compost) recorded survival rate similar to biofumigation treatments but were significantly lower than chemical control treatment. Bio-Compost treatment did not result in a good result regarding total and marketable yield head fresh and dry weight. There was no detected significant effect of the studied treatments on stem diameter, L?ascorbic acid (vitamin C), phosphorus and potassium content     

Field management effects on damping-off and early season vigor of crops in a transitional organic cropping system

Transitioning farmland to certified organic vegetable production can take many paths, each varying in their costs and benefits. Here, the effects of four organic transition strategies (i.e., tilled fallowing, mixed-species hay, low-intensity vegetables, and intensive vegetable production under high tunnels), each with and without annual compost applications for 3 years prior to assessment, were characterized. Although transition cropping strategies differed in soil chemistry (P < 0.05), the magnitude of the changes typically were marginal and pairwise comparisons were rarely significant. In contrast, the compost amendment had a much greater impact on soil chemistry regardless of cropping strategy. For example, percent C and total P increased by 2- to 5-fold and K increased from 6- to 12-fold. Under controlled conditions, damping-off of both edamame soybean (cv. Sayamusume) and tomato (cv. Tiny Tim) was reduced from 2 to 30% in soils from the mixed-hay transition. In the field, damping-off of both crops was also significantly lower in plots previously cropped to hay (P < 0.05). Although not always significant (P < 0.05), this pattern of suppression was observed in all four of the soybean experiments and three of the four tomato experiments independent of compost application. The compost amendments alone did not consistently suppress damping-off. However, plant height, fresh weight, and leaf area index of the surviving seedlings of both crops were greater in the compost-amended soils regardless of the transitional cropping treatment used (P < 0.05 for most comparisons). These data indicate that mixed-hay cropping during the transition periods can enhance soil suppressiveness to damping-off. In addition, although compost amendments applied during transition can improve crop vigor by significantly enhancing soil fertility, their effects on soilborne diseases are not yet predictable when transitioning to certified organic production.     

Simple estimation of available water capacity in soils of semiarid and subhumid environments

Soil available water capacity (AWC) is an important factor affecting soil productivity in semiarid and subhumid environments and is mainly determined by the soil textural composition. As the soils of these environments usually present fairly uniform textures across depth, we hypothesized that it would be possible to accurately estimate the whole-profile AWC using surface information. Our objective was to test this hypothesis in the Argentine Semiarid Pampas. Information was collected from 152 sites where AWC was measured in 20?cm layers up to a depth of 140?cm or up to the upper limit of the petrocalcic horizon, when present. In each case, whole profile AWC was estimated using a one-step and a two-step approach, comparing multiple regression and artificial neural networks as modeling techniques. Both modeling methods were effective (R²?>?0.76, P?相似文献