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Application of appropriate organic amendments as the carriers of bacterial consortium may improve the remediation efficiency of HMs-polluted soil. A greenhouse experiment was designed and carried out to investigate the capability of biochar, and activated carbon prepared from ostrich manure and almond husk as the carriers of bacterial inoculants in the phytoremediation of a calcareous soil polluted with Pb, Ni, Cd and Zn by maize. Results showed that the application of biochar and activated carbon prepared from ostrich manure increased root (78–129%) and shoot (72.3–272%) dry weight, as compared to the control. The values of metal accumulation in both maize root and shoot were in the order of Cd>Zn>Ni>Pb. While biochar and activated carbon prepared from ostrich manure significantly increased both root and shoot metals uptake, those prepared from almond husk drastically decreased the uptake of some metals. The foremost mechanism involved in the phytoremediation of Cd, Ni and Pb was phytostabilization while that of Zn was due to the phytoextraction. Results of the present study demonstrated the effectiveness of ostrich manure-derived biochar and activated carbon as an efficient treatment in the phytoremediation of multi-metal-polluted soils and the mitigation of HMs phytotoxicity. [ABSTRACT FROM AUTHOR]

Purpose: The cation exchange capacity (CEC) is a pivotal soil attribute that influences soil chemistry, fertility, and productivity. Nevertheless, the conventional techniques employed for CEC measurements present challenges in terms of complexity, cost, and laboriousness. Hence, there is a demand for expedited, cost-effective, streamlined alternative methodologies that can yield accurate outcomes. The objective of this study was to employ and compare various techniques, including Pedotransfer Functions (PTFs) based on fundamental soil properties, support vector regression (SVR), sequential orthogonalized partial least squares (SOPLS) as a multiblock data analysis method, and Spectrotransfer Function (SPTF) utilizing visible-near infrared (VNIR) and mid infrared (MIR) diagnostic wavelengths to estimate the CEC of calcareous soils with diverse land uses in the semi-arid region of Fars province, Iran. Materials and methods: A total of 130 samples were gathered from the soils of the study region, CEC was measured using sodium acetate, and the spectral reflectance in the VNIR and transmission in the MIR regions were measured, and prediction models were created using linear support vector regression (L-SVR), radial basis function support vector regression (RBF-SVR), partial least squares regression (PLSR), and multiblock data analysis algorithms, after different spectral preprocessing methods. Results and discussion: The results generally indicated that spectroscopy models performed better than PTFs in predicting CEC with the multiblock SOPLS showing the best results (R2 = 0.92, RMSE = 1.67 cmol(+) kg−1, and RPIQ = 4.34). The performance of the models followed the order: SOPLS > SPTF > L-SVR > RBF-SVR. Conclusion: Our findings indicate that spectroscopy coupled with SOPLS analysis can be a robust, viable, fast, cheap, and efficient alternative assessment method with acceptable accuracy for estimating soil CEC in calcareous soils, instead of the difficult, costly, and cumbersome conventional measurement approaches or other estimation methods. [ABSTRACT FROM AUTHOR]

Plants develop several external and internal mechanisms to increase their tolerance to heavy metals (HMs) toxicity including cadmium (Cd). Symbiosis with arbuscular mycorrhizae fungi (AMF) is one of the plants' strategies to tolerate HMs toxicity. Nitric oxide (NO), as a signaling molecule, is also involved in physiological responses of plants to various stresses. The present work was conducted as a factorial completely randomized design with three replications to study the effects of Funneliformis mosseae fungi and Sodium nitroprusside (SNP, 100 mM) as a donor of NO alone, in combination (AMF + SNP) on corn plant growth, and internal detoxification mechanisms of Cd toxicity in a Cd-contaminated calcareous soil (0, 25, 50, and 100 mg Cd kg−1). The results showed that under Cd stress, AMF inoculation and/or foliar application of SNP significantly increased plant growth (32% to 103% for shoot and 44% to 84% for root) by decreasing Cd concentration in corn plant tissues (23% to 46% for shoot and 19% to 40% for root). Cd-induced oxidative stress was mitigated by AMF and/or SNP by enhancing the activities of antioxidant enzymes, including superoxide dismutase (SOD) and catalase (CAT), and concentration of non-enzymatic antioxidants such as glutathione (GSH) and phytochelatin (PC). Increasing the tolerance index (TI) and decreasing the transfer factor (TF) in the corn plants treated with AMF and/or SNP, confirm the efficient role of SNP and AMF in stimulating the detoxification mechanisms of Cd within the plant cells, which was more pronounced at the lowest Cd level (25 mg Cd kg−1). In conclusion, symbiotic associations of corn plants with AMF alone or in combination with SNP mitigated the detrimental effect of Cd toxicity in corn grown in Cd-contaminated calcareous soil. The corn's internal detoxification mechanisms lowered the Cd concentration in plant tissue which resulted in the improvement of the corn's growth parameters. [ABSTRACT FROM AUTHOR]

Irrigation of plants by contaminated water with metals is very common in countries facing freshwater scarcity. To enhance plant growth via improved absorption of essential metals including Zn from wastewater the magnetization of water as a modern approach, can be used. With the aim of investigating the effects of brown coal application and magnetizing contaminated water on the absorption of Zn and the yield of maize, a greenhouse experiment was conducted. The experiment was factorial arranged in a completely randomized design with four levels of brown coal (0, 1, 2, and 4% w/w), and 5 types of irrigation water (distilled water, water contaminated with Cu-sulfate, water contaminated with Cu-nitrate, magnetized water contaminated with Cu-sulfate, and magnetized water contaminated with Cu-nitrate). Maize was irrigated according to the treatments of irrigation types, so that the total concentration of Zn added to the pots receiving Zn-contaminated water reached 1200 mg kg−1 at the end of experiment. Results showed that plants irrigated with Zn contaminated water significantly increased shoot dry matter yield, as compared to that of control treatment, due to high buffering capacity of the studied calcareous soil for stabilization of Zn. Magnetized water significantly increased mean shoot and root Zn uptake, uptake efficiency, phytoextraction efficiency, translocation factor, and translocation efficiency. Due to the improvement of Zn uptake by maize following the use of magnetized water, it is tentatively concluded that magnetization of waters with high level of Zn may be used for correcting Zn deficiency in calcareous soils. [ABSTRACT FROM AUTHOR]

Immobilisation is an effective technique in the remediation of heavy metals polluted soils. A laboratory experiment was conducted to clarify the kinetics of Zn and Cd release using citric, oxalic, acetic and tartaric acids and to evaluate the effectiveness of fish scale powder (FSP), chitin (CTN) and chitosan (CTS) in the immobilisation of these metals in a calcareous soil exposed to high levels of Zn and Cd. Characterisation of Fourier-transform infrared spectroscopy (FTIR) revealed the presence of amines, amides, alkenes and phosphate esters in fish scale and its derivatives. Citric acid released Zn and Cd much higher than tartaric, acetic and oxalic acids. Addition of fish scales derivatives drastically decreased the cumulative release of Zn and Cd in the order of CTS> CTN> FSP. Zn release data well fitted to pseudo-second-order model only in the presence of citric and tartaric acid and to Elovich model in the presence of acetic and oxalic acids. Cd release data were mostly fitted to pseudo-second-order model followed by Elovich model. Results of the present study demonstrate the high capability of citric acid in releasing metals, and high effectiveness of fish scales derivatives especially chitosan in immobilising Cd and Zn in polluted soils. [ABSTRACT FROM AUTHOR]

Immobilisation is among efficient strategies in the remediation of heavy metals, including chromium (Cr)-polluted soils. A greenhouse trial was conducted to investigate the effectiveness of chitosan- and hematite-modified biochar and bacterial inoculations on the immobilisation of Cr in polluted soil under maize cultivation. Application of modified biochars and inoculation with Pseudomonas putida significantly increased both maize root and shoot dry matter yields but decreased Cr phytoextraction efficiency. Root and shoot concentration and uptake as well as mean translocation factor of Cr drastically decreased following the application of unmodified or modified biochars. Bacterial inoculation significantly decreased mean translocation factor and also root and shoot concentration and shoot uptake of Cr. Chitosan-modified biochar was the most influential treatment in decreasing Cr uptake by maize followed by pseudomonas putida inoculation treatment. Results reported herein demonstrated satisfied impacts of chitosan-modified biochar and inoculation with pseudomonas putida in increasing dry matter yield and decreasing Cr uptake in maize grown on Cr-polluted soil. According to the results of present study, modified biochars application and bacterial inoculation are influential treatments which prevent Cr toxicity probably through the transformation of mobile and mobilisable Cr forms to unavailable form in soil. [ABSTRACT FROM AUTHOR]

Modification of biochar using chitosan and hematite made the biochar product more effective for hexavalent chromium (Cr (VI)) reduction in contaminated soils. Release experiment was conducted to examine Cr (VI) reduction in different treatments (control, unmodified biochar and two modified biochars with chitosan or hematite). The results indicated that the application of all treatments significantly decreased the release rate of Cr in comparison to the control treatment. Chitosan-modified biochar application increased Cr (VI) reduction from 28.53% (biochar) to 46.23%. In the case of hematite-modified biochar, it increased Cr (VI) reduction from 28.55% (biochar) to 38.95%. Two kinetic equations including pseudo-first-order and pseudo-second-order models employed to describe the time-dependent Cr release data. Between the kinetic equations estimated, the pseudo-second order best fitted to experimental data. In the presence of Pseudomonas putida, cumulative Cr release rate decreased by 2.38 mg kg−1 (50.29%) in hematite–biochar and 1.768 mg kg−1 (39.73%) in unmodified biochar as compared with control (4.43 mg kg−1). According to results reported herein, modification of biochar with chitosan or hematite is promising since made biochar more effective in removing Cr from Cr-polluted calcareous soils. [ABSTRACT FROM AUTHOR]

Iron (Fe) deficiency is common when grain crops are grown in calcareous soils. The study was conducted to determine if the DTPA-extractable Fe concentration and Fe uptake of sorghum and corn were greater when Fe fertilizers were co-applied with sugar processing residuals than without residuals. The glasshouse pot experiment was a 3 × 3 × 3 complete factorial with three Fe fertilizer sources (none, 5 mg Fe kg−1 of FeSO4, 5 mg Fe kg−1 of Fe-EDDHA (Fe-ethylene diamine-N,N'-bis (2-hydroxyphenylacetic acid)) combined with three residuals (filtercake, bagasse and sugar beet) that were applied at rates of 0, 1.5 and 3% (w/w) and cropped continuously with sorghum-sorghum-corn. Cumulative shoot Fe uptake was greater in pots amended with filtercake and sugar beet than bagasse. Application of 3% bagasse reduced the cumulative shoot Fe uptake by 36%, compared to the unamended control (P <.05). Application of Fe-EDDHA or FeSO4 increased cumulative shoot Fe uptake by 9%, compared to the unfertilized control. The DTPA-extractable Fe concentrations were consistently higher in soil amended with filtercake and Fe-EDDHA, and declined with time. Since co-application of Fe fertilizer and residuals did not increase Fe uptake, this practice is not expected to improve Fe availability in calcareous soils. Filtercake and sugar beet residuals are alternative Fe sources for grain crops in calcareous soils. [ABSTRACT FROM AUTHOR]

In order to study the effect of water deficit stress (WDS), plant growth promoting rhizobacteria (PGPR)-enriched and non-enriched vermicompost tea(VT) and vermiwash(V) on the growth and nutrients uptakes of maize, a greenhouse experiment was conducted. The two-factor experiment was set up in a completely randomized design with three replications. The factors included: 1) liquid organic fertilizers (LOFs) with five levels (control, VT, V, vermicompost tea enriched with bacterium (VTB) and vermiwash enriched with bacterium (VB)) and 2) WDS with three levels (Field Capacity (FC), 80% FC and 60% FC(. At each irrigation interval, the volume of the used LOFs was equivalent to 60% of the volume of water required for 60% FC. At 60% FC, shoot dry matter (SDW), shoot N, P, Zn, Cu, and Fe uptake significantly decreased compared with those of FC and 80% FC, whereas shoot K uptake significantly increased. At all WDS levels, application of LOFs led to increase in SDW and shoot nutrients uptake. The highest amount of studied traits was obtained in VTB and VT treatments. Generally, VT treatments were more effective than V. Furthermore, PGPR-enriched LOFs were more effective than non-enriched ones. Application of LOFs may be considered as a practical approach for amplifying drought tolerance and reducing the risk of water scarcity in maize cultivation. [ABSTRACT FROM AUTHOR]

Phytoremediation is an appropriate technology used to remove pollutants from environment components. A greenhouse trial was conducted to test the hypothesis that application of surfactant levels and inoculation with Pseudomonas fluorescens bacterium and/or Piriformospora indica fungus enhances the phytoremediation of cadmium (Cd). Maize seeds were sown in Cd-polluted soil, and after 2 months Cd status in plant tissues and Cd phytoremediation criteria was determined. Results showed that application of surfactant increased root and shoot dry weight. Mean Cd uptake in roots and shoots increased following the application of 2 and 4 mmol kg−1 Tween 80, respectively. Application of 2 mmol kg−1 Tween 80 increased mean Cd uptake efficiency, while application of 4 mmol kg−1 Tween 80 increased phytoextraction and translocation efficiencies. Inoculation with P. indica and P. fluorescens was mostly effective in increasing Cd uptake and Cd phytoextraction efficiency, respectively. Co-inoculation with P. indica and P. fluorescens had no superiority to application of each inoculant alone. Since most of the Cd remained in roots, phytostabilization is probably the main mechanism controlling Cd phytoremediation by maize. According to the results, application of Tween 80 and inoculation with P. indica and P. fluorescens effectively enhanced phytoremediation of Cd-contaminated soil by maize. [ABSTRACT FROM AUTHOR]

A 12-week incubation experiment was conducted to determine the pattern and rate of N mineralized from organic materials. Treatments consisted of sheep manure (SM), cattle manure (CM), poultry manure (PM), sewage sludge (SS) at 1% (W/W) level, and unfertilized treatment with three replications. The concentrations of nitrate (NO3)- nitrogen (N) and ammonium (NH4)-N were determined in day 1 and 1, 2, 4, 8, and 12 weeks after the beginning of incubation. Results indicated that the magnitude of N mineralized during the incubation time periods was in the order of CM (134 mg kg−1) > PM (83 mg kg−1) > SS (56 mg kg−1) > SM (55 mg kg−1), and different management is required for obtaining optimum N-use efficiency. In conclusion, improving N-uptake efficiency in manure- and SS-amended soils depends on the pattern and rate of N mineralization to synchronize N released with crop N demand periods. [ABSTRACT FROM AUTHOR]

Zinc (Zn) is an essential micronutrient for crop growth. This metal can be found in chemical forms or fractions in the soil. The objective of this study was to investigate the distribution of Zn in special chemical forms using the sequential extraction method after treating eight calcareous soils by zinc sulfate and municipal solid waste (MSW) compost. Zn was separated in seven defined forms as exchangeable (Ex), carbonate (Car), organic (Om), manganese oxide bound (MnOX), amorphous iron oxide bound (FeAOX), crystalline iron oxide bound (FeCOX), and residual (Res). According to the results, the mean concentrations of Zn in chemical forms in untreated soils from higher to lower were 31.84, 8.13, 2.64, 2.57, 0.45, 0.39, and 0.16 mg kg−1for the Res, FeCOX, Car, FeAOX, Om, MnOX, and Ex forms, respectively. The total applied Zn to the studied soils from both the sources of zinc sulfate and MSW compost after incubation for 30 days was converted to chemical forms in the following order: Car > Res > FeCOX > Om > FeAOX > MnOX > Ex. On average, 30.3% of total Zn from zinc sulfate and 28.8% of total Zn in the MSW compost were converted into the Car form. The high content of calcium carbonate (CaCO3) in the studied soils is an important factor affecting the conversion of Zn forms, mostly in the Car form through the application of both the inorganic and the organic sources of Zn. [ABSTRACT FROM AUTHOR]

Phytoremediation is a cleanup technology for the removal of contaminants from polluted soils. The influences of humic acid (HA) and four plant growth regulators, i.e. gibberellic acid, salicylic acid, 3-indoleacetic acid, and 6-benzylaminopurine on the phytoremediation of Pb by maize were investigated in a pot trial on a Pb-contaminated soil. Foliar spray of 6-benzylaminopurine and salicylic acid significantly increased mean root dry matter but none of growth regulators had a significant effect on that of shoot. Addition of HA decreased root dry matter and had no significant effect on that of shoots. Application of all growth regulators except gibberellic acid significantly increased root Pb uptake. Application of salicylic acid significantly increased mean uptake efficiency and shoot Pb concentration and uptake. Although addition of HA significantly increased mean phytoextraction and translocation efficiencies, these responses were mainly attributed to the role of HA in the reduction of both root dry weight and Pb uptake, meaning that HA is not promising in Pb phytoremediation by maize. Among the four plant growth regulators evaluated, salicylic acid was the most effective in enhancing phytoremediation through phytostabilization of Pb. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effects of poultry manure (PM) and its derived biochars on chemical properties of a calcareous soil. PM and biochars prepared at 200°C (B200), 300°C (B300) and 400°C (B400) were applied to a calcareous soil at 2% level (w/w) and incubated for 150 days. Selected soil chemical properties and phosphorous, potassium, iron, manganese, zinc and copper availability and recovery were determined at 1, 15, 45 and 150 days of incubation. Soil nutrients availability, organic carbon (OC), electrical conductivity (EC) and cation exchange capacity (CEC) increased by addition of all organic substances. Biochars prepared at higher temperatures were more effective in increasing soil OC with higher durability compared to other treatments. The addition of PM and B200 decreased soil pH, whereas B400 increased it. Although the highest soil EC was observed in B300- and B400-treated samples in the early stages of incubation, the rate of increase in soil EC was higher for PM- and B200-treated soils compared to other treatments. It was concluded that biochar prepared at 300°C had the highest positive effect on nutrients availability and lasts longer in calcareous soil compared to the other produced biochars and PM. [ABSTRACT FROM PUBLISHER]

The effect of different kinds of amendments including coal fly ash (CFA), municipal solid waste compost (MSWC), rice husk biochars prepared at 300°C (B300) and 600°C (B600), zero valent iron (Fe°) and zero valent manganese (Mn°) were evaluated to determine their ability to stabilize lead (Pb) in Pb-spiked soil. The Pb-spiked soils were separately incubated with amendments at the rates of 2 and 5% (W/W) for 45 and 90 days at 25°C. The efficacy of amendments treatment was evaluated by desorption kinetic experiment and sequential extraction producer. According to the results, with increasing time, considerable changes in distribution of chemical forms of Pb occurred and carbonate-bound fraction significantly decreased, while amorphous Fe-bound fraction significantly increased. The applied treatments efficiently decreased the mobility factor of Pb compared to control treatment. Application of Mn°, Fe°, CFA, MSWC, and B600 in soils significantly decreased Pb desorption rate with respect to control treatment. Biphasic pattern of Pb desorption kinetic was fitted well by the model of two first-order reactions. In general, present study showed that from the practical point of view, all applied amendments (except for B300) were effective in Pb immobilization; however, application of Mn° at 5% (W/W) rate was the best treatment to immobilize Pb, so it can be recommended for the immobilization of Pb in calcareous polluted soil. [ABSTRACT FROM PUBLISHER]

Lead (Pb) contamination of soils is a widespread problem. Mycorrhizal inoculation and synthetic chelators such as ethylenediaminetetraacetic acid (EDTA) may be useful for improving phytoremediation efficiency in Pb-contaminated soils. A greenhouse experiment was performed to study the influence of inoculation with arbuscular mycorrhizal fungus (AMF),Glomus mosseae, and addition of EDTA on phytoremediation of Pb by sunflowers (Helianthus annuus) in a calcareous soil. The experiment was a completely randomized design in a factorial arrangement with five levels of Pb, two levels of mycorrhizal treatments, and two levels of EDTA. Inoculation increased root colonization as Pb levels increased, but the addition of EDTA decreased it. Shoot and root dry matter yields increased by inoculation; however, they decreased with EDTA and Pb levels in co-application treatments. Pb concentration in shoots was significantly higher than that in roots, indicating a translocation factor greater than 1. Inoculation or addition of EDTA significantly increased Pb in roots and its translocation to shoots. The uptake index (UI) value increased in co-application of EDTA and AMF and the individual application of them; it is, therefore, concluded that both AMF and EDTA are effective in phytoremediation of Pb by sunflowers in the studied soil. [ABSTRACT FROM PUBLISHER]

A laboratory study was performed to investigate the influence of soil texture (sandy loam vs. clay loam), Pb supply (as Pb(NO3)2without or with compost) and Pb levels on the extraction of available Pb by diethylene triamine pentaacetic acid (DTPA) and its desorption patterns at ten shaking periods. The soils were polluted with five Pb levels without or with compost and incubated for 1 month. Kinetic models commonly used to study the release of the nutrients were used in this study. Results showed that Power function model described the pattern of Pb desorption better than other models. The amount of extracted Pb increased as the Pb levels increased and was found to be higher in sandy loam soil treated with Pb without compost than that of clay loam soil treated with Pb with compost. Theavalue (Pb desorption constant) was the highest in sandy loam soil amended with Pb without compost. The lowest value ofa, however, was observed in clay loam soil amended with Pb with compost. Theabcoefficient (initial desorption rate of Pb) was higher in sandy loam than clay loam soil, demonstrating higher initial release rates of Pb in the coarser-textured soil. Addition of Pb without compost resulted in a higher increase inabvalue in comparison with Pb with compost, in both the soils. [ABSTRACT FROM AUTHOR]

Maize yield is mainly controlled by nitrogen (N) fertilizers. Failure to predict economic optimum N rate causes over-fertilization of N through traditional application methods. Five field trials were conducted to study soil-crop N relationships in maize under field conditions. Optimum level of N application in this study was much lower than conventional N fertilization in calcareous soils of southern Iran, demonstrating over-fertilization of N fertilizers by farmers. Linear regression equations were found between total nitrogen (TN) and chlorophyll meter readings (CMR) (years 2001 and 2002) in both locations demonstrating that chlorophyll meter might be used in predicting TN in maize shoot. Results indicated that soil sampling location influenced on soil NO3-N concentration at 4–6 leaf stage. In conclusion, N use efficiency can be improved by in-season soil NO3-N testing. It appears that in Kooshkak and Bajgah experimental stations, soil samples for NO3-N testing should be collected from shoulder and bottom of furrows, respectively. [ABSTRACT FROM AUTHOR]

The objective of the investigation was to evaluate the effect of applied phosphorus (P) and cadmium (Cd) on Cd chemical forms determined by sequential extraction and the relationship between these forms and plant responses, i.e., dry weights, concentration, and total uptake of Cd and P in a greenhouse experiment. Treatments consisted of five levels of Cd (5, 10, 20, 40 and 80 mg kg−1 soil as cadmium sulfate) and four levels of P (0, 15, 30 and 60 mg kg−1 soil as monocalcium phosphate), which were added to the soil and left to equilibrate for 1 month under greenhouse conditions. Spinach seeds (Spinacea oleracea L., cv Viroflay) were sown and then grown for 8 weeks. The chemical composition in the aerial part of the pant and soil was determined. Application of Cd decreased plant dry matter and increased Cd concentration in the plant, whereas at each level of applied Cd, P increased plant dry matter and decreased plant Cd concentration. All chemical forms of Cd in soil, as determined by a fractionation method, were increased following Cd application, the highest being the carbonatic form. Phosphorous application decreased exchangeable and carbonatic forms of Cd, whereas it increased other forms. [ABSTRACT FROM PUBLISHER]

Adsorption and release are the most influential reactions controlling zinc (Zn), manganese (Mn) and copper (Cu) availability in soils. Characteristics of native Zn, Mn and Cu release by ethylenediaminetetraacetic acid (EDTA) in two calcareous soils for periods from 1 min to 24 h were studied. The pattern of Zn, Mn and Cu release from both soils fitted well with power function, Elovich and parabolic diffusion models. The magnitude and rate of release was greatest for Mn, followed by Zn and Cu, respectively. This trend suggests a higher ability of the studied soils to replenish soil solution Mn, compared with Zn and Cu. The results showed that higher Mn release in clay soil compared with sandy loam soil was considerably related to higher initial Mn release rates in the former compared with the latter. However, Cu release rates of the two soils at initial times were not significantly different. Higher Cu release in clay soil was, therefore, attributed tohigher Cu release rates at subsequent time intervals. It is assumed that the different Zn release rates of these soils were due to consistent differences in Zn release rates throughout the release periods. [ABSTRACT FROM AUTHOR]

A greenhouse experiment was conducted to study the soil-plant phosphorus (P) correlation at different growth stages of spinach (Spinacia oleracea L.). Treatments consisted of three levels of phosphorus [0 20, and 60 mg kg-1 as Ca(H2PO4)2] and two levels of organic matter (0% and 2% w/w as feedlot cattle manure). Plant and soil samples were taken at 4, 5, 6, 7, and 8 weeks after seedling emergence and were analyzed for plant nutrients. Results showed that correlation between soil and plant P concentration was significant and positive at the 4th week but significant and negative later on. Plant P concentration was the greatest at the 4th week. During all growth stages, dry-matter yield of plant increased with increase in soil P concentration, suggesting the importance of maintaining adequate levels of phosphorus in soil, especially during the early stages of growth. Application of organic matter significantly increased soil and plant P concentrations. [ABSTRACT FROM AUTHOR]

Information on soil zinc (Zn) distribution is essential for understanding its chemical reactions and bioavailability. An experiment was conducted to evaluate the effect of wheat straw, cow manure, and vermicompost applied with Zn rates on Zn distribution in a calcareous soil. A sequential extraction scheme was used to fractionate Zn into soluble and exchangeable, bound to carbonate, organically bound, bound to manganese (Mn) oxide, bound to amorphous iron (Fe) oxide, bound to crystalline Fe oxide, and residual forms. In untreated soil, Zn was mainly in the residual fraction. Increasing rates of applied Zn increased all forms of Zn. Carbonate and residual forms showed the greatest increase. Organic materials application increased all fractions, except Mn-oxide form, and this increase was more pronounced for the organically bound form. Concentration of soluble, exchangeable, and organically bound forms was greatest in cow manure-amended samples as compared to other organic materials, suggesting that cow manure contained more bioavailable Zn than other organic materials. [ABSTRACT FROM AUTHOR]

Understanding time-dependent copper (Cu) desorption behavior is critical for improving the prediction of Cu availability in soils. This study was conducted to evaluate the influence of municipal waste compost, sheep manure, and wheat straw on desorption characteristics of Cu and to evaluate the suitability of different kinetic models to describe the Cu release pattern in two calcareous soils. Diethylenetriaminepentaacetic acid (DTPA) and ethylenediaminetetraacetic acid (EDTA) were employed to extract Cu from soils. Best-fitted kinetic models including Elovich, simple Elovich, two-constant rate, and parabolic diffusion were selected based on their low standard error and high coefficient of determination. Extractable copper significantly decreased with increasing rates of sheep manure and wheat straw but increased with increasing rates of municipal waste compost amendment. Results revealed that copper was more readily desorbed from clay soil compared to silt loam soil. The copper desorption patterns were almost similar for both extractants; however, EDTA extracted more Cu from soils. [ABSTRACT FROM AUTHOR]

An experiment was conducted to evaluate the effect of zinc (Zn) rates and vermicompost levels on distribution of Zn forms of a calcareous soil. After incubation periods, soil samples were air dried, and a sequential extraction scheme was used to fractionate Zn into soluble and exchangeable, bound to carbonate, organically bound, bound to manganese (Mn) oxide, bound to amorphous iron (Fe) oxide, bound to crystalline Fe oxide, and residual forms. In untreated soil, Zn was mainly in the residual fraction. Increasing rates of applied Zn significantly increased all forms of Zn. Carbonate and residual forms showed the greatest increase. Application of vermicompost significantly increased all fractions except Mn-oxide form. This increase was more pronounced for organically bound, soluble, and exchangeable forms, indicating an increase in bioavailability of soil Zn. Incubation time significantly decreased soluble, exchangeable, and organically bound forms but increased other forms of Zn, meaning a significant reduction in Zn phytoavailability in soil with time. [ABSTRACT FROM AUTHOR]

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

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

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]

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]

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]

The fate of antibiotics and their effects on plant growth may be changed by the application of fertilizers. The present study was carried out to investigate the effect of sulfadiazine (SDZ), rice husk compost (RHC), rice husk biochar (RHB), and mycorrhiza (MR) on the growth attributes of Iranian Echium amoenum Fisch & C.A. Mey. A greenhouse experiment as a completely randomized design with six treatments of bio/organic-fertilizers (no bio-fertilizer (NF), RHB, RHC, MR, RHB + MR, and RHC + MR) and three levels of SDZ application (0, 100, and 200 mg kg−1) was performed for 7 months with three replicates. Shoot and root SDZ concentrations were determined using high-pressure liquid chromatography–diode array detection (HPLC–DAD) instrumentation. The results revealed that the application of RHC, RHB, and MR had a significant impact on the reduction of the toxicity effects of SDZ on plant properties. The lowest values of growth parameters belonged to the 200 mg kg−1 of SDZ with no bio-fertilizers, while the highest growth parameters were observed in the treatments of RHB + MR, and RHC + MR with no SDZ application. Also, chlorophyll pigments content was affected by used treatments and the lowest rates of chlorophyll a (4.24), chlorophyll b (2.99), and carotenoids (2.88) were related to the 200 mg kg−1 of SDZ with no biofertilizers application. The co-application of bio-fertilizers and SDZ (at both levels of 100 and 200 mg kg−1) decreased SDZ uptake by both shoot and root in comparison with the control. The same results were obtained with macro (NPK) and micro (Fe, Zn, Cu, and Mn) nutrients uptake by the shoot in which the lowest values of nutrients uptake were observed in treatment of 200 mg kg−1 of SDZ with no bio-fertilizers. Furthermore, in the case of the effect of the used treatments on root colonization, the results showed that the lowest value (7.26%) belonged to the 200 mg kg−1 application of SDZ with no bio-fertilizers. Generally, this study demonstrated that bio-fertilizers could be considered as an effective strategy in controlling the negative effects of antibiotics on the growth properties and nutrients status of the plants grown in such contaminated soils. • Sulfadiazine decreased plant growth in the absence of fertilizers treatments. • The amount of sulfadiazine was reduced in pots that received bio/organic fertilizers. • Negative impact of antibiotic relieved by organic fertilizers more than mycorrhiza. • Root colonization increased in co-treatments of fertilizers and sulfadiazine. [ABSTRACT FROM AUTHOR]

Growing environmental concern regarding multi elements-contaminated soils reveals the necessity of paying more attention to environmentally friendly remediation techniques such as phytoremediation. A large number of factors influences phytoremediation of potentially toxic elements (PTEs) and investigation on a variety of these factors need appropriate statistical approaches such as "Taguchi optimization" which effectively decreases time and cost of experiments. In the present study, based on the Taguchi optimization method, the effects of several biological (plant type and mycorrhizal fungi (AMF)) and chemical (chelating agents, surfactants and organic acids) factors, on the phytoremediation of soils contaminated with zinc (Zn), lead (Pb), cadmium (Cd) and nickel (Ni) were investigated. The goal was to find out the most effective factors as well as the best level for each factor. The values of dry weights in roots and aerial parts of the studied plants were in orders of maize > sorghum > sunflower and sorghum > maize > sunflower, respectively. AMF was the main factor in increasing dry weight of shoots. Inoculation of AMF caused increases in root and shoot uptake of some PTEs. showed that phytoremediation of PTEs is element-dependent; as Zn showed the highest translocation factor (TF) and bioconcentration factor (BCF) values, while Ni showed the lowest ones and the intermediate values belonged to Pb and Cd. These results show the diverse distribution of elements in plant parts, as Zn and Ni were mostly accumulated in shoot and root, respectively. Although different factors caused impacts on phytoremediation criteria, the role of plant type in the phytoremediation of PTEs was at the first rank. Mean TF of PTEs in sunflower was 6.3 times that of maize. Sunflower showed high TF value for the four elements and translocated most of the PTEs from root to the aerial parts demonstrating phytoextraction as the main mechanism in this plant. Maize and sorghum, however, showed low TF and accumulated most of PTEs in their roots revealing phytostabilization as the main mechanism. In general, it can be concluded that plant type was the most influential factor in the phytoremediation of PTEs followed by EDTA and AMF. Taguchi optimization revealed the appropriateness and significance of different chemical and biological treatments on phytoremediation criteria of different elements. Image 1 • Plant type showed the first rank in a significant number of phytoremediation criteria. • Chemical treatments were more effective than biological treatments in phytoremediation of multi-metals contaminated soil. • Among the chemical treatments, the role of EDTA on the phytoremediation of multi-metal polluted soil was predominant. • Taguchi optimization makes it possible to conduct comprehensive phytoremediation study with multiple factors. [ABSTRACT FROM AUTHOR]