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1.
ABSTRACT

The objective was to evaluate the effects of soil compaction on phosphorus (P), potassium (K), zinc (Zn), copper (Cu), iron (Fe) and manganese (Mn) diffusive fluxes. The experiment consisted of two Oxisols and eight compaction pressures. The soil samples were placed in diffusion chambers, simultaneously with two ion-exchange membranes (anionic and cationic), compressed and incubated for 20 days. The P, K, Zn, Cu, Fe, and Mn diffusive fluxes (PDF, KDF, ZnDF, CuDF, FeDF, and MnDF) were determined. The compaction decreased the PDF in the oxidic-gibbsitic soil, and increased KDF, ZnDF, CuDF, and MnDF, in both soils. There was a higher diffusion of Zn, Cu, and Mn in the kaolinitic than the oxidic-gibbsitic soil. The descending order of cationic-microelement diffusive flux was MnDF > ZnDF ? FeDF > CuDF. Presumably, Fe was mainly diffused as organic complexes with net negative charges, whereas Zn and Mn as free ions and, or, inorganic and organic complexes with positive charges.

Abbreviations: CuDF, cupper diffusive flux; FeDF, iron diffusive flux; KDF, potassium diffusive flux; MnDF, manganese diffusive flux; PDF, phosphorus diffusive flux; ZnDF, zinc diffusive flux; AEM, anion-exchange membrane; CEM, cation-exchange membrane  相似文献   

2.
Iron (Fe) availability is low in calcareous soils of southern Iran. The chelate Fe-ethylenediamine di (o-hydroxy-phenylacetic acid) (Fe-EDDHA), has been used as an effective source of Fe in correcting Fe deficiency in such soils. In some cases, however, its application might cause nutritional disorder due to the antagonistic effect of Fe with other cationic micronutrients, in particular with manganese (Mn). A greenhouse experiment was conducted to evaluate the influence of soil and foliar applications of Fe and soil application of manganese (Mn) on dry matter yield (DMY) and the uptake of cationic micronutrients in wheat (Triticum aestivum L. var. Ghods) in a calcareous soil. Results showed that neither soil application of Fe-EDDHA nor foliar application of Fe sulfate had a significant effect on wheat DMY. In general, Fe application increased Fe uptake but decreased that of Mn, zinc (Zn), and copper (Cu). Application of Mn increased only Mn uptake and had no significant effect on the uptake of the other cationic micronutrients. Iron treatments considerably increased the ratio of Fe to Mn, Zn, Cu, and (Mn + Zn + Cu). Failure to observe an increase in wheat DMY following Fe application is attributed to the antagonistic effect of Fe with Mn, Zn, and Cu and hence, imbalance in Fe to (Mn + Zn + Cu) ratio. Due to the nutritional disorder and imbalance, it appears that neither soil application of Fe-EDDHA nor foliar application of Fe-sulfate is appropriate in correcting Fe deficiency in wheat grown on calcareous soils. Hence, growing Fe-efficient wheat cultivars should be considered as an appropriate practice for Fe chlorosis-prone calcareous soils of southern Iran.  相似文献   

3.
Salt-affected soils in arid and semi-arid tracts of the Indian Punjab are prone to deficiency of micronutrients. Nine profiles from alluvial terraces, sand dunes and palaeochannels in the southwestern Punjab were investigated for total and diethylenetriamine-penta-acetic acid (DTPA) extractable Zn, Cu, Mn and Fe. Soil physiography exerted significant influence on the spatial distribution of micronutrients. Total contents varied from 20–78 for Zn, 8–32 for Cu, and 88–466 mg kg?1 for Mn and 0.82–2.53% for Fe. DTPA-extractable contents varied from 0.10–0.98 for Zn, 0.14–1.02 for Cu, 0.54–13.02 for Fe and 0.82–9.4 mg kg?1 for Mn. Total contents were higher in fine-textured soil than in coarse-textured soils. Concentration of micronutrients in the surface layer was low and there occurred more accumulation in the Cambic horizon. Organic carbon, pH, clay, silt and calcium carbonate exerted strong influence on the distribution of micronutrients. DTPA extractable Zn, Cu, Mn and Fe increased with increasing organic carbon but decreased with increase in pH and calcium carbonate content. Total micronutrient contents increased with increase in clay, silt and calcium carbonate contents and decreased with increase in sand content.  相似文献   

4.
论述了临沂市土壤中硼、锌、锰、铜、铁等5种主要微量元素的状况与其它因素的关系。有效硼含量0.09~3.67 mg/kg,平均0.35 mg/kg;有效锰22~572 mg/kg,平均244 mg/kg;有效锌0.15~4.02 mg/kg,平均0.53 mg/kg;有效铜0.09~5.78 mg/kg,,平均1.03 mg/kg;有效铁3.2~162 mg/kg,平均21.5 mg/kg;有效锰2.0~131.4 mg/kg,平均23.4 mg/kg。不同土壤类型的以上5种微量元素有明显差异,其特征是砂姜黑土缺锌,棕壤、水稻土富含铁、铜、锰、锌;成土母质是影响土壤微量元素的重要因素之一,发育在基性岩上的土壤一般含量较高,而由红土母质发育的土壤则含量较低。土壤有机质含量与土壤微量元素有明显正相关关系,其中速效锌、速效硼和速效铜与有机质的关系尤为显著。  相似文献   

5.
湘北丘岗地区红壤和水稻土微量元素的有效性研究   总被引：5，自引：2，他引：5  
本文对湘北丘岗区土壤微量元素Cu、Zn、B、Mo、Mn和Fe的有效性进行了研究 .结果表明 ,该区大面积土壤缺Zn、缺B ,也有部分土壤缺Cu和Mo,而有效Mn含量较为丰富 .微量元素有效性与成土母质的关系极为密切 ,土壤 pH、有机质含量及土壤质地也是影响微量元素有效性的重要因素  相似文献   

6.
The production of secondary metabolites by plants growing in natural populations is conditioned by environmental factors. In the present study, we have investigated the relationships among soil properties, micronutrients in soils and plants, and cardenolide production from wild Digitalis obscura (Scrophulariaceae) populations. Young and mature leaves and soil samples were collected in ten different populations, corresponding to three Mediterranean bioclimatic belts (Thermo‐, Meso‐, and Supramediterranean belts). Soil (total and EDTA‐extractable) and leaf micronutrients (Fe, Mn, Zn, and Cu), and leaf cardenolide accumulation have been determined. Significant negative correlations were observed between Fe, Mn or Zn concentration in leaves and soil pH, as well as between Fe or Mn in leaves and carbonate content of soils. Only EDTA‐extractable Mn was significantly correlated with Mn content in the plants. With regard to cardenolide content in leaves, this parameter was negatively correlated with Znleaf in young leaves and with Mnleaf in old leaves. Positively correlated, however, were Fe and cardenolide content in young leaves. The influence of environmental conditions and leaf micronutrient contents on cardenolide accumulation is discussed.  相似文献   

7.
Abstract

Three extracting reagents were evaluated by correlation analyses to provide the best index of Zn, Cu, Mn and Fe availability to wheat (Triticum aestivum L.) plants growing under open field conditions. Twenty one soils were selected to obtain the widest range in properties of soils of the land wheat cultivated. The magnitude of the extractive power varied in the following order: 6NHCl ? EDTA + NH4OAC, pH4.65 > DTPA‐TEA, pH 7.3. The mild extractants, EDTA and DTPA, gave the same order of removal of micronutrients being Zn < Cu < Fe < Mn. The acid extractant was on the contrast more effective on Cu and Fe with respect to Zn and Mn, respectively. Wheat concentrations of Zn, Mn and Fe were significantly correlated to soil micronutrients. Highly significant relationships were found for Zn extracted by DTPA solution (r = 0.737***) and for Mn and Fe extracted by EDTA solution (r = 0.710*** and r = 0.564**). Plant Zn and Mn were also well predicted by the acid extraction. The absence of correlation for plant Cu vs. soil Cu occurred probably because of wheat concentrations almost constant, ranging from 5.0 to 8.0 mg/kg.  相似文献   

8.
Low and unstable fruit yield, poor quality of fruits, and excessive fruit dropping are major problems in a lime crop and are due to either micronutrient deficiencies or nutrient imbalance. A study was conducted to assess the micronutrient status in a lime orchard at the Central Soil and Water Conservation Research and Training Institute (CSWCRTI)’s research farm in Kota, Rajasthan, India. Plant and soil samples were collected during September and October in 2006–2007. The micronutrients extracted with diethylenetriaminepentaacetic acid (DTPA) in soils were in the order of manganese (Mn) > iron (Fe) > zinc (Zn) > copper (Cu). The mean values of DTPA Mn, Fe, Zn, and Cu in surface soils varied from 13.98 to 22.70, 2.48 to 8.66, 0.79 to 1.19, and 0.14 to 0.46 mg kg?1, respectively, whereas in subsurface soils they varied from 12.94 to 23.06, 4.84 to 6.52, 0.51 to 0.83, and 0.07 to 0.20 mg kg?1, respectively. Results reveal that except for Fe, the other DTPA-extractable micronutrients decreased with depth. Total Mn, Fe, Zn, and Cu in plant leaves varied from 22 to 83, 70 to 630, 40 to 932, and 37 to 3057 mg kg?1, respectively, indicating greater or toxic concentrations of total micronutrient in leaf samples. Total Mn, Fe, Zn, and Cu in petiole samples varied from 7 to 60, 235 to 574, 70 to 827, and 101 to 2623 mg kg?1, respectively. High concentration of Cu and Zn in leaves resulted in Fe and Mn deficiencies (exhibited as leaf chlorosis) in lime plants. Results of the study indicated that Fe and Mn deficiencies are major disorders in lime plantation. Similarly, the measure of DTPA-extractable micronutrients showed the low statuses of Fe and Cu and marginal status of Zn in soils along the Chambal region.  相似文献   

9.
Abstract

Reclamation of sandy and calcareous desert lands in. Egypt for intensive cropping has considerable effect on the fertilizer requirement for most crops. The yield records, together with frequent visual appearances of micronutrient deficiency symptoms on economically important crops were the main reasons for investigating the status of micronutrients in these areas by means of leaf and soil analyses. Sites were selected to represent sandy and calcareous soils in newly reclaimed areas as well as loamy alluvial ones in the Nile‐Valley and Delta. Over 10000 soil and leaf samples were collectes in the last 5 years to evaluate the soil/plant fertility status within the area. The major deficiencies were found to be of Fe Mn and Zn revealed in both soil and plant analyses. Regarding soil type effects, Fe‐deficiency dominated on calcareous soil, Zn‐deficit on the sandy soils and Mn‐deficiency mostly on alluvial soils. Leguminous crops were most sensitive to Fe‐deflciency whereas cereals; especially maize and rice were most sensitive to Zn‐deficiency. It is problem that using Zn, Mn, Fe fertilizer will become a common practice in Egypt for different crops in the near future.

In some west‐Delta calcareous areas, high B was found in both soils and plants. Also, Cu accumulation accurred due to the heavy use of Cu‐fungicides which may eventually become a major pollution problem.  相似文献   

10.
Micronutrient status in soils and crops can be affected by different fertilization practices during a long-term field experiment. This paper investigated the effects of different fertilization treatments on total and DTPA-extractable micronutrients in soils and micronutrients in crops after 16 year fertilization experiments in Fengqiu County, Henan Province, China. The treatments of the long-term experiment included combinations of various rates of N, P and K in addition to two rates of organic fertilizer (OF) treatments. Winter wheat and summer maize were planted annually. Soil macro- and micronutrients along with pH and organic matter (OM) were analyzed. Grains and above ground parts of both crops in the final year were harvested and analyzed for Cu, Zn, Fe and Mn. The results showed that soil Cu, Zn, Fe and Mn concentrations did not change among the different treatments to a significant level, except for a slight decrease of soil Zn in the CK (no fertilizer application) compared to the OF treatment. The DTPA-extractable soil Zn, Fe and Mn concentrations increased from 0.41 to 1.08 mg kg−1, from 10.3 to 17.7 mg kg−1, and from 9.7 to 11.8 mg kg−1, respectively, with increasing soil OM content, thus showing the importance of soil OM in micronutrient availability for crops. The NPK treatment also had higher DTPA-extractable micronutrient concentrations in soil. Deficiency of N or P resulted in a low yield but high micronutrient concentrations in crops except Cu in maize stalks. Higher available soil P significantly decreased crop micronutrients, possibly because of their precipitation as metal phosphates. Maize stalks contained higher concentrations of micronutrients than those of wheat straw, whereas wheat grain had higher micronutrients than those of corn grain. The transfer coefficients (TCs) of micronutrients from straw to grain were significantly different between winter wheat (1.63–2.52 for Cu; 2.31–3.82 for Zn; no change for Fe; 0.55–0.84 for Mn) and summer maize (0.24–0.50 for Cu; 0.50–1.21 for Zn; 0.02–0.04 for Fe; 0.07–0.10 for Mn). In conclusion, application of organic matter significantly increased the DTPA-extractable concentrations of Zn, Fe and Mn compared to the CK, grain and vegetative tissue in the CK and NK had higher micronutrient concentrations than those in other treatments.  相似文献   

11.
Available micronutrient status of zinc, copper, manganese, and iron (Zn, Cu, Mn, and Fe) in surface soil samples under a rice–wheat system collected from farmers' fields in 40 districts representing different agroclimatic zones of the Indo‐Gangetic Plain (IGP) were determined. The selection of farmers, villages, blocks, and districts within an agroclimatic zone was made on the basis of a multistage statistical approach. In Trans‐Gangetic Plains, the diethylenetriaminepentaacetic acid (DTPA)–extractable Zn ranged from 0.11 to 5.08, Cu ranged from 0.22 to 4.72, Mn ranged from 2.9 to 101.2, and Fe ranged from 1.05 to 97.9 mg kg?1. In the Upper Gangetic Plains, the DTPA‐extractable Zn ranged from 0.04 to 2.53, Cu ranged from 0.06 to 4.32, Mn ranged from 11.1 to 421.0, and Fe ranged from 3.48 to 90.2 mg kg?1. In the Middle Gangetic Plains, the DTPA‐extractable Zn ranged from 0.17 to 8.60, Cu ranged from 0.09 to 7.80, Mn ranged from 3.0 to 155.1, and Fe ranged from 9.22 to 256.7 mg kg?1. In the Lower Gangetic Plains, the DTPA‐extractable Zn ranged from 0.04 to 3.46, Cu ranged from 0.21 to 4.38, Mn ranged from 9.54 to 252.2, and Fe ranged from 3.60 to 182.5 mg kg?1. The intensively cultivated Trans‐Gangetic transect representing the midplain and Siwalik had more available micronutrients than the arid plain. Midplain and arid plain showed 17 to 20% of soil samples were low to medium in Zn and 5 and 8% were low in Fe. In the Upper Gangetic Plains, only 25% samples were deficient in Zn, especially in central and southwest plains. In the Middle Gangetic Plains, 20 to 30% of samples were deficient in Zn, and very few samples were deficient in other micronutrients. In the Lower Gangetic Plains, a majority of the samples were medium to high in micronutrients except in Barind and Rarh Plains where 30% of samples were deficient in Zn. In the Lower Gangetic Plains, the available micronutrients were plentiful. Available micronutrients increased with increase in organic C content and decreased with increase in sand content, pH, and calcium carbonate. These soils are alluvial in nature, and there was no definite pattern of micronutrient distribution with depth in the profile. However, there was more accumulation in the Ap horizon than in the B horizon.  相似文献   

12.
Abstract

Soil extraction techniques to measure the status of available micronutrients for plants are important in the diagnosis of deficiency or toxicity. Mehlich 3 (M3), EDTA (pH=8.2), DTPA‐TEA, and Soltanpour and Schwab (SS) solutions were confronted for their ability to extract simultaneously copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe). Argentinean soils from different taxonomic orders with widely varying properties were investigated. The values obtained showed that DTPA‐TEA and SS solutions extracted similar amounts of Zn, Fe, and Mn, while EDTA dissolved comparatively higher amounts of Fe and Mn. Mehlich 3 yielded the highest extractions for the four micronutrients. Soil pH not only affected the extraction of Mn by DTPA‐TEA, SS, and EDTA extractions, but also the extraction of Fe by EDTA. The organic carbon affected the determination of Fe and Zn in all cases. The correlations of the different tests for Cu, Zn, Mn, and Fe were significant. The results suggest that for the determination of the bioavailable status of micronutrients, any of the studied tests could be applied using the soil edaphic properties as factors to improve the correlations between them and standardize the methods.  相似文献   

13.
Desilication and leaching are processes that accompany plinthilization, leading to nutrient depletion. Soils from 12 profiles in a plinthitic landscape were analyzed for extractable micronutrients [iron (Fe), zinc (Zn), manganese (Mn), and copper (Cu)]. Soils of the landscape from crestal to lower‐slope position contain plinthite in the profile, whereas those of the valley floor are devoid of plinthite. The micronutrients were extracted using diethylenetriaminepentaacetic acid (DTPA) and 0.1 M hydrochloric acid (HCl). The results showed that 0.1 M HCl extracted more of the micronutrients than DTPA. The DTPA‐extractable Fe, Zn, Mn, and Cu in all the soils ranged from 1.15 to 12.44 (mean, 3.69); 0.71 to 2.75 (mean, 1.86); trace 12.44 (mean, 3.35), and trace 3.76 (mean, 0.63) mg kg?1, respectively. The DTPA‐extractable micronutrient contents were generally greater than the critical available level (4.5 mg kg?1 for Fe, 0.8 mg kg?1 for Zn, 1.0 mg kg?1 for Mn, and 0.2 mg kg?1 for Cu). The 0.1 M HCl‐extractable micronutrients in the landscape ranged from 8.00 to 30.40 (mean, 15.19); 0.30 to 6.49 (mean, 1.35); 1.00 to 27.20 (mean, 7.74); and 0.26 to 15.0 (mean, 2.77) mg kg?1 for Fe, Zn, Mn, and Cu, respectively. Both DTPA‐ and 0.1 M HCl‐extractable micronutrients were generally lower in the plinthitic horizons than in the nonplinthitic horizons and higher in the Ap than the subsoil horizons. Correlation analysis showed a significant relationship between DTPA‐Fe and DTPA‐Mn, Cu, and organic carbon (r = 0.913**, 0.411**, and 0.385**). There was a significant and positive relationship between 0.1 M HCl‐extractable Mn and organic carbon (C), total nitrogen (N), and available phosphorus (P) (r = 0.413**, 0.337**, and 0.350**, respectively).  相似文献   

14.
A two‐year lysimeter experiment was conducted using winter wheat plants on two texturally contrasting soils (soil A and soil B). The main objective of this study was to evaluate the influence of increasing doses (5, 10, 15, 20, and 251 ha‐1) of solid phase from pig slurry (SP) on soil extractable copper (Cu), zinc (Zn), iron (Fe), and manganese (Mn) and on wheat micronutrients composition and uptake. As the control, a basic dressing of NPK fertilizer was applied. Results showed that increasing additions of SP significantly enhanced extractable Cu, Zn, Fe, and Mn content on the topsoil for both soils tested. In addition, a significant increase was detected for extractable Cu, Zn, and Mn content with increasing application rates of SP for subsoil A, but no significant differences were detected for subsoil B. A significant increase in the contents of Fe, Mn, and Zn in the plants as well as total uptakes were observed from increasing doses of SP. Copper content in the plants was not significantly affected. Finally, a strong pH effect was exerted in the Mn and Zn uptake by the plants.  相似文献   

15.
长期施肥对潮土耕层土壤和作物籽粒微量元素动态的影响   总被引：4，自引：0，他引：4  
Micronutrient status in soils can be affected by long-term fertilization and intensive cropping.A 19-year experiment (1990-2008) was carried out to investigate the influence of different fertilization regimes on micronutrients in an Aquic Inceptisol and maize and wheat grains in Zhengzhou,China.The results showed that soil total Cu and Zn markedly declined after 19 years with application of N fertilizer alone.Soil total Fe and Mn were significantly increased mainly due to atmospheric deposition.Applications...  相似文献   

16.
Liming reduces acidity neutralizes aluminum (Al3+) and manganese (Mn2+) toxicities and increases calcium (Ca2+) and magnesium (Mg2+) concentrations in many acid soils of the world. However, it reduces the availability of other cationic micronutrients that are essential for plant growth. Therefore, an experiment was conducted in greenhouse conditions for assessing the effects of higher lime rates in foliar and grain boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) concentrations of 15 soybean genotypes [Glycine max (L) Merrill]. The lime rates were calculated to raise base saturation (V) to 40 and 70%. The soybean genotypes were classified as efficient and moderately efficient in lime-use, the most efficient cultivar was BRS 295RR, and the least efficient was TMG 7161RR and BMX Força RR. The lime rates × genotypes interaction was significant for foliar Cu. The grain the interactions were significant for B, Cu, Fe, and Mn concentrations. Foliar and grain B, Cu, Fe, Mn, and Zn concentrations varied significantly among the genotypes. The Ca and Mg concentrations in the leaf, grain, and soil showed a positive correlation with foliar B concentrations and a negative correlation with leaf and grain Cu, Mn, and Zn concentrations.  相似文献   

17.
Abstract

The study reported herein was intended to determine the effect of (i) wet‐incubation and subsequent air‐drying, and (ii) oven‐drying on DTPA‐Fe, Zn, Mn, and Cu.

Analysis of wet‐incubated soils showed significant decreases in DTPA‐Fe, Mn, and Cu at the 1% and Zn at the 10% level of probability. Air‐drying of these moist‐incubated soils increased the levels of Fe, Zn, and Cu to values close to their original levels. Levels of Mn sharply deviated from their original values after air‐drying of incubated soils. Correlation coefficients (r) between the amounts of extractable nutrients in original air‐dry soils and wet‐incubated soils were 0.54, 0.87, 0.91, and 0.13 for Fe, Zn, Cu, and Mn, respectively. Oven‐drying increased the levels of DTPA‐extractable micronutrients from 2 to 6 fold.  相似文献   

18.
Abstract

Previous studies carried out on metal fractionation have shown that more than 95% of metals are in the solid phase of pig slurries (SPPS), with copper (Cu), and zinc (Zn) being the commonly occurring micronutrients in animal slurries. The input of micronutrients associated with the application of SPPS could be an important pathway for the supply of these essential elements to arable crops in bioavailable forms, especially in calcareous soils, which induce the immobilization of these elements. The aim of this work was to study the effect of application of pig manures (fresh and composted) derived from the SPPS on the micronutrient—iron (Fe), Cu, Magnesium (Mn), and Zn—concentration on amended calcareous soils in horticultural plants (cucumber and Milan cabbage). In addition, the effect of composting and application rates were analyzed. The experiment was conducted in field conditions on a Xerofluvent soil with a clayey‐loam texture. The organic wastes used in this study were uncomposted and composted solid fractions of swine manure slurry (UC‐SPPS and C‐SPPS, respectively) at two different rates (supplying 300 kg N ha?1 and 450 kg N ha?1 respectively). A mineral fertilizer treatment equivalent to 300 kg N ha?1 and a control treatment without fertilization were also included for comparison. The use of SPPS amendment induced a biomass production similar to the mineral fertilizer for cucumber, but higher in Milan cabbage plants, without any yield increment associated with the increased application rate of SPPS or composting. Micronutrient concentration in cucumber and cabbage plants was affected by the SPPS amendment, with an increase of Mn and Zn uptake and a decrease of Cu, compared to the control. The increasing application rate of SPPS did not induce a general increase in the plant uptake of micronutrients; the opposite was true for the crops grown in the C‐SPPS‐amended soils.  相似文献   

19.
Abstract

A study was carried out to investigate the status of four micronutrients, iron (Fe), copper (Cu), manganese (Mn), and zinc (Zn), and five other trace elements, cobalt (Co), chromium (Cr), nickel (Ni), lead (Pb), and strontium (Sr), in paddy soils of Bangladesh. Soil samples were digested by hydrofluoric acid (HF)‐nitric acid (HNO3)‐perchloric acid (HClO4) for determination of total contents of the nine elements, while DTPA, ASI and 0.1 Mhydrochloric acid (HC1) methods were used for determination of available Fe, Cu, Mn, and Zn. Total trace element contents were found to vary with physiography on which soils are distributed. In general, Ganges Tidal Floodplain soils had the highest content, whereas terrace soils had the lower content. Among the soil properties examined, clay content had a good relation with total trace element contents in the topsoil, except for Sr. Based on the variation with physiography or clay content, the nine trace elements could be grouped into six groups: Cu, Fe and Zn, Pb, Co and Cr and Ni, Mn, Sr. According to the extractable levels of four micronutrients, Bangladesh paddy soils had the medium to optimum amounts of Fe and Cu, but were deficient sporadically in Mn and extensively in Zn. It was indicated that paddy soils of Bangladesh are yet to be polluted with heavy metals.  相似文献   

20.
Although a positive response to iron (Fe) is, usually, expected in calcareous soils; this has not been always the case; and in some instances a depressing effect has been observed. An induced micronutrient imbalance is suspected. This experiment was designed to study the effect of Fe fertilizer on the plant micronutrients. Twenty three highly calcareous soils (18–46% calcium carbonate equivalent; pH 7.7–8.4; and a wide range of extractable Fe) from southern Iran were used in an eight‐week greenhouse experiment to study the effect of Fe fertilizers on soybean [Glycine max (L.) Merr.] growth and chemical composition. The statistical design was a 23 × 3 factorial arranged in a completely randomized block with three replications. Treatments consisted of 23 soils and three levels of applied Fe (0, 10, and 20 mg Fe/kg as FeEDDHA). Uniform doses of nitrogen (N), phosphorus (P), copper (Cu), manganese (Mn), and zinc (Zn) were applied to all pots. Dry matter (DM) and micronutrients concentrations and uptakes of plant tops were determined and used as the plant responses. Application of Fe either had no significant effect on DM or even decreased it. The plant concentration and uptake of Fe increased significantly in all soils. The concentrations and uptakes of Cu and Zn did not change but those of Mn decreased significantly. The negative effect of Fe application was, therefore, attributed to the interference of Fe with Mn nutrition. The mechanism involved appears to be the restriction in Mn translocation from soil to root and/or from root to the plant tops.  相似文献   

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