نشریه تحقیقات سامانه ها و مکانیزاسیون کشاورزی
پیاپی 67 (پاییز و زمستان 1395)

Soil aeration by imported machines were reportedly unsatisfactory due to creation of shallow holes, taking off some patches of the turf and time consuming work needed for collecting the excavated cores. Considering these problems, a machine was developed to suit Iran’s lawn spaces. To develop an appropriate aerator, the shape of the plugs was studied at the first step and for this purpose six types of plugs with conical and cylindrical cross section (with and without slot) with tips cut diagonally and perpendicularly were built. The plugs were compared in an experiment based on complete randomized blocks design with 3 replication in an urban lawn space with clay soil in terms of the required static force for cutting the thatch and penetrating to the soil as well as the length of projected cores. The results showed that the conical plugs with beveled tips had a 28 millimeter longer cores than the cylindrical plugs with similar tip using approximately equal forces for insertion. Having chosen the appropriate shape of plug, a split roller with a relatively large diameter were constructed for installing plugs around it and the whole device attached to a walking tractor. Comparing the developed machine with a commercial self-propelled aerator revealed that the developed aerator improved the length of the cores and depth of the holes. The split roller in the machine which windrowed the cores also caused a 65% decrease in labor requirement for collecting the cores and did not have dug patches of turf.

In this research, the pneumatic planter made in karaj Tarashkade company and the driller made in Dezful Sanatkaran company, was compared and evaluated. The independent variables include, the type of planter at two levels (row crop planter and driller), two types of seed bed (smooth bed and plowed land), three ground speed (3, 5 and 7 km/h), 4 seed type (tomato, onion, radish and lettuce). The dependent variables include the seed’s lateral dispersion coefficient compared to the straight line, the seeds breakage percentage and the effect of metering devise on seed breakage and viability and the rate of seed shattering losses per hectare. In this test, a statistical software program MSTATC and split plot based on randomized complete block design with three replications was used. The results showed that: The optimal Index values for the rate of seeding per hectare is obtained was (0.07 kg), seed’s lateral dispersion coefficient in the straight line obtained (2.5 mm), percentage of seeds breakage and effect of the metering device on viability after passing the metering device was (0%). Therefore with respect to the seed’s lateral dispersion coefficient compared to the straight line and the rate of seed shattering losses per hectare index, row crop planter is better than driller. With respect to the seeds breakage percentage index and due to the misalignment of the cell's seed planters, row crop planter had more breakage than driller. With respect to the effect of metering devise on seed viability index, there was no significant difference between the two planters.

Suitable harvesting time reduces the losses in the field and also at milling stage. This research evaluated the effect of different harvesting times on milling properties of two paddy varieties (Hashemi and Gohar) that was conducted at Haraz technology development center (Iran). The harvesting was started when the moisture of paddy was 23% w.b (85 and 115 days after transplanting for Hashemi and Gohar varieties respectively) and continued until shattering was occurred for both varieties. Totally, the harvesting was done at nine times. Results showed that the effect of harvesting time has significant effect (P

Poultry industry is one of the biggest and most developed industries in Iran. One of the important issues in broiler industry is the energy consumption. In this study, the energy consumption flow and the amount of energy production were investigated for broiler farms in Alborz province. Data were collected through interviews and questionnaires. Input energies were the feed, fuel (natural gas and diesel), electricity, labor, equipment and chicken, and the output energies were the broiler and manure. The total of input and output energies obtained were 125.2, 24.9 GJ/1000Birds, respectively. Energy indices, including energy ratio, energy efficiency and specific energy were obtained were 0.2, 0.019 kg/MJ and 52.55 MJ/kg, respectively. The highest share of energy consumption belonged to fuel (gas and diesel) with 50.84% and feed with 42.43% , and the chicken and labor with 0.39 and 0.06 % were the lowest share among the input energies.

The optimal use of rotary seed coater needs the knowledge of the physical properties and the behavior of seed motion in rotary drum. One of the most important parameters in such equipments is the rotational speed of the drum which causes the rolling action of seeds. In this research a new method was used for measuring these properties which was based on the motion of seeds in a less than 50% filled rotating drum. Firstly the angle of repose of three types of seed (vetch, wheat and tomato seed) with different shape was measured with different methods and the values ​​obtained were compared. Then, the lower and upper angle of repose were also measured by rotary drum. At the final step, the rotational speed of the drum were gradually increased from 0 to 100 rpm. The speed of the drum which caused the seeds rolling motion to start and end was also measured. The results showed that the shape of the seeds had a great impact on the type of motion in the rotating drum and it was obtained that the vetch seeds had the widest speed range with rolling mode of motion (from 1 to 65 rpm). However, this range for tomato seeds is from 8 to 40 rpm and for wheat seeds from 6 to 49 rpm. Finally the increase of filling degree of frum from 25% to 40%, resulted the rolling mode of motion for all of seeds began and end sooner.

Due to the high labor costs in the production of rice, use of rice planting and mechanization is one of the basic strategies for sustainability and preparing healthy and strong seedling, transplanting and reducing the cost of rice production. Crop response to mechanized planting with planting machines due to differences in the density and type of planting is different. Therefore, this study aimed to achieve the most suitable criteria on for transplanting age of four varieties of rice. Experiments were conducted in the year of 2009 was conducted at the Chaparsar Rice Research Station (Tonekabon city). crop, using a split-plot design in a randomized complete block design with three replications. The main factor included four levels of transplanting ages (20, 27, 33 and 40 days) and the subplots were four varieties of rice cultivars (Hashemei, Khazar, Hybrid and Shiroodi). Analysis of variance showed that transplanting age affected most of the factors and data shows significant differences at the level of 5, 1 and 0.1 percent. Effects of rice varieties also were significant on all factors. Correlation coefficient of data was positive and showed significant relationship with the parameters. The highest yield was achieved for 20 days rice transplanting age with the amount of 5166.9 kg per hectare. Among cultivars, the highest yield belonged to the Shiroodi verities with 5899.9 kg per hectare. Therefore, to achieve the highest yield potential of shiroodi verities, the 20 day transplanting ages is recommended for planting the rice transplanting by walking type transplanters.

Transplantation is one of the most effective ways to increase economic efficiency of some agricultural products like rice and vegetables. The aim of this study was to design, construct and evaluate a simple and inexpensive seeder for fast and accurate seeding in transplant trays. Modeling was performed using CATIA software. The prototype consists of a cylindrical vacuum distributor with holes of 1 and 2 mm diameters, pressure brake mechanism, the cam & forwarding mechanism for pushing tray step by step, and a power transmission mechanism (consisting of the sprocket and belt). To evaluate the machine and determine the optimum conditions, average operating errors including none-planting and multiple-planting errors were obtained for two kinds of seeds (cucumber and lentil). A factorial experiment based on a completely randomized design was applied. Independent variables were the diameter of holes (1 and 2 mm) and pressure (-8 and -15 kpa for cucumber and -7 and -13 KPa for lentils). The results showed that the better performance was achieved under higher vacuum condition and smaller diameter. The optimum condition was obtained at diameter of 1 mm and pressure of -15 and -13 KPa for the seeds of cucumber and lentil, respectively. The optimal capacity was 240 trays (25200 seed) per hour and an average of none-planting and multiple-planting errors were 19.1% and 8.9%, 16.13% and 7.81% for the seeds of cucumber and lentil, respectively.

Temperature management is an important subject in maintaining the quality of horticultural products after harvest. One of the methods in suitable control of temperature, is precooling, that is conducted before storing of the product which increases shelf life and storage time the fruits. On the other hand, estimation of cooling parameters (half and seven-eighths cooling times) need precise sensors and is time consuming in precooling operations. In this research, airflow velocities as an effective factor in cooling at three levels of 0.5, 1, and 1.3 m s-1 was considered. Parameters including lag factor, cooling coefficiency and half and seven-eighths cooling times were calculated based on recorded data of the temperature sensors. Finally, using the dimensionless numbers, Fourier and Reynolds, the estimation of regression models obtained for cooling times and compared with experimental data. With increasing airflow velocity, cooling times decreased and convective heat transfer coefficient was enhanced up to 58.46%. The overall results showed that for sphere shaped products like pomegranate, using Fo-Re correlation, cooling times are estimated with suitable precision (maximum error for half and seven-eighths cooling times 11.46 and 10.83, respectively) and without using complex equations.