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The aim of this research was to study and compare release characteristics of copper (Cu) in 2 groups of soils from Guilan province in northern (SNI) and Fars province in southern Iran (SSI) with significant differences in Cu availability and other soil properties. The patterns of Cu release from the soils by ammonium bicarbonatediethylenetriaminepentaacetic acid (AB-DTPA) were studied using 5 kinetic models. Results showed that the power function, simple Elovich, and parabolic diffusion in SSI, and the power function and simple Elovich in SNI, were the best fitted models. The greater rates and magnitude of Cu released from SNI compared with SSI could be interpreted as the greater capability of the former in maintaining Cu concentration in the sufficient range. The difference in Cu release rates was considerable during initial times. Mean initial Cu release rate from SNI was ~3 times higher than that of SSI. The results reveal that the cation exchange capacity (CEC) and pH were the most influential soil factors causing differences in Cu release patterns between these 2 groups of soils. Greater CEC and lower pH in SNI compared with SSI, are mainly responsible for greater initial rates of Cu release in the former. Difference in CEC and pH of these 2 groups of soils was mainly attributed to different soil organic matter, carbonate content, and clay mineralogy. Additional keywords: copper release, cation exchange capacity, pH, kinetics., Introduction Copper (Cu) availability is low in uncontaminated soils, and deficiencies of this element have been reported in some soils (Lehman and Hatter 1984). In most agricultural soils, Cu availability [...]

In the present study, the effects of different cadmium (Cd) levels of irrigation water (0, 5, 10 and 20 mg L-1) on corn plants (foliage) under different irrigation intervals (1, 3, and 7 days) were investigated. Clear Cd toxicity symptoms appeared on the plants at the end of the experiment. The results showed that stem dry weight (DW) followed by transpiration (T) and plant height were the measured plant parameters most sensitive to increasing Cd levels of irrigation water. In addition, Cd reduced water uptake by corn and led to more soil moisture. The results also demonstrated that corn might produce more shoot biomass with Cd application, which should be taken into consideration if no visible symptoms of Cd toxicity and considerable amounts of the metal uptake are present. Cadmium application through irrigation did not show a marked impairment in the nutrient status of the plants. Moreover, accumulation of Cd in the leaves was more than the stems by 24, 56, and 27% at 1, 3, and 7-day irrigation frequencies, respectively. Also, corn stem was found to be more sensitive to Cd than leaf. The results showed that corn might be used for phytoremediation of Cd under optimum moisture conditions and light contamination of the soil. Furthermore, shoot Cd concentration followed an asymptote pattern as a function of soil Cd, which was expressed by a plateau-type model under each irrigation interval. [ABSTRACT FROM AUTHOR]

The interaction of salt and water stress to infect the roots by Macrophomina phaseolina, and affect the ion composition and growth of sorghum (Sorghum bicolor) was studied in a greenhouse experiment (19-35°C). Treatments consisted of 4 levels of salinity (0, 1400, 2100 and 2800 mg of NaCl kg-1 soil) and three water stress levels (3, 7 and 10 irrigation intervals). Infested soil containing 100 viable microsclerotia g-1 of a melon isolate of M. phaseolina and non-infested soil were used for all treatments. The experiment was arranged in a completely randomized design with four replications. Six-week-old sorghum seedlings after their transferring to infested and non-infested soil were exposed to salt stress, after which, water stress was started. Shoot dry weights were reduced by increasing salinity levels. This reduction was more pronounced in infested soil than in non-infested. Increasing irrigation intervals reduced salt injuries. Shoot and root colonization by M. phaseolina significantly increased by increasing salinity levels up to 1400 mg of NaCl kg-1 soil. Moreover, salinity and M. phaseolina interaction increased the concentrations of Na+ and Cl- compared to salt stress per se, but negatively correlated with increasing irrigation intervals. Concentration of K+ was in contrast with Na+ and Cl-. Also, disease symptoms appeared only in the highest irrigation intervals (7 and 10 days). Consequently, more infected crown and root were observed by increasing irrigation intervals and NaCl levels up to 1400 mg kg-1 soil. [ABSTRACT FROM AUTHOR]

Manganese (Mn) deficiency is common in calcareous soils of southern Iran. The ability of these soils to replenish the soil solution Mn depends highly on their Mn-release characteristics. Kinetics of native Mn release by ammonium bicarbonate diethylenetriaminepentaacetic acid (AB-DTPA) from 10 highly calcareous soils were studied for the periods of 1 to 1440 min. Results showed that Mn-release rates were initially fast, followed by a much slower rate. Among seven kinetic models tested, two constant-rate, simple Elovich, and parabolic diffusion models best predicted the pattern of time-dependent Mn release well, much better than zero-, first-, second-, and third-order models. Significant correlations were observed between constant values of parabolic diffusion with those of simple Elovich model (Kp and Q0 with β s and α s, respectively), which demonstrated that Mn release from calcareous soils of southern Iran is probably a diffusion-controlled process. Results of stepwise regression analysis between constant values of the best-fitted models and selected soil properties showed that the content of easily reducible Mn oxides (ERMn) was the only soil property capable of predicting some constant values of the best-fitted models. According to the equations, Mn-release rates increased as the amount of ERMn increased. It is therefore concluded that ERMn is probably the main source of Mn release in these calcareous soils. Further research to assess the relationships of constant values of the best-fitted models with plant growth parameters in calcareous soils is warranted. [ABSTRACT FROM AUTHOR]

There is little information on Nickel (Ni) adsorption by calcareous soils of Iran. The pattern of Ni retention and its relationships with soil properties in soils from the southern part of Iran (SSI) and northern part of Iran (SNI) was studied. Amount of Ni adsorption was calculated after the equilibration of 1 g soil samples in duplicate with 25 mL of 0.01 M CaCl2 solution containing 10 to 1000 mg Ni L- 1. Freundlich, Langmuir, Temkin, Dubinin-Radushkevich, and Redlich-Peterson isotherms were fitted to Ni adsorption data. The fits to Langmuir, Freundlich, and Redlich-Peterson adsorption models were closer than other isotherms. The intercept of Freundlich equation (AF) and maximum buffering capacity of Langmuir (bLXm) was significantly correlated with clay in SSI whereas in SNI it was related to pH and organic matter (OM). Adsorption maxima (Xm) of Langmuir isotherm was correlated with cation exchange capacity (CEC) in both groups of soils. Variation of Redlich-Peterson constants (aRP and kRP) in SSI was due to combined effects of CEC, acid oxalate extractable Fe (Feo) and OM while they did not show significant relationship with soil properties in SNI. It appeared that clay, CEC, OM and pH are the main factors regulating Ni retention in the soils studied while calcium carbonate equivalent does not significantly affect Ni retention. [ABSTRACT FROM AUTHOR]

The effects of soil salinity and water stress on Verticillium wilt, ion composition and growth of pistachio were studied in a greenhouse experiment (18–32°C). Treatments consisted of three levels of salinity (0, 1200 and 2400 mg NaCl/kg soil), three levels of water stress (3, 7 and 14 day irrigation regimes) and two Pistachio cultivars (Sarakhs and Qazvini, common rootstocks in Iran). Infested soil containing 50 microsclerotia/g of a pistachio isolate of Verticillium dahliae was used for all treatments and non-infested soils were used as control. The experiment was arranged in a completely randomized design with three replications. Eight-week-old pistachio seedlings were transferred to infested and non-infested soil and then exposed to salt stress and thereafter water stress. Shoot dry weights of both rootstocks were reduced significantly with increasing NaCl levels; however, increasing irrigation regimes reduced salt injury. Salt stress significantly increased shoot and root colonization by V. dahliae in both cultivars. Moreover, increasing of salinity level was positively correlated with increasing concentrations of Na+, K+ and Cl− in both cultivars, but negatively correlated with increasing irrigation regimes. Based on these results, Sarakhs and Qazvini were found to be sensitive and tolerant to the effect of irrigation regimes, salinity and Verticillium wilt disease, respectively. Although there were no interactive effects of irrigation and salinity on V. dahliae infection. [ABSTRACT FROM AUTHOR]

The effects of three sodium chloride (NaCl) levels (0, 1200, and 2400 mg kg- 1 soil) and three irrigation intervals (3, 7, and 14 d) on the growth and chemical composition of two Pistacia vera rootstocks ('Sarakhs' and 'Qazvini') were investigated under greenhouse conditions. Eight-week-old pistachio seedlings were gradually exposed to salt stress which afterward, water stress was initiated. At any irrigation interval, plant height and shoot and root dry weights of both rootstocks were reduced with increasing salinity. However, increasing irrigation intervals alleviated the adverse effects of soil salinity. A negative relationship observed between relative shoot growth and electrical conductivity of soil saturation extract (ECe) confirmed the above findings. Under 3-d irrigation interval, the ECe required to cause a 50% growth reduction was lower than those under 7- and/or 14-d irrigation intervals. Shoot and root chemical analyses indicated that the salinity as well as irrigation regime affected the concentration and distribution of sodium (Na+), potassium (K+), and chloride (Cl-) in pistachio. The concentration of Na+, K+ and C1- ions increased with a rise in NaCl level, and was generally declined with increasing irrigation interval. Based on plant height, shoot and root dry weights and the concentrations of Na+, K+, and C1- in the plant tissues, at lowest irrigation intervals 'Sarakhs' shows a higher sensitivity to soil salinity than 'Qazvini', but with increasing irrigation interval, 'Sarakhs' and 'Qazvini' can be classified as resistant and sensitive to salinity, respectively. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted in a greenhouse on a calcareous soil (fine, mixed, mesic, Fluventic Haploxerepts) to study the interaction of zinc (Zn) and boron (B) on the growth and nutrient concentration of corn (Zea mays L.). Treatments consisted of a factorial arrangement of seven levels of B (0, 2.5, 5, 10, 20, 40, and 80 mg kg- 1as boric acid), two sources of Zn [zinc sulfate (ZnSO4 · 7H2O) and zinc oxide (ZnO)], and three levels of Zn (0, 5, and 10 mg kg- 1) in a completely randomized design with three replications. Plants were grown for 70 d in 1.6 L plastic containers. Applied Zn significantly increased plant height and dry matter yield (DMY) of corn. Source of Zn did not significantly affect growth or nutrient concentration. High levels of B decreased plant height and DMY. There was a significant B × Zn interaction on plant growth and tissue nutrient concentration which were rate dependent. In general, the effect of B × Zn interaction was antagonistic on nutrient concentration and synergistic on growth. It is recommended that the plants be supplied with adequate Zn when corn is grown in high B soils, especially when availability of Zn is low. [ABSTRACT FROM AUTHOR]

The interaction between soil salinity and infection caused by Verticillium dahliae was studied in pistachio (Pistacia vera) in a greenhouse experiment. Treatments consisted of 0, 1400, 2800, and 4200 mg sodium chloride (NaCl) kg- 1 soil and three rootstocks (Sarakhs, Badami, and Qazvini cultivars). They were gradually exposed to salinity stress before and/or after root inoculation with a water suspension of 107 conidia/mL of a pistachio isolate of V. dahliae. Salt stress significantly increased rootstock shoot and root colonization by V. dahliae. All rootstocks were susceptible to V. dahliae, but symptoms of the disease appeared earlier in Sarakhs, a salt sensitive cultivar. Moreover, salinity and V. dahliae interaction increased the concentrations of sodium (Na), potassium (K) and chloride (Cl), but decreased the K/Na ratio in all rootstocks. Shoot and root tissues of inoculated Sarakhs and Qazvini (a salt tolerant) contained the highest and the lowest concentrations of Na, K,and Cl, respectively. In salinity treatments, shoot and root dry weight of all rootstocks decreased as compared with controls. Sarakhs showed smaller shoot and root dry weight than Qazvini and Badami. Also, increasing the NaCl level increased accumulation of Na, K, and Cl in shoot and root of the rootstocks. Sarakhs showed higher concentrations of ions in the shoot and root. Based on shoot and root dry weights and ion accumulation, Sarakhs and Qazvini were susceptible and tolerant to salinity, respectively. [ABSTRACT FROM AUTHOR]

Highly calcareous soils are abundant in Iran. The calcium carbonate equivalent (CCE) of these soils reach up to 650 g kg -1 . Although phosphorus (P) fertilizer is being widely used in these soils, little information, if any, is available about P status in such soils. The objectives of this study were to 1) determine inorganic P forms in 18 surface soils of southern Iran, 2) study P readsorption during different stages of fractionation schemes, 3) assess the ability of NaOH to extract aluminum (Al)‐P, and 4) evaluate the relationships between P availability indices and inorganic P forms. Eighteen soil samples with a wide range of physicochemical properties were selected for this study. Inorganic P forms was determined by sequential extraction with NaHCO 3 , NH 4 OAc, NH 4 F, NaOH, citrate dithionite (CD), and H 2 SO 4 , which are referred to as Ca 2 ‐P, Ca 8 ‐P, Al‐P, Fe‐P, occluded P (O‐P), and Ca 10 ‐P. Phosphorus readsorption in different stages was determined by 1 M MgCl 2 . Furthermore, a fractionation scheme without an NH 4 F step was used to evaluate the ability of NaOH to extract Al‐P. NaHCO 3 (Olsen‐P) and MgCl 2 ‐extractable P (Exch‐P) were regarded as P-availability indices. The abundance of different P forms was in the order Ca 2 ‐P [ABSTRACT FROM AUTHOR]

Desorption of copper (Cu) is an important factor in determining Cu availability in calcareous soils. Kinetics of native and added Cu desorption by DTPA (diethylene-tnaminepentaacetic-acid) from 15 highly calcareous soils of southern Iran were studied in a laboratory experiment. Our results showed that two constant-rate, Elovich, simple Elovich, and parabolic-diffusion equations were the best-fitted equations among eight kinetic models used. The copper desorption pattern based on the parabolic-diffusion equation revealed that the rate of native Cu desorption was higher in the first 2 h followed by a slower release rate, which suggests that two different mechanisms are involved. The trend may describe why the DTPA soil test has been considerably successful in predicting Cu availability in calcareous soils. Stepwise multiple regression equations indicated that CCE (calcium carbonate equivalent), CEC (cation exchange capacity), and clay content are the most important soil characteristics that predict the rate constants of the kinetic models. Mean extractant recovery percentage (ERP) of the soils was only 20%, which indicated that after 20 days, DTPA extracted only one-fifth of added Cu. Regression equations indicated that as soil OM (organic matter) content increased, the value of ERP decreased. From results reported herein it seems that CCE, CEC, and clay are the most important factors controlling Cu release from highly calcareous soils of southern Iran. However, the initial soil Cu desorption rate is probably controlled by CEC. [ABSTRACT FROM AUTHOR]

Despite the economic importance of pistachio ( Pistasia vera L.) crop, very little information is available on its water needs and nutrient requirements. Therefore, the effects of three irrigation frequencies (1, 3, and 7 d) and five potassium (K) levels (0, 75, 150, 225, and 300 mg kg - 1 ) on the plant water relations and growth of three pistachio cultivars (‘Badami,’ ‘Ghazvini,’ and ‘Sarakhs’) were studied in a greenhouse experiment. After 30 weeks, the dry weights of leaves, stems, and roots were measured and the total leaf area determined together with the number of leaves per pot and stem height. The effect of water frequency and K application on the leaf water potential, osmotic potential, and turgor potential was studied. Water frequency decreased all of the above growth parameters. Shoot dry weights were reduced by 50% and 68% for ‘Badami,’ 42% and 66% for ‘Ghazvini,’ and 26% and 46% for ‘Sarakhs’ at the three and seven-day irrigation intervals, respectively. Root dry weights were significantly reduced by 27% and 47% for ‘Badami,’ 18% and 48% for ‘Ghazvini,’ and 10% and 28% for ‘Sarakhs’ at the three and seven-day irrigation intervals, respectively. Leaf water potential, and turgor potential were unexpectedly increased by increase in water frequency. However, water frequency decreased leaf osmotic potential. The K application had no significant effect on the leaf water potential, osmotic potential, and turgor potential. It seems that NH 4 OAc-extractable K (70 mg kg - 1 ) was probably sufficient for optimum seedling growth of pistachio. Furthermore, ‘Sarakhs’ proved to be the cultivar most tolerant to drought stress in the present study. [ABSTRACT FROM AUTHOR]

Soil application of inorganic source of iron (Fe) is not effective in correction of Fe deficiency in calcareous soils. The chelate form of Fe is, therefore, used for that purpose. Application of Fe‐chelate, however, may reduce crop yields due to the reduction of some nutrients availability including manganese (Mn). A greenhouse experiment was conducted in a completely randomized design to study the effect of Fe and Mn on the dry matter yield (DMY), interaction of Fe‐Mn, and concentration and uptake of other nutrients in chickpea ( Cicer arietinum L. var. Pars). Treatments consisted of three Mn levels as Mn SO 4 ·4H 2 O and four Fe levels (Foliar and soil application of FeSO 4 ·7H 2 O and Fe‐EDDHA, respectively). Results showed that both foliar and soil application of Fe decreased mean shoot DMY, but Mn addition had no significant effect. Foliar application of Fe and addition of Mn increased mean shoot Fe concentration and uptake. Soil application of Fe and Mn increased mean shoot copper (Cu) concentration and uptake. Mean shoot zinc (Zn) concentration or uptake was not affected by Fe or Mn. These results showed that the suppressing effect of Fe on plant Mn concentration was not due to the reduction in root: shoot ratio, dilution effect, Fe toxicity or reduction in Mn uptake by root. Therefore, it may be concluded that the antagonistic effect of Fe on the translocation of Mn from root to shoot is the main reason for reduction in shoot Mn concentration in chickpea. [ABSTRACT FROM AUTHOR]

Most agricultural soils in Iran are usually low in organic matter (OM). Therefore, increasing OM in these soils is of great concern. Environmental pollution caused by chemical fertilizers has created an interest in the integrated use of organic wastes with inorganic fertilizers. The main purpose of this greenhouse study was to evaluate the impact of two organic wastes and phosphorus (P) on the growth, and elemental composition of spinach (Spinacia oleracea L.) and soil chemical properties. Treatments consisted of four levels of municipal waste compost, MWC (0, 1, 2, and 4%), five rates of poultry manure, PM (0, 1, 2, 3, and 4%), and three P levels (0, 25, and 50 mg kg−1 as KH2PO4). Application of P and MWC alone or in combination significantly increased the top dry weight of spinach. However, spinach growth was markedly increased up to 3% PM and suppressed with the higher rate, probably due to an excess of soluble salts in the soil. Moreover, the enhancing influence of P on spinach seedling growth was more pronounced at lower levels of MWC and PM. Plant P concentration tended to increase with increasing P, MWC, and PM application rates, whereas nitrogen (N) concentration was only affected by the two organic wastes treatment. Manganese (Mn) concentrations decreased, and copper (Cu), lead (Pb), and cadmium (Cd) increased by soil P application. However, P addition significantly decreased zinc (Zn) concentration only in MWC-treated spinach. Spinach plants enriched with either of the two biosolids accumulated more Mn, Zn, Pb, Cd, chloride (Cl), and sodium (Na) than control plants. Furthermore, spinach grown on MWC-amended soil contained higher Mn, Zn, Cu, and Pb and lower N, Cl, and Na than those raised on PM-treated soil. Postharvest soil sampling indicated that application of the two biosolids significantly increased concentration of soluble salts, (ECe), OM, TN, NaHCO3-extractable P, and DTPA-extractable iron (Fe), Mn, Zn, Cu, Pb, and Cd. [ABSTRACT FROM AUTHOR]

Cadmium (Cd) sorption by selected calcareous soils with a wide range of soil physical and chemical properties was investigated. Twogram samples of each soil were equilibrated for 24 h with 40mL 0.01M CaCl2 containing 5 to 500 mgCd L&sup-1;. The Cd sorption data well fits to Freundlich, two-surface Langmuir and Temkin adsorption isotherms. However, the fit to Langmuir adsorption model was closer than that of Freundlich or Temkin. The Freundlich coefficient (k) was significantly correlated with cation exchange capacity (CEC), calcium carbonate equivalent (CCE), and clay content (Clay). The slope in the first surface was greater than that of the second surface, indicating a higher rate of Cd sorption at low Cd equilibrium concentrations and a proportionally smaller increase in Cd retention at higher initial Cd solution concentrations. Stepwise regression analysis indicated that 67% of the variation in the adsorption maxima of the second surface (b2) was due to the combined effect of CEC and CCE. Temkin adsorption coefficients, namely k1 was significantly related to CEC and b2 was positively correlated with CEC, CCE, and clay content. [ABSTRACT FROM AUTHOR]

Mineral nutrition of wheat (Triticum aestivum L.) in highly calcareous soils low in available nitrogen (N) and manganese (Mn) requires further investigations. The purpose of this experiment was to determine the effect of N and Mn on the growth, nutrient concentration and uptake, and chlorophyll meter readings (CMR) in wheat grown in greenhouse conditions. The experiment was conducted on a highly calcareous soil (fine-loamy, carbonatic, thermic, Typic Calcixerepts) relatively low in available N and Mn. Treatments consisted of a factorial arrangement of five N rates (0, 50, 100, 200, and 400mg kg&sup-1; as NH4NO3) and three Mn levels (0, 15, and 30mg kg&sup-1; as MnSO4) in a completely randomized design with four replications. Plants were grown for 60 d and hand-held chlorophyll meter (Minolta SPAD-502) readings were used to evaluate dry matter (DMY) and N, Mn, iron (Fe), zinc (Zn), and copper (Cu) concentration of wheat in aerial parts. Applied N increased DMY and concentration and uptake of N, Mn, Fe, Zn, and Cu, and Mn:Fe ratios. A significant correlation was obtained between DMY and applied N (R2=0.75). Manganese had no significant effect on DMY, N, Zn, Cu concentration and uptake, and Fe uptake. However, Mn rate increased Mn concentration and uptake and Mn:Fe ratio and reduced Fe concentration. Interaction of N×Mn did not affect DMY, concentration, or uptake of any of the nutrients. The CMR increased significantly with N rate but was not influenced by Mn addition. Highly significant correlations were observed between CMR and DMY (R21/40.84), and the concentrations of N (R2=0.97), Mn (R2=0.70), Fe (R2=0.73), Zn (R2=0.93), and Cu (R2=0.90). It is concluded that portable chlorophyll meter is a quick, reliable, and nondestructive tool for assessing DMY and nutrients affecting leaf greenness in wheat. However, further investigation in field conditions is recommended. [ABSTRACT FROM AUTHOR]

Application of nitrogen (N) fertilizers without knowing the nitrogen supplying capacity (NSC) of soils may lead to low N use efficiency, uneconomical crop production, and pollution of environment. Twenty-five surface (0–20 cm) soil samples (pH 7.9–8.3; organic matter 7.8–35.0 g kg−1; calcium carbonate equivalent 253–648 g kg−1) from cultivated lands of Fars Province of Iran were used in laboratory and a 6-week greenhouse experiment to compare seven methods of estimating NSC of calcareous soils. The methods used were (i) determination of –N produced following the anaerobic incubation of soils; (ii) determination of –N extracted from soils by 2 M KCl; (iii) determination of –N extracted from soils by H2O; (iv), (v), (vi) measuring the amount of ultraviolet (UV) light absorption by soil extracts at 200, 205, and 260 nm; and (vii) determination of –N from the “second derivative” of light absorbance of soil extracts in the range of 200–280 nm. The soils, provided with sufficient nutrients other than N, were planted with corn (Zea mays L., cv Single Cross 704) and total N taken up by aerial parts of the plants was taken as the NSC of soils. Regression equations obtained between plant N uptake and each of the methods showed that absorbance at 205 nm was the best method, predicting 70.5% of the variabilities in NSC, when used alone. The “second derivative” method, when used along with organic matter and clay contents of the soils, predicted 84.2% of the variabilities in NSC. It is suggested that UV absorption methods be considered as a measure of NSC because they are more rapid, less laborious, and consume less chemicals than biological and conventional chemical methods. [ABSTRACT FROM AUTHOR]

Phosphorus (P) soil test methods have had limited success in prediction of lowland rice (Oryza Sativa L.) response to P fertilization. Therefore, the relative efficiency of Olsen, Colwell, Bray1, Soltanpour, Mehlich 3, Morgan, Sr-citrate, and Resin to predict P availability in waterlogged soils was evaluated by incubating 23 calcareous soils under oxidized and reduced soil conditions and P response of rice was assessed in a greenhouse experiment. Anion exchange resin extracted the highest amounts of P from both waterlogged and air-dried soils followed by Colwell, Morgan, Olsen, Sr-citrate, Mehlich 3, Soltanpour, and Bray 1. Reducing soil conditions increased the amount of P extracted by all soil test methods. The highest correlation coefficient was observed between Olsen and Colwell extractable P under both oxidized and reduced soil conditions. Olsen method gave the best correlation coefficients with rice growth parameters (dry matter yield and P uptake), followed by Colwell and Soltanpour under aerobic and Soltanpour under anaerobic conditions. Furthermore, the relationship between top dry weight and/or P uptake and P extracted by Olsen, Colwell, Soltanpour, Sr-citrate, and Resin were improved when organic matter (OM), pH, clay content (Clay), electrical conductivity (EC[SUBe]), and calcium carbonate equivalent (CCE) were included in the multiple-regression equations. The results reported in the present study suggest that Olsen test method appears to be a more appropriate extractant for predicting P availability for rice under oxidized and reduced soil conditions. The relatively high variability in physical and chemical characteristics of the calcareous soils of southern Iran, due to variations in topography and geology justify more correlation and field calibration studies to improve P availability evaluation. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency is common in calcareous soils. Application of FeEDDHA is effective in correction of Fe deficiency in such soils. However, it may decrease concentration and uptake of some micronutrients including manganese (Mn). The effect of Fe on Mn status of different soybean [Glycin max (L.) Merr.] genotypes was studied in a greenhouse experiment in a completely randomized design with three replicates. The treatments consisted of three Fe levels (0, 2.5, and 5 mg Fe kg−1 as FeEDDHA) and 12 soybean genotypes. Results showed that application of Fe increased top dry weight of Wells, Black hack, Elgin, and A3237, but decreased that of Steel and A3935 and had no effect on other genotypes. Addition of Fe increased concentration and uptake of Fe, but decreased that of Mn in all genotypes. The Fe:Mn ratio greater than 0.4 in plant tops when both Fe and Mn were in the nutrient sufficiency range were considered to be an indication of tolerance to Fe deficiency, as these genotypes did not respond to Fe fertilizer. Regression equations showed that the highest reduction of Mn concentration occurred at 2.5 mg Fe kg−1. Manganese concentration was reduced by 13, 17, and 19% due to the dilution effect only in Black hack, A3237, and Elgin, respectively. Iron application did not cause either Fe toxicity in soybean or suppression in root:shoot ratio. It seems that Fe addition reduced Mn concentration in some soybean genotypes probably either by reduction of Mn concentration and/or translocation of Mn from root to shoot. The fact that soybeans are highly sensitive to Fe and Mn deficiencies and use of expensive FeEDDHA might accentuate Mn deficiency or imbalance in soybeans demonstrates a need to screen out and select soybean genotypes resistant to Fe stress. [ABSTRACT FROM AUTHOR]

Zinc (Zn) deficiency has been observed in lowland rice (Oryza sativa L.) in Iran. Relatively high pH and abundant calcium carbonate of soils are responsible for Zn deficiency in the plant. However, the Zn status in paddy soils of Iran has not been reported. Therefore, available Zn in 20 highly calcareous soils with a wide range of chemical properties was evaluated with DTPA-CaCl2, EDTA-(NH4)2CO3, DTPA-NH4HCO3, EDTA, and Mehlich 3, using rice as a test crop. The results showed that extraction of Zn decreased in the order: Mehlich 3, EDTA, DTPA-NH4HCO3, EDTA-(NH4)2CO3, DTPA-CaCl2. A significant positive correlation was found between Zn extracted by all chemical extractants with the exception of EDTA. The highest correlation was observed between DTPA-CaCl2 and EDTA-(NH4)2CO3 extractable Zn. Application of Zn significantly increased mean top dry weight, Zn concentration, and Zn uptake by rice. Apparent Zn recovery of applied Zn was quite low in all soils, probably due to conversion of Zn to unavailable forms. The critical level of soil available Zn with DTPA-CaCl2, EDTA-(NH4)2CO3, DTPA-NH4HCO3, EDTA, and Mehlich 3 was 0.30, 0.70, 0.76, 2.2 and 2.5 mg kg-1, respectively. Plant dry matter and Zn uptake were significantly correlated with DTPA-CaCl2, EDTA-(NH4)2, DTPA-NH4HCO3 and Mehlich 3 extractable Zn. However, Zn extracted by EDTA-(NH4)2CO3 and DTPA-CaCl2 best explained the variation in plant dry matter, whereas DTPA-NH4HCO3 extractable Zn was more appropriate to predict the variation in Zn uptake by rice. Moreover, inclusion of pH and ECe in a multiple regression equation led to the best prediction of top dry weight and Zn uptake by the EDTA-(NH4)2CO3 soil test. It seems that EDTA-(NH4)2CO3 is the most suitable chemical extractant to differentiate the Zn responsive paddy soils from nonresponsive ones in view of its high statistical relationship with the rice growth parameters. [ABSTRACT FROM AUTHOR]

Documented plant responses to copper (Cu) are rare and consequently Cu soil tests have not received much individual effort. However, soil extraction techniques to measure the status of available Cu for plants are important in the diagnosis of deficiency or toxicity. In the present study, DTPA-CaCl2, EDTA-NH4OAc, EDTA-(NH4)2CO3, DTPA-NH4HCO3, and EDTA were evaluated for their relative efficiency to extract Cu from 26 soil series with a wide range of chemical properties. Wheat (Triticum aestivum L.) was used as a test crop. The results showed that Cu extractability decreased in the order: EDTA-(NH4)2CO3, DTPA-NH4HCO3, EDTA, EDTA-NH4OAc, and DTPA-CaCl2. Significant positive correlations were found between extractable Cu among the five extractions. Stepwise multiple regression equations showed that organic matter (OM) and clay content followed by cation exchange capacity (CEC) and calcium carbonate equivalent (CCE) were the most influential soil characteristics affecting extractable Cu. Mean top dry weight, Cu concentration and Cu uptake were significantly higher in Cu-treated plants than those in untreated plants. Significant correlations were found between Cu extracted with DTPA-CaCl2 and EDTA-(NH4)2CO3 and Cu uptake by wheat. However, the two extractants were not adequately efficient to predict Cu uptake with each accounting for only about 30% of the variation. Among soil properties tested, clay, pH, OM, and CCE correlated negatively and CEC positively with wheat top dry weight, whereas, pH, CEC, and CCE related positively and clay, and OM negatively with Cu uptake. In conclusion, it appears that none of the five test procedures in view of their relatively low coefficient of determinations with plant response proved to be a promising extractant for the determination of available Cu in the soils tested. [ABSTRACT FROM AUTHOR]

The Langmuir, Freundlich, and Temkin isotherms were fitted to copper (Cu) adsorption data of 20 highly calcareous soils of Fars Province, ranging widely in relevant physical and chemical characteristics. One-gram samples of each soil were equilibrated for 24h with 30mL of 0.01M CaC1[sub 2] containing 50 to 500 mg Cu L[sup -1]. The amount of Cu retained by soil solids was calculated based on the difference between the initial and equilibrium Cu concentrations. The Cu adsorption data showed a highly significant fit to the Freundlich, Temkin, and linear form of Langmuir adsorption isotherms. The fit to Langmuir and Temkin equations were, however, closer than that of Freundlich. Adsorption maxima (b) calculated from Langmuir isotherm was positively correlated with clay, cation exchange capacity (CEC), and calcium carbonate equivalent (CCE), whereas, Langmuir bonding energy coefficient (K) was related only to clay. Organic matter (OM), clay, and CEC were found to have a significant relationship with Freundlich coefficients (n and k). Temkin coefficients (k[sub 1] and k[sub 2]) were positively correlated to CEC and clay. The distribution coefficient (i.e., maximum buffering capacity) was also highly significantly correlated with CEC and clay. It is concluded that the sites of Cu retention in the calcareous soils are clay, OM, and calcium carbonate. [ABSTRACT FROM AUTHOR]

Water‐soluble zinc (Zn) fertilizers are rapidly converted to insoluble forms in calcareous soils resulting in lower efficiency of such fertilizers. A knowledge of distribution of native and applied Zn in such soils is necessary for understanding the fate of applied Zn fertilizers and finding ways to increase their efficiency. This experiment was conducted to obtain such information in selected highly calcareous soils of Iran. A sequential extraction method was used to fractionate the Zn forms of surface horizons (0–20 cm) of 20 highly calcareous soils [16 to 58% calcium carbonate (CaCO3) equivalent; pH 7.9 to 8.5] which had previously received 0, 10, or 20 mg Zn/kg as zinc sulfate (ZnSO4) and had been under one corn (Zea mays L.) crop in the greenhouse. The forms determined were exchangeable (EXZN), sorbed (SRZN), organic (ORZN), carbonate (CRZN), residual (RSZN), and sum of forms (SMZN). The native SMZN ranged from 32.4 to 66.7 mg/kg with a mean of 49.9 mg/kg. Application of 10 and 20 mg Zn/kg as ZnSO4 increased the mean to 57.7 and 62.7 mg/kg, respectively. Concentration of different forms of Zn in the soils was determined to be in the following order: RSZN >>> CRZN > SRZN > EXZN > ORZN. The concentration of native EXZN+SRZN+ORZN forms constituted less than 5% of SMZN, while concentration of CRZN alone ranged from 4.37 to 16.05% with a mean of 8.36%. Application of ZnSO4, while significantly increased the concentration of all forms of Zn, had a pronounced effect on CRZN. Averaged over all soils, 58 and 60% of the applied ZnSO4 was converted to CRZN for the 10 and 20 mg Zn/kg, respectively. Regression equations relating different Zn forms to soil physical and chemical properties indicated that the Zn forms are significantly influenced by soil properties. It was concluded that conversion of applied ZnSO4 to CRZN was mainly responsible for retention of this fertilizer in highly calcareous soils, making it temporarily unavailable to plants, and therefore decreasing its apparent recovery by the first crop. [ABSTRACT FROM PUBLISHER]

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Spatial patterns for several soil parameters such soil texture, Exchangeable Sodium Percentage (ESP), Electrical Conductivity (ECe), soil pH, Cation Exchange Capacity (CEC) were examined in saline and sodic soils in Arsanjan plain, Southern Iran, in order to identify their spatial distribution for implementation of a site-specific management. Soil samples were collected from 0-30, 30-60 and 60-90 cm soil depths at 85 sampling sites. Data were analyzed both statistically and geostatistically on the basis of the semivariogram. The spatial distribution model and spatial dependence level varied between soil parameters. Soil pH and ESP had the minimum and maximum variability at all depths, respectively. Soil properties indicated moderate to strong spatial dependence. ECe exhibited moderate spatial dependence at three depths; pH and ESP had a moderate spatial dependence at 0-30 cm and strong spatial dependence at 30-60 and 60-90 cm depths. Clay and CEC exhibited strong spatial dependence for the 0-30 cm and weak spatial dependence at 30-60 and 60-90 cm depths. Sand and silt had a non-spatial dependence at 0-30 cm and weak spatial dependency at 30-60 and 60-90 cm depths. The spatial variability in small distances of ECe, CEC, pH and ESP generally increased with depth. All geostatistical range values were greater than 1168 m. The results reported herein indicated that the strong spatial dependency of soil properties would lead to the extrinsic factors such as ground water level and drainage. It is important to know the spatial dependence of soil parameters, as management parameters with strong spatial dependence will be more readily managed and an accurate site-specific scheme for precision farming more easily developed.

The binding of [125I]-recombinant basic FGF (rec bFGF) to rat hepatic plasma membranes was investigated. [125I] rec bFGF bound to an apparent single class of high affinity binding sites (KD = 69 pM; Bmax = 9.61 fmoles/mg proteins). The absence of low affinity sites was confirmed by the inability of sulphated polysaccharides and heparinase to interfere with FGF binding. A good correlation existed between the ability of bovine pituitary-derived bFGF, rec bFGF and bovine brain-derived aFGF to displace [125I]rec bFGF from these binding sites and their in vitro potency on bovine aortic endothelial cell proliferation.