نشریه مکانیزاسیون کشاورزی
سال هفتم شماره 4 (زمستان 1401)

Biomasses are one of the major sources of renewable energy and suitable alternatives to fossil fuels. An application for biomass energy is fuel pellets which are made from agricultural waste, plant residues and manure, are compacted and contain higher energy per unit of volume. In this research, different proportions of pellets were prepared from two types of rice straw biomass and sugarcane bagasse (25%, 50%, 75% and 100%) and their combination with natural binders (frankincense, Arabic gum, eremurus) at three levels (5%, 10%, 15%). The effect of these variables were investigated on the density, fracture resistance, stability and calorific value of the manufactured fuel pellets. The comparison of results means showed that the optimum proportion for fuel pellet production is a combination of 75% sugarcane bagasse and 25% rice straw, which combined with the frankincense natural binder. This proportion has the highest failure strength, durability, and heating value at 15% binder level.

The aim of this study was to investigate the amount of sugarcane losses during harvesting at the Imam Khomeini Sugarcane Agro-Industrial Company located in the Shoaibiyeh region.  Analytical hierarchy process was used to prioritize the factors affecting the level of losses. The statistical results obtained from measuring the losses showed a direct relationship between the age of the farm and the amount of sugarcane losses during harvesting. This relationship was examined with an accuracy of one percent. Additionally, using the recorded information, four effective criteria along with 23 sub-criteria were considered. Questionnaires based on pairwise comparisons were prepared and completed by agriculture and industry officials to determine the weights of the criteria and sub-criteria. Based on the obtained weights of the criteria, the lack of skilled and expert human resources (operator skills) (0.426), improper farm management (0.368), improper crop harvesting management (0.229), and the lack of adjustment of harvesting machines and improper technical management (0.076) were ranked in order. Improper control and management of the sugarcane transportation basket (0.194), insufficient training for operators (0.176), and the lack of placement of the product (plant deployment) on the cultivation surface (0.148) were the three most important sub-criteria based on their highest weights. After calculating the amount of sugarcane losses, the revenue obtained from the losses was estimated. This was calculated for all the farms studied in this research, and the economic results showed that the average income obtained from sugarcane losses was equivalent to 123.70 $ ha-1.

Agricultural soils improvement and amendment has an inevitable importance. The implementation of new tillage methods and using some additives such as superabsorbent, in order to optimally use of water in rainfed farms to increase the yield of crops, has particular importance in this relation. Superabsorbent polymers are organic compounds that are able to absorb water several times of their own volume or weight without changing their physical structure. The purpose of this research is to investigate pre-compaction stress as a measure of resistance of soil compaction in the presence of superabsorbent polymers. In this research, the pre-compaction stress was determined using the confined compression test (CCT). The factorial experiment was carried out in the form of a completely random design with three replications on the samples with humidity of 15% and 10% and density of 1.4, 1.5 and 1.6 at five levels of 0, 1, 2, 3 and 4 grams of polymer per kilogram of soil. The results of the tests showed that with the increase in the amount of superabsorbent, pre-compaction stress and compaction index increased. The maximum effective amount of superabsorbent is three percent by weight, which creates moisture suitable for agricultural products. In both humidity of 10 and 15%, the highest pre-compaction stress was equal to 2.8.

Today's energy-intensive human life, caused investigating different sources of energy supply. It is extremely important to use renewable energy sources to generate scattered electricity, due to the high cost of electricity transmission lines, and also necessity of pollution reduction and environmental protection. One of the sustainable energy resources is biomass, which cow dung is a subset of it. In this study, the number of the cows in the Mashhad County were estimated. Also, the electricity consumption in agricultural sector of Mashhad County was estimated for the year 2035. Finally, according to the available energy from cow dung, the possible energy supply was calculated for agricultural sector of the region. Electricity production from cow dung and energy needed in agricultural sector for Mashhad was estimated to be 6797 and 12342019 MWh, in 2035, respectively. Therefore, the amount of energy from cow dung is less than 0.1 percent of the energy needed. This source of energy (cow dung) is recommended for producing thermal use or scattered electricity. The use of other sources of biomass could be a solution to provide some part of energy demand from clean resources.

Iran is the second largest producer of apricots in the world and study of drying methods of this fruit is necessary to reduce the corruptibility. In this study, the effects of ultrasonic pretreatment and thickness of apricot slices on drying kinetics in a hot air dryer were investigated. The effect of ultrasonic pretreatment at three levels of 10, 20 and 30 min and thickness at three levels of 3, 5 and 10 mm on drying time, modeling, effective moisture diffusivity and color changes during apricot drying process were studied. The results indicated that increasing the duration of pretreatment and decreasing the sample thickness increase the drying rate and decrease its duration. In the treated samples, the highest drying time with 300 min was for 10 mm thickness-control samples and the shortest time with 40 min was for 3 mm slices under 30 min ultrasonic pretreatment. Midilli model had the best fitting with the experimental data. 30 min ultrasonic pretreatment for 10 mm thickness samples and the control sample with 3 mm thickness, with 2.62×10-7 and 2.99 × 10-8 m2/s had respectively the highest and lowest effective moisture coefficient. Ultrasonic wave did not affect the color of the samples but the color change index (ΔΕ) for the control samples was occurred due to the chemical reactions such as Millard reaction between sugars and proteins and the formation of Melanoidins.

The effect of no tillage, conservation and conventional tillage were investigated on some characteristics of soil and machine. This study was conducted in a split plot design with three main treatments, three sub-treatments and three replications. The treatments consisted of soil tillage methods in three levels: conventional tillage, minimum tillage and no tillage in the main plots and the amount of plant residues in three levels including: without residues, retaining 30 percent and 60 percent of residues in the subplots. The results showed that no tillage and minimum tillage, significantly, reduce fuel consumption (by a maximum of 76% and 60% reduction compared to the conventional method, respectively). A significant reduction in the maximum operating time by 81% and 59% was seen. The reduction of mechanical power used in land preparation and planting operations was at most 66% and 23%, and the reduction of the amount of plant residues returned to 82% and 39%, respectively. The conventional tillage method compared to minimum tillage and no tillage, significantly, reduced the diameter of the soil clods by 21% and 35%, and increased the seed germination rate of seeds by a maximum of 2% and 5%. The soil tillage methods and amount of residues have a significant effect on the soil penetration resistance.