نشریه مکانیزاسیون کشاورزی
سال چهارم شماره 2 (پاییز 1397)

  In the past decades, herbicides were generally applied at a uniform rate to the entire field. But uniform application causes environmental problems such as soil and groundwater pollution and economic problems. General concern about the negative effects of using herbicide was resulted to the development of a new herbicide application system. Variable flow rate technology is being used extensively in precision agriculture. But, it is not developed sufficiently in our country. In this study two types of systems were designed to achieve a suitable variable rate spraying system. For the first step, motorized valve was utilized. Laboratory tests were conducted  with TeeJet nozzle at three different operating pressure levels (2 to 4 bar) and four rotational positions of a servo motor ( 30 , 45, 60, 80 degrees). The performance reduction of the machine due to the pressure variations is one of the disadvantages of this system. The pressure variations caused the spray pattern to be non-uniformed and it also affected the droplet size. For the second tests, a solenoid valve was used which was controlled by pulse width modulation. The duty cycle and operating pressure as effective factors were examined on the spraying angel. The experiments were performed in the form of factorial based on completely randomized design in three replications. The spraying angel measured at five levels in the combined treatment of the duty cycle (20%,30%,50%,70%,90%) and operating pressure at three levels (2,3,4 bar).The duty cycle and pressure had a positive effect on spraying angel and flow rate as well. The spraying angle variation was just 3% when the duty cycle was changed from 20% to 90%.

Spraying is a major operation to control the bio elements that are harmful for farming products. Considering the high costs of chemical spraying and related environmental issues, the proper management is important. In the meantime, reduction in nozzle drift can be considered as one of the main factors in preventing the risk of pesticide environmental pollution, as well as reducing pesticide waste and proper spray uniformity. For this purpose, design, fabrication and evaluation of air assisted nozzle on boom sprayer was conducted using a factorial completely randomized design with three replications. The experiments were performed using three types of air assisted nozzles: air- liquid-air (ALA), liquid (L), liquid-air- liquid (LAL) at four levels of air assisted speed (0, 2, 4 and 7.5 m/s), and also four levels of wind speed (0, 2, 3 and 4 m/s). In the research, the drift, sediment, uniform spraying, volume median diameter of 50 and 90%, numerical median diameter and spraying quality indicators were evaluated. A spectrophotometry device for measurements and MATLAB and SAS 9.1 statistical software were used for analysis. Results showed that the effects of air assisted nozzle and wind speed on the drift, sediment, uniform spraying, volume median diameter of 50 and 90% and spraying quality indicator were significant (). Also results indicated that the third type of nozzle (LAL) at 4 m/s assistant air speed and 4 m/s wind speed had the highest sediment (144.87 l/ha) and the lowest drift (0.06%), while the lowest sediment (31.16 l/ha) and the highest drift (0.69%) were found for the third nozzle (LAL) without assistant air (as control group) and in 2 m/s wind speed. The minimum coefficient of variation (0.42 the most uniformity in spraying) was related to the third nozzle with 4 m/s assistant air speed and 4 m/s wind speed, but the maximum coefficient of variation (4.08) belonged to the first nozzle with 7.5 m/s assistant air speed  but without any blowing wind.

 In this study, the energy analysis of an air-cooled photovoltaic-thermal (PV/T) equipped with fins was investigated. A PV panel with the same characteristics without cooling fluid was used to compare the results as the control system. A fan with air flow rate of 0.033 kg s-1 was used to create forced convection flow. In the lower part of the air channel, a plate with trapezoid fins was mounted to create turbulent flow in the air channel to increase the heat transfer coefficient between the plate and air fluid. Six temperature sensors LM35 were used to record air temperature and a computer program in MATLAB was developed to compute the theoretical performance. The results showed that the use of air flow reduces the temperature of solar cells and thus increases the PV/T output voltage by about 9% over all hours of the experiment compared to the control system (PV). The theoretical and experimental thermal efficiency of the PV/T was calculated as 0.51 and 0.47, respectively. Also, the average difference between theoretical and experimental temperature was about 8%. The maximum difference between air outlet temperature and ambient temperature in measured and predicted were 7.06 and 10.25, respectively, and the minimum differences were 1.40 and 2.97, respectively.

One of the applications of solar systems in agriculture is in product dryers. Drying of agricultural products after harvesting stage is one of the major units operations in order to increase the length of storage and maintain its quality. The purpose of this research is to model and design a solar flat plate air collector in order to supply the energy need of a grain drying warehouse with an area of 36 square meters and assumed capacity of 1.5 tons of corn for each loading. The amount of the required energy to reduce the moisture content of corn (from 23% to 13%)  was calculated as 961.1 MJ/1.5 tons. To provide this amount of energy, two types of collectors, type A (without obstacle) and type B (with obstacle installation in the air channel) were analyzed by Matlab code. The use of obstacles in the air channel increased the thermal efficiency of the collector from 37 to 55 percent in the single cover type and from 48 to 62 percent in the double cover type. The average of the best tilt angle of the collector installation was recorded at 27.5 degrees in south direction. The required energy supply time (961/1 MJ/1.5 tons) for a solar system with an area of 30 square meters, for A and B type collectors was calculated as 41.25 and 27.69 hours in single cover and, 31.14 and 24.1 hours in two cover, respectively.

The reduction in fossil reservoirs and the bioenvironmental pollutions entails the use of more efficient higher quality fuels that generate less pollution and are renewable. Biodiesel is an appropriate biofuel to replace gasoil and it is produced from natural oils. The current research investigates the energy of biodiesel production from chicken fat based on LCA method. The information pertaining to the amounts of the consumed inputs and the amount of the output energy in a number of chicken farms in Isfahan. Questionnaires, interviews and experiments were used for the study. In this cycle, two main products, i.e. the edible chicken meat and the biodiesel, were considered as the outputs. The total energy of the inputs for the production of biodiesel out of 1000 kg of live chicken was equal to 47486.09 MJ and the total energy of the outputs was 12380.55 MJ. The net energy in this cycle was a huge figure with a negative sign and the energy ratio was found lower than 1 and this is reflective of the high energy consumed in producing such a fuel. The results indicate that the largest share of the consumed energy pertains to the chicken farming operations. Although the energy indices indicate low energy efficiency in the conditions of the study, due to the use of wastes in the studied cycle, this method of biodiesel production is recommended however with attempts to improve its efficiency.

 Land application of manure due to their degradability and preservation of natural environment is one of the important alternatives for chemicals in the sustainable agricultural. Today's it is possible to spread manures by machines as like as distributing chemical fertilizers on the farm's surface. There are several parameters to assess the performance of these manure spreaders such as the spreading width, the longitudinal and transverse uniformity of fertilizer distribution. In the present research by using a semi integral manure spreader machine, the impact of the position of screen blades in two position of open and closed angles (as the main factor) and adjacent transverse distance of 8, 10, 12, 14, 16 and 18 meters (as a sub factor) were evaluated. Experiments were carried out by using a split plot design in a randomized complete block with three replications. By selecting the appropriate position of screen blades and adjacent transverse distance (work width), real field capacity, field performance and accuracy of the tests were obtained on the manure spreader. The results showed that the most suitable operating mode was the closed angle blade position and 12 to 14 meters distance between two adjacent transverse. In this condition, the actual field capacity and field performance of the machine and accuracy of the tests were about 5.1 ha/hr, 64.2% and 94.5%, respectively.

Precooling is an important process that carried out on the fruits such as Apple due to extend the shelf life. In this research, the new package was designed and constructed. Then, the effect of various performance parameters during the precooling process such as the airflow rate and types of packages was studied on the 7/8 th cooling time and cooling uniformity to select and introduce the best package. The results indicated that the Polyethylene package had the lowest 7/8 th cooling time; however, it is not suitable for export of apple due to the high moisture loss during the precooling (23-26%). The highest cooling time and lowest cooling uniformity was related to the commercial package because of its unsuitable vents deign. The results showed that the cooling time of fruit in the new designed of package decreased 30.5 and 25.9 % as compere with the commercial package in the airflow rate of 0.5 and L s-1kgp-1, respectively. In addition, the cooling process was uniformity and the standard error between the 7/8 th cooling time of fruit was 19.6 % lower than that one for the commercial package. Increasing the airflow rate from 0.5 to 1.5 L s-1kgp-1 led to decreasing the 7/8 th cooling time in the range of 16.8 to 39.7 % in the all packages. Because of the lowest moisture loss, highest cooling uniformity and lowest cooling time, the new designed package was introduced as the best packages to cooling process of apple and its cold storage.

Wheat is one of the strategic crops that have been harvested in recent years by advanced combine harvesters. In this study, traditional combines were evaluated in terms of natural losses, head and back losses, field capacity, purity percentage and yield in field conditions in Qom (Iran). The total number of combine harvesters in this area was 110 out of which 20 samples with the experimental design of completely randomized design were selected. 35% of samples were New Holland Combine harvester TC5070, 30% John deer JD1055, 15% JD1165 and the remaining (20%) were New Holland TC5080, John deer JD955, JD1450 and Sampo 3065L. In terms of losses rates in different parts of the harvesters, 0.06% was related to the back of the machine and 1.35% of it was related to the head. The natural losses rates was 1.66% and total losses was 3.07% in this province. Three traditional combine harvesters (TC5070, JD1165 and JD1055) were compared statistically. The results showed that there was a significant difference between the harvesters in terms of field capacity at  5% level. The effective capacity of the TC5070, JD1165 and JD1055 combines was 1.23, 0.88 and 0.83 ha.h-1,respectively. According to the results, it is recommended to use JD1165 and TC5070 combine harvesters due to their low losses, acceptable purity percentage and suitable field capacity.

The inaccessibility of natural gas, the high price of fossil fuels and shortage of fuel stations in major part of rural areas caused the huge glut of solid biomass (wood coal) for provision of energy demand by rural households. The consumption of fossil fuels resulted in various environmental impacts, in which, the depletion of natural resources and jungles is the most obvious one. Biogas as an important energy source is produced by anaerobic digestion of organic wastes such as animal waste. Due to the high heating value of biogas than the direct burning of biomass, it can be used as an alternative to energy resource in rural areas. In this study, the potential of average annual biogas production from the accessible livestock waste in each rural houshod at West Eyvan County, Ilam province, was investigated as 9343.44 m3 (energy equivalent of 35505.07 kWh). Also, the average energy consumption from wood, petroleum and liquid gas was calculated as 37374.6 kWh). Therefore, in the case of biogas production, each average household (4 people) 1 can supply all its thermal requirements.

For energy consumption analysis in animal husbandry, determination of energy equivalent for concentrate feed is a challenge and a point of difference between studies.  This study was conducted for determination of the energy consumption in concentrate feed production. Data was collected from Niroo-Sahand feed factory in Tabriz (in Iran). The primary based energy inputs from electricity, fuels, transportation, machinery and feed materials were intended. The output was concentrate feed (CF) in factory gate in a cradle to gate boundary of the study. The total energy consumption was 8.48 MJ per kg of CF which could be used as its energy intensity in future studies. The energy content of CF was calculated to be 17.47 MJ per kg according to calorimeter experiment. Most of the energy input by 90% was belong to the indirect energy input from ingredient feed materials. Following, 5.8% of the energy input was from transportation of the feed materials from origins to factory. Inside the factory 0.315 MJ per kg of CF was consumed for processing consisted 3.7% of total energy input. Inside of the factory, 60.3% of the energy input was from electricity (primary energy based). To improve the energy intensity of CF, the field operations in feedstuff productions in origins should be considered.

Onion is one of the main crops in East Azarbayjan. Thrips are the most important pests that cause heavy loss in onion yield every year. Thrips mostly inhabit on the lowest part of onion stem where its leaves have been joined together. A successful Thrips control depends on a proper deposition of pesticide using of a suitable sprayer and spraying method. The lack of knowledge of farmers about the spraying methods, equipments and their spraying rate have led to high consumption of agricultural pesticides and increase in resistance of this pest to conventional poisons. In this study in order to solve the above mentioned problems, four types of sprayers were compared with each other. The experimental design was randomized complete block design (RCBD) with 5 treatments and 4 replications in the field tests and 4 treatments and 12 replications in the laboratory tests. The evaluated sprayers included the following, motorized knapsack sprayer with cone nozzle, motorized backpack mist blower (atomizer), motorized backpack micronair sprayer and motorized backpack electrostatic sprayer. The evaluated parameters in this study were droplets size and density of them (No/cm2), spraying quality, spraying pattern in effective width, percentage of effect on Thrips control, yield crop and onion bulb size. The results showed that there is a significant difference among studied sprayers at 1% level in aspect to sprayed droplets characteristics and controlling of onion Thrips. The micronair sprayer was the most effective on controlling Thrips, minimum droplet size, maximum density and spraying quality. Without any spraying, the yield loss of about 10 t/ha was measured.

The soil engaging components of a planter have an important role on its performance. This study was conducted for comparison of the effect of three openers disks arrangment (tilted plain disk + tilted plain disk, tilted plain disk + perpendicular plain disk and tilted plain disk + perpendicular notched disk) on furrow moisture content change. Measurements was directly at openning time and after three time intervals (48, 96 and 144 hours after furrow opening) in two soil conditions (with Cone indexes of 0.39 and 1.04 MPa) with repeated measures design. Variance analysis has been revealed a significant difference between treatments on  the loose and  firm soils moisture content. According to the means comparison, moisture lost was the lowest, equal to 5.07% on tilted plain disk + perpendicular plain disk treatment. On tilted plain disk + tilted plain disk and tilted plain disk + perpendicular notched disk treatments it was 8.6% and 11.07 %, respectively. According to the results, in firm soil conditions it is recommended to use the tilted plain disk + perpendicular plain disk arrangment.

Effect of conservation tillage on soil properties and crop yield may be influenced by climate condition, soil type, and crop type and rotation. Therefore, evaluation of different tillage methods in different climate conditions, soil textures, and crop rotations is necessary. In this research, the effect of conservation tillage methods on soil properties, cotton yield, and its economic efficiency was evaluated in wheat-cotton cropping system in arid climate condition of Fars province (Iran). The study was conducted in the form of a complete block experimental design with three treatments and four replications in Darab Agricultural Research Station for four years. The treatments were reduced tillage, no-tillage, and conventional tillage (control treatment). The results showed that the tillage method had significant effect on moisture retention in the soil so that the no-till and reduced tillage increased moisture retention in the soil compared to the conventional tillage by 15.22 and 5.47%, respectively. The tillage methods had no significant effect on the soil infiltration, soil aggregates, and cotton yield. Economic evaluation revealed that the conventional tillage had the highest economic efficiency followed by the reduced tillage and no-till. However, the economic returns of all treatments were positive. If a proper management be applied during replacing the conventional tillage with conservation tillage methods, the advantages of conservation tillage could be reached in cotton planting.

Due to the increasing consumption of fossil fuels in the world as well as their increasing cost and environmental impacts, the great need and interest to replace them with renewable energy resources has increased. Anaerobic digestion is a biochemical process that is able to convert almost all kinds of multi-dimensional biodegradable organic matters under anaerobic conditions to biogas. According to water content, anaerobic digestion methods are classified as wet and solid state. The solid-state anaerobic digestion has been claimed to be advantageous over liquid AD for a number of reasons including smaller reactor volume, lower energy requirements for heating and minimal material handling. In this paper, biogas production from solid state anaerobic digestion of municipal sewage sludge was studied. A series of single-stage batch mesophilic (37 ± 1oC) anaerobic digestions were performed at a total solids concentration of 20% in 1 liter reactor volume. The evaluation of municipal sewage sludge characteristics showed that this substrate has a good potential for solid state anaerobic digestion (Total solids, volatile solids and C/N ratio were obtained 25.7%, 50.7% and 11.7, respectively). The biogas yield was achieved 362 ml/g VS, which methane content of biogas was 213 ml (58.8%). The volatile solids reduction, a significant parameter to measure productivity of anaerobic digestion, was obtained to be 63.7%.

Olive harvesting is the most important step in olive cultivation because of its direct impact on the quality of olive oil. Harvesting method and harvesting time are two effective factors in harvesting olive. This research was carried out in the olive orchard of Mazrae Novin Iranian Agro-Industry Farm, located in the cities; Manjil & Roudbar in Guilan province, Iran. In this research, olive trees were pruned in the central leader method. An Italian Verdegiglio VMA 95 trunk shaker was used to harvest the olive fruit for both table olives and oil olives stages. Vibration times by the shaker were at four levels (5, 10, 15 and 20 seconds). The percentage of the harvest and the harvesting rate, in each stage of the harvest (table and oil olives) were calculated. Based on the results of the project, the percentage of the fruit harvest and the harvesting rate in vibration times were significantly different in each stage of the harvest (table and oil olives). The maximum percentage of the fruit harvest for table and oil olives were 64 and 86, respectively. The highest harvesting rate for table and oil olives were 102.79 and 127.32 kg/h, respectively The best duration to shake the olive trees was found to be 10 seconds.

 Cereals are one of the strategic products and each year a large area of ​​agricultural land is dedicated to their cultivation. Cultivation of cereals is considered to be the main agriculture in Iran. One of the most sensitive and difficult stages of cereal production is the harvesting stage almost more product loss occurs at this stage. Forward speed, cylinder rotation speed and blower rotation speed of Harvester are important operation parameters that affect harvester losses. In order to evaluate the effect of these parameters on total grain loss, this studying was conducted in 3×3×3 factorial pattern with randomized blocks design. The independent variables in the experiments were forward speed (3, 4 and 5 km/h), cylinder rotating speed (1100, 1200 and 1300 rpm) and blower rotating speed (600, 700 and 800 rpm). For a real evaluation, these factors and their levels were chosen based on operators’ experiences. The experiments were done in Moghan Agro-Industrial & Livestock Co. (MAIL) with CLAAS combine harvester (Tucano 320 model).  The results of this study showed that the minimum loss related to the 4 km/h, 1300 rpm and 800 rpm for forward speed, cylinder rotation and blower rotation speed, respectively.