Interaction of Iron with Copper,Zinc, and Manganese in Wheat as Affected by Iron and Manganese in a Calcareous Soil

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.     

Kinetic behavior of Fe(o,o-EDDHA)-humic substance mixtures in several soil components and in calcareous soils

Ferric ethylenediamine- N, N'-bis-(o-hydroxyphenylacetic)acid chelate (Fe(o, o-EDDHA)) is one of the most effective Fe fertilizers in calcareous soils. However, humic substances are occasionally combined with iron chelates in drip irrigation systems in order to lower costs. The reactivity of iron chelate-humic substance mixtures in several soil components and in calcareous soils was investigated through interaction tests, and their behavior was compared to the application of iron chelates and humic substances separately. Two commercial humic substances and two Fe(o, o-EDDHA) chelates (one synthesized in the laboratory and one commercial) were used to prepare iron chelate-humic substance mixtures at 50% (w/w). Various soil components (calcium carbonate, gibbsite, amorphous iron oxide, hematite, tenorite, zincite, amorphous Mn oxide, and peat) and three calcareous soils were shaken for 15 days with the mixtures and with iron chelate and humic substance solutions. The kinetic behavior of Fe(o, o-EDDHA) and Fe non-(o,o-EDDHA) (Fe bonded to (o,p-EDDHA) and other polycondensated ligands) and of the different nutrients solubilized after the interaction assay was determined. The results showed that the mixtures did not significantly reduce the retention of Fe(o, o-EDDHA) and Fe non-(o,o-EDDHA) in the soil components and the calcareous soils compared to the iron chelate solutions, but they did produce changes in the retention rate. Moreover, the competition between humic substances and synthetic chelating agents for complexing metal cations limited the effectiveness of the mixtures to mobilize nutrients from the substrates. The presence of Fe(o, p-EDDHA) and other byproducts in the commercial iron chelate had an important effect on the evolution of Fe(o, o-EDDHA) and the nutrient solubilization process.     

Effect of commercial amino acids on iron nutrition of tomato plants grown under lime‐induced iron deficiency

The objective of this work was to study the effect of root and foliar application of two commercial products containing amino acids from plant and animal origin on iron (Fe) nutrition of tomato seedlings cultivated in two nutrient media: lime and normal nutrient solutions. In the foliar‐application experiment, each product was sprayed with 0.5 and 0.7 mL L^–1 2, 7, 12, and 17 d after transplanting. In the root application experiment, 0.1 and 0.2 mL L^–1 of amino acids products were added to the nutrient solutions. In both experiments, untreated control plants were included as well. Foliar and root application of the product containing amino acids from animal origin caused severe plant‐growth depression and nonpositive effects on Fe nutrition were found. In contrast, the application of the product from plant origin stimulated plant growth. Furthermore, significantly enhanced root and leaf Fe^III‐chelate reductase activity, chlorophyll concentration, leaf Fe concentration, and Fe^II : Fe ratio were found in tomato seedlings treated with the product from plant origin, especially when the amino acids were directly applied to the roots. These effects were more evident in plants developed under lime‐induced Fe deficiency. The positive results on Fe uptake may be related to the action of glutamic acid, the most abundant amino acid in the formulation of the product from plant origin.     

Iron and/or acid foliar spray versus soil application of Fe-EDDHA for prevention of iron deficiency in Valencia orange grown on a calcareous soil

A two-year experiment was conducted in an iron(Fe)-deficient orchard with calcareous soil to find out an alternate method for soil application of Fe ethylenediamine-N,N'-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA) in orange trees. Foliar sprays of Fe-EDDHA (5 g l^?1, pH = 7.8), sulfuric acid (pH = 3), citric acid (5 g l^?1, pH = 2.4), Fe (II) sulfate solutions (250, 500, and 750 mg Fe l^?1) with their initial pH (6.5, 6.35, and 6.12) and reduced ones to pH of 3 were compared with soil applied (75 g tree^?1) Fe-EDDHA and a control test. Although optimum chlorophyll content, leaf Fe concentration, fruit quantitative and qualitative attributes were resulted from soil application of Fe-EDDHA, repeated sprays of Fe-EDDHA or acidified Fe solutions created suitable results. Acidification of Fe solutions made them more effective in alleviation of leaf Fe concentration and Fe chlorosis, probably due to remobilization of inactive Fe within the plant and prevention of Fe oxidation and precipitation in foliar solutions.     

Effectiveness of iron chelates and FeSO4 for correcting iron chlorosis of peanut on calcareous soils

The effectivenness of different Fe chelates to correct lime induced chlorosis of peanut (Arachis hypogaea) was tested on calcareous soils in Cyprus. Among the chelates tested, Fe‐DTPA and Fe‐EDTA were less effective than Fe‐EDDHA. In one experiment. Fe‐EDDHMA Was less effective while in another experiment was equally effective compared to Fe‐EDDHA . Three different commercial chelates of the form Fe‐EDDHA were equally effective in correcting iron chlorosis. The stability of the Fe‐EDDHA chelate in the soil does not affect its efficiency in curing chlorosis of peanut due to the short growing season for this crop. Ferrous sulfate applied without an acidifying soil amendment was not effective to correct iron chlorosis of peanut.     

Alleviation of Alkalinity-Induced Fe Deficiency in Eggplant (Solanum melongena L.) by Foliar Application of Different Fe Sources in Recirculating System

This study was carried out to investigate the effects of foliar sprays of different iron (Fe) sources on eggplant grown in alkaline aquaponic solutions. Four treatments were used, untreated control, foliar application of iron sulfate (FeSO₄), ferric ethylenediaminetetraacetic acid (Fe-EDTA) and ferric ethylenediamine bis(2-hydroxyphenyl)acetic acid (Fe-EDDHA). The results showed that overall growth was significantly increased by foliar Fe application, and the highest values of vegetative growth parameters were recorded in plants treated with FeSO₄. The Fe treatment led to a significant increase of shoot Fe concentration, and the highest Fe was observed in plants sprayed with FeSO₄, compared to Fe-EDTA and Fe-EDDHA. The lowest chlorophyll content was observed in untreated plants. The highest SPAD index, maximal quantum yield of photosystem (PS II) photochemistry (F_v/F_m) and performance index (PI) values of young and old leaves were found with FeSO₄ treatment. It is concluded that application of foliar Fe must be performed in the aquaponic system, to overcome Fe deficiencies in alkaline conditions.     

Interaction of iron chelates with several soil materials and with a soil standard

Frequently the effectiveness of iron (Fe) chelates is low because they can be retained or destroyed by soil materials. The high cost of these Fe fertilizers makes it necessary to study soil material reaction with Fe chelates. Commercial Fe chelates with EDTA, EDDHA, and EDDHMA as ligands and their standards, prepared in the laboratory, were shaken for one hour with various soil materials [amorphous Fe(III) oxide, acid peat, calcium (Ca)‐montmorillonite and calcium carbonate (CaCO₃)] and with a soil standard made in the laboratory. After agitation, the chelate‐soil mixtures were filtered and the micronutrients and chelated Fe that remained in solution were determined. Among the soil materials used, amorphous Fe(III) oxide and acid peat had the greatest affect on the amount of chelated Fe remaining in solution. The type of chelating agent was the next major factor that affected the availability of soluble Fe following reaction with the soil materials. Another factor was the commercial formulation of the Fe chelates. The chelates comprised of EDDHA or EDDHMA maintained the highest percentages of chelated Fe in solution after interaction with the solid phases, except for the acid peat. The last soil material, acid peat, retained more chelated Fe for the Fe chelates with EDDHA or EDDHMA than with EDTA as the chelating agent. The commercial Fe‐EDDHA chelates had greater losses of chelated Fe than their standard after interaction with all the solid phases. The commercial Fe‐EDDHA chelate (Sequestrene) and the commercial Fe‐EDDHMA chelate (Hampirón) solubilized the highest amount of copper (Cu) from soil standard. This was attributed to the presence of by‐products in the commercial formulations since the Fe‐EDDHA standard did not have Cu in solution after the interaction. Therefore, the commercial Fe chelate by‐products are able to form Cu‐complexes which could affect chelated Fe and its availability to plants.     

Effects of green iron nanoparticles on iron changes and phytoavailability in a calcareous soil

Green iron nanoparticles (Fe NPs) can be a practical solution to combat iron (Fe) deficiency in calcareous agricultural soils. The main aim of the present work was to assess the effects of green Fe NPs on Fe availability in calcareous soils. For this purpose, green Fe NPs were synthesized using green tea (G-Fe NPs), Shirazi thyme (T-Fe NPs), walnut green hull (W-Fe NPs), and pistachio green hull (P-Fe NPs) extracts and applied as a source of Fe fertilizer to sorghum (Sorghum bicolor L. Moench) plants. Results of X-ray diffraction (XRD), scanning electron microscopy (SEM), and dynamic light scattering (DLS) indicated that the green Fe NPs were amorphous in nature and the polyphenols obtained from plant-part extracts acted as both capping and reducing agents. Similar to the behavior of Fe-ethylenediamine-N,N''-bis(2-hydroxyphenyl) acetic acid (Fe-EDDHA) in calcareous soils, G-Fe NPs, T-Fe NPs, W-Fe NPs, and P-Fe NPs increased Fe release compared with the control and FeSO₄ treatment. Cumulative Fe release data fitted well to the power function, intra-particle diffusion, and Elovich kinetic models. According to the pot experiment, the increment in soil Fe availability upon Fe-EDDHA and Fe NPs application led to an increase in Fe uptake, growth, and photosynthetic pigment contents of the sorghum plants. Although further research is needed to evaluate the residual effect and environmental impact of green Fe NPs, they may be an appropriate substitute for traditional Fe fertilizers in calcareous soils.     

Influence of Iron Application Methods on Seasonal Variations in Antioxidant Activity of Peanut

The influence of foliar and soil applications of iron (Fe) on variations in antioxidant activity of peanut was investigated in a field experiment. For each method, five levels of Fe–ethylenediamine-N,N'-bis (EDDHA) (in the soil application, 0, 5, 10, 15 and 20 kg ha^?1, and in the foliar application, 0, 1, 2, 3 or 4 gL^?1) were applied. The results revealed that the Fe content of leaves increased significantly by both application methods. In addition, immediately after every spraying of Fe on the leaves, the activities changed significantly: Catalase and peroxidase increased but superoxide dismutase decreased during the growing season. By soil applications, the enzyme activities increased gradually and yet continuously decreased at the last period of the plant growth. For both applications, greater levels of Fe (4 gL^?1 and 20 kg Fe-EDDHA ha^?1 for sprayed and soil applications, respectively) had more positive effects on the activities of peroxidase and catalase than on superoxide dismutase.     

Improvement of Iron Uptake in Table Grape by Addition of Humic Substances

Two experiments in consecutive years were conducted at a table grape plantation located in southeastern Spain. The objective was to test whether the addition of commercial organic compounds could improve the uptake of iron (Fe) by plants. A commercial humic substance and two mixtures of amino acids were used as organic compounds in the first experiment and FeEDDHA was the source of Fe. The joint addition of FeEDDHA and organic compounds improved Fe nutrition. The humic substance was more effective than the amino acids in increasing Fe uptake. In the following year, a similar experiment was conducted by progressively replacing part of the chelate with the humic substance. An increase in foliar Fe and phosphorus (P) and a decrease in sodium (Na) levels were observed. The best results with respect to nutrient foliar content and nutrient relationships were obtained for a range of substitutions for the chelate by the humic substance of from 30% to 50% with no loss in yield or fruit quality.     

GROWTH AND IRON-MANGANESE RELATIONSHIPS IN DRY BEAN AS AFFECTED BY FOLIAR AND SOIL APPLICATIONS OF IRON AND MANGANESE IN A CALCAREOUS SOIL

Manganese (Mn) deficiency may be induced by adding large quantities of iron (Fe), provided that soil manganese is marginally deficient. Results of a greenhouse study showed that iron soil application did not influence shoot dry matter yield of dry bean due to the fact that the iron:manganese ratio in aerial parts of dry bean was higher than 0.4. A foliar spray of 2% iron sulfate significantly reduced it probably due to the high level of shoot iron and iron:manganese ratio greater than 4. Iron application decreased concentration/uptake of shoot manganese due to the iron-manganese antagonistic relationships. Mangenese soil application is not an effective method in correction of manganese deficiency induced by iron fertilizers. Iron did not affect root manganese uptake, indicating that manganese absorption was not affected by iron application. Both manganese/iron soil tests are recommended in calcareous soils with manganese soil test in marginal range.     

Effects of foliar Fe and Zn fertilizers on storage root Fe,Zn, and beta-carotene content of sweet potato (Ipomoea batatas L.)

Foliar sprays of iron (Fe) and zinc (Zn) fertilizers are effective in improving Fe and Zn concentrations in sweet potato. The objective of this experiment was to examine the effects of foliar fertilization with Fe and Zn in association with amino acids (AA) on Fe and Zn biofortification and the nutritional quality of sweet potato under both greenhouse and field conditions. Compared with treatment CK, foliar Fe, Zn, and Fe-Zn fertilizer applications could biofortify Fe and Zn concentrations and other nutrients in sweet potato to different extents. However, when 0.4% (wt/vol) AA was added to Fe-Zn fertilizer, the average Fe and Zn concentrations were increased by 70.2% and 59.8% under greenhouse conditions, and 52.9% and 43.7% under field conditions, respectively. The Fe-Zn-AA fertilizer application also resulted in incremental increases in root yield and beta-carotene content. This research identified some useful foliar fertilizers for accelerating Fe and Zn accumulation in selected sweet potato cultivars.     

Analysis of iron chelates in commercial iron fertilizers by gel chromatography

A gel chromatographic method for the quality control of iron chelate fertilizers is described. The iron chelates are separated on a column of Sephadex G-10 and the eluates are analysed for iron. Using a sample quantity of 25 mg in a volume of 5 ml water and eluting with 0.15 M soidum chloride solution, a separation was achieved of commercial products of Fe-EDDHA or Fe-EDDHMA. The chromatographic analysis of Fe-EDTA or Fe-DTPA calls for a better resolution. This was obtained by decreasing the sample quantity and eluting with 0.035 M calcium chloride solution of pH 7.0. In this way it is possible to eliminate the interference of iron chelates of moderate stability which can be present in commercial products containing Fe-EDTA or Fe-DTPA.     

ELEMENTAL SULFUR IMPREGNATED WITH IRON AS A FERTILIZER SOURCE FOR KENTUCKY BLUEGRASS

Elemental sulfur (S) impregnated with Fe (S-Fe) fertilizer was evaluated on Kentucky bluegrass (KBG; Poa pratensis L.) in three glasshouse studies: (1) with/without Fe as S-Fe, ferrous sulfate (FS), or iron-ethylenediamine-N,N’-bis(2-hydroxyphenylacetic acid) (Fe-EDDHA) to soil (49 kg Fe ha^?1), or foliar Fe-EDDHA (5 kg Fe ha^?1) on two cultivars; (2) 0, 49, 197, or 592 kg Fe ha^?1 of S-Fe deep mixed or surface mixed on two soils; (3) 0 or 49 kg Fe ha^?1 applied as S-Fe on four cultivars. A field study comparing 0 and 49 kg Fe ha^?1 applied as S-Fe to KBG was also conducted. Soil applied S-Fe was assimilated in shoots as efficiently as Fe-EDDHA applied to soil or foliage. Shoot Fe increased significantly with increasing S-Fe in a curvilinear response when deep mixed with soil and in a linear response when surface applied. However, no Fe source tested impacted yield or verdure in these studies.     

生物质炭对旱作土壤生物性状及养分有效性的调控效应

通过盆栽试验研究了生物质炭施用对贵州中部地区旱作土壤微生物群落数量、酶活性和土壤养分有效性的影响。结果表明:对不同类型旱作土施用5%～15%(炭/土质量比)的生物质炭后,黄泥土、黄砂土中真菌、放线菌、细菌数量和硝化细菌、氨化细菌数量以及磷酸酶、过氧化氢酶、脲酶活性均表现出明显的增加,特别是黄砂土;而大泥土中放线菌、真菌数量和硝化细菌数量以及磷酸酶和过氧化氢酶活性出现较明显的提高,但氨化细菌数量及脲酶活性出现大幅度降低。此外,黄泥土、黄砂土施生物质炭后有效N、P、K、Ca、Mg、B含量表现出不同程度的增加,但土壤有效Fe、Mn、Cu、Zn含量则出现不同程度的下降;而大泥土中有效P、K、Fe、Mn、Cu、B的含量呈现不同程度的提高,但土壤有效N、Ca、Mg、Zn的含量出现不同程度的减少;其中这3类旱作土壤施炭后土壤有效Zn含量均表现出显著的下降。黄泥土、黄砂土及大泥土施用5%～15%的生物质炭后均能明显提高白菜及莴笋的产量,其中黄砂土施生物质炭的增产效果最好,其次是大泥土。不同类型旱作土壤施炭后土壤有效性养分数量变化存在较大的差别,施用生物质炭时要根据土壤特性配合使用一定比例的氮、磷、钾及适量的微量元素肥料,更有利于促进作物的生长。     

Lime and Micronutrients Interaction in Soybean Genotypes Adapted to Tropical and Subtropical Conditions

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.     

The use of iron chelates in compound fertilizers containing trace elements

Abstract

The chemical behaviour of iron chelates, incorporated in compound fertilizers with inorganic micronutrient compounds, was studied. Pot experiments were conducted to evaluate the effectiveness of these products in controlling iron deficiency. A commercial compound fertilizer, containing 0.09% Fe as Fe‐DTPA, 0.12% Cu, 0.16% Mn and 0.04% Zn as sulfates, proved to be ineffective in preventing iron chlorosis in Chamaecyparis lawsoniana ’Alumii’, growing on sphagnum peat at two lime levels. The same fertilizer formulation with 0.09%‐ Fe as Fe‐EDDHA did prevent iron chlorosis at both lime levels. Fe‐EDTA, incorporated in the compound fertilizer, gave good results at the lower but not at the higher lime level, due to the low stability of Fe‐EDTA at high pH. Data from laboratory experiments showed that copper replaced the chelated iron in the compound fertilizer containing Fe‐DTPA, causing the iron to precipitate. The strong competition between copper and iron for the organic ligand is due to a specific affinity of copper for DTPA, resulting in a copper chelate with high stability constant and a molar ratio of copper to chelating agent of 2 : 1.

In the case of Fe‐EDDHA and Fe‐EDTA the competition between iron and copper is much weaker. In contrast to Fe‐DTPA, these chelates remain rather stable when incorporated in fertilizers containing micronutrients.     

Mineral fertilizers with iron influence spring rape,maize and soil properties

ABSTRACT

Because of low content of available iron (Fe) in soils and its poor mobility in plants, iron fertilization is necessary. Different forms of iron (mineral salts, chelates, nanomaterials) and fertilization strategies (soil and foliar application of solid or liquid fertilizers) are used. The effect of solid mineral fertilizers (A: a mixture of ammonium nitrate and dolomite; B: a mixture of ammonium nitrate and sulfate) enriched with iron sulfate was assessed during a three-year pot experiment. Iron addition did not change the yield of spring rape (first year) or maize (second and third year) significantly, and the effect on iron content in the plants was ambiguous. Fertilizer B with iron had the greatest yield-forming effect, increasing the yield of aboveground parts by 355–874%, and of roots by 211–692% in particular years. All fertilizers (especially containing sulfur) acidified the soil. After the experiment, pH of the soil fertilized with sulfur was 4.1, and of the unfertilized soil – 5.2. Iron addition increased the content of mobile and exchangeable iron in the soil by 12–110% and 2–58%, respectively, but not the content of the fraction bound to MnO_x. Combination of sulfur and iron fertilization has a potential to improve soil abundance and plant yield.     

Fe(III)-EDDHA and -EDDHMA sorption on Ca-montmorillonite, ferrihydrite, and peat.

The effectiveness of Fe chelates as Fe sources and carriers in soil can be severely limited by the adsorption of Fe chelates or chelating agents in the solid phase. To study this phenomenon, well-characterized peat, Ca-montmorillonite, and ferrihydrite were used as model compounds, and the adsorption of Fe-EDDHA and Fe-EDDHMA chelates were studied. Sorption isotherms for the meso and racemic isomers of these chelates on the soil materials are described. The variability of sorption with pH in peat and ferrihydrite was also determined because both have variable surface charge at different pH values. In montmorillonite, at low concentrations, the retention of Fe from the Fe-EDDHMA chelate is greater than the one of the Fe-EDDHA chelate. As well as the concentration increased, the inverse situation occurs. The behavior of both meso and racemic isomers of chelates in contact with Ca-montmorillonite is similar. The Fe-meso-EDDHA isomer was highly adsorbed on ferrihydrite, but the racemic isomer is not significantly retained by this oxide. For Fe-EDDHMA isomers, the racemic isomer was more retained by the oxide, but a small sorption of the racemic isomer was also observed. Results suggest that Fe-EDDHA chelates were more retained in peat than Fe-EDDHMA chelates. The most retained isomer of Fe-EDDHA was the meso isomer. For Fe-EDDHMA, the adsorption was very low for both racemic and meso isomers.