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Plant nutrient composition of can be used as an evaluation criterion for optimum plant growth. The objectives of present study were to (a) derive critical compositional nutrient (CND) norms for survived wheat fields and sufficiency ranges as CND nutrient index for validation samples, (b) provide a squared CND threshold nutrient imbalance index (CND r2) and compare with DRIS nutrient imbalance indices, (c) determine balanced nutrients concentration with CND indices. The yield cutoff value was 4,232 kg.ha-1. The CND indexes results indicate that Zn is the most deficient nutrient in wheat, followed by Cu, Fe, Mn and B, whereas N is the most excessive nutrient, followed by K, Ca, Mg and P. In the validation trials, the yield cutoff value were reported 5.023 kg.ha-1. The calculated CND r2 in the validation population was lower than that of the survey wheat fields, indicating a more balanced concentration of nutrients due to the application of fertilizer treatments. Significant principal component (PC) loadings were obtained after the varimax rotation. The first three PCs in high- and low-yielding subgroups and whole data set indicated 52.8, 54.6 and 48.8 % total variance, respectively. This study revealed that the decline in the wheat yield was due to the nutrient imbalance associated with multi nutrient deficiency (Zn, Cu, Fe, Mn and B) and multi nutrient excess (N, K, Ca, Mg and P).

In this study, Pb was added to the soil at rates of 0, 100, 200, 300, 400, and 500 mg kg−1 as Pb (NO3)2 and then incubated at 27 °C and soil moisture of 0.7 field capacity for 180 d. Soil biologica...

The present research aimed at investigating zinc (Zn) sorption capacity of the biochars derived from apple wood (WB) and rice straw (RB) feedstocks at two 300 and 600°C pyrolysis temperatures (WB300, WB600, RB300 and RB600, respectively) in aqueous solutions. Kinetic and equilibrium sorption experiments were conducted via batch technique. In equilibrium adsorption experiments, the study used the concentration range of 5-200 mg Zn L− 1 and focused on the solution pH effect on Zn adsorption in biochars under the following conditions: unadjusted and adjusted pH (4 and 6) and three ionic strength levels (0.01, 0.03, 0.1 M KNO3). Zinc desorption experiments were conducted under all above mentioned conditions but without pH adjustment at five separate stages. Kinetic data analysis indicated that Zn adsorption in biochars reached the near steady state within 24 hours with the sorption rate order of WB300 − 1, on average, for WB300, WB600, RB300, and RB600, respectively. The initial increased pH solution from 4 to 6 caused an increase in Zn adsorption in RB600, RB300 and WB600, however the sorption maxima in WB300 was detected at pH 4. The rise in solution ionic strength from 0.01 M to 0.1 M dropped the Zn adsorption capacity in all the studied biochars. Findings suggested that rice straw derived biochars showed a better performance than woody biochars in Zn sorption and retention from aqueous solutions. In addition, this ability increased with increasing pyrolysis temperature in both types of biochars. Finally, the study revealed that rice straw biochars, produced at high pyrolysis temperatures, can serve as economical and efficient absorbents for Zn removal from aqueous solutions.

The desorption kinetics of Cd, Pb, and Zn was investigated as a function of sewage sludge amount (0, 10, and 30 g kg−1), incubation time length (30 and 120 days) and plant cultivation (Mentha piper...

Novel adsorbents that remove P from contaminated waters can be potentially used as slow release P-fertilizers. In this study, Mg-Al layered double hydroxide (Mg-Al-LDH) and Mg-Al-LDH functionalized...

Background: The increasing amount of sewage sludge (SS) and more legislative regulation of its disposal have stimulated the need for developing new technologies including gamma irradiation to recycle SS efficiently. Objective: To evaluate the effects of gamma irradiated and non-irradiated SS (SSGI and SSNI, respectively) on essential oil (EO) content and composition of Ocimum basilicum L. Methods: A greenhouse experiment was conducted with 15, 30, and 60 g kg-1 of SS irradiated with absorbed doses of 5, 10, and 20 kGy gamma-ray and soil without SS and irradiation as the control treatment. The essential oil was isolated by hydro-distillation and analyzed by Gas chromatography and Gas chromatography-mass spectrometry techniques. Results: The applications of SSGI and SSNI at all levels except 15 g kg-1 significantly enhanced EO content compared to the control. The using of 60 g kg-1 SS in each absorbed dose significantly reduced EO yield relative to the control, while it was significantly increased under 15 and 30 g kg-1 SSNI and SSGI. Also, in 60 g SS kg-1, the restriction effects on EO yield were mitigated with increasing the absorbed dose of gamma-ray, but it was insignificant with increasing absorbed dose to 10 and 20 relative to 5 kGy. The methyl chavicol as a major constituent of EO was significantly increased in SSGI and SSNI as compared with the control. However, the increment in the methyl chavicol content was not significant between the treatments ≥ 30 g kg-1 SSGI or SSNI and 15 g kg-1 SS at absorbed dose of ≥10 kGy. 98 Conclusion: To improve essential oil content and composition, application of ≤ 30 g kg-1 sewage sludge with 5 kGy absorbed dose of gamma-ray can be suggested at similar conditions.

The effluent and sludge samples collected at the Municipal Wastewater Treatment Plant of Southern Tehran were irradiated with doses of 5, 10 and 20 kGy using a 60Co gamma source and without irradiation (control) in a completely randomized design with three replications. In the term of total and fecal coliforms load, the gamma ray was more effective in the effluent disinfection than in the sludge. Approximately, three logs reduction in total and fecal coliforms were observed at the dose of 20 kGy in the sludge. The complete inactivation of the coliforms load in the effluent was achieved by 10 kGy gamma ray, whereas for sludge, it was not achieved even at 20 kGy. The improvement in the irradiated effluent quality was demonstrated by the significant reductions in chemical oxygen demand, biochemical oxygen demand, turbidity, pH, EC and concentrations of nitrate and phosphate. The other characteristics of the effluent and sludge did not change and/or changes did not show any trend as a result of treatments except concentrations of nitrogen and copper in the sludge and calcium and potassium in the effluent. The results proved that gamma ray can be applied as an effective technique for the reuse of effluent and sludge in agricultural soils.

Irradiation of sewage sludge (SS) with gamma-ray is regarded as a promising alternative and rapid method for risk mitigation of this waste in ecosystems. The effects of 13 treatments (15, 30, and 60 g kg−1 of non-irradiated SS and irradiated with doses of 5, 10, and 20 kGy gamma-ray and soil without SS and irradiation as the control treatment) was investigated on the growth, herbage yield, leaf chlorophyll index, and concentrations of macronutrients in basil (Ocimum basilicum L.) root and shoot in a completely randomized design with three replications under greenhouse conditions. The results showed that application of gamma-irradiated and non-irradiated SS positively affected the concentrations of nitrogen, phosphorus, potassium, sodium, calcium, and magnesium in basil shoot and root. The highest and lowest dry weights of root and shoot, plant height, leaf area, and leaf chlorophyll index were observed in 30 g kg−1 SS irradiated with 20 kGy absorbed dose and 60 g kg−1 non-irradiated SS, respectively. In ≤ 30 g kg−1 SS, the gamma irradiation absorbed dose did not significantly change the growth parameters, thus the use of ≤ 5 kGy absorbed dose may be suggested to stimulate positive effects on basil growth. Also, in 60 g kg−1 SS, the restrictive effects were mitigated by increasing the absorbed dose, but the use of ≥ 5 kGy absorbed dose may not cost-effective. Therefore, in order to improve nutrition and growth of basil plant, application of ≤ 30 g sewage sludge irradiated with 5 kGy absorbed dose of gamma-ray per kilogram soil can be suggested under similar conditions.

Agricultural practices affect arbuscular mycorrhizal fungal (AMF) hyphae growth and glomalin production, which is a recalcitrant carbon (C) source in soil. Since the spatial distribution of glomalin is an interesting issue for agronomists in terms of carbon sequestration, digital maps are a cost-free and useful approach. For this study, a set of 120 soil samples was collected from an experimental area of 310 km2 from the Sarab region of Iran. Soil total glomalin (TG) and easily extractable glomalin (EEG) were determined via ELISA using the monoclonal antibody 32B11. Soil organic carbon (OC) was also measured. The ratios of TG/OC and EEG/OC as the glomalin–C quotes of OC were calculated. A total of 17 terrain-related attributes were also derived from the digital elevation model (DEM) and used as static environmental covariates in digital soil mapping (DSM) using three predictive models, including multiple linear regression (MLR), random forests (RF), and Cubist (CU). The major findings were as follows: (a) DSM facilitated the interpretation of recalcitrant C source variation; (b) RF outperformed MLR and CU as models in predicting and mapping the spatial distribution of glomalin using available covariates; (c) the best accuracy in predictions was for EEG, followed by EEG/OC, TG, and TG/OC.

Silicon (Si) application shows beneficial effects on growth and salt tolerance of plants; however, its effects on the rice (Oryza sativa L. var. Hashemi) growth, superoxide dismutase (SOD) activity and concentrations of chlorophyll and proline have not been fully understood under different levels and sources of soil salinity. In this research, the effects of four salinity levels (0.46, 2, 4, and 8 dS m−1), two salt compositions (NaCl and four-salt combination) and four Si rates (8, 100, 200 and 300 mg kg−1 soil) as silicic acid (H4SiO4) on rice growth characteristics and SOD activity were studied in a greenhouse. Salt composition included NaCl, Na2SO4, CaCl2 and MgSO4 at a molar ratio of 4:2:2:1. The experiment was arranged in a factorial framework in a completely randomized design with three replications. Increasing soil salinity level significantly decreased dry matter (about 40%), number of tillers (about 12%), leaf area (about 55%), concentrations of leaf chlorophyll (about 45%) and Si (about 40%), whereas caused a severe increase in proline concentration (more than 200%) and SOD enzyme activity (up to 65%). Deleterious effect of salinity on dry matter and leaf area as well as its stimulating influence on proline accumulation and SOD activity was more intense in NaCl-treated plants than those subjected to a combination of salts. Source of salinity had no significant effects on dry matter, number of tillers and chlorophyll concentration. Si treatment strongly enhanced these parameters, except for proline that declined in plants subjected to Si. The suppressing effect of salinity on the rice growth characteristics can be alleviated by soil Si fertilization. The stimulating effects of soil Si fertilization on dry matter as well as chlorophyll concentration became more pronounced at the higher salinity levels. Consequently, when rice plants are to be grown in salt-affected soils, it is recommended to supply them with adequate Si.

Heavy metal pollution has become one of the most serious environmental problems. The aim of this study was to achieve an efficient treatment process of effluents containing 1 mM copper (Cu2+) and cadmium (Cd2+) ions using a combination of gamma irradiation, methanol and TiO2 nanoparticles under different pH values. The results showed that in acidic conditions, removal of Cu2+ and Cd2+ ions by physical adsorption was less than 15% and adsorption of Cd2+ was more than that of Cu2+. In the same condition, the Cu2+ removal percentage by irradiation was greater than that of Cd2+. In basic solutions, due to precipitation of Cd and Cu hydroxides, it was not possible to carry out adsorption experiments on Cd2+ and Cu2+ ions removal by TiO2 and gamma irradiation. Cu2+ and Cd2+ ions removal processes under different conditions could be depicted by the first order kinetics model. The combined application of TiO2 and methanol enhanced Cu2+ and Cd2+ ions removal at all pH levels examined. However, using the combination of TiO2 and methanol at acidic solutions facilitated completely removal of Cu2+ and Cd2+ ions. So that, only using 50 kGy irradiation dose with combination of TiO2 nanoparticles and methanol led to the removal of 99% of coexisting Cu2+ and Cd2+ ions from the acidic wastewater.

Two experiments were carried out in 2013 and 2014, to investigate changes in grain filling rate (GFR), grain filling duration (GFD) and yield of mung bean in response to salicylic acid (SA) and silicon (Si) under salt stress (0, 3, 6 and 9 dS m−1). In experiment 1, four levels of SA (0, 0.5, 1 and 1.5 mM), but in experiment 2, two levels of SA (0 and 1 mM) and Si (0 and 2 mM) were applied. In experiment 1, GFR, GFD, yield components, biological and grain yields and harvest index were decreased with increasing salt stress. Application of different levels of SA, especially 1 mM, increased GFR, but decreased GFD. In experiment 2, GFD under salinity was shorter than that under non-saline condition, resulting in comparatively smaller grains. Application of Si and particularly SA accelerated grain development under all salinity treatments. The superiority of SA treated plants in GFR, grain weight and grains per plant resulted in greater grain yield per plant under saline and non-saline conditions.

We investigated the effects of silicon (Si) and the levels and sources of salinity on the growth and some physiological properties of wheat (Triticum aestivum cv. Chamran) in a sandy loam soil under greenhouse conditions. Treatments comprised four Si levels (8, 50, 100 and 150 mg kg−1 soil), four salinity levels (0.46, 4, 8 and 12 dS m−1) and two salinity sources (sodium chloride (NaCl) and four-salt combination). Salts combination included NaCl, sodium sulfate (Na2SO4), calcium chloride (CaCl2) and magnesium sulfate (MgSO4) at a molar ratio of 4:2:2:1. The experiment was arranged as a completely randomized design in a factorial manner, with three replications. Increasing salinity level resulted in a significant decrease in shoot dry weight, chlorophyll content and catalase (CAT) activity, and it caused a marked increase in proline and glycine betaine (GB) concentrations and superoxide dismutase (SOD) enzyme activity. The stimulating effect on GB accumulation and SOD activity was more intense in N...

The aim of this study was to apply fifteen remote sensing indices extracted by Landsat 8 OLI imagery for predicting and spatially mapping of soil salt composition, major electrolytes and ionic strength (IST) as difficult-to-measure soil chemical properties and parameters. For this, an area with extension of 22300 ha was selected from the east shore of Urmia Lake, Iran with extremely saline and sodic soils. This article also focuses on the importance of data mining techniques in advanced digital soil mapping (DSM). In addition to routine chemical analysis, the Visual MINTEQ software was utilized for computing the saturation index of salt composition as well as ionic strength. The positive values of saturation indices were only identified for calcite, dolomite and gypsum in the study area. For mapping the aforementioned properties, Random Forests, Cubist and decision tree were the three candidate modeling approaches. The bootstrapping technique according to the calculated prediction intervals was then used to inspect the associated uncertainty of all created digital maps. Regarding optimality, the Cubist model was identified as the most efficient model for our data set and environmental covariates. The prediction of monovalent (i.e. Na+, K+ and Cl−) ion concentrations, but not divalent (i.e. Ca2+, Mg2+and SO42−) ion concentrations, was generally quite good with calibration and validation dataset. The most important finding of this paper was the successful prediction of spatial distribution of IST using solely remotely-sensed indices. The outcomes of this study are of great importance for the remote sensing society, by means of applying the respective remote sensing indices and identifying the most effective techniques.

The potential use of a layered double hydroxide (magnesium aluminum nitrate (Mg-Al)-LDH) to suppress the leaching of nitrate from a calcareous sandy loam soil and to enhance the nitrogen utilization efficiency of maize was assessed. The results of column studies showed that nitrate leaching efficiently decreased by 24, 46, and 76% compared to control when 2.5, 5, and 10 g LDH kg–1 soil were applied, respectively. Nitrate leaching was also reduced by use of LDH in pot experiments. The hindrance effect of LDH in using ammonium nitrate was higher than urea. Application of 2.5, 5, and 10 g LDH kg–1 soil increased mean nitrogen uptake of maize by 14, 20, and 44% over the control. The studied LDH has a potential to be used as a nitrate-selective exchanger to reduce risks of nitrate leaching. However, the use of Mg-Al-LDH (4:1) can be limited because of its relatively high solubility in soil.

This study aimed to prepare, characterize, and investigate nitrogen (N) release pattern of urea-impregnated biochar (UB), hydrochar (UH), zeolite (UZ) as carriers, and urea-hydroxyapatite nanohybrids (U-HAP) in water and a calcareous waterlogged soil. The results indicated that the urea had interactions with carriers and hydroxyapatite nanorods which controlled the release of urea. The UH, UB, UZ, and U-HAP reduced the urea release by 4.5, 6.5, 9.0, and 11.5 times, respectively compared to the urea only. The kinetics of urea release from these fertilizers showed the best fit of the Korsmeyer-Peppas model following the Fickian diffusion law. Another experiment was carried out using 14 treatments including control, rice straw, hydrochar, biochar, and zeolite with and without urea application and UH, UB, UZ, and U-HAP fertilizers. The extractable-NH4+ was measured using 2 M KCl solution in different times (0, 0.5, 1, 3, 6, 12, 20, 30, 45, 70, and 100 days) after application of prepared fertilizers. The results showed that >85% of the applied urea was converted to NH4+ within 12 days in the urea-alone treatment. However, 20 days after the application of the UH, UB, UZ, and U-HAP in soil, 89.9, 76.5, 75.0, and 58.1 percent of urea was converted to NH4+, respectively. After the application of all controlled-release urea fertilizers, the extractable-NH4+ concentration increased initially but after 20 days decreased with time and the rate of reduction was lower in the UB, UZ, and U-HAP as compared to other treatments. Also, the kinetics of extractable-NH4+ showed the best fit to the Extreme model. The results showed that the UB, UZ, and U-HAP slowly released urea which may reduce N loss and increase its use efficiency in calcareous paddy soils.

Gamma irradiation is regarded as a promising alternative method for sewage sludge (SS) treatment. To evaluate the human health risk and effects of gamma irradiated and non-irradiated SS (SSGI and SSNI, respectively) on micronutrient and heavy metal concentrations in basil (Ocimum basilicum L.) as a test plant, a greenhouse experiment based on completely randomized design was conducted with control (without SS and irradiation) and 15, 30 and 60 g kg−1 of SSNI as well as SSGI (irradiated with doses of 5, 10 and 20 kGy) with three replicates. The results indicated that the concentrations of copper, zinc, iron, nickel, lead, and cadmium in SSGI and SSNI treatments were greater than the limits set by FAO/WHO for vegetables or by European Commission for food. The target hazard quotient (THQ) of all metals except lead in the treatments with >15 g kg−1 SSGI or SSNI and the hazard index (HI) in the control treatment were lower than the threshold value of 1, but the HIs in SSNI and SSGI treatments were greater than the threshold value. Nevertheless, no significant differences existed between most THQs and HIs from dietary intake of basil grown in SSGI as compared with SSNI. It was concluded that the basil cultivated under tested levels of SSGI and SSNI is not permissible for human consumption.

The aim of this study was to determine the influence of sewage sludge (SLU) amendment on the desorption characteristics of zinc (Zn), lead (Pb), and cadmium (Cd) in contaminated calcareous soils. Three levels of SLU (0, 1, and 3% w/w) were added to the two calcareous contaminated soils. Samples were incubated for 30 days and equilibrated with 0.005 M DTPA for 0.25 to 240 h. The addition of SLU significantly increased the amount of DTPA-extractable Zn in soils. While the amounts of Cd, Pb, dissolved organic carbon (DOC), and pH showed a significant increase only in 3% w/w of SLU, with the exception of Cd desorption in 1% w/w of SLU, kinetics of Zn, Pb, and Cd extraction increased together with an increase in the level of applied SLU. The best models for describing desorption data were explicitly power function and Elovich. The rate constants of Zn and Pb had significant correlations with DTPA-extractable Zn and Pb, DOC and pH, which affect Zn and Pb desorption. Also, the rate constants of Cd had significant correlations with CEC that can be deemed as equivalent to the fact that Cd desorption is controlled by surface adsorption, particularly in the lower sludge application amount. These results can be used for management of sewage sludge application in contaminated calcareous soils.

This research was conducted in a greenhouse to evaluate the effects of exogenous application of salicylic acid (SA) (1 mM) and 6-benzylaminopurine (BAP) (50 μM) on physiological performance of faba bean (Vicia faba) under different levels of NaCl salinity (0, 4, 8 and 12 dS/m). The experiment was arranged as factorial on the bases of randomized complete block design in three replications. Leaf Na+ content, root and leaf soluble sugars, antioxidant enzymes activities such as catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD) and lipid peroxidation increased, but K+, K+/Na+ and membrane stability index (MSI) decreased as a result of salt stress. However, foliar sprays of BAP and particularly SA reduced Na+ content and lipid peroxidation, while enhanced the K+ content, K+/Na+, soluble sugars, antioxidant enzymes activities and MSI under different levels of salinity. It was, therefore, concluded that exogenous application of these growth regulators (GR) can considerably improve salt tolerance and physiological performance of faba bean.

A greenhouse experiment was conducted to assess the effects of magnetic field, arbuscular mycorrhizal fungi (AMF), and phosphorus (P) concentration in the nutrient solution (0, 5, 10, 20, o...

In order to study the effects of soil and foliar applications of iron (Fe) and zinc (Zn) on flowering, flower yield and essential oil production of German chamomile a pot experiment was conducted under greenhouse conditions at the Faculty of Agriculture, University of Tabriz, Iran in 2012. The experiment was arranged as completely randomized design with 12 treatments and three replications. Treatments were as follow: T1: control – without Fe or Zn fertilizers, T2: 30 mg FeSO4.7H2O kg-1 dry soil, T3: 22 mg ZnSO4.7H2O kg-1 dry soil, T4: 30 mg FeSO4.7H2O + 22 mg ZnSO4.7H2O kg-1 dry soil, T5: foliar spraying of FeSO4.7H2O (3.5 g L-1), T6: foliar spraying of FeSO4.7H2O (7.0 g L-1), T7: foliar spraying of ZnSO4.7H2O (2.5 g L-1), T8: foliar spraying of ZnSO4.7H2O (5.0 g L-1), T9: T5+T7, T10: T5+T8, T11: T6+T7, T12: T6+T8. The foliar spraying was done two times during the growing period. The results revealed that the flower number, flower yield, essential oil content and essential oil yield were significantly increased by soil and foliar applications of Fe + Zn, compared with the control (untreated). The highest flower number (477 plant-1), flower yield (11.6 g pot-1), essential oil content (0.88 %) and essential oil yield (119 mg pot-1) were recorded for the soil application of Fe + Zn (T4) by 58, 68, 21.4 and 105 % increment compared to the control, respectively. Foliar application of Fe + Zn (T12) was placed at the next rank; however this treatment had no significant difference with the soil application of Fe + Zn (T4). Other treatments did not show significant differences with the control. Generally, the results showed that soil or foliar application of Fe + Zn can be effective on increase or improve of quantity and quality of chamomile yield. Moreover, use of foliar application as a low cost method especially in areas with alkaline or calcareous soils can be recommended.

The present study was conducted in order to investigate the effects of silicon and salinity on growth, chemical composition and physiological properties of rice var. Hashemi, in the greenhouse of agricultural college of University of Tabriz during 2011. It was arranged as factorial based on a completely randomized design with three factors consisting of silicon at four levels (control, 100, 200 and 300 mg/kg soil), salinity at four levels (control, 2, 4 and 8 dS/m) and source of salinity at two levels (NaCl and combination of different salts) with three replications. The results showed that increasing soil salinity resulted in a decrease in shoot dry weight, catalase activity and concentrations of phosphorus, potassium and reducing sugars, and an increase in glycine betaine content in the plants. The comparison between two sources of salinity also revealed that plants treated with a combination of salts experienced less vigorous decrease in dry weight and potassium, and reducing sugars' concentrations. Meanwhile, the enhancement in glycine betaine content appeared to be less intense in these plants. Hence, it could be concluded that the salinity resulting from a combination of different salts caused less damage to plants than NaCl salinity. Silicon supplementation resulted in increasing of shoot dry weight, catalase activity and concentrations of reducing sugars, glycine betaine, phosphorus and potassium. Therefore, silicon nutrition alleviated suppression effects resulting from the presence of soil salts, which means, enhanced the salt tolerance of rice.

This study was conducted for evaluating the combined effect of soil moisture, phosphorus (P) and zinc (Zn) levels on crop evapotranspiration (ET), leaf water potential (LWP), water use efficiency (WUE) and various tuber attributes of potato ( Solanum tuberosum L. cv. Agria) under greenhouse conditions. This investigation was conducted as a factorial experiment based on randomized complete blocks design with Zn at three levels (0, 10 and 20 mg Zn per kg dry soil as ZnSO 4 ·7H 2 O), P at three levels (0, 30 and 60 mg P per kg dry soil as Ca(H 2 PO 4 ) 2 ·H 2 O) and soil moisture at three levels (0.5 FC–0.6 FC, 0.7 FC–0.8 FC and 0.9 FC–FC) using three replications. The various attributes of potato tubers including tuber numbers, dry matter content (DM), yield, WUE and indicators of water deficit stress intensity (ET and LWP) were measured routinely during the crop growth period. The results showed that the water deficit stress resulted in a significant decrease in ET, tuber numbers, yield and WUE. Application of P significantly increased the ET, tuber numbers and yield and Zn application significantly affected the tuber numbers. The P × soil moisture interaction effect was significant for ET, LWP, tuber numbers and yield. While the Zn × soil moisture interaction was significant only for yield. The results showed that the two way interactions of Zn, P and soil moisture were mainly synergistic on the most of above mentioned attributes. In general, to achieve the optimum yield of potato tubers in similar soils, application of 10 mg Zn and 30 mg P per kg of dry soil could be recommended under full-irrigated conditions. The regression analysis showed that the yield of potato was increased by application of P under water deficit conditions.

The adsorption–desorption behavior of nitrate on Mg–Al layered double hydroxide (4:1) was compared with that of phosphate and sulfate as two common anions in soil solution. Based on the results, the kinetics of anion adsorption on the LDH followed a pseudo-second order model. The adsorption process was found to be exothermic for nitrate and endothermic for phosphate and sulfate. The adsorption data were best described by the Freundlich model for nitrate and by the Langmuir model for phosphate and sulfate. In this study, the synthesized LDH exhibited higher adsorption rate and adsorption capacity for nitrate compared to sulfate and phosphate. The maximum adsorption capacity values were 1.90, 0.28 and 0.13 mmol g− 1 for nitrate, phosphate and sulfate, respectively. However, the Langmuir equation constants related to the adsorption energy were found to be 0.210, 10.731 and 3.021 L mmol− 1, respectively. The distribution coefficient (Kd) was higher for nitrate than phosphate and sulfate at high initial concentrations. Moreover, the values of hysteresis index based on the Freundlich exponent were 97.5, 22.5 and 79.0% for nitrate, phosphate and sulfate, respectively. The FTIR spectroscopy indicated a strong band related to the nitrate intercalated into the interlayer space of the LDH.

Silicon (Si) is one of the most abundant elements in the earth's crust, although its availability may be affected by some edaphic and abiotic factors such as soil moisture and salinity. In a laboratory experiment, effects of silicon (Si), salinity, and soil moisture on changes of extractable Si, iron (Fe), and manganese (Mn) concentrations were investigated on a sandy loam calcareous soil. The experiment was arranged as a factorial completely randomized design with three replications. Two levels of Si (8 and 200 mg per kg of soil), three salinity levels [0.46 dS m−1, 8 dS m−1 as sodium chloride (NaCl), and 8 dS m−1 as four-salt combination], two soil moisture regimes (–20 kPa and waterlogged), and four incubation times (0, 7, 30, and 45 days) were applied. Salt composition consisted of sodium chloride, sodium sulfate, calcium chloride, and magnesium sulfate at a molar ratio of 4:2:2:1. Acetic acid–extractable Si, Fe, and Mn were determined after 0, 7, 30, and 45 days of incubation. Waterlogging caused sig...

The ArcGIS Geostatistical Analyst aims to effectively bridge the gap between geostatistics and geographical information system analysis by enabling to model spatial phenomena and accurately predicting values within the study area. This approach was conducted to forecast the distribution patterns of some soil biological indices in Mirabad area, North West of Iran. Three different land uses (apple orchard, crop production, and rich pasture) were selected to conduct the experiments in a randomized completely blocks design with five blocks. Soil samples (0–30 cm) were collected on mid July 2010. Soil biological indices i.e. (i) substrate induced respiration, (ii) microbial biomass carbon, (iii) the activity of urease; (iv) alkaline phosphomonoesterase, and also (v) dehydrogenase were determined. Kriging and inverse distance weighting methods were applied to assess the spatial variability of five stated indices. Ordinary kriging was applied because it is the most general and widely used method. Digital soil biological indices maps will be the last output of integrating geostatistics and geographical information system. The study, while addressing spatial variability of soil biological properties, also discusses the accuracy of modeling as well as spherical model is now distinguished as the best fitted model. Assessing spatial variability of alkaline phosphomonoesterase activity has the lowest accuracy than urease and dehydrogenase activities. The geostatistical results showed that management practices might not have relevant effect on microbial biomass carbon and enzyme activities. But, the statistical analysis revealed significant differences between pasture and two other land uses.

Glomalin is the most abundant gylcoprotein in soil which produces by glomeral fungi in symbiosis with plant roots. It improves soil physical, chemical and biological properties. Assimilated plant C which is allocated to the mycorrhizal fungus, appears as a recalcitrant glycoprotein (glomalin) in cell walls of hyphae and spores. Considering global warming due to increasing greenhouse gases, this phenomenon could be important in carbon sequestration and reducing CO 2 in atmosphere. Chemical fertilizers could affect symbiotic relations of these fungi, which in turn affect glomalin production. In a pot culture experiment, the sterile soil was treated with 0, 100, 200 mg N kg -1 soil as urea or 0, 20, 40 mg P kg -1 soil as triple superphosphate, in two separate factorial experiment based on completely randomized design with three replications. Corn plant ( Zea mays L.) was inoculated with Rhizophagus clarus (formerly, Glomus clarum ) or Rhizophagus intraradices (formerly, Glomus intraradices ) in each set of experiment. Easley extractable glomalin (EEG) and total glomalin (TG) in soil were determined by Bradford method at the end of experiment. Root colonization by both fungi increased EEG and TG compared to the non-mycorrhizal control ( p