جستجوی مقالات مرتبط با کلیدواژه "خاک های آهکی" در نشریات گروه "آب و خاک"

One of the limiting factors in crop yield in calcareous soils of arid and semi-arid regions is the deficiency of micronutrients in these soils. This study was conducted to examine the effects of various commercial humic acids (HAs) and fulvic acids (FAs) on the release of manganese (Mn) in 15 calcareous soils. The results indicated that the application of all five different HAs used in this study had no significant effect (P<0.05) on the release of Mn, but the effects of FAs varied in different soils, the majority of them resulted in a significant increase (P<0.05) in Mn release. In 20% of the soils, either three or all five FAs, and in 26.7 % of the soils, either two or four of the FAs resulted in a significant increase in Mn release. In one soil, none of the FAs were effective in increasing Mn release. Two FA samples, FA1 and FA5, were much more efficient in releasing Mn, indicating that the effectiveness or ability of the marketed or commercial FAs to release Mn, on an equal weight basis, is not the same and varies greatly among them. The difference was, to some extent, due to the ability of these humic substances to form strong (multidentate) complexes with Mn or act as a chelating agent. The results also indicated that effectiveness was dependent on soil characteristics, which were related to the binding strength of Mn with surface functional groups of soils and the solubility of Mn minerals in the soil.

Most of the soils of sugarcane fields in the Khuzestan province are calcareous and have little organic matter. The availability of nutrients such as phosphorus and the efficiency of phosphorus fertilizer application are low in these soils. In calcareous soils, a significant part of phosphorus fertilizers, becomes insoluble after entering the soil and are out of reach of plants. This study aimed to evaluate the application of phosphorus fertilizers, based on their acidic solution, in order to evaluate the status of nutrients and quantitative and qualitative yield of sugarcane. For this purpose, treatments of 0, 10, 20 and 40 kg ha-1 of urea phosphate fertilizer were applied in 100 m2 square plots of cultivated sugarcane cultivar with second regrowth age (R2). The results showed that the application of phosphorus fertilizer compared to the control, significantly (P≤0.05) increased the quantitative and qualitative yield of sugarcane, so that the highest yield of millable cane was observed in 20 kg ha-1 of urea Phosphate treatment (61.3 ton ha-1 with 18.2% increase). However, applying of 40 kg ha-1 of urea phosphate, only a 10.5% increase was observed compared to the control. On the other hand, the negative effect of high phosphorus concentrations on nitrogen concentration in leaves was evident, especially in the early growth period. The leaf ratio of nitrogen to phosphorus (N:P), regardless of the type of treatment, averaged 1:6.9. But the average leaf ratio of nitrogen to potassium (N/K) was 2.7:1, which was significantly different from the optimal values required for maximum growth of sugarcane. In general, the results showed that urea phosphate application in available phosphorus-deficient soils, depending on soil and plant conditions, has a significant role in increasing sugarcane yield. On the other hand, disturbtion of the balance of nutrients by deficiency or excess of nutrients in the plant, leads to a significant reduction in growth and quantitative and qualitative yield in sugarcane.

Due to the importance of nickel (Ni), and the effect of common soil additives on Ni fractions distribution, the present study was conducted to evaluate the effect of zeolite and vermicompost on nickel fractions over time. The experimental design consisted of a factorial combination of two levels of vermicompost (zero and 2% by weight), three levels of zeolite (zero, 4% by weight of Firoozkooh zeolite, and 4% by weight of Semnan zeolite), and two soil texture (clay and sandy loam) in a completely randomized design in triplicates. Treatments were contaminated with 50 and 100 mg nickel/kg soil. Ni fractions were extracted and measured at 20 and 60 days. The results showed that in initial soils, Car-Ni in sandy loam soil was higher than in clay soil, while the content of Fe, Mn- Ox Ni, OM-Ni, and Res-Ni in the clay soil was higher. In sandy loam soil, more nickel was recovered in Exch- and Car-fractions, while nickel recovery was higher in Mn, Fe-Ox Ni, OM-Ni, and Res-Ni in the clay texture. Zeolite addition caused a significant decrease of Exch- and Car-Ni in the clay soil on 60d and 100 mg/kg Ni level. Exch-Ni was reduced due to vermicompost application. Vermicompost application caused the decrease in Fe, Mn Ox-Ni in both studied soils and times, and OM-Ni increased by vermicompost application. Aging generally reduces the Exch-Ni but changes in Car-Ni over time depending on the soil texture. Aging did not affect Mn, Fe-Ox Ni, and Res-Ni, while OM-Ni increased over time in clay soil.

Information on soil pollution assessment and suitable extractants to determine the available amounts of heavy metals in calcareous and saline soils of Iran are limited. Therefore, this study aimed to compare EDTA pH 4.65, EDTA pH 8.6 and, DTPA pH 7.3 extractants to characterize availability of heavy metals including copper, cadmium, lead, and nickel in calcareous and saline soils of Khuzestan Province. To this end, 63 soil samples were collected from wheat fields of the province and wheat was planted under greenhouse conditions using randomized complete design with three replications. Due to salinity limitation, sequential leaching by two pore volumes of each soil was applied. Plant available amounts of copper, cadmium, lead and nickel in soils were measured with the extractants before and after leaching. Result demonstrated that DTPA pH 7.3 and EDTA pH 4.65 extracted the lowest and the highest amounts of heavy metals, respectively. Salinity reduction had different impacts on the heavy metals extraction based on the type of the metal and extractants, such that uniform and similar trends were not observed for the extracted metals. There was a significant positive correlation between the extracted copper of all three extractants and wheat copper content. This correlation for DTPA pH 7.3 extractant (r = 0.32, P ≤ 0.01) was higher than EDTA pH 4.65 (r = 0.27, P ≤ 0.05) and EDTA pH 8.6 (r = 0.25, P ≤ 0.05) extractants. For cadmium and lead, only positive and significant correlations (r = 0.33, P ≤ 0.01 and r = 0.28, P ≤ 0.05, respectively) were obtained between DTPA extract and their concentrations in wheat. No significant correlation was recorded between wheat nickel content with any of the extractants. Based on the results, it seems that the DTPA may be introduced as the most suitable extractant to determine the available copper of wheat in the calcareous and saline soils of Khuzestan. However, by considering the soil salinity, leaching requirement, and the weak correlations between the studied extractants and the plant available soil cadmium, lead, and nickel, further studies are recommended for assessment of these heavy metals.

Soil erosion is one of the most important and serious threats to food security and as a consequence of human life. In order to perform soil protection activities against soil erosion, knowledge about the amount of soil loss tolerable is very important. In fact, the soil loss tolerable is the potential for soil erosion, loss of productivity and lost production, and the final criterion for controlling soil erosion and degradation of land. Soil thickness methods, particularly Skidmore equation, based on their ability to estimate the tolerable amount of soil loss have been widely used. In the mathematical function developed by Skidmore based on soil thickness, the soil loss tolerable is calculated based on the soil's current depth, the lowest and maximum soil depth for sustained growth of crops, and the upper limit of tolerable erosion in accordance with the environment. Since the determination of soil loss tolerance by soil thickness method and the Skidmore equation requires time, cost and energy, the researchers have tried to estimate the soil tolerance is supported by regression methods using pedotransfer functions and easily available soil properties. Therefore, the present study was carried out with the aims of determining the tolerable tolerance of soil loss by thickness method and the development of regression pedotransfer functions for estimating this property in the upstream of the dam.

The study is place on Kamfiruz Watershed with an area of 422 km2, an average annual precipitation of 443 mm and an average annual temperature of 14 °C. It is closed to the Dorudzan Dam sub-basins and is considered as one of the five parts of Marvdasht plain in Fars province. For this work, 60 soil profiles were excavated by excavating machine. In addition to measuring the depth of soil, some physico-chemical soil properties were measured from the surface layer (0-30 cm) including; soil texture, organic matter, salinity, percentage calcium carbonate, mean weight diameter in the laboratory and filed. In order to develop regression models for estimating the tolerable soil loss, information from 60 soil profiles was divided into two data-sets. One set of the data with 42 samples (70% of whole samples) was used for developing the models and another set of the data with 18 soil samples (30% of whole samples) was used for validation. Multiple linear regression was used to develop the linear models. The same soil properties used in the multiple regression method were considered as inputs in the tree regression method to estimate the tolerable amount of loss.

The results showed that the minimum and maximum Z1 parameters (the lowest soil depth for stable growth of crops in the study area) were considered as 0.25 and 0.51 m based on the current depth of soil. Organic matter of the soils with the highest standardized coefficient (Beta = 0.44) and the highest correlation (-0.77) with soil loss tolerance was the most important soil properties for estimating the soil loss tolerance. In the regression model, only the coefficients of four characteristics of permeability, soil aggregate stability, pH and organic matter appeared among the soil grazing characteristics and entered into the model. Based on the evaluation statistic, tree regression method with the highest determination coefficient in both calibration data sets (R2 = 0.96) and validation (R2 = 0.78) and the lowest error value in the validation data (RMSE= 0.29 ton ha-1 year-1) and validation (RMSE = 0.125 ton ha-1 year-1) were more efficient than the multiple regression method in estimating the tolerable soil loss.

Soil loss tolerance was estimated using regression methods (multiple linear regression and regression tree) in Doroudzan Watershed, Fars province. The soil loss tolerable determined using Skidmore method, was 1.04 tons per hectare per year ranging from 0.29 to 2.25 ton ha-1 year-1. The soils of this area are slightly deep and their depth varies from 0.4 m in the marginal areas in the upstream parts of the catchment area of the dam and the slope of mountain up to 2 meters in the center of the plain with agricultural lands uses. In general, the tree regression method had a better performance than linear regression method for estimating the soil loss tolerance based on the statistical indices.

Increasing knowledge and soil quality evaluation in different ecosystems is important to improve sustainable land use management and to decrease land degradation. Therefore, the present study was planned to analyse the effects of different land use (irrigated farms, rain fed farms, orchards and rangelands), texture and topography on soil quality of Shazand Watershed with an area of 1740 km2. For this purpose, 140 soil samples were taken from top layer of the soil (0 to 30 cm) from homogeneous units representing an area of more than one square kilometers. Hence, various soil properties such as electrical connectivity (EC), pH, bulk density (BD), gravel, sand, silt, clay, calcium carbonate (CaCO3), nitrogen (N), soil organic carbon (SOC) were analyzed. Consequently, the effect of land uses, textures, slopes, and elevation on the measured soil properties were examined using multivariate analysis of variance (MANOVA). The result of MANOVA indicated that the different land uses had no significant effect (P> 0.05) on different soil properties. Also, the minimum effective properties on soil quality were determined by the minimum data set (MDS) with the help of principal components analysis (PCA). Finally, soil quality index values were calculated using discriminant analysis (DA). The results of PCA and DS showed that the EC, OM, CaCO3 and pH were influenced by soil texture, slope and elevation, respectively. Then, the comparison of mean soil quality values using the least significant differences (LSD) indicated poor soil quality on slopes less than 15% and elevations above 2000 m. The results of this research could be used for choosing appropriate management practices to control land degradation and to achieve sustainable development goals in different ecosystems of Shazand Watershed.

Cupper (Cu) is one of the micronutrients and the release rate of this element is an important factor in determining its bioavailability in calcareous soils. In this research, the kinetics of native Cu extraction by DTPA was studied in 21 calcareous surface soils (0-30 cm) and the best kinetics model to describe the data was selected. For this purpose 20 mL of 0.005 M DTPA solution was added to 10 g air dried soil and shacked,then during the 0.16 to 200 hours the concentration of Cu was determined. Furthermore the abilities of  zero, first, second and third order equations, simple Elovich, two constant rate, parabolic diffusion, Lagergern first order and Blanchard equations in description of the kinetics process were evaluated. According to the results, the rate of Cu extraction by DTPA was increased with time then reached a relative equilibrium in 72 hours. The best models for describing kinetics of Cu extraction during 200 hours were the simple Elovich and two constant rates. Also within 0.16 to 20 hours besides these two equations, the parabolic diffusion was one of the best models, too. Lagergern first order and Blunchard equation despite the wide range of correlation coefficients did not have a good fitness with the 21 studied soils. The αsβst product of simple Elovich equation (qt = 1/βs ln(αsβs) + 1/βs lnt ( in initial 15 minutes was larger than 1 for all studied soils. The amounts of constant b in the constant rate equation (qt = atb) were positively and negatively correlated with sand concentration (r= 0.47 *) and CEC values (r=-0.45*), respectively. The highest correlation coefficientsbetween the kinetics parameters of superior equation, was observed between the ab with βs.

Due to unsuitable soil physical conditions, calcareous soils, and the existence of a huge amount of sulfur in the country, the study of sulfur effects on the soil structure and other soil properties is necessary. Therefore, the effects of different rates of sulfur including: 0, 750, 1500 and 3000 kg/ha, when accompanied by Halothiobacillus neapolitanus bacteria, on the soil properties in the corn-wheat rotation in two years were investigated. Parameters of soil pH, EC, sulphate, organic carbon, soil structure and wheat yield were measured. For the quantification of soil structure and quantity evaluation of sulfur effect on the soil structure, with measuring the aggregate size distribution, the mean weight diameter (MWD) and geometric mean diameter (GMD) of the aggregate indices, and the amounts of fractal dimension were determined. The r results indicated that with the progress of the experiment and further application of sulfur along with thiobacillus bacteria, aggregation and aggregate stability were increased. The effect of sulfur treatments on MWD and GMD was significant; based on quantification indices, it had 28 percent positive effect on the soil structure. Sulfur with 3 percent reduction of fractal dimension had a significantly positive effect on the soil structure. Application of sulfur decreased a small amount of soil pH and increased 12 percent of the soil EC and 40 percent of the soil sulphate. So soil structure improvement and reclamation of soil physical condition can be very effective on the soil conservation and sustainability of the production resources and the conservation of environment.

The present study was conducted to evaluate zinc availability and forms, as well as their relationships with soil properties in some soil samples of Kermanshah and Ilam provinces. Sequential extraction included Mg(NO3)2 (soluble + exchangeable), NaOAc pH = 5 (carbonatic fraction), Na-hypochlorite at pH = 8.5 (organic fraction), hydroxylamine hydrochloride at pH 2 (Mn oxides associated Zn), hydroxylamine hydrochloride (amorphous Fe oxides associated Zn), ammonium oxalate (crystalline Fe oxides associated Zn), and HNO3 (the residual Zn). DTPA-Zn was in the range of 0.34-3.7 mg/kg. The results showed that soluble+ exchangeable, Mn oxides and crystalline Fe oxides associated Zn were not detectable by atomic absorption. Distribution of Zn fractions was in the order of Organic-Zn < Car-Zn < amorphous Fe oxides-Zn < Res-Zn. Organic matter bound Zn and amorphous Fe oxides associated Zn and the residual fractions showed a significant negative correlation with the calcium carbonate equivalent. It seemed s that calcium carbonates were the major factor in controlling the Zn content in the studied soils.

Understanding the distribution of different P forms in soil aggregate fractions is important in evaluating the risk of P run-off and leaching in the agricultural soils. The objective of the present research was to determine the effect of aggregate size on soil phosphorus availability and fractionation in 10 calcareous soils. Micro aggregate (< 0.25 mm), macro aggregate (> 0.25 mm) and whole soil were separated by dry sieving. Olsen P, total P, organic P, and inorganic P fractions in micro aggregate, macro aggregate, and whole soil were determined. Soil inorganic P fraction was determined by a sequential extraction procedure including: dicalcium phosphate (Ca2-P), octa calcium phosphate (Ca8-P), apatite (Ca10-P), P absorbed by Al oxide (Al-P), P absorbed by Fe oxide (Fe-P) and P incorporated in to Fe oxide (O-P). The results showed that the amounts of (Olsen P), (Ca2-P), (Ca8-P), (Ca10-P), (Organic P), (Al-P), (Fe-P), (O-P) and (Total P) in 70, 60, 40, 40, 60, 70, 60, 50 and 70 percent of soils, respectively, in the micro aggregates were significantly higher than those of the macro ones. Finally, by increasing the P content, particularly the smaller sized aggregates, it was likely that the eroded material would favor greater P loss.

Soil phosphorus (P) buffering capacity of the soil is very important in plant nutrition and it is the most important soil property for determination of P release potential. In this study, 23 soil samples from different horizons of five orders along a climo-toposequence were collected to determine P sorption characteristics, P buffering indices and their relationship with the soil properties. According to the results, the L-shaped adsorption isotherm obtained from all the soil samples showed a high relatively tendency of the soils for P adsorption at low concentrations, which was well-fitted by the Freundlich, Langmuir and Temkin equations. This study also indicated that the adsorption processes in P concentrations less than 20 mg/l and precipitation processes in P concentration greater than 20 mg/l control the soil phosphorous. Among the different soil characteristics, organic matter and cation exchange capacity have a significant positive correlation with most of the P sorption properties. The overall results of this study showed that the Histosols and Mollisols orders (located at the end of the studied area), Aridisols and Inceptisols (located at the beginning of the study area) and Alfisols (located in the middle of the study area) have had the high to the low values of P buffering capacity, respectively. Therefore, simultaneous low and frequent application of organic and chemical fertilizers are suggested to reduce the P adsorption and to increase the P release at the end of the study area due to high phosphorus adsorption capacity.

Knowledge about different forms of Cu and determining the amount of each one provides useful information for evaluation of soil Cu status and also understanding soil Cu chemistry. To obtain such information, the amount and distribution of Cu in different fractions of 21 composite soil samples of East Azerbaijan Province were determined by modified sequential extraction procedure introduced by Singh et al and the relationships of these fractions with each other and with soil properties were also investigated. According to the results, total Cu concentrations of soils ranged from 21.50 to 90.57 mg/kg with a mean value of 37 mg/kg. Sand and silt percentage with Cu associated with amorphous Fe oxides had significant correlation. Silt content had significant correlation with organically copper and amorphous Fe oxides bounded Cu. Both calcium carbonate equivalent and active calcium carbonate equivalent had significant correlation with exchangeable copper. Among the copper forms, Cu-Ex, Cu-CFeOX and total Cu had positive and significant relations with soluble Cu and among them Cu-CFeOX had highest correlation coefficient value (r =0.53*). The order of various forms of soil Cu was found to be as follows: Residual copper (Cu-Res) > crystalline Fe oxides bound (Cu-CFeOX) > amorphous Fe oxides bound (Cu-AFeox) > organically bound (Cu-OM) > carbonates bound (Cu-Car) > soluble exchangeable (Cu-Ex) > Mn oxide bound (Cu-Mnox). In this study a significant correlation was also observed between some forms of Cu, which is presumably a reflection of the existence of a dynamic relation between them in soil.

Vast parts of the world soils including Iran have calcareous soils in which due to the high pH and fixation of many micronutrients including zinc (Zn), the deficiency of these nutrients are seen. Total Zn content in soils does not give any information about it’s availability to plants. Therefore, available zinc in 28 calcareous soils with a wide range of physical and chemical properties was evaluated with DTPA-CaCl2, EDTA-NH4OAc, DTPA-NaOAc, DTPA-NH4HCO3, EDTA and Mehlich3 on pistachio seedling as a test plant. Experiment was done as a completely randomized design with three replications and 28 soil types under greenhouse conditions. The results showed that the ability extractants to extract zinc are as follows: Mehlich3 > DTPA-NaOAc > EDTA> EDTA-NH4OAc > DTPA-CaCl2 = DTPA-NH4HCO3. Use of multiple regression equations showed that amount extractability of Zn by some extractants from the soil by some of the physical and chemical properties soil, such as clay, CEC and CCE was dependent. There was a significant correlation between concentration and uptake zinc of the leaves and stem and extractability of Zn by the extractants . So that the amount of zinc extracted by DTPA-NH4HCO3 highest correlation (R= 0.634**) with the concentration zinc of pistachio seedlings leaf, so extractant DTPA-NH4HCO3 can be used to evaluate available zinc the pistachio in calcareous soils.

The most abundant of agricultural soils in Iran, are calcareous. In calcareous soils, phosphorus fertilizers use efficiency is low. The usage of soil microorganisms is one of the effective ways to increment the uptake of phosphorus in calcareous soils. This microorganisms using various mechanisms, including the production of plant hormones or the production of organic and inorganic acids to dissolve the insoluble phosphorous compounds. Mycorrhizal symbiosis is also one of the most recognized and important symbiosis relationship found in the world. In a mycorrhizal symbiosis,plants can be able to absorb more nutrients and water from soil and fungus plays a protective role as a growth enhancer and make the plants more tolerable to biotic (pathogens) and abiotic (drought, cold and salinity) stresses .This research conducted to study phosphate solubilizing bacteria and mycorrhiza roles on sorghum growth and phosphorus availability to this plant.
To achieve the desired goals, a pot experiment was conducted as a factorial in completely randomized design with sixteen treatments in three replications. The treatments were combination of four P levels of zero, 25, 50, and 75 mg kg-1 P2O5 from triple super phosphate source, the two treatments of inoculation and without inoculation of phosphate solubilizing bacteria and the two treatments of inoculation and no inoculation of mycorrizal fungus. Required fertilizers based on initial soil test results were supplied. Accordingly, the same amount of nitrogen, 80 mg kg-1 (30 mg kg-1 before planting and 50 mg kg-1 after planting twice) as urea source, 10 mg Zn kg-1 and 5 mg kg-1 Cu per kg soil as the forms of Zinc sulphate (ZnSO4.7H2O) and copper sulphate (CuSO4.H2O) were added to each soil sample. Required Phosphorus also was calculated based on treatments and added to potting soil. Each pot size was 5 kg. every sample was thoroughly mixed and then were placed in pots. At the same time the seeds were inoculated. In harvesting time, some parameters such as plant height and diameter, wet and dry foliage yield, and phosphorous uptake were measured and analyzed statistically. After harvesting time also soils phosphorous content were measured and analyzed.
Results The results indicated that by utilizing the phosphate solubilizing bacteria, stem diameter, dry matter yield, phosphorous uptake, and soils phosphorous content after harvesting significantly increased. These findings indicated that the use of phosphate solubilizing bacteria affected plant growth. Such results have been previously reported. Ramezanian (31) reported that application of PGPR will be increase wheat stem height and diameter. Li et al (18) and Larsen et al (16) reported that soil microorganisms, including growth promoting bacteria through a variety of mechanisms such as ACC deaminase production or an increase in available phosphorus can stimulate plant growth and increase height and diameter of the stem. Glick et al (13) showed that plant growth promoting bacteria through the production of plants hormones increases plant height and stem diameter, and ultimately improve plants yield. Increases yield of plants through the use of phosphate solubilizing bacteria previously has been reported by other studies. Mycorrizal inoculation also had a significant effect (P

The status of soil K forms and its relationship with K content in wheat grain at harvest period may be important for nutrient fertility management. For this purpose, 40 surface (0-20 cm) and subsurface (20-40 cm) soil samples and also grain samples from wheat fields of Darab region were randomly sampled in 2014. Then physicochemical properties of the soils and the contents of soluble, exchangeable and non-exchangeable K and contents of K in wheat grains were determined. Results indicated that content of soluble, exchangeable and non-exchangeable K in the studied soils ranged 15-70, 91-443 and 396-1182 mg kg-1, respectively. Significant relationships were obtained between soil K forms and clay, calcium carbonate and CEC. Although it is expected that content of easily available K (soluble and exchangeable K) was low at late stage of wheat growth, most soils had sufficient K content. The positive and significant relationship among different K forms was indicative of the K forms equilibration at the time of wheat harvesting. Although there is not a relationship between K content in wheat grain and soil K forms, it was shown that K content of wheat grain was correlated with soil exchangeable K and clay content in fine-textured soils (clay > 30%). It means that ammonium acetate may be a suitable extractant for estimation of soil K status and plant available K of heavy-textured soils in the studied region.

Information about different forms of Fe and determining the amount of each one of them is important for evaluation of soil Fe status and also understanding of soil Fe chemistry. To obtain such information, amount and distribution of Fe in different fractions of 21 soil composite samples of East Azerbaijan Province were determined by modified sequential extraction procedures introduced by Singh et al and the relationships of these types with each other and with soil properties were also investigated. According to the results, total Fe concentrations of soils, determined by Sposito et al method ranged from 15.25 to 50.84 g kg-1 with a mean of 29.84 g kg-1 and by aqua-regia method ranged from19.54 to 47.75 g kg-1, with a mean of 30.38 g kg-1. The amount of different forms of iron was determined to be as follow: Residual iron (Fe-Res)> iron associated with the crystalline iron oxides (Fe-CFeOX)> iron associated with the amorphous iron oxides (Fe-AFeOX)> manganese- oxide- associated Fe (Fe- MnOX)> organic matter-associated Fe (Fe-OM)> exchangeable iron (Fe-Ex) ≥ carbonates-bound iron (Fe-Car). Simple correlation coefficients showed that soil pH had a significant negative correlation with Fe-CFeOX, active calcium carbonate equivalent had a significant negative correlation with Fe-MnOX and CEC had a significant positive correlation with Fe-Ex, Fe-Res and total iron. Clay content had a significant positive correlation with Fe-Ex, Fe-Res and total iron and had a significant negative correlation with Fe-MnOX. Also silt content had a significant positive correlation with organic matter and significant negative correlation with manganese- oxide- associated Fe. In this study, a significant correlation was also observed between the Fe forms themselves, which is presumably a reflection of the existence of a dynamic relationship between the chemical forms of an element in soil.

Variety of soil reactions govern the distribution of metal micronutrients that includes complexation with organic and inorganic ligands, ion exchange, adsorption and desorption processes, precipitation and dissolution of solids and acid-based equilibria. The relative importance of these reactions depends on many factors such as soil physical, chemical, and mineralogical properties and the nature of metal ions. Environmental factors such as climate, physiographic position, and soil development may affect variability of some soil properties and thereby nutrient availability. The present research was conducted to find relationships between Iron, manganese, zinc, and copper availability and some major soil properties, physiographic condition and soil development.
Golpayegan region is located in northwest of Isfahan province in central Iran. The mean elevation of the studied area is 1790 above sea level. Annual precipitation was about 244mm and mean monthly temperature ranges from -6 in January to 34°C in August. The soils were developed on different physiographic conditions including piedmont plains, alluvial-fan, plateaus, and flood plains belonging to Entisols and Aridisols. Soil samples (0–60 cm) were collected from 98 grid points with 2000m distance in the agricultural area of Golpayegan. Particle size distribution, calcium carbonate, organic carbon, available potassium and phosphorus of the soils were measured by SWRI standard methods. Available Zn, Cu, Mn, and Fe were determined by addition of 10 g soil to 20mL 0.005M diethylentriaminepentaceticþ. The solutions were shaken for 2 h at 25°C, centrifuged, filtered, and Fe, Mn, Zn, and Cu concentrations were measured by an atomic absorption spectrophotometer.
Results Studied soils were developed on calcareous material and about 60% of samples have more than 20% of calcium carbonate. Available Fe ranged from 1.4 to 6.5 mg kg-1 (mean 15.8 mg kg-1). Significant relationships were also found between DTPA-extractable Fe, organic matter (OM) and calcium carbonate. The results indicated that organic matter (OM) is the most influential soil characteristics that predict Fe availability. DTPA-extractable Mn in the soils ranged from 1.8 to 19.8 mg kg-1 (mean 7 mg kg-1). There were also no relationship between available Mn and soil properties. It has been reported that Mn availability in soils is mainly influenced by oxidation-reduction rather than other factors. Available Zn in the studied soils ranged from 0 to 2.4 mg kg-1 (mean 0.8 mg kg-1) and had significant correlations with particle size and OM contents. This result showed the importance of soil exchanger phase (clay and OM) in Zn availability in calcareous soils, and was in agreement with the findings of Wu et al. (2006) in soils of North Dakota. DTPA-extractable Cu ranged from 0.2 to 2.4 mg kg-1 (mean 0.9 mg kg-1). According to the report of Lindsay and Norvell (1978), 90% of soils had sufficient Cu. However, there were variations among soils in available Cu as a function of physiographic position. The highest values were found in the soils developed on piedmont plains. Significant relationships between available Cu and some major soils properties such as sand, clay, OM, and calcium carbonate were also found. This result was in agreement with findings of Wu et al. (2010) who concluded that soil properties influencing the spatial distribution of Cu availability.
Nutrient availability is one of the most critical concerns of plant production in calcareous soils of Golpayegan . Different pedogenic processes, variable deposition and transport, and different weathering regimes affect micronutrient content, distribution, and availability. Results indicated that Fe deficiencies followed by Mn and Zn in the studied soils are more critical than Cu deficiencies. In fact, 90% of soils had sufficient Cu. Mainly micronutrient availability in the studied soils was related to soil texture and organic matter, although Mn availability showed no relationships with major soil properties. It was concluded that the availability of Fe, Zn, and Cu may be predicted to some extent using some factors such as soil properties and physiographic condition. Availability of Fe, Zn, and Cu in Torrifluvents developed on piedmont plain was higher than in other soils and this may be due to the high amounts of OM and clay, whereas Haplocalcids developed on plateaus had the lowest content. Generally, it was concluded that the mentioned factors affect metal distribution and cycling in the soils and thereby metal availability for plants. On the other hand, prediction of micronutrient availability using these factors can be taken into consideration for better management.

This research was conducted to evaluation of extraction methods for determining the available iron (Fe) and active Fe in corn plant (Zea mays L.) at 21 calcareous surface soil samples in the East Azerbaijan province. In a greenhouse experiment, corn plant single cross 704 cultivar has been cultivated with 3 replications. After 60 days, the plant growth parameters were measured. According to the results, DTPA and AB-DTPA had the highest linear correlation coefficient with growth indices of corn such as active Fe concentration, chlorophyll index, Fe content, fresh weight and shoot dry weight as well as with some physical and chemical properties of soils. AB-DTPA due to a correlation coefficient greater than DTPA and simultaneous extraction of multiple nutrients was chosen as the best extractant. On the average, rapid ammonium oxalate and AC-EDTA extracted the maximum and minimum amounts of Fe, respectively. The both of 1.5% o-phenanthroline and 1N HCl methods were suitable for measuring corn active Fe concentration. Significant correlation (r=0.66 ,p

Pistachio is one of the most important crops in many regions of Iran with respect of production and export. There are more than 470000 ha of nonbearing and bearing pistachio trees mainly in Kerman province. Despite the economic importance of this crop, very little information is available on its nutritional requirements. Pistachio trees like other crops need to macro and micro nutrients. one of these elements is manganese (Mn). Manganese is an essential mineral nutrient, playing a key role in several physiological processes, particularly photosynthesis, respiration and nitrogen assimilation. This element is normally supplied to the plants by soil. Therefore, soil conditions affect its availability to plants. Soils with high pH, calcareous soils, especially those with poor drainage and high organic matter, are among the soils which produce Mn-deficient plants. Calcium carbonate is the major inactivation factor of Mn in calcareous soils. The soils of Iran are predominantly calcareous in which micronutrients deficiency, including Mn, is observed due to the high pH and nutrient fixation. The objective of this research was to examine the effect of manganese application on growth and chemical composition of pistachio seedlings in some calcareous soils with different chemical and physical properties.
For this purpose a greenhouse experiment was carried out as factorial (two factors including soil type and Mn levels) experiment in completely randomized design with three replications. Treatments were consisted of three levels of Mn (0, 10 and 20 mg Mn Kg-1 soil as Manganese sulfate) and 12 different soils from Rafsanjan region in Southern Iran. Soil samples were air dried and crushed to pass through a 2-mm sieve, and some physical and chemical properties of soils such as texture, electrical conductivity, pH, organic matter content, calcium carbonate equivalent, cation exchange capacity and iron, manganese, copper and zinc availability were determined. Then plastic pots were filled with 5 kg of these soils. Pistachio seeds (cv Badami Zarand) were placed in muslin sacks and pretreated for 24 h with Benomyl solution. The germinated seeds were planted in each pot, and each pot was irrigated with distilled water. Nitrogen and phosphorous were applied uniformly to all pots at the rate of 50 mg kg−1 soil as ammonium nitrate and potassium dihydrogen phosphate forms, respectively. Zinc, iron and copper also were added to treatments at level of 5 mg kg−1 soil as zinc sulfate, iron sequestrine138 and copper sulfate. After 24 weeks, the seedlings were cut at the soil surface, and the roots were washed free of soil. Leaves, stems and roots were dried at 70 oC for 48 h in an oven. The total leaf, stem, and root dry weights were recorded. The ground plant samples were dry- ashed at 550oC, dissolved in 2 N HCl, and made to volume with hot distilled water. Plant Mn, Cu, Zn and Fe concentrations determined by atomic absorption spectrophotometry. All data were statistically analyzed according to the technique of analysis variance (ANOVA) by MSTATC.
Results indicated that the application of manganese increased leaf, stem and root dry weight of pistachio seedlings so that the maximum amount of the dry weight of roots stems and leaves of pistachio seedlings were observed at 10 mg Mn kg-1soil. Application of 10 mg Mn kg-1 soil increased leaf, stem and root dry weight by 19.2%, 25.2% and 23.9% in comparison to control, respectively. Chemical composition (concentration and uptake) of shoot of pistachio seedlings was also affected by Mn application. Mn application decreased the concentration and uptake of iron, concentrations of copper and zinc in Pistachio seedling shoots so that the highest concentrations of these elements were observed in control treatment. Reductions in concentrations of zinc and copper elements in 10 mg Mn kg-1 treatment were not statistically significant but in 20 mg Mn kg-1 treatment they were significant.
The results of this research showed that the application of 10 mg Mn kg-1soilto highly calcareous soils significantly increased most of growth parameters of pistachio seedlings in comparison to control. Although higher amounts of manganese (20 mg Mn kg-1 soil) reduced the growth parameters than the previous level. In overall, the results of this study indicated that for optimum growth and chemical composition of pistachio seedlings in calcareous soils, application of 10 mg Mn kg-1 sol is necessary.

Phosphorus (P) is the second limiting nutrient in soils for crop production after nitrogen. Phosphorus is an essential nutrient in crop production. Determination of forms of soil phosphorus is important in the evaluation of soil phosphorus status. Various sequential P fractionation procedures have been used to identify the forms of P and to determine the distribution of P fractions in soils (Chang and Jackson, 1957, Williams et al., 1967; Hedley et al., 1982), but are not particularly sensitive to the various P compounds that may exist in calcareous soils. A Sequential fractionation scheme has been suggested for calcareous soils by which three types of Ca-phosphates i.e. dicalcium phosphate, octacalcium phosphate, and apatite could be identified (Jiang and Gu, 1989). These types of Ca-phosphates were described as Ca2-P (NaHCO3-extractable P), Ca8-P (NH4AC-extractable P) and Ca10-P (apatite type), respectively. In this study, the amount and distribution of soil inorganic phosphorus fractions were examined in 49 soil samples of Fars province according to the method described by Jiang and Gu (1989).
Based on the previous soil survey maps of Fars province and According to Soil Moisture and Temperature Regime Map of Iran (Banaei, 1998), three regions (abadeh, eghlid and noorabad) with different Soil Moisture and Temperature Regimes were selected. The soils were comprised Aridic, xeric, and ustic moisture regimes along with mesic, and hyperthemic temperature regimes. 49 representative samples were selected. The soil samples were air-dried and were passed through a 2-mm sieve before analysis. Particle size distribution was determined by hydrometer method (Gee and Bauder 1996). Also, Cation exchange capacity (CEC; Sumner and Miller 1996), calcium carbonate equivalent (Loeppert and Suarez 1996), organic matter content (Nelson and Sommers 1996), and pH by saturated paste method (Thomas 1996) were determined . Inorganic phosphorus sequential fractionation scheme was preformed according to the method described by Jiang and Gu (1989). Olsen-P fraction that was extracted by NaHCO3 (Olsen and Sommers 1982) was regarded as P-availability index. Also, Total-P by perchloric acid (HClO4) digestion (Sparks; 1996) and organic P were determined.. All of the extraction procedures were performed in duplicate and the amounts of P were colorimetrically measured in the supernatants by the ascorbic acid method of Murphy and Riley (1962).The relationships between forms of P and some of the soil properties were established using correlation method.
The chemical data of the soils showed that soils were calcareous with CCE range between 9.94 to 74.27 % ( average 51.10%) and pH range between 7.02 to 8.36 (average 7.85). Also, the amounts of CEC were between 5.35 to 29.39 cmol () kg-1(average 16.68 cmol () kg-1). The results showed a wide range in content of Phosphorus fractions. The amount of total Phosphate ranged from 301.87 to 1458.68 mg kg-1 with an average of 626.63 mg kg-1 . Calcium Phosphate ranged from 147.83 to 666.90 mg kg-1 with an average of 324.79 mg kg-1, that comprised 85 and 52 percent of inorganic and total Phosphorus, respectively. The amount of Fe-P ranged from 0.38 to 59.18 mg kg-1 with an average of 7.56 mg kg-1 that comprised 13.64 and 8.34 percent of inorganic and total Phosphorus, respectively. Also, the amount of Al-P ranged from 20.49 to 123.09 mg kg-1 with an average of 52.28 mg kg-1that comprised 1.97 and 1.21 percent of inorganic and total Phosphorus, respectively. The results of correlation study showed that available Phosphorus was significantly correlated with Ca2-P, Ca8-P, Al-P, Ca10-P, and Pt (total phosphorus). So, in calcareous soils, awareness of soil properties and phosphorus fractions and their relationships are important for evaluation of phosphorous status in soil and understanding of soil chemistry that influence soil fertility.
The relative abundance of inorganic P forms were in order of Ca10 – P > Ca8- P > Al –P> Ca2-P> Fe-P. Among the inorganic P fractions, Ca-P had the highest value and varied from 147.83 to 666.90 mg kg-1, which accounted for 53 percent of the sum of P fractions, occurred in H2SO4 extractable P fraction, which is attributed to primary Ca–P minerals, indicating their weak weathering nature. Also, correlation study showed that available Phosphorus was significantly correlated with Ca2-P, Ca8-P, Al-P, Ca10-P, and Pt. This result indicate that these fractions probably can be used by plant.