نشریه تحقیقات سامانه ها و مکانیزاسیون کشاورزی
پیاپی 79 (پاییز 1400)

The four-wheel drive and rear-wheel drive tractors are commonly used in agricultural operations. In order to investigate the effect of a type of driving system a series of tests were performed usin the three driving systems of foour wheel drive, rear wheel drive and front wheel drive in different axle loads of 0, 150 and 300 kg, tire inflation pressures of 170, 200 and 230 kPa and travel speeds of 1.26, 3.96 and 6.78 km/h. Bulk density was measured as an indicator of soil compaction at different depths of 10, 20, 30 and 40 cm. Also, under the different conditions, the drive wheel slip was measured. To carry out the tests, the four-wheel tractor of Goldoni 240 was used which has the ability to work with mentioned driving systems. The experiments were carried out under controlled conditions in a soil channel  with the length of 3 m and a width and depth of 1 and 0.6 m, respectively. Test were conducted in completely randomised block design with three repetations and results were analysied using SPSS 22 software. The results showed that by changing the driving system from 4WD to RWD and FWD, there was a significant increase in soil density, with the lowest density associated with 4WD system and the highest density related to FWD. The reason for increasing the density by changing the driving system can be attributed to different slip levels in each of these systems due to the lower slip percentage of the 4WD system than the other two systems.  Increasing axial load increased soil boulk density. Of note that with increasing the axial load, the stress was transferred from the surface soil to the subsoil layers. As the axial load on tire increases, the subsoil density was closer to the surface layer. Increased axial load on tire and decreasing tire pressure reduced wheel slip. Stepwise regression model with determination coefficient of 0.92 and according to calculated standard coefficients showed that axial load, soil depth, type of driving system, tractor speed, and finally tire pressure, have the greatest effect on soil bulk density, respectively.

A large part of fuel consumption in agriculture is related to the poultry industry. Fuel consumption in our country's poultries is more than international standards. High consumption of fossil resources in this industry, despite the cheapness of fuel in Iran and the allocation of subsidized fuel, imposes a high cost on poultries and reduces the possibility of their competition in global markets. Also, the quality of heat provided to chickens is one of the main concerns of the poultry industry, which plays a key role in production efficiency. In poultry heating, heating systems of hot air furnaces (conventional heaters, jet heaters), underfloor heating systems and umbrella radiant systems and tubular radiant heating systems are used. According to the present study, among the common heating systems, tubular radiant heating systems with energy consumption of 6.8 MJ/m2, the lowest energy consumption and suitable temperature uniformity at a height of 30 cm with mean temperature of 28.52±2.50°C. They had. Underfloor heating systems had the best temperature uniformity with mean of 26.10±2.18°C, but their energy consumption was estimated to be 30% higher than that of tubular radiation system. Conventional heater system with mean temperature of 25.83±5.16°C and jet heater system with mean temperature of 23.94 ±5.41°C in terms of temperature uniformity is the worst condition and conventional heater system with energy consumption of 14.3 MJ/m2 and Underfloor heating with energy consumption of 30.3 MJ/m2 had the highest energy consumption.

In recent years, the cultivation of peanuts has increased in the Moghan region, which currently has an annual planting area of more than 6,000 hectares. This study was performed to select the most suitable planter with the desired planting pattern. The experimental design was carried out in a randomized complete block design with six treatments and four replications, in 2020. Treatments include a1 and a2, planting with a distance between rows (ridges) of 75 cm and between plants (12 and 17 cm), respectively, a3 and a4, twine planting with a distance between rows of 75 cm and between plants (22 and 28 cm), respectively, and a5 and a6 , planting was one row with a distance between rows of 50 cm and between plants (25 and 30 cm), respectively. Parameters measured were uniformity of seed depth, planter field capacity, seed germination, mechanical damage to seed, yield and yield components of peanut. The results indicated that planter type was significant at the 1% probability level for uniformity of seed lateral, planter field capacity and seed germination and at the 5% probability level for Number of pods per plant and peanut yield. However, there was no significant effect on 100-seed weight and mechanical damage to seeds. It was found that planting with a two-row pneumatic planter obtains the best results in terms of green percentage uniformity, seed cross distribution and yield. The highest uniformity of horizontal distribution and germination of seeds were 79.25% and 95%, respectively. The maximum yield in this tow row planter was 4995.30 kg.ha-1 with a distance between plants of 28cm. Therefore, compared to planting a row with a distance between the ridges of 75 cm, the average yield was increase 400 kg.ha-1.

This research includes the design, manufacturing, and evaluation of a live mulch planter unit. In order to address the problems of using agricultural machinery in performing live mulch planting in the furrows or simultaneously with the main crop, a prototype planting unit was designed. In this planter, a seed-drop plate was used to convey the seeds from the metering device to the ground. The result of this project was a prototype of a planter with the ability to plant 19.6 to 163.2 grams per minute of live mulch (hairy vetch) with a tolerance of 0.54 grams along the entire width of a 75 cm furrow. Laboratory and field experiments were conducted to evaluate its performance in actual field conditions, based on planting accuracy and field efficiency. The Laboratory test was performed according to ASAE S341.2 DEC92 standard for Grain Drill evaluation. Results of the initial evaluation of the planter showed that changing the rotational speed of the metering device significantly affected seed output on the drop plate in terms of seeding rate. The position of the outlets did not differ significantly in terms of seed damage. Increasing rotational speed of the metering device significantly increased the tendency of metering mechanism to damage seeds. Increasing rotational speed of the metering device significantly decreased index of non-uniformity in all outlets.Results of the initial evaluation of the planter showed that changing the rotational speed of the metering device significantly affected seed output on the drop plate in terms of seeding rate. The position of the outlets did not differ significantly in terms of seed damage. Increasing rotational speed of the metering device significantly increased the tendency of metering mechanism to damage seeds. Increasing rotational speed of the metering device significantly decreased index of non-uniformity in all outlets.

In this study, technical and economical potential of using solar energy for heating cucumber greenhouses in Jiroft region were studied. For this purpose, the climatic suitability of the region was determined. According to the data and thermal requirement of greenhouse, capacity of a flat panel solar water heater was calculated and was compared with the conventional system, gasoil heater. The results of paired t-test showed that there was no significant difference between the two greenhouses in terms of CO2 content, average temperature and relative humidity, but there were significant differences in terms of chlorophyll content and yield between the two greenhouses, at the probability level of one and five percent, respectively. There was a significant difference, with a higher average of conventional system. The results of data analysis in Kamfar software showed that in terms of economic indicators, the use of solar water heaters for heating greenhouses in this area is justifiable in the fifth year and the return on investment is 5.32 years.

Sour orange (Citrus aurantium L.) synonymous with the name "C. bigaradia Duh, C. Vulgalis" is native to Southwest Asia, and it has a rounded and acidic fruit known as bitter sour orange, sour orange or Seville names. It is also necessary to process food products, one of which methods is the thermal processes based on heat transfer mechanism via conduction, convection and radiation. Given that color is one of the appearance characteristics of food products for customer selection and marketability, in this study, an ohmic heating system in three input voltage gradients (8.33, 10.83, 13.33 V / cm) and three percent weight loss (10, 20 and 30%) of the total weight made in the heating process. After the heating process, color change was performed using Image J software and the factors L *, a *, b *, BI, C, TCD were measured and the results were analyzed using the response surface method. The results showed that for L *, b *, browning index, chroma index and TCD had the highest estimation coefficient for weight loss percentage and for a * value of process voltage had the highest estimation coefficient. Also, except for the factor a *, where the quadratic model is suitable for the two model factors, for the other factors, the linear model is obtained against the mean of the appropriate model by the response surface.