نشریه مهندسی زراعی
سال چهل و چهارم شماره 4 (زمستان 1400)

Cooling systems such as refrigeration and air conditioning are considered as basics of everyday life. In these years, the demand for both energy/associated services to address economic and social along with ameliorate human comfort and health is continuously increasing. Since approximately 1850, the global use of fossil fuels (coal, oil and gas) has dramatically raised to dominate energy supply. However, the required energy for the above-mentioned applications is mainly generated by non-renewable electricity. Due to the depletion of fossil fuels as a source of electricity, the development of renewable energies for such systems is necessary. Considering all these issues, as cooling needs, most of the time coincides with the solar radiation availability; therefore, exploring solar energy seems an exciting idea. A number of investigations were performed to design/develop new cooling techniques using solar energy. A solar cooling system is capable of considerably reducing the environmental effects of traditional refrigerating machines while allowing significant energy saving. The present work searches for the best choice of configuration/design factors of food refrigeration systems combined with solar-powered absorption chillers unit in Ahvaz city as a case study.

 In the present study, a linear parabolic collector with specific dimensions, was made, so that first, the initial design of the collector with longitudinal dimensions of 1 and a width of 0.6 meters was selected by Katia software, and then using related relations and calculations of other structural parameters based on which the collector was built, the collector simulation was performed using NASA radiation data for the place and time of the experiments and by using the Transient Simulation Software and its performance in the days of the month July, August and September 2019 were reviewed and evaluated. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2. Also, the necessary calculations were performed on the results of performance tests by Excel software, and diagrams of changes in the radiant energy absorbed by the collector and the efficiency of the radiated energy absorbed were drawn from 10:00 AM to 6:00 PM. Using the diagrams obtained from the system simulation in TRNSYS (Transient System Simulation Tool) software, it is concluded that the built-in collector has the ability to produce a fluid with a temperature above 98 degrees Celsius required for the absorption chiller in July, August, and September.

 According to the evaluations of the collector's performance in the three months of July, August, and September from 10 AM to 6 PM showed that collector energy and efficiency reached their maximum values in July with 318.240 w-h/m2 and 63.05 %, respectively. While in August, the amount of energy and efficiency was found to be 299.311 w-h/m2 and 61.94%, respectively. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2.The minimum value of the parameters were recorded as 283.379 w-h/m2 and 61% in September, respectively. The potential analysis conducted showed an excellent saving potential in terms of energy obtained. According to the results, the useful collector energy was achieved to be 227.664 w-h/m2, 217.006 w-h/m2, and 210.406 w-h/m2 in July, August, and September, respectively. According to the obtained results, the maximum refrigeration load needed for the studied cold storage was about 126324 w. According to the results, the average energy obtained for the collector in the three months of July, August, and September was about 216.054 w-h/m2. Finally, the area of the collector was calculated, the results showed that the required surface of the collector was found to be 584.687 m2.

 The development of renewable energies for such systems is necessary. Solar cooling system for food products cold storage in Ahvaz city is a promising and innovative alternative to decline the peak energy consumption generated by the combustion of fossil fuels, especially during the summer months.

In Iran, salinity is a pervasive and limiting Factor of agricultural sustainable production. Plants in saline conditions are exposed to limited absorption of nutrients, water and toxicity of some elements and subsequently, their yield will be affected by salinity. Moreover, being calcareous, the salinity of soil and irrigation water, low organic matter in the country's arable soils, and excessive consumption of phosphate fertilizers cause a lack of available nutrients for the plant uptake. As regards more than three billion people in the world suffer from a lack of micro nutrients, the bio-enrichment in strategic products such as wheat is necessary.

 This study was carried out in Khuzestan province in a calcareous and saline soil with silty clay texture under wheat cultivation as a factorial experiment in a randomized complete blocks design with three replications. Factors included four levels of zinc (zero, 30, 60 and 120 kilograms per hectare of zinc sulfate) and the four levels of iron (zero, 2.5, 5, 7.5 kilograms per hectare of Fe- EDDHA). Zinc fertilizer treatments were used as application in soil and simultaneously with basic fertilizers (phosphorus and potassium fertilizers). While, iron fertilizer treatments were applied as irrigation fertilizer during wheat tillering stage. At the end of the growth season, wheat yield components (1000-seed weight, number of grains per spike, biomass weight, grain yield, number of tillers per square meter) and quality characteristics including hectoliters, seedling number, protein percentage, grain hardness and moisture content in different treatments were determined. MSTAT-C statistical software and Duncan's multiple range test were used to compare the means of the studied treatments.

The results showed that the interactions of zinc and iron on 1000-grain weight, number of grains per panicle and number of tillers and simple effects of zinc on total yield were significant (p< 0.01). The highest wheat grain yield was obtained in the treatment of 120 kilograms per hectare of Zn and 2.5 kilograms per hectare of iron and was equal to 6723 kilograms per hectare. The results showed that increasing one element alone had a negative effect on the number of plants per square meter. So that the lowest number of tillers per square meter (489 tillers per square meter) was observed when 60 kilograms per hectare of zinc fertilizer was consumed without iron fertilizer application. In other words, the imbalance in the amount of nutrients caused a significant reduction in the number of plants per square meter. Although the role of iron in yield and yield components of wheat in saline conditions was less than the element zinc, but the combined use of zinc and iron in a certain ratio had a positive effect on the yield components of wheat. Despite the less effect of iron application than zinc on wheat yield and yield components in saline conditions, the combined application of zinc and iron in a certain ratio had a positive effect on the wheat yield components. Combined and separate application of iron and zinc had no significant effect on wheat grain quality indicators including hectoliters, hardness and moisture. While the application of the most value of zinc caused a significant decrease in the wheat grain zeleny index. Higher levels of zinc fertilizer reduced the zeleny number of wheat grain, but the results showed that iron fertilizer levels followed the opposite trend rather than the element zinc. The least protein content (12.8%) was obtained in the treatment of 120 kg zinc fertilizer per hectare, which showed a statistically significant difference with the control treatment. Based on economic analysis, the application of 30 kg of zinc fertilizer per hectare, 2.5 kg of iron fertilizer per hectare and the combined application of both zinc and iron fertilizers resulted in a benefit-to-cost ratio of 2.3, 3.1 and 2, respectively.

 Based on the economic analysis of treatments, their effect on qualitative and quantitative yield of wheat and the role of these micronutrients in human health, application of 30 kg ha-1 Zn fertilizer (as application in soil) and 2.5 kg ha-1 Fe fertilizer (as Irrigation fertilizer) in the wheat tillering stage was suggested in saline soil and climate conditions of khuzestan province.
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Land-use changes may influence various natural and ecological processes, including soil nutrients, soil moisture, soil erosion, land productivity and biodiversity. Compact cropping and lack of suitable management approaches in agricultural fields all over the world have affected soil properties in vast areas and led to changes in soil quality. The cultivation of sugarcane in the south of Iran started 60 years ago. The cultivation of sugarcane was mechanized in the southwest of Iran in the late 1950s. Over the past 40 years, the sugarcane yield has been declined from 110 to 50 tons per hectare over the same period. The long-term cultivation period (6 to 7 months), high water consumption (30,000 cubic meters per hectare at 25 to 30 turns irrigation), extensive heavy machinery uses in the planting stage, and sugarcane harvesting may change soil properties. In order to determine how these changes are taking place, it is necessary to examine the land qualitatively and quantitatively to prevent further destruction of this vast God-given source. Due to the fact that few types of research have so far been conducted on the long-term effects of cultivation on the physical and chemical properties of soil, this study aimed to investigate the effect of long-term sugarcane cultivation on some chemical and physical properties of soil in the Karoun Agro-industry Unit in Shoushtar city, Iran.

 This research was carried out to investigate the effect of long-term sugarcane cultivation on soil chemical and physical properties in Karoun Agro-industry Unit in Dimcheh with the geographical coordinates Latitude: 32° 02' 60.00" N Longitude: 48° 50' 59.99" E and 68 meters above mean sea level located at 12 kilometres to the west of Shoushtar city in Khuzestan province of Iran. The total area of the land is 45,000 hectares. This area has warm and dry climate conditions. The dominant soils of the area are classified in the large Calcic Haplousteps group. This study was carried out as a factorial experiment based on a complete randomized design with two factors, including fields in seven levels and depth in three levels (0-30, 30-60 and 60-90 cm) and three replications. Soil samples were collected from three depths in six fields with long-term sugarcane cultivation and adjoining uncultivated land. Then, some chemical properties were measured by standard methods Soil texture by hydrometric method, soil organic matter content by wet oxidation method, the soil sodium bicarbonate extractable phosphorus by Olsen method and available K using 1 N NH4OAc were measured. Also, total porosity and mean weight diameter were calculated based on conventional equations. Statistical analysis of data was performed by SAS 9.2 software, and the comparison of means was made using Duncan's multidomain test at a 1% probability level. Figures were also drawn using Microsoft Excel software.

 Results indicated that land-use changes and long-term sugarcane cultivation result in soil chemical properties changes. By land-use changes, the amount of sand decreased from 22.55% in virgin soil to 6.67% in sugarcane fields. The apparent density and the mean weight diameter by changing the use of virgin soil to sugarcane farms increased by 16% and 67%, respectively, though this result was opposite for the total porosity. Also, land-use changes from virgin soil to sugarcane fields increased organic matter and absorbable phosphorus and reduced potassium absorbable and carbon-to-nitrogen ratio. Overall, changes in chemical properties in surface soil (0-30) were more than other depths (30-60 and 60-90). Also, estimating the correlation coefficients between different traits under the studied treatments showed that sand was correlated with all traits except clay and organic matter. In contrast, the clay had a positive and significant relationship with the mean weight diameter of soil aggregates.

 This research showed that the soil chemical properties of different sugarcane fields significantly changed by the land-use changes of long-term sugarcane cultivation. Thus, the land-use changes, abundant irrigation and leaching increased the organic matter, the mean weight of the diameter of aggregates and the apparent density of the soil. Also, the amount of phosphorus absorbed by sugarcane and fertilization increased, while the amount of organic matter of C/N and soil absorption potassium decreased in cultivated land. Potassium is essential for sugarcane growth, and the reduction of potassium absorbable can cause limitations in its growth and performance. On the other hand, concerns about soil density and change in the optimal plant growth conditions due to heavy agricultural machinery are clear and severe. Therefore, creating a cultivated system with minimal density is essential. Also, soil chemical properties monitoring and maintaining the quality of the studied soils must be considered in land management approaches.

The application of biochar in soil as a method for disposal of organic wastes from environment has been considered by environmental scientists in recent years, due to the unique properties of these components. Biochar is a carbon-rich compound that is produced by burning different types of organic wastes under anaerobic or limited supply of oxygen, which called pyrolysis. Biochar due to its physicochemical properties such as porous structure, expanded specific surface area, high organic carbon content, active functional groups, and also high cation-exchange capacity could able to stabilize organic and mineral compounds. Many studies showed that the biochars enhance soil fertility and improve plant growth but if we want to recommend or apply a specific biochar as an amendment of soil, it's necessary to know about the effects of this biochar on the soil properties and growth of plant. So, the aim of this study was to find out the effect of two biochar (biochar of Date Palm's Leaves (DPL biochar) and biochar of Pistchio Harvesting wastes (PW biochar)) on the growth and heavy metals concentrations of Maize (Zea mays L.) under two different soil textures (Sandy and Sandy Loam).

This study was conducted in a greenhouse condition on the growth of maize in two types of soil (Sandy and Sandy Loam) with application of 5 levels (0, 1, 2, 3 and 5% w/w) of two different types of biocahr (DPL biochar and PW biochar). Maize were cultivated in treatments for 38 days and at harvesting the shoot and root dry weight and shoot height were measured. Also, the concentration of heavy metals (including Fe, Zn, Cu, Mn, Ni, Pb, and Cd) in plant shoots were evaluated.

The result showed that the growth of maize severely decreased due to the application of the biochar and the negative effect of PW biochar was more than DPL biochar. Meanwhile, the negative effect of PW biochar on plant growth in sandy soil was more than other one (i.e. Sandy Loam soil), which medium (2 and 3% w/w) and high (5% w/w) levels of this biochar caused the plant to stop growing. Also application of 5% of DPL biochar in Sandy Loam soil caused in a decrease of about 19, 69 and 72% in plant height, shoot dry weight and root dry weight of maize in compared with control (without biochar application in this soil), respectively and these ratios were about 15, 44 and 31% with application of 3% DPL biochar; while with application of 3% of PW biochar in sandy loam soil has decreased plant height, shoot dry weight and root dry weight of maize about 17, 53 and 37%, in compared to control respectively. These results approved the greater negative effect of PW biochar on plant growth. Assessment of soil salinity as the application of different levels of biochars showed that these materials increased salinity and thus had a negative effect on plant growth. In overall, the results of this study showed that the use of different biochars have different effects on plant growth, since most of biochars have high salinity, coarse-textured soils could more affected by salinity, because of the lower water holding capacity of this soils. Since, biochar is a stable substance, the results of the concentration of elements in the shoot of plants showed that the concentration of most elements not significantly affected by the application of biochar, however the increase in Fe concentration in sandy soil due to application of PW biochar, also Mn uptake in the effect of applying 1% of DPL biochar was observed. On the other hand, the results of this part of the research showed that DPL biochar at higher levels has even reduced the concentration of Mn in the plant. The results of this section also showed that the application of biochar in sandy loam soil, although it was significant on the concentration of heavy metals Pb and Cd in the plant and had slightly increased them, but their concentration was less than critical levels (dangerous) for human health.

The effect of biochar on improving plant growth can be greatly influenced by the combined effect of biochar properties and soil conditions. The results showed that despite the many benefits of the soil application of biochar in the different scientific literatures, it is necessary to study the effect of biochar on soil properties and plant growth before applying any type of biochar in the soil.

Soil microorganisms play an important role in maintaining soil quality through the decomposition of organic matter and nutrients cycling. The quantity of plant residue has a positive effect on the accumulation of organic carbon in the soil. One of the most important problems hampering the release of nutrients from plant residues is the high content of lignocellulose in their structure. Therefore, biological treatment has been considered as a candidate to improve lignocellulosic conversion and more release of nutrients from them. Salinity reduces microbial biomass and decreases their activity in decomposition of soil organic matter and organic matter input into soil. Due to the importance of the role of microorganisms in the storage and release of energy and nutrients in the soil, in recent years, increasing attention has been paid to the estimation of microbial activity and biomass in soil. Therefore, the aim of this study was to study the effect of salinity, inoculation of Pleurotus astreatus and wheat residue on respiration, microbial biomass carbon, organic carbon, carbon availability index and metabolic quotient.

The experiment was conducted as a completely randomized design with factorial arrangement in three replications under controlled laboratory conditions at Gorgan University of Agricultural Sciences and Natural Resources. Factors included three salinity levels (0, 8 and 15 dS m-1), two fungal levels (0 and 5%) and two wheat residue levels (0 and 1%, w/w). Salinity treatments including (control), 8 and 15 dS m-1 was applied using a mixture of salts (NaCl, KCl and MgCl2 with a molar ratio of 3:2:1). Wheat straw was treated pleurotus fungus and the treated straw was then thoroughly mixed into the soil. To activate the microbial population, soil moisture was adjusted to about 70% of the field capacity and the containers were pre-incubated at room temperature for 2 weeks. The samples were incubated at 25±2°C for 90 days. Microbial biomass carbon, organic carbon was measured at monthly intervals, microbial respiration was measured weekly and substrate-induced respiration (SIR) was measured once at the end of the incubation period.

The results show that salinity has a negative effect on microbial activity and population, but wheat residues reduce the effect of salinity stress on soil microbial community. Inoculation of Pleurotus into the soil also increased the respiration and microbial biomass. The interaction of wheat residues and Pleurotus on microbial activity in saline soil was greater than their effect alone. According to the results, the simultaneous addition of Pleurotus and wheat residue increases organic carbon (%98), microbial respiration rate (90%), substrate respiration (69%) and microbial biomass carbon (79%) and decreases the metabolic coefficient (6%). Salinity reduced respiration (78%), microbial biomass carbon (81%) and carbon availability index (23%), which indicates a decrease in carbon for microbial activity in saline soils. The lowest and highest microbial activity and biomass were in saline soil (15 dS m-1) not treated with wheat residues and Pleurotus (S2F0R0) and in non-saline soils treated with wheat residues enriched with Pleurotus (S0F1R1), respectively. The results showed that higher salinity level (15 dS m-1) further decreased the measured characteristics including carbon availability index, respiration and microbial biomass carbon compared with 8 dS m-1 salinity level in all treatments. In non-treated soil with wheat residue and Pleurotus, salinity level of 8 dS m-1 reduced MBC by 43, 46 and 44 % compared to control (non-saline) soil. The results showed that there was a significant negative correlation between microbial respiration rate and salinity (P <0.01, r = - 0.87). Salinity reduced microbial respiration rate and the effect of salinity on reducing microbial respiration rate of soil with EC 15 dSm-1 was higher than lower salinity level (8 dSm-1). Also, inoculation of Pleurotus in soil led to increase microbial respiration rate compared with non-treated one. According to the results, salinity levels of 8 and 15 dSm-1 reduced carbon availability index in soil treated with Pleurotus and wheat residue by 18% and 23%, respectively, compared to non-saline soil.

The addition of wheat straw enriched with Pleurotus astreatus increased microbial respiration, organic carbon, microbial biomass carbon, substrate-induced respiration and carbon availability index due to the increase of available substrate. Therefore, in saline soils with carbon restriction, increasing the level of organic matter, increased microbial activity and biological potentials in the soil. However, further information on responses of microbial indicators to the joint effect of salinity and Plant residues enriched with other microorganisms is required.ReceivedReceived in revised formAcceptedKey words:Carbon availability index, Microbial biomass carbon, Microbial respiration rate, Soil organic carbon, Substrate-induced respiration

Date fruit production has an important position in either Iran or the world. Life and economy of many of people who live in the West Asia and North Africa (WANA) depend on this agricultural product. Date palm crown access, as one of important operations of date fruit production, is performed in a traditional manner with a tool talked “Parvand” yet. It results in various ergonomic and safety problems, such as fall from height, sunstroke, and musculoskeletal disorders (MSDs). Meanwhile, mechanization could not adequately adopted by date palm growers. Possibly, ergonomic interventions in forms of simple tools mitigate ergonomic and safety problems in date palm crown access operation.

 In this study, some ergonomic interventions were investigated to improve the present status of ergonomic and safety status of this operation with employing nine workers from Ramshir city, Khuzestan province, Iran. Evaluated date palm climbing tools were as follows: Parvand (traditional tool), Parvand+rubber shoes (intervened tool), harness (intervened tool), and harness+rubber shoes (intervened tool). Parvand consisted of a backrest and a towing wire. In two last mentioned intervened tools, harness was replaced with backrest in Parvand. Indeed, harness was the brief name of composition of harness and towing wire. Comparisons were done based on some ergonomic, safety, bio-mechanical, and technical indices. Ergonomic evaluations included physical and cognitive ones. Body discomfort (BD), heart rate (HR), worker energy expenditure (EE), working oral temperature (OT), and physiological strain index (PSI) were the physical indices. Perception-based heat Strain Index (PeSI) and acceptance of climbing tools in view of workers were the cognitive Indices. Acceptance comprised workers’ perception about safety, work speed, ease of use, technical properties, and preference of the tools. Safety evaluation was conducted using failure mode and effects analysis (FMEA) which resulted in a risk priority number (RPN) for each climbing tools. Bio-mechanical evaluations were performed using 3DSSPP software (to find the compression and shear forces on L5/S1 disc) and the investigation of mechanical stresses of Parvand and harness (to achieve the factor of safety (FoS) of tools). Technical index was the total time cycle (TTC) to perform date palm crown access (install climbing tool, ascending, and descending). Statistical analysis was conducted using IBM SPSS 24. During evaluation, workers’ qualitative feedbacks around intervened tools were recorded.

 Mean age, height, mass and body mass index of workers were 33.1 years, 1.71 m, 74.0 kg, and 25.3 kg/m2, respectively. According to the statistical analyses, there was no any significant difference among climbing tools regarding BD, HR, EE, OT, PSI, PeSI, RPN, and TTC. Bio-mechanical evaluations showed that all four climbing tool caused a low risk compression force on L5/S1 (<3400), whereas interventions including harness were significantly higher than those including Parvand. Traditional and Parvand+rubber shoes with shear forces of 1120.9 and 1119.6 N, respectively, on L5/S1 disk resulted in high injury risk (>500 N) and were significantly higher than other two methods in which harness was used (p<0.001). FoS was achieved for Parvand and harness 1.21 and 3.53, respectively. Therefore, only harness could cover the minimum FoS required to work in height (2.4) according Ministry of Cooperative, Labor and Social Welfare’s regulations. During cognitive evaluations, harness+rubber shoes gained the highest safety level (score of 17) as well as the highest preference level (score of 14), whilst, Parvand+rubber shoes had the highest cognitive-based acceptance score (score of 58). Workers’ qualitative feedbacks, in order of frequency, were as follow: harness ropes should be wider (33%); towing wire-harness joint should be upper (from pelvis toward waist) (22%); harness ropes should be softer (especially around the thighs) (22%); harness should be integrated (i.e. without rope, like a short) from pelvis to thighs (11%); rope buckle should be used so that harness is more easily-and fast worn (11%).

 Safety and work speed can be two main factors in the preference of a date palm crown access tool. Overall, intervened tools had a better state concerning safety, whereas, the qualifications were almost equal considering ergonomics. Notwithstanding it, the intervened tools had the lacks around work speed and technical properties which should be amended. Besides the attempts for development of date palm mechanization, further studies may be conducted on intervened date palm climbing tools, especially harness+rubber shoes method, based on workers’ qualitative feedbacks to gain a more appropriated level.

 Phosphorus (P) is one of the most necessary plant nutrients and the second key plant nutrient after nitrogen, which deeply affects the overall growth of plants. Most of the present P in calcareous soils is biologically unavailable, therefore mobile P is rare despite the abundance of both organic and inorganic forms of P in soils. It has been well-known that P use efficiency of triple superphosphate (TSP) fertilizer in alkaline soils is low. Due to the increase in the price of phosphate fertilizers and their low plant absorption (10–30%), the use of indigenous phosphate solubilizing bacteria (PSB) to increase P-fertilizer-use efficiency and reduce its application amount can be a perfect way. The combined use of bio-fertilizers and superphosphate is an important component of integrated nutrient management, which leads to sustainable agriculture. This research was carried out to investigate the contribution of native phosphate solubilizing Pseudomonas sp. along with superphosphate application to increase soil P solubility, yield and nutrient concentration of maize and improve some soil properties in a calcareous soil with low organic matter and phosphorus.

Eleven strains of Pseudomonas sp (Pseudomonas sp. Pseudomonas koreensis) bacteria were obtained from the Gene Bank of Iran Soil and Water Research Institute. The phosphate solubilizing activity of each bacterium was evaluated in Sperber medium quantitatively (liquid) and qualitatively (plates). Each bacterium was cultured in two plates with three replications and incubated at 28 °C. Then the colony and halo diameter were measured on the third, fifth, seventh, tenth, and fourteenth days after incubation. To evaluate phosphate solubility by bacteria in a liquid medium, 50 ml of Sperber medium was prepared and sterilized with three replications. Then 1 ml of fresh culture suspension of each bacterium with a population of 107 cells/ml was inoculated into each Erlenmeyer flask (treatments and controls) and incubated at 150 rpm and 150 ° C for 14 days. Soluble phosphorus (Vanadate-molybdate method) and pH on the first, third, tenth and fourteenth days of incubation were measured. To assay the interaction effects of bacteria and triple superphosphate fertilizer on quantitative and qualitative yield of maize plant and characteristics of soil cultivated in a soil with low level of organic matter and phosphorous, a factorial based on randomized completely design including 8 bacteria (B0, B1, B2, B3, B4, B5, B6, B7) and 4 triple superphosphate fertilizer levels (0, 40, 70 and 100% of the critical limit of soil phosphorus) with 3 replications was conducted in greenhouse conditions. Sterilized pots containing 7 kg of washed sands and soil (in a ratio of one to three) were prepared. A certain amount of triple superphosphate fertilizer was added to each pot based on the treatments. The K as potassium sulfate and N as urea were used based on soil test and fertilizer recommendations for maize. Five germinated seeds (704 single cross cultivar) were planted in each pot. Seeds sown were inoculated with 1 ml of the fresh bacterial suspension inoculum (1×108 CFU ml-1). Then after two weeks, three plants per pot were preserved and the rest were removed. Pots including different treatments were irrigated, up to 80% moisture content of field capacity (FC), by distilled water using a weight method. After 90 days, the dry weight of the plant was calculated (oven at 70 ° C for 48 hours). To analyze the nutrients in the plant, roots and shoots were powdered separately by mill and digested through dry burning method. The amount of phosphorus, potassium, nitrogen, iron, zinc, copper and manganese were measured in shoot and root of the plants. Besides, the soil of each pot was sampled and after air drying and passing through a 2 mm sieve, some characteristics of the cultivated soil such as pH, EC, P (ava), TNV, Fe, Mn, Cu, Zn were measured and compared with the initial soil properties (before planting). Data statistical analysis was performed using SAS software and the mean comparison of treatment was carried out using Duncan's method.

The results of phosphorus solubilizing bacteria effect on the dissolution of insoluble mineral phosphates in solid and liquid media showed the largest halo diameter (19.11 mm) and the highest dissolution of P (156.25% compared to the control) after the fourteenth day incubation was belong to strain P21-1 and strain P55-1, respectively and a decrease in pH (45.5- 47.3 %). The results of the mean comparison showed that P0B3 treatment could increase the shoot dry weight by 47.45 %. P40B1 treatment was able to increase 61.62% of root dry weight. P70B6 and B70B2 treatments were also able to increase P in shoots by 17.64%, P100B4 treatment could increase root phosphorus by 160%. Besides, the combined use of bio-fertilizer and superphosphate increased the elements of iron, zinc, manganese, P, and reduced the electrical conductivity of the soil.

 All strains used in this study were able to dissolve phosphorus in both liquid and solid media. The results showed that the co-application of biofertilizer and phosphorus fertilizer increased the growth of maize plant (shoot and root dry weight) and shoot and root phosphorus concentration compared to the control. In addition, the use of these treatments increased the available phosphorus, iron and zinc in soil and decreased the electrical conductivity of the soil. Therefore, the findings of this study indicate that the use of inoculants containing Pseudomonas sp. and Pseudomonas koreensis can be considered as a suitable supplement to triple superphosphate fertilizer in crop cultivation strategies.