Agricultural Mechanization and Systems Research
Year:2018 | Volume:18 | Issue:69 |Papers Count:10

Researche results indicates that 20 to 55 percent of the available tractor energy is wasted at the traction /soil interface, because of soft agricultural soils, tire tread for traction plays a major role. Using computer simulations to study the interaction between tire and soil, the number of physical tests and development costs can be greatly reduced. Finite element simulation of complex systems is a very effective way for investigation as is used in the soil bin tire test. In this investigation experiments were conducted for tires without tire tread, the tire tread at an angle less than the angle of the tread on the tires with full tread design, the tire tread wider than the width of the tread of the tire with full tread design, the tire tread longer (greater height) than the height of the tire tread with full tread design and tread of the tire with greater distance (distance between the step tread) than the distance in tire with complete tread design. The simulation results showed that a in absence of tread on the tire traction and the linear velocity was reduced. Also as the tire tread angle with regards to axle decreased the traction increased. But resulted in variable and oscillation under variable linear velocity condition. Furtur an increase in the width of the tread reduced the amount of traction and an increase in the height of tread increased the traction force, but caused a oscillatory and variable linear velocity. Finally an increase in the distance between two treads caused oscillatory and variable traction force and linear velocity.

Mechanical weed control in field can reduce the environmental concerns due to application of herbicides and the related costs. Present study was conducted in the form of randomized complete block experimental design with six treatments and four replications in Zarghan research center of Fars Province to determine the effect of opener geometry on weed seeds bank. Treatments consisted of bent leg opener, narrow point opener with rake angles of 53° and 90° , sweep opener, disc opener and moldboard plow as control. In this project, weed seeds bank and weed seeds location in soil was also studied. Results indicated that opener geometry affected the weed seeds translocation. The bent leg opener had the highest and the lowest weed seeds percentage in the soil surface and deeper layers with 26. 7% and 7. 4%, respectively. However, moldboard plow had the lowest and the highest weed seeds percentage in the soil surface and deeper layers with 12. 7% and 14. 8%, respectively. These results indicates that the bent leg opener reduced vertical displacement of weed seeds in soil and also reduced weed seeds translocation from surface to depth of soil. Therefore, the bent leg opener can reduce weed seeds bank in the long time.

The purpose of this research was to introduce a new laboratory test procedure which could be used under field condition. In this context, the performance of a pneumatic planter was investigated under laboratory conditions for maize, castor, fababean, sorghum, sugarbeet, watermelon and cucumber seeds. The effect of operational speed and vacuum pressure were evaluated by examining the quality of feed index, precision in spacing (coefficient of variation), miss index and multiple indexes. The most suitable operating parameter values for maize, castor, sorghum and sugar beet seeds were obtained at the first level of operating speed and 4. 0 kpa pressure; for watermelon seed: second level of speed and 4. 5 kpa pressure; for cucumber seed: first level of speed and 4. 5 kpa pressure. Furthermore, in order to determine the relationship between most important operating parameters affecting the performance of the Pneumatic metering device and seed physical properties, regression models were developed. According to the results, the vacuum pressure of Pneumatic planter could suitability and acceptably be described by two final models with values of root mean square error 6. 7×10-2 and 5. 7×10-2 and reduced chi-square 8. 2×10-2 and 5. 6×10-2 for the first and second model, respectively.

The most common types of post hole diggers are the auger styles including the engine powered and tractor mounted types which neither are applicable in current situations of Iran. In this study a hydraulic driven post hole digger was developed which is applicable in restricted spaces and has the ability of digging 15-20 cm wide holes to a depth of 50 cm. In contrast to tractor and engine powered types, in the developed machine the auger is screwed down at a relatively slow rotational speed under a vertical force and the soil compacted between the auger’ s flights is brought out of the hole as the auger is lifted. In order to choose an appropriate auger for this machine three types of spiral augers with conical tips (two size of flights pitch) and flange tip and a cylindrical type were evaluated. The results showed that spiral augers with conical tip, the lowest energy consumption and time requirement was the most appropriate for this digger. I order to have a better evacuation of holes in hard and frictional soils, augers with smaller pitch are recommended whereas bigger pitches of auger are more appropriate for sticky soils to avoid soil compaction between the auger’ s flights.

Biogas production from anaerobic digestion of livestock manure is one of valuable energy resources. The use of stirrer and mixing of substrate can improve biogas production rate in digesters. Present research was carried out in order to model and trend analysis of biogas production and mixing effect in a full scale batch reactor 1200 lit. With liquid volume of 800 lit using geostatistic. Variograms were used for modeling biogas production in three states: (I) without stirring and (II), (III) stirring at 40 and 100 rpm, respectively. Then, the proposed models were evaluated by reproducing observed data using kriging. Cross validation and statistical indices such as determination coefficient and remaining sum of squares were the assessment criterion. Simulation results showed that biogas production trend under uniform flow condition had most data structural continuity with correlation of 0. 97 and in state of (III) with correlation of 0. 33 had the lowest data structural continuity.

Solanum Tubrsosum L. is considered as the fourth important crop of the world. Ardebil is the first province in producing mini-tubers by aeroponic technique, which is free from microbes and viruses and has high productivity ratio. In this regard, an experiment was conducted in Ardebili Greenhouse Complex in 2016 to analyze and compare the energy of aeroponics and ordinary systems in producing Solanum Tubrsosum L. mini-tubers. Results showed that energy ration (ER) is relatively higher in aeroponics system than the one in ordinary system. Similarly the case is same for conditions of energy productivity (EP) index. The very high specific energy consumption was seen in cultivation under soil (ordinary) system as compared to aeroponics system, which indicates the lower efficiency of this system in producing mini-tubers. Unfortunately, the net energy (NE) index in soil (ordinary) system has similar conditions for all other Iran greenhouse products. However, the aeroponics system has positive net energy and therefor is more desirable than soil system. Generally, aeroponics system was found to be more advantage according to annual energy indexes, period, and mini-tuber. Therefore, this system can be suggested as one of stable systems based on energy to produce Solanum Tubrsosum L. mini-tubers.

Residue management and optimizing nitrogen fertilization are important factors in sustainable no tillage systems. A field study was conducted to evaluate the consequence of different residue methods and fertilizer levels of nitrogen on grain nitrogen uptake, accumulation of soil nitrate residual and corn yield under no till system. The experimental design was a randomized complete block with spit-plot arranged in three replications. The residue management systems consisted of three levels of leaving the residues (R. M1), removing residues from field (R. M2) and chopping and leaving the residues on the field (R. M3) as the main plot and four rates of N fertilizer as the subplots which included of: 150, 200, 250 and 300 kg N ha-1. The results showed that different residue managements and N fertilizer rates had a significant effect on soil nitrate accumulation and grain nitrogen uptake. The maximum accumulation of soil nitrate was observed for the R. M2 treatment and the minimum soil nitrate residual occurred for the R. M3. The R. M2 × N3 interaction reduced residual soil nitrate by 27. 2% compared to R. M2 × N4 treatment. The findings revealed that R. M3 and R. M1 treatments reduced grain N uptake by 4. 5% and 9. 4% compared to R. M2, respectively. The results of this study revealed that R. M3× N3 interaction had a greater impact on crop yield and grain N uptake than when R. M3 or N3 treatment was used alone.

The most important limiting factors in reduction of mechanization degree of cotton harvesting are access to suitable harvester for a specific planting pattern and lack of suitable varieties. In order to evaluate the performance of cotton picking combines in conventional planting patterns, three cotton picking combines (self-power three-row cotton picker that was designed and built in Khorasan Razavi Agricultural Research Center, self-propelled two-row cotton picker and tractor-mounted two-row cotton picker) were studied. In this context, the effects of type of cotton picker (three levels), forward speed (2. 1, 3. 4 and 4. 8 km/h) and cotton variety ( Khordad and Varamin) were investigated and the effect on parameters such as weight percentage of cotton losses at first and second picking stages, weight percentage of cotton waste, efficiency, effective field capacity and fuel consumption were recorded. The results showed that self-propelled three-row cotton picker had the highest effective field capacity (0. 48 ha/hr. ) and the lowest efficiency percent (64. 9%) as compared to the other cotton pickers. The highest efficiency (74. 68%) belonged to self-propelled two-row cotton picker. The lowest weight percentage of cotton losses (7. 87%) was obtained at 1. 2 km/hr. forward speed. The economic analysis and comparison of cotton pickers showed that the self-propelled three-row cotton picker, due to lower initial cost as compared to others cotton pickers, had the lowest period of initial cast return (3. 29 years).

Plastic debris remaining in the field after harvest is one of the difficulties in farming using plastic mulch. In this study, the performance parameters of a domestic plastic remover machine in collecting plastic mulches were evaluated. The dependent factors were fuel consumption, plastic tearing frequency during collecting and the total collecting time. The independent factors included film thickness 20 and 30 μ m), forward speed (2. 7, 3. 8 and 5. 4 km/h) and the time interval between harvesting and plastic collection (5 and 10 days). The tests were performed in triplicate using a factorial experimental design. Experiments were carried out in selected farms of Fars province by using a two-wheel drive MF399 tractor. The results showed that using thick plastic (30 μ m) reduces the plastic tearing frequency and hence with a lower number of stops, reduces the fuel consumption and increases the efficiency of the machine during plastic collection. To increase the efficiency of plastic collection, when using 30 μ m plastic, the forward speed of 5. 4 km/h is recommended. The best plastic collection time with the minimum tearing frequency recommended are 5 and 10 days after harvesting for 20 and 30 μ m thickness plastics, respectively. According to the results the least fuel consumption was observed for collection of 30 μ m plastic and with forward speed of 5. 4 km/h. According to results obtained the simultaneous collection of drip irrigation tapes and plastic mulch reduces costs and increases the efficiency of the plastic mulch remover.

In this study, a distributor of the pressurized pneumatic cylinder for seed sowing machine was fabricated and the device was evaluated by a grease belt. In order to evaluate the distributor, two factors were investigated: grease belt speed, with three levels of 0. 5, 1 and 1. 5 meters per second and three levels of air pressure inside of the distributor cylinder of 600, 850 and 1050 Pa, using wind separation method. The results of a factorial experiment in a completely randomized test design were evaluated by using SAS software and comparison of data was performed using LSD test. The effect of cylinder pressure and planter forward speed on the percentage of distributor pore filling, multi-planting, no-Planting, deviation from the line of cultivation and seed distribution uniformity were evaluated. The results showed that the filling percentage increases by an increase in cylinder pressure or by a decrease in velocity. The no-planting and multi-planting percentage had a reverse effect on the filling percentage. Furthermore, cylinder pressure and velocity did not affect the amount of deviation from the line of cultivation and also seeds were distributed more uniformly at low-pressure. According to the results of this study, the use of pneumatic planter by using a pressurized cylinder distributor for planting row crops, particularly mung bean is recommended.