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Phosphorus (P) fertilizer recommendations for calcareous-sandy soils low in organic matter need further investigation. Therefore, the objectives of this study were to evaluate the effects of P and manure on corn (Zea mays L.) growth and chemical compositions and P recommendations for calcareous sandy soils with low organic matter under greenhouse conditions. Treatments consisted of a factorial arrangement of P levels (0, 25, 50, and 100 mg kg-1 soil as KH2PO4), manure rates (0, 10, 20 and 30 g dried sheep manure per kg soil) and three soils (Soil 1, sandy loam, initial P 10.8 mg kg-1 ; Soil 2, sandy loam, initial P 7.6 mg kg-1 ; and Soil 3, loamy sand, initial P 5.5 mg kg-1 ) in a completely randomized design with four replications. Results showed that P application in Soil 1 decreased corn dry matter. However, application of 25 or 50 mg P kg -1 soil increased corn yield significantly in Soils 2 and 3, respectively. Maximum corn yield was obtained when 30 g kg -1 manure was added to sandy loam soils and 20 g kg-1 to loamy sand soil. Application of P and ma-nure significantly increased plant P concentration and uptake in all three soils. Zinc con-centration in plants treated with Phosphorus was higher than in the control in soils 1 and 2. Such a trend was not observed in soil 3, but manure application increased it. Iron con-centration in plants treated with P increased in soils 1 and 2 but was decreased in soil 3; however, manure application increased it in all soils. Plant Mn concentration and uptake responses to P and manure application was not consistent. Applied P, in general, in-creased plant Mn Concentration in soils 1 and 2, but had no effect on plants in Soil 3. Manure effect on plant Mn concentration was not consistent. It seems that addition of manure to sandy soils can improve soil productivity and increase corn yield. Due to the low P buffering capacity of sandy soils, application of high rates of P can increase P con-centration to an undesirable level in soil solution. This may depress plant growth and also availability of some micronutrients like Fe and Zn to corn plants. Therefore, P fertilizer recommendations for sandy soils should be based on the soil test P level. Manure applica-tion is recommended for sandy soils, due to its positive effects on nutrient uptake and plant growth. Prior to any phosphorus fertilizer recommendations for sandy soils the re-sults of this experiment should be verified under field conditions and measuring P concen-tration in soil solution at different stages of plant growth is highly recommended.

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Background: Measures of nutrient availability such as concentrations of carbon (C), nitrogen (N) and phosphorus (P) are important indicators of terrestrial ecosystems productivity. Current research illustrates the C, N and P stoichiometry of litter and soil in a coastal mixed forest stand, northern Iran.
Materials and Methods: To this, the Carpinus betulus (CB), Acer velutinum (AV), Pterocarya fraxinifolia (PF), Quercus castaneifolia (QC) species were considered; litter and soil (0-15cm depth) samples were taken under tree canopy cover.
Results: Litter and soil C: N ratio differed among the tree species, showing the highest (61.08 and 31.44) and lowest (21.90 and 3.59) under the QC and CB tree species, respectively. The litter and soil C: P ratio varied among the study sites and ranked in order of QC (52.4 and 27227.04) > PF (30 and 1465.61) > AV (15.74 and 630.54) ≈ CB (13.42 and 566.28). The higher amounts of litter N: P ratio were significantly found under QC (0.86) > PF (0.73) > CB (0.61) ≈ AV (0.55), whereas soil N: P ratio were significantly higher under CB (177.69) > PF (123.53) ≈ AV (121.60) > QC (109.25), respectively.
Conclusion: We found the species that differed in traits could influence C, N and P dynamics and its stoichiometry. The Q. castaneifolia species with different root traits that resulted in different vertical and horizontal distributions of C, N and P, reflecting differences in nutrient uptake by plants and microbial dynamics, drove the biggest changes in litter and soil C, N and P.

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The effect of 1,25-dihydroxycholecalciferol [1,25-(OH)2 D3 ] supplementation on laying hen diets was evaluated using diets high and low in Ca (3.0% and 1.8% ) and high and low in P( 0.52% and 0.33% ). Since two levels of 1,25- (OH)2 D3 supplementation (0 and 5 µg/kg diet ) were applied, the experiment was a 2 X 2 X 2 factorial arrangement in a com-pletely randomized design using nine individually housed hens per each 8 treatments (72 in total). The hens were fed the diets for 28 days and records were kept on body weight, egg production, feed intake, egg weight, and egg specific gravity. At the end of the ex-periment, the hens were bled for plasma Ca and P determination and after being eutha-nased the left tibia removed for bone ash measurement. The corn-soybean meal based diet contained 0.1% Cr2O3 as an indicator for determining Ca, P and phytate phosphorus re-tention at 14 and 28 days. 1, 25-Dihydroxycholecalciferol supplementation had no effect on hen weight, egg production or feed intake. However, large increases in egg specific gravity were obtained when 1, 25-(OH)2 D3 was fed to hens receiving the low Ca diet. All of the treatments had significant effects on bone ash. The greatest effect of 1, 25-(OH)2 D3 on bone ash was obtained in those hens fed the high Ca and P diet that was then supple-mented with 1,25-(OH)2 D3 (49.3% vs 53.9% bone ash). At day 14, the high Ca diets de-creased phytate P retention while at d 28 the high P diets decreased phytate P retention.

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Phosphorus (P) sorption in soils is a key process governing its availability to crops. There has been scanty information available on the P sorption characteristics of calcare-ous soils of Western Azarbaijan Province, Iran. In this study, P sorption characteristics and their relationship to soil properties were determined in 36 soil samples belonging to 15 agricultural soil series located in the south of Urmia, Western Azarbaijan Province. Total CaCO3 contents ranged from 10 to 48.5%. Active CaCO3 contents ranged from 1.7 to 20% and were significantly related (r = 0.61, P<0.001) to the total CaCO3 of the soils. NaHCO3-extractable P contents ranged from 4 to 38 mg P/kg soil. The amount of P sorbed by the soils differed among various soil series. The results showed that equilibrium solution P concentration (EPC) was lower (<0.2 mg/L) than the requirement for most crops. The amount of P adsorbed by the soils at 0.2 mg/L EPC ranged from 5 to 114 mg/kg soil. The phosphate adsorption was well described by the Freundlich (r2 = 0.96) and Langmuir (r2 = 0.88) isotherms. The Langmuir maximum adsorption (Xm) and Freundlich coefficient (aF) estimated from Langmuir and Freundlich equations ranged from 127 to 238 mg P /kg soil and from 43 to 211 mg P/kg, respectively. Soil clay content was significantly related to the soil P sorption indices, P0.4 (P sorbed at 0.4 mg P/L, r = 0.40, P<0.01), PBC (P buffering capacity, r = 0.54, P<0.001), aF (r = 0.48, P<0.01), and Xm (r = 0.40, P<0.01). Total CaCO3 and active CaCO3 were found to be less important factors affecting P adsorption.

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Application of phosphorus (P) fertilizers as solid or liquid fertilizers to soils leads to re-actions of orthophosphate ions with various soil components which remove P from the so-lution phase and convert it to less soluble phosphates. This study was aimed at determin-ing soil properties that affect the rate of phosphate retention in 28 contrasting calcareous soils from different geographical regions (14 soils from Western Azarbaijan in Iran (WAI) and 14 soils from Western Australia in Australia (WAA). The results showed that the mean apparent recoveries of applied available P (Olsen P-based recovery) after 160 d of incubation at field capacity was found to be 7% for the soils of WAI and 25% for the soils of WAA. A study of correlation coefficients showed that, for the soils of WAA, there was a negative relationship between the recovery of applied P and the clay content (r = -0.59, P≤ 0.05), whereas there was a positive relationship between the recovery of P and the active CaCO3 (ACCE) content (r = 0.64, P ≤ 0.01). For the soils of WAI, there was a negative correlation between the Olsen P-based recovery and the clay content (r = -0.61, P ≤ 0.01). The decline in extractable P with time was best fitted to a second order kinetic equation. The kinetic rate constant (k) ranged from 0.092 to 0.55 mg kg-1d-1 for the soils of WAI and from 0.31 to 0.92 mg kg-1d-1 for the soils of WAA. The kinetic rate constant (k) increased with increasing the ratio of the clay content to ACCE for all soils of WAI. A re-gression analysis study showed that the ratio of clay/ACCE was the major factor govern-ing P retention.

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Most areas of the world where rainfall is limiting are characterized by low agricultural output and, ironically, high population growth rates that generate increased food de-mand. Arid and semi-arid regions permit a range of vegetative biomass production, from rainfed crops to native pasture, and sparse steppe shrubs to true desert. Given the harsh climatic conditions in areas such as West Asia-North Africa, where less than 10% of the land area is amenable to rainfed cropping, soil resources are fragile and cropping condi-tions precarious. Yet with appropriate manipulation of soil fertility and crop management within a systems context, including breeding of improved cultivars, conservation tillage, and rotations, substantial production increases can occur at the farmer's level. While irri-gation has increased considerably in the past few decades, having a major impact on crop yields, surface and ground water sources remain limited. Applied research specific to the region has shown that crop output can be considerably enhanced with adequate nutrition, most of which has to be added as commercial fertilizer. The substantial yield increases that have taken place in several countries of the region have been attributed to three fac-tors: water, fertilizers, and improved varieties. Technologies that potentially produce such high yield increases include identification of nutrient stresses and taking corrective action, and, where appropriate, adapting the plant to the soil conditions. If managed properly, innovative cropping systems to overcome these constraints can improve rather than de-grade soil conditions. Regardless of the advances in biotechnology, crop adaptation, and integrated cropping systems, chemical fertilizers will, in future, play an even greater role in the nutrition of both rainfed and irrigated crops in Mediterranean agriculture. Crop nutrition research will have to keep pace with agronomic developments. The future chal-lenge in soil fertility-crop nutrition lies as much in overcoming obstacles to technology transfer as in the generation of new knowledge. This selective review is based mainly on the author’s research experiences in the field of soil fertility and crop nutrition in the WANA region for the past 32 years. It seeks to highlight research developments within the context of the region's crop production constraints, culminating in a perspective on future research challenges within the framework of cooperation between international in-stitutions and the region’s national research and development programs.

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Native phosphate solubilizing bacteria (PSB) were isolated from four areas (Ankober, Keyt, Mehalmeda and Molale) of Ethiopia to study their effect on releases of soluble phosphorus from insoluble P sources. The highest bacterial number was found at Keyt (2.6103 g-1soil) and the least at Molale (15 g-1soil). Five efficient PSB were selected for further study based on their ability in forming a higher clear zone diameter than the other isolates. These isolates were identified based on phenotypic characters as Pseudomonas sp. Anb-105, Meh-008, Meh-101, Meh-303 and Meh-305. The phosphate solubilizing efficiency of these five isolates along with Jim-41 isolate from the National Soil Research Centre were studied using different P sources [Tricalcium Phosphate (TCP), Egyptian Rock Phosphate (ERP), Bikilal Rock Phosphate (BRP) and Old Bone meal (OB)] in an incubation study. The results revealed that all the PSB isolates significantly (P 0.01) solubilized a higher amount of TCP, ERP and OB over the uninoculated control. The highest amount of solubilization was achieved for TCP with Meh-305 (39 mg per 50 ml) followed by ERP with Meh-101 (31 mg per 50ml) at pH 3.82 and 3, respectively. Although Meh-008 and Jim-41 isolates solubilized significant amount of BRP during the 20 days of incubation, the soluble P obtained was very small as compared to other P source tested.

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This research aims to isolate phosphorus-solubilizing fungi from the sediments of warm-water fish farms and evaluate their performance in phosphorus solubilizing from various insoluble sources of phosphorus (tricalcium phosphate, iron phosphate, aluminum phosphate, and calcium phytate). For this purpose, four stations in Mazandaran province were sampled and isolated using NBRIP solid culture medium (49 mushroom isolates, including 19 isolates from organic phosphorus-containing culture medium and 30 isolates from inorganic phosphorus-containing culture medium). Then, the ability of isolates to dissolve phosphorus in solid and liquid culture medium was evaluated. Among the isolates, isolates PS3D, PS3F, and PS5F had the best performance among isolates solubilizing organic phosphorus (average phosphorus release 179.85-191.08 mg/liter). TS4E isolate was also selected as the best inorganic phosphorus solubilizing isolate. Then these isolates were molecularly identified by S18 rDNA gene sequencing and were registered as Talaromyces austrocalifornicus (PS3D), Trichoderma harzianum (PS3F), Aspergillus niger (PS5F) and Penicillium oxalicum (TS4E). In the final stage, the ability of these isolates to dissolve phosphorus in microcosm conditions (water and sediment-containing jars) was evaluated for 15 days. Contrary to the performance of these fungi in a liquid culture medium, the amount of soluble phosphorus in microcosm conditions showed a decreasing trend compared to day zero. However, the amount of phosphorus in the treatments containing mushrooms was higher than the control group. In general, the performance of the fungi introduced in this study has been positive in phosphorus release.

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Objective: Organophosphorus hydrolase (OPH) is a homodimeric enzyme that can hydrolyze phosphoester bonds and reduce the toxicity of organophosphorus compounds. This makes OPH a suitable element for the biodegradation of these compounds. Methods: We successfully cloned the OPH gene from Pseudomonas diminuta, after optimization for Pichia pastoris, into a yeast expression vector (pPICZαB). After transformation and induction of recombinant yeasts, the expressed enzyme was investigated for its biochemical and kinetical parameters. Results: The enzyme was purified 7.49-fold to a specific activity of 0.421×10³ U/mg protein from the supernatant with a yield of 33%. The purified enzyme was able to degrade organophosphates. It had an optimal activity and stability up to 50°C, and a pH range of 7.0-10.0. The enzyme had a Km of 45.96 µM and a Vmax of 11.23 µM/min (421 µM/min/mg) for paraoxon as a substrate. This enzyme was sensitive to divalent cations and inactivated by denaturing compounds such as SDS. The molecular mass of the purified enzyme as estimated by SDS–PAGE analysis was approximately 40 kDa. Conclusion: In this study, the purified enzyme effectively hydrolyzed paraoxon, an organophosphorus compound. The activity and stability of this enzyme at high temperatures and pH, and low Km in comparision with bacterial isolates could make it an attractive biocatalyst for applied bioremediation and biosensing

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One of the major water pollution factors in receiving water bodies is the presence of excessive nutrients (nitrogen & phosphorous compounds) due to wastewater discharge to the environment. If phosphorus level exceeds its discharge standard (6 mg/L), it will cause eutirification which resulted in secondary water pollution due to algal blooming crisis. Development of different methods to remove phosphorus from the year 1950 was performed in response to the need of reducing the discharged phosphorus amount to surface waters. Phosphorus is removed using different chemical and biological methods that have disadvantages such as greater capital and operational costs, operational problems, high sludge production and safety operational & maintenance requirement. So phyto-remediation method can be used to overcome these disadvantages. This useful technology is actually a genneric term for several ways in which plants can be used to clean up contaminated soils and water. Considering this fact phyto-remediation is a bioremediation process in which a particular type of plant used to remove, transfer, stabilize, degrade and volatilize of contaminants (such as pathogens, heavy metals, pesticides, solvents, crude oil, arsenic, cyanide and radioactive elements) by accumulation, stabilization, extraction, rhizofiltration, rhizodegradation or volatilization mechanisms. Phytoextraction is the name given to the process where plant roots uptake polltants from the soil and translocate them to their above soil tissues. Rhizofiltration is similar in concept to Phytoextraction but is concerned with the remediation of contaminated groundwater rather than the remediation of polluted soils. The contaminants are either adsorbed onto the root surface or are absorbed by the plant roots. Phytostabilisation is the use of certain plants to immobilise soil and water contaminants. Contaminant are absorbed and accumulated by roots, adsorbed onto the roots, or precipitated in the rhizosphere. Selection of appropriate plant and microbial species, biological accumulation and transmission of pollutants, contaminant concentration and its disposal are the most important factors in phyto-remediation process. Environmental factors including ambient temperature, solar radiation, the presence of nutrients, water and oxygen and the type of material removal will also affect the process. In this study reed, bamboo and umbrella plant were evaluated in removal phosphorus from water in different concentration of 2,10, 25, 50 and 100 ppm in vitro condition (ambient temperature of 23-25 ◦C, DO of 4.5 – 6.5 and pH of 6.5- 8.5). According to the results, the maximum phosphorous removal was observed in reed plant pilot at concentration of 25 ppm. The percent removal efficiencies were found to be 17.3, 35.81, 87.94, 78.77, 48.63, 52.4, 92.01 for reed, 15.66, 21.07, 68.08, 57.89, 34.41, 48.33 and 73.69 for bamboo and 15.89, 21.5, 37.23, 32.41, 22.33, 30.48 and 54.47 for umbrella plant at mentioned concentrations, respectively. Overall phosphorous removal for reed plant, bamboo and umbrella plant were 59, 45.5 and 30.65, respectively.

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Urban runoffs usually contain a large variety of pollutants such as heavy metals, organic compounds, nutrients, solids, and de-icing agents. These are normally accumulated on impervious urban surfaces over time. Hence, the runoff itself becomes a wastewater that could create substantial degradation of water quality in receiving area. There are many alternative management strategies for treating these contaminants. Most of the approved stormwater management measures are difficult to be implemented on a wide scale (due to infrastructure and space/cost constraints). Permeable pavement is one of the urban runoff management methods that are widely used in order to reduce storm runoff flow and volume, and minimize pollution conveyance to receiving waters. Pervious pavement systems consist of a permeable pavement surface layer and one or more underlying aggregate layers designed to temporarily store storm-water. Runoff treatment using three aggregate layers, namely steel slag, limestone and silica aggregates were applied both as filter and pavement base layers. The research was conducted at laboratory scale and in continuous mode. All the experiments were conducted in cylindrical reactors of 0.6 m height and 0.2 m diameter. Each column was filled up to an average depth of 0.5m (0.1 m for filter layer and 0.4 m for the base layer). In order to determine the lifespan of the media, synthetic runoff in successive cycles was injected into the column continuously. Results from the study showed that the base and the filter layers of the permeable pavement can reduce the total range of runoff pollutants effectively with high removal percentages. In all experiments the rate of pollutant removal at the initial time of reaction was faster. However, these were gradually decreased and after 120 hours approximately the maximum removal efficiency was achieved. Comparing the effects of the three aggregates types, the steel slag aggregates exhibited better performance. The treatment process showed that the maximum removal of COD, phosphate and total solids from runoff in 3 hours, were 61, 59 and 70 percent respectively. These were increased to 98, 96 and 99 percent after 120 hours. In addition, the total capacity of slag aggregates for removing COD, P-PO4 and TS parameters were estimated to be 3.43, 0.21 and 22.10 g/Kg respectively. The testing results indicated that after the slag aggregates, limestone materials showed a high ability to remove pollutants from runoff waters as compared with the silica aggregates. The kinetic study resulted that the pseudo-second order kinetics equation, compared with the pseudo-first order and intra-particle diffusion models, described better the removal of organic compound absorption (COD removal) from the storm water. In this study the rate constant of the reaction (K) for the COD removal via steel slag, limestone and silica aggregates were estimated to be 0.31, 0.31 and 0.30 g mg−1 min−1 respectively. The correlation coefficients (R2) under different conditions were also calculated to exceed 97%. Since steel slag is a byproduct of steel production factories, its application as a road-building material, would be an appropriate alternative pavement layer in protecting the environment and conserving the natural resources.

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Poinsettia as an ornamental pot plant is widely grown in peat-based substrates with high phosphorus (P) fertilization. The aim of current study was to evaluate the P demand of poinsettia according to its depletion ability during the growth stages by using a mechanistic simulation model. For this purpose, rooted poinsettia cuttings were grown in the medium with 80: 20 (V: V %) peat+ mineral component (generally is called as clay) and treated with different P levels of 0, 10, 35, 100, and 170 mg P [L substrate]-1. The yield and quality performance of the plants were evaluated thoroughly. Also, depletion of P around the root surface and the effect of buffering power on the depletion profile were assessed by means of mechanistic simulation model. The results showed that in peat-based substrates, P was transported to the root surface mainly by mass-flow. The simulation approach as well revealed that the well supplied plants cultivated in the peat-substrates needed a higher concentration gradient (30-50 µM) to drive the necessary flux and that the amount of plant available P (Cs) was limiting at later growth stages. The optimum yield and quality of poinsettia was obtained at the P application rate of 35 mg L-1 substrate, with Cs of 11-12 and 15-16 mg [L substrate]-1 at planting and 53 days after planting. It has been concluded that, to ensure a sufficiently high concentration gradient, P had to be supplemented by frequent fertigation at later growth stages but not at the early growing stage.

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Objective: Organophosphorus (OPs) compounds are widely used in many pesticides, insecticides and chemical nerve agents. These compounds are hazardous for humans and the environment. Organophosphate hydrolase (OPH) is a homodimeric protein initially isolated from Pseudomonas diminuta MG and Flavobacterium species. This enzyme is able to degrade a broad spectrum of toxic OPs compounds. Using immobilized OPH commonly presents a variety of advantages versus the free form of the enzyme. Advantages include an increase in stability, cost reduction by simple recovery and reutilization of the enzyme, quick and easy separation of the reactant and product in the reaction medium. Methods: Plasmid pET-26b (+) was used to generate the OPH protein under the control of the T7lac promoter. E. coli BL21 (DE3) pLysS was used as the host for expression of the OPH enzyme. Recombinant OPH was secreted into the extracellular medium and the purified enzyme was immobilized on the surface of Bacillus subtilis spores by the adsorption method, for the first time. Results: Approximately 42% to 45% enzymatic activity was determined to be associated with spores. Optimal pH and temperature of the enzyme were not altered by the presence of the spores. Thermo and pH stabilities of the immobilized enzyme was higher than the free form of the enzyme. Conclusion: Bacillus subtilis spores are safe for humans and the environment. Therefore this system can be considered an environmentally friendly biocatalyst for degradation of OPs. 

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We evaluated the effect of different concentrations of Phosphite (Phi) (0, 0.25, and 0.50 mM) in nutrient solution on lettuce and chard. The fresh and dry biomass of lettuce shoots and heads, root volume, and P accumulation in roots showed no significant differences compared to the controls for different Phi concentrations in nutrient solution. In chard, no statistical differences were found among Phi concentrations for P concentrations in roots and shoots, total free amino-acids in leaves, chlorophyll-b, and soluble sugars. The phosphorus concentration in lettuce shoots was 15.6 and 50.6% higher in plants treated with 0.25 and 0.50 mM of Phi, respectively, compared with the controls. In lettuce, phosphorus levels in roots, total free amino-acids and soluble sugars in leaves were statistically greater for 0.25 mM of Phi in nutrient solution. The concentration of chlorophyll-a, b and total chlorophyll in lettuce leaves increased positively with Phi concentration in nutrient solution. The addition of more than 0.25 mM of Phi to the nutrient solution for chard negatively affected the fresh and dry biomass weight of shoots and roots, and P accumulation in roots and shoots. The concentration of chlorophyll-a, b and total chlorophyll in chard leaves was statistically higher with 0.25 mM of Phi in nutrient solution. We conclude that Phi has differential effects on lettuce and chard physiology, and positive plant responses may be observed when Phi is used up to 0.25 mM in sufficient P conditions.

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This study aimed to investigate the residue levels and dissipation rates of chlorpyrifos, diazinon, and their oxon derivatives in greenhouse-grown tomatoes and to evaluate the acute and chronic Hazard Quotients (HQ) for consumption of these products. The quantification analyses of chlorpyrifos and diazinon and their degradation products were performed using Gas Chromatography Coupled with Mass Spectrometry (GC-MS/MS). The Monte Carlo simulation technique was used to evaluate the variability and uncertainty of the data and to achieve more accurate results in the health risk assessment process. The chronic HQ values of chlorpyrifos and diazinon residues ranged from 0.24 to 0.85 and 0.06 to 1.09 for adults, 0.45 to 1.34 and 0.12 to 1.66 for adolescents, and 0.71 to 1.80 and 0.21 to 3.78 for children, respectively. After five days of storage in room and refrigerator temperatures, the HQ values of diazinon and chlorpyrifos were higher than the acceptable limits. According to the Monte Carlo simulation, the HQ and the estimated daily intake (EDI) values were more affected by the consumption rate followed by pesticide concentration and body weight. Therefore, due to the high frequency of tomato consumption, it is necessary to reduce the concentration of pesticides in this product in order to reduce human health risk.