J. Khallizadeh; E. Dordipour; M. Baranimotlgh; A. Gharanjiki
Abstract
Introduction: Iron deficiency is one of the most important nutritional disorders in plants, particularly in calcareous soils and deeply affects the yield and quality of the product. Due to the major role of iron in the synthesis of chlorophyll, chlorosis occurs in young leaves in deficiency conditions. ...
Read More
Introduction: Iron deficiency is one of the most important nutritional disorders in plants, particularly in calcareous soils and deeply affects the yield and quality of the product. Due to the major role of iron in the synthesis of chlorophyll, chlorosis occurs in young leaves in deficiency conditions. In such condition, biochar can help to increase OM, soil fertility level, and iron use efficiency and, to reduce iron chlorosis. The aim of this study was to investigate the effect of iron- impregnated biochar on the availability of iron and the elimination of soybean iron chlorosis in a calcareous soil.
Materials and Methods: Calcareous soil with iron deficiency (0-30 cm) was collected from the east of Golestan province and prepared for cultivation. Two types of biochar were produced from wheat straw and particleboard through slow pyrolysis (increasing 5 °C/min) at 300 °C for 2 hours under restricted oxygen conditions in an electric furnace, and then impregnated with iron sulfate solution. FTIR spectra and SEM images of biochars surfaces were also provided. A pot experiment was conducted as a factorial based on a completely randomized design with four replications. Factors were biochars (wheat straw biochar (WB) and particleboard biochars (PB) each one with 2.5% w/w), iron impregnated biochars (Fe impregnated wheat straw biochar 2.5% w/w (Fe- IWB1) and 5% w/w (Fe-IWB2), 2.5% w/w (Fe-IPB1) and 5% w/w (Fe-IPB2) Fe impregnated particleboards, Fe- Sequestrene (S) and control without Fe and biochar (C), and two soybean cultivars (Williams and Saman). The sown pots were maintained near the field capacity for 12 weeks. Then, SPAD numbers, concentration and uptake of active iron in young and senile leaves and active iron content in soil were determined after harvest.
Results and Discussion: With increasing application of iron impregnated biochar, active iron content increased in the soil. SPAD numbers of the upper leaves of both soybean cultivars in Fe impregnated biochars were significantly higher than those of non-impregnated biochars and control treatments (P ≤ 0.05). Iron chlorosis symptoms in soybeans decreased following the increased application of Fe impregnated biochars, consequently, there were no iron chlorosis symptoms in 5% Fe impregnated biochar treatments. Also, the active iron concentration of the upper leaves and the amount of leaf active iron uptake significantly increased as a result of Fe impregnated biochars application in both soybean cultivars compared to control and non-impregnated biochars (P ≤ 0.05). The highest concentration of active iron in upper leaves was observed in 5% w/w Fe impregnated biochars treatments, but its value for cultivar Williams in Fe impregnated wheat biochar was higher than that in Fe impregnated particleboard biochar. The results of the SEM images indicated that wheat biochar had more quantity of and fine pores (also CEC) than that of the particleboard biochar, and the surface areas of both biochars were rough and dark after impregnation with iron, indicating the adsorption or accumulation of iron at their surfaces. Also, there was a significant positive correlation between the active iron concentration with SPAD numbers in the upper leaves (r = 0.88 **) and dry weight of soybean shoots (r = 0.87 **). Cultivars responses to Fe impregnated biochars showed that iron uptake and active iron concentration in the upper leaves of Williams variety were significantly less than those of Saman variety at both levels of Fe impregnated biochars (P ≤ 0.05), which indicates that cultivar Williams is more susceptible to the iron chlorosis. The results of this experiment and reports from other studies show that the application of impregnated biochars from nutrients besides increasing SOM, permeability and soil moisture, CEC and soil fertility level, also increases the acquisition and use efficiency of iron in the plant.
Conclusion: The results of this study showed that due to the strong adsorption of soil iron, non-impregnated biochar application in the level of 2.5% had no significant effect on the concentration and uptake of active iron and spad numbers of the plant. However, using Fe impregnated biochar and increasing their application in calcareous soils with iron chlorosis resulted in a significant increase of active soil iron content, concentration and uptake of active iron and SPAD numbers of the plant, and, conversely, a decrease of leaf chlorosis. Therefore, besides improving the physical, chemical and biological properties of the soil, the application of Fe impregnated biochar can also be a promising approach to eliminate iron chlorosis in sensitive plants, particularly soybeans in calcareous soils.
Yones Abdoli; siroos jafari; abas Beshkar
Abstract
Introduction: The Fe forms diversity is related to parent materials, climate, soil process, biocycles, water table fluctuation, redox, organic matter and etc. in soil. The main Fe forms are Fed (extracted by dithionite citrate bicarbonate), Feo (extracted by oxalate ammonium) and Fe crystals. Feo/ Fed ...
Read More
Introduction: The Fe forms diversity is related to parent materials, climate, soil process, biocycles, water table fluctuation, redox, organic matter and etc. in soil. The main Fe forms are Fed (extracted by dithionite citrate bicarbonate), Feo (extracted by oxalate ammonium) and Fe crystals. Feo/ Fed ratio also shows active Fe forms. Magnetic susceptibility (MS) increases when ferri-magnetite is formed due to soil processes. This characteristic (MS) changes with parent material, climate, relief, and organism. Therefore, this study was undertaken to evaluate different Fe forms and MS with soil forming factors in some gypsic soils of Khuzestan province.
Material and Methods: The study area was located in Ramhormoz and Haft-Kel regions in Khuzestan province. Soil moisture and temperature regimes were ustic and hypertermic, respectively. Soil parent material consisted of the eluvial deposit of Gachsaran and Aghajari geological formations. The soil profiles location was selected according to topography map, ETM+ Landsat satellite images, and then 14 soil pedons were dug and described according to the standard methods. All horizons or layers were sampled and 5 pedons were selected for the analysis of different Fe forms. Fed and Feowere, respectively, extracted by citrate-bicarbonate-dithionite (CBD) and oxalate ammonium, and Fe cocentration was then determined by atomic absorption spectrometry. Furthermore, MS was determined by MS2 meter Barlington Dual frequency in low (0.46 kHz) and high (4.6 kHz) frequencies. All MS were calculated for carbonates, gypsum, and OM free. These calculations were also done for Fe forms in these samples. The statistical analysis was carried out with SPSS and Pierson methods between Fe forms and MS. The Duncan’s test was used to compare the mean values.
Results and Discussion: Pedons were classified as Entisols, Inceptisols, and Aridisols soil orders. The range of clay content, pHe, ECe, CEC, OM, CCE and gypsum was 15-59%, 7.1-8.5, 0.6-58.1 dS/m, 4.2-22.4 cmol(c)/kg, 0.3-2.4%, 21.2-39.7%, and 0-78.7%, respectively. All epipedons were classified to be ochric and developed soils had cambic diagnostic horizon (Bw) in subsurface. Feo content was maximum in young soil under poor drainage, and minimum Feo content was observed for developed pedons with good drainage class. The sepedons have not been cultivated yet. Feo was maximum at surface soils in all pedons, and decreased with increasing depth. A decreasing trend was observed from surface to subsurface for Fe content in cultivated soils. This negative trend was not, however, detected in poor drainage class or pedons with lithologic discontinuity. This trend can be ascribedto more organic matter content in surface soil in comparison with subsurface soil. Organic matters increase soil acidity and therefore, Feo can not be converted to other Fe forms under this circumstance. Maximum Feo was determined under poor drainage class in low lands. In addition, Fed displayed no trend from the surface to depth at most pedons. Maximum Fed was foundin old plain and the hill slope summit. This Fed was positively strongly correlated with soil development trend. Fed had a positive association with clay content (r=0.463), and negative correlation with sand content (r= -0.411), salinity (r= -0.533), and total carbonate, gypsum and OM (r= - 0.389). Feom (Feo menerogic) was maximum in Byz (4.04 gr/kg soil) and minimum content for Feomwas found in Byb (0.29 gr/kg soil). Maximum andminimum Fedmwas measured in Cy (9.21 g/kg) and Bg2 (1.54 g/kg), respectively. The Feo/ Fed ratio was largerin young soil and decreased with time. These values decreased from the surface to depth with the range from 0.07 to 0.8. The greatest and lowest Feo/ Fedwere, respectively, observed inthe hills and the low lands. There was no significant difference in Feo/ Fed between hill and plain.
MS changed from 5 to 25.5. Maximum and minimum MS was detected in the hills and the low lands. MS decreased with depth in almost all horizons. The highest and lowestMS were, respectively, found in pedon 3 (Byb horizon) and pedon 12 in the Bw3 horizon. The MS minerogenicwas statistically significantly associated to sand content (r=0.56**) and significantly negatively correlated with total carbonates, gypsum, OM (r=-0.667**), silt content (r= -0.506) and clay content (r= -0.456). The positive relationship between sand content and MS can be explained by the effect of magnetic materials inherited from the parent materials.
Conclusion: Fed and Feo- Fed showed a close correlation with soil development. Feo/Fed ratio increased with decreasing soil age. Feo content had a positive correlation with total carbonate, OM, salinity. MS was more in older soils such as hill physiographic unit but it was low in younger soils or soils with weak drainage. MS was greatly affected by sand material size which seems to be linked to parent materials. MS showed no trend with soil development but land use, drainage and parent material largely impacted MS and different Fe forms in these gypsiferous soils.
leila tabande; M. R.Bakhshi
Abstract
Introduction
Among essential plant microelements, iron (Fe) exert the highest restriction of crop production in Fars Province. Trace elements in the soil is composed of forms into 5 groups. These are the water-soluble and variable, adsorbed, chelate creating with complex compounds, secondary clay minerals, ...
Read More
Introduction
Among essential plant microelements, iron (Fe) exert the highest restriction of crop production in Fars Province. Trace elements in the soil is composed of forms into 5 groups. These are the water-soluble and variable, adsorbed, chelate creating with complex compounds, secondary clay minerals, forms insoluble metal oxide minerals, and primary minerals. Water-soluble, changeable, adsorbed or form in chelates to be present as balance in the soil is noted and to be important for plants in nutrition.
Materials and Methods
In a greenhouse experiment was done with Soybean planting, the effects of Fe chelate (FeEDDHA) fertilizer levels on William cultivar of soybean (Glycine max L.) growth and chemical composition were studied by using a completely randomized design with 3 replications. Treatments were consisted of 10 soil samples and 3 levels of Fe applications (control, 5 and 10 mg.kg-1 as Fe EDDHA). Beside some physical and chemical soil properties and Extractable iron content with DTPA and EDTA were determined. By sequential extraction methods of Singh & Sposito ( 1982), chemical forms of Iron, exchangeable iron (Exch-Fe), organic bounded iron (OM-Fe), amorph iron oxides bounded iron (AFeOX-Fe), crystal iron oxides bounded iron (CFeOX-Fe) contents of soils were determined. Then, Concentration and uptake of Fe, Mn, Cu and Zn in plant were calculated.
Results and Discussion
carbonate, organically, amorphous oxide, crystalline iron oxide bounded and residual forms of iron were 0.0053, 0.0016, 0.44, 21.1 and 78.6% of the total iron as average, respectively. Therefore, content of carbonate, organically bound iron of soil, represented only a small fraction would not be considered as important as the total iron. In other words, crystalline iron oxide bound iron and residue iron forms constitued an important part of total iron.
Considering the average iron content of the soil related to chemical forms of iron was arrenged such as:
Res-Fe>CFeOX-Fe>AFeOX-Fe>Car-Fe> OM-Fe > Exch.-Fe
Applications of Fe had significant effect on dry matter, concentration, and uptake of Fe, Zn, Cu and Mn, extractable forms via extracting DTPA, EDTA, organic and exchangeable forms in soybean compared to control. Among chemical forms of iron, organic form with the amount of available iron plant (extraction by DTPA) had significant positive correlation. Also, many of the physical and chemical properties of calcareous soils studied, were significantly correlated with some chemical forms and amount of iron uptake by plant. DTPA extractable iron had negative correlation with pH ( R2= 0.514*) and EDTA extractable iron had positive correlation with organic matter (R2= 0.428*).
Conclusions
Application of Fe EDDHA, was leaded to significant increase organic and plant available (DTPA) forms of iron and due to significant regression equation (r=0.435*) between two chemical forms of iron (organic and DTPA extracted), it can be inferred that, the bulk of available iron plant was in form of organically bound. One reason for the positive reaction to the use of Fe EDDHA, subjected to a significant increase absorbable forms of iron in the studied soils.
Keywords: Chemical and Physical properties of soil, DTPA, EDTA, Iron, Sequential extraction
leila zare; abdolmajid ronaghi; Seyed Ali Akbar Moosavi; Reza Ghasemi
Abstract
Introduction: Vermicompost is one of the important bio-fertilizer which is the product of the process of composting different organic wastes such as manures and crop residues using different earthworms. Vermicomposts, especially those are derived from animal wastes,contain the large amounts of nutrients ...
Read More
Introduction: Vermicompost is one of the important bio-fertilizer which is the product of the process of composting different organic wastes such as manures and crop residues using different earthworms. Vermicomposts, especially those are derived from animal wastes,contain the large amounts of nutrients compaired with the composts prepared from crop residues. Vermicomposts contain plant available form of nutrients such as nitrate nitrogen, exchangeable phosphorus and potassium, calcium and magnesium. Nowadays, the use of vermicompost in sustainable agriculture to improve the growth and quality of fruits and crops is very common. Drought occurs when the amount of moisture in soil and water resources and rainfall is less than what plants need for normal growth and function. Two thirds of farm lands in Iran have been located in arid and semi-arid regions with annual rainfall less than150 mm that has been distributed irregularly and unpredictable during growth season imposing water stress in most crops. It indicates the importance of water management and proposing different strategies for mitigating detrimental effect of water stress in croplands. Due to the fact that crops nutrient management under drought and water stress using organic fertilizers is an effective method in reaching to high yields in sustainable agriculture, the objective of the present study was to investigate the influence of vermicompost application on reducing the adverse effects of water stress on the growth and chemical composition of corn in a calcareous soil.
Materials and Methods: In order to study the influence of water stress and application of vermicompost on corn dry matter yield and nutrients concentration of corn shoot, a greenhouse factorial experiment (4×3) in completely randomized design with three replications was conducted in college of agriculture, Shiraz university, Shiraz, Iran. The factors consisted of four vermicompost levels (0, 10, 20 and30g kg-1soil equal to 0, 20, 40 and 60 Mg ha-1) and three moisture levels(100, 80and 60%of field capacity(FC)). The soil samples were collected (0-30 cm depth) from a calcareous soil (Fine, mixed, mesic, Typic, Calcixrepts), located at Bajgah, Shiraz, Iran. Soil samples were mixed thoroughly with different levels of vermicompost and transfred to plastic pots. Six corn seeds were planted in each pot and were thinned to three uniform plants, one week after germination. Eight weeks after germination, corn shoots were harvested, dried and recorded. Plant samples were grind using a portable grinder and transferred to the laboratory for chemical analysis. The collected data were statistically analysed using SAS software (9.1.3) package.
Results and Discussion: The results indicated that with increasing the levels of vermicompost, dry matter yield and concentrations of total nitrogen (TN), phosphorus (P), iron (Fe), copper(Cu) and zinc (Zn) in corn shoots were significantly increased. But, due to the antagonistic relationship between manganese (Mn) and Zn or Fe,concentrations of Mn were significantly decreased. However, the concentration of Mn was in the sufficiency range. The highest dry matter yield and concentrations of nitrogen and phosphorus in corn shoot was observed at 30 g kg-1 vermicompost treatment, with 19, 10 and 20 % increase (compared to the control), respectively. The application of 30 g kg-1 vermicompost increased the concentrations of Zn, Cu and Fe by 41%, 90% and 75%, respectively and concentration of Mn decreased by 11.88%, compared to the control. Increasing the levels of water stress increased significantly the concentration of nutrients in corn shoot due to the reduction of corn biomass. The highest increase in nutrient concentrations was observed at 60% FC moisture level. Nitrogen and phosphorus concentrations in corn shoots by 12.5and 22.5% and Zn, Cu, Fe and Mn by 25, 83, 43and29% were higher compared to those of control (100% FC), respectively. The interaction effects of water stress and vermicompost on the concentrations of shoot N and Cu were significant and both were incresead by simultanoeus application of vermicompost and levels of water stress. The applicaion of 30 g kg-1 vermicompost (about 60 ton ha-1) under 60% FC moisture level increased significantly dry matter yield and the concentrations of nitrogen, phosphorus, zinc, copper and iron in corn shoot by 29%,5.5%, 23, 110, 41 and 71 percent compared to the control, respectively. However, because of the antagonistic relationships,the iron or manganese concentrations were reduced, but were yet in the sufficiency range. The use of 30 g kg-1 vermicompost under 80% FC moisture level Also increased significantly the concentrations of nitrogen, phosphorus, zinc, iron and copper by 9, 23, 24, 59 and 43 percent compared to the control, respectively.
Conclusion: The applicaion of 30 g kg-1 vermicompost increased significantly dry matter yield and the concentration of nitrogen, phosphorus, zinc, copper and iron in corn shoot under water stress treatments. In conclusion, the application of vermicompost mitigated the detrimental effects of water stress on corn dry matter yield and concentration of nutrients due to the positive effects of compost on physical, chemical and biological properties of the calcareous soil.
vahid mozafari; fariba khaleghi
Abstract
Introduction: Salinity is one of the main problems which limits crop production, especially in arid and semi-arid areas such as Iran. Iran is the most important producer of pistachio in the world. However, its performance is low in many areas. Most pistachio plantations are irrigated with saline water ...
Read More
Introduction: Salinity is one of the main problems which limits crop production, especially in arid and semi-arid areas such as Iran. Iran is the most important producer of pistachio in the world. However, its performance is low in many areas. Most pistachio plantations are irrigated with saline water and with low quality (28). On the other hand, nitrogen is a dynamic element which is a constituent of amino acids, proteins, nucleic acids and Enzymes and it has a vital role in plant physiology, growth, chlorophyll formation and production of fruit and seeds (34). Gibberellic acid is known as phytohormon which varied physiological responses in plants under stress. acid gibberellic increases the photosynthesis and growth under stress and impact on the physiology and metabolism of plant (29). Based on previous studies, production and activity of plant hormones are affected by natural factors and plant nutrient requirements and the nitrogen has an important influence on production and transmission of acid gibberellic plant shoot. Therefore, in this study the effect of acid gibberellic and nitrogen on some characteristics of physiology parameters and micronutrient pistachio seedlings (Cv. Qazvini) under saline conditions was studied.
Materials and methods: Experiment under greenhouse condition and factorial in a completely randomized design with three replications was conducted in greenhouse agriculture college, Vali-E-Asr University of Rafsanjan. Treatments consisted of three levels of salinity (0, 1000 and 2000 mg of sodium chloride per kg of soil), three levels of nitrogen (0, 75 and 150 mg per kg of ammonium nitrate source) and three acid gibberellic levels (0, 250 and 500 mg per liter). Adequate soil with little available salinity conditions was collected from the top 30-cm layer of a pistachio-culture region of Kerman province. After air drying and ground through passing a 2 mm sieve, some of the physical-chemical properties of this soil include pH (7/63), Tissue (Sandy loam), electrical conductivity (ECe) (1 dS m-1), Silt (23.1%), Clay (5.5%), Organic matter (0.5%), Olsen phosphorus (P) (5.35 mg kg-1), Ammonium acetate-extractable K (100 mg kg-1) were determined. Nitrogen treatments 3 weeks after planting, dissolved in irrigation water was added to pots. Salinity, after the establishment of the plant (5 weeks after planting), divided into two equal parts and one-week interval dissolved with irrigation water was added to the pot. as well acid gibberellic treatments, as spray after salt treatment was applied at three times and at intervals of one week.
Results and discussion: The results showed that the salinity content of carotenoid and Chlorophyll fluorescence parameters significantly reduced but with increasing acid gibberellic and nitrogen application, mentioned parameters were significantly increased, compared to controls. The ability of photosynthesis improved and increased productivity. Mozafari et al studied the pistachio, reported that with increasing salinity from zero to 150 and 300 mM NaCl, carotenoids decreased more than 16% and 22% compared to control respectively. Carotenoids play a most important role in light, protecting plants against stress condition. Salinity application increased leaf proline, but with application of 150 mg nitrogen and 500 mg per liter foliar application of acid gibberellics, this parameter increased by 55 and 26 percent, respectively. Also, combined use of these two treatments increased proline content by 79 percent compared to control. The researchers stated that the increasing gibberellin concentration caused leaf proline increased, so spraying 100 and 200 mg per liter gibberellin significantly increased leaf proline compared with the non-application of gibberellin. The results also showed with increasing salinity increased iron, manganese and zinc concentrations shoots and roots and decreased copper concentrations, but using 150 mg of nitrogen and acid gibberellic consumption concentrations of copper element increased. Hojjat nooghi and Mozafari (28) reported, the used salinity of 60 mM NaCl increased shoot Fe concentration, but by applying the same amount of salinity in the root iron concentration decreased compared with the control. Research has shown that the copper concentration in the leaves and shoot of corn planted in soil decreased with increasing salinity. Micronutrient absorption reduction such as copper in salt condition can result in greater absorption of nutrients such as sodium, magnesium and calcium. The researchers in the study reported that with increasing nitrogen in the form of nitrate and ammonium, zinc concentration in plant tissues increased along with increasing salinity and lower shoot dry weight, zinc concentration was increased in two wheat cultivars too.
Conclusion: The results of this experiment showed that under saline conditions, acid gibberellic and nitrogen applied alone or in combination improved physiology parameters and increased nutrient concentration of pistachio seedling.
javad seyedmohammadi; leila esmaeelnejad; hassan ramezanpour; kamran eftekhari
Abstract
Introduction: Paddy soils are important and the base of agriculture in Guilan province. It is necessary to recognize these soils for understanding of their limitations and optimum use. Unsaturated soil submerging is the cause of collection of chemical and electrochemical process that has significant ...
Read More
Introduction: Paddy soils are important and the base of agriculture in Guilan province. It is necessary to recognize these soils for understanding of their limitations and optimum use. Unsaturated soil submerging is the cause of collection of chemical and electrochemical process that has significant effects on soil fertility. Eh, rH and pH are important indexes that are used to investigate oxidation and reduction condition in submerged soils and have abundant effects on activity and sorption rate of nutrients. Decrease of Eh and rH in poorly drainage of paddy soils affects availability and solubility of nutrient. Different Fe forms are used for analysis of soils evolution trend and submerging influences on changes of Fe forms. The aim of the present study was conducted to investigate the effect of redox potential changes on soil characteristics and analysis of soils evolutional trend in different physiographic units.
Materials and Methods: The study area with 40000ha (at the east of Rasht city) is located between 49° 31' to 49° 45' E longitude and 37° 7' to 37° 27' N latitude in North of Guilan Province, Northern Iran, in the southern coast of the Caspian sea with different water table depth. The climate of the region is very humid with the mean annual precipitation of 1293.6 mm. The mean annual temperature is 15.8°C. The soil moisture and temperature regimes are Aquic, Udicand Thermic, respectively. The parent materials are derived from river sediments. The soils formed on the plateaues and upper terraces, river alluvial plain and lowland physiographic units were classified as Inceptisols and the soils formed on coastal plain physiographic unit as Entisols. Air-dried soil samples were crushed and passed through a 2mm sieve. Particle-size distribution, organic carbon and cation exchange capacity were determined by hydrometric, wet oxidation and ammonium acetate methods, respectively. Eh by Eh electrode, total iron, free iron and amorphous iron were determined using nitric acid, dithionite-citrate-bicarbonate and ammonium oxalate methods, respectively. The means of different Fe forms values compared through LSD test.
Results and Discussion: It can be seen especial morphological and physicochemical characteristics in studied paddy soils with high groundwater table due to artificial submerging in rice growing seasonDifferent Fe mottles such as orange mottles include lepidocrocite mineral was observed in studied soils. Low redox potential with average 145/7mV and rH with average 19.6 in lowland and coastal soils implicate intense reduction condition. In lowland soils Eh was lower than other units and it was lower in top horizons than to sub horizons in all of units. Eh index had inverse relationship with organic matter, because of high organic matter amount caused high activity of anaerobic micro-organisms, increase of iron reduction and reduction soils degree decrease. rH index amounts showed that studied soils had reduction condition and presence of brown iron and black manganese minerals proved this condition. CEC was high in top soil of physiographic units due to high amount of organic matter and clay content. Clay particles in plateaues were lower than other units because of alteration and suitable aeration and showed high evolution in these soils. Clay coatings were not observed due to high ground water table and its alternative fluctuation. Results showed amorphous iron in surface horizons with average amount of 24.3g kg-1 was higher than subsurface in all soils and had positive correlation with organic matter, because of high activity of anaerobic micro-organisms that prevent from transformation of amorphous iron to crystallized iron, therefore amorphous iron amount increased in presence of organic matter. Pedogenic iron was high in A and B horizons with regard to BC and C horizons due to aeration and weathering. In lowland and coastal land Fed was lower than plateaues and upper terraces and river alluviums units because of ground water presence and its alternative fluctuation. Fed-Feo index showed crystallized iron oxides, high amount of Fed-Feo index proved soils evolution and high weathering. Feo/Fed ratio was related to amorphous pedogenic iron and high amount of this index showed few evolution of soil. Fed/Feo and Fed-Feo indexes indicated the lower rate of crystallized iron with average 6.8g kg-1 in lowland and coastal soils and implicated the lower evolution of these units' soils, due to higher surface groundwater and its more fluctuation than soils of plateaues, upper terraces and river alluviums unites with average amount of crystallized iron 15/8g kg-1.The comparison of different Fe forms using LSD method showed significant difference at the 0.01 level for different Fe forms values in different physiographic units.
Conclusion: Submerging, high groundwater table and severe fluctuation caused noticeable changes in morphological, physical, chemical and electrochemical properties of studied paddy soils. Noticeable organic matter amount added to soil and their burial by puddling operation and slow decomposition were effective factors in redox potential changes of studied wet soils. In equal anaerobic condition, more organic matter caused to decrease redox potential in surface horizons of soils with aquic condition and reverse, lower organic matter caused increasing in redox potential. lower amount of Eh and rH proved severe reduction condition in lowland. Investigation of Fed-Feo and Feo/Fed showed that their amount in lowland and coastal land were lower than plateaus and river alluviums, therefore lowland and coastal soils had lower evolution. Mean comparison of different Fe forms values using LSD method showed significant difference at the 0.01 level for different Fe forms in different physiographic units.
salimeh rahemi; R. Khorassani; A. Halajnia
Abstract
With due attention to the low availability of iron in calcareous soils and different ability of plant species in iron acquisition, the study and identification of iron-efficient plants is necessary to reduce the use of chemical fertilizers. In this way, a greenhouse experiment was conducted to study ...
Read More
With due attention to the low availability of iron in calcareous soils and different ability of plant species in iron acquisition, the study and identification of iron-efficient plants is necessary to reduce the use of chemical fertilizers. In this way, a greenhouse experiment was conducted to study of iron uptake efficiency in different wheat varieties, as a randomized complete blocks design with factorial arrangement. Treatments consisted of three levels of Fe (0, 2 and 6 mg kg-1) and three varieties of wheat (Falat ٫Parsi ٫Pishtaz) with three replications. The results showed that iron application had no effect on shoot dry weight and iron uptake in Parsi and Pishtaz varieties, but increased those in the Falat variety. The study of influx and root-shoot ratio, which are two important factors in the iron uptake by plant, showed that the Parsi and Pishtaz varieties had higher influx than the Falat variety. In the Parsi variety as well as influx, the root length had an important role in iron uptake efficiency. In the Falat variety with increasing amounts of iron uptake, relative shoot dry weight, influx and root-shoot ratio were increased. Therefore, the Falat variety in comparison to two other varieties was not an iron efficient plant. Lack of response to Fe fertilizer in the Pishtaz and Parsi varieties indicated some other specific uptake mechanisms were involved at low Fe levels in soil. Finally, the results showed that the Pishtaz and Parsi varieties were more efficient in iron uptake than Falat variety.
