Agricultural Machinery
Mohammad Amin Asoodar; Afshin Marzban; Fatemeh Afsharnia
Abstract
Introduction Wheat is the main food commodity of Iranian population and major cultivating crop, grown on nearly half of the country’s rain-fed area as well as one-third of the irrigated area. Despite the availability of high yielding cultivars for different climates, the average wheat grain yield ...
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Introduction Wheat is the main food commodity of Iranian population and major cultivating crop, grown on nearly half of the country’s rain-fed area as well as one-third of the irrigated area. Despite the availability of high yielding cultivars for different climates, the average wheat grain yield in the country is around 3527 kg ha-1. Lower wheat grain yield could be due to unavailability of recommended varieties seed, delay in planting, inappropriate planting methods, excess use of fertilizers and inefficient water management. Irrigated wheat production in arid and semi-arid regions of Iran is generally practiced under conventional tillage systems. Crop producers in southwestern part of Iran are traditionally using conventional tillage (plowing with moldboard plow followed by double disking) for cultivating various crops. Most of the farmers use grain drills for sowing wheat because of uniformity of planting depth as compared to seed spreaders. The aims of the study were to determine whether different methods of sowing, such as grain drills (followed by flooding irrigation), row crop planting, and combination of furrowers (75 and 60 cm) and seeders (12 cm of sowing space) alter the agronomic performance of winter wheat. Therefore, selection of suitable sowing method plays an important role in the placement of seed at proper depth, which ensures better emergence and subsequent crop growth. Material and methods The study was conducted on a silt clay loam soil (Carbonatic Typic Torrifluvent) in research farms of Ramin Agriculture and Natural Resources University, Ahvaz, Iran, with wheat-wheat- corn crop rotation. The soil was representative of a large area of arable land in the Khuzestan province. Conventional tillage was practiced by moldboard plow ( 25 cm depth) followed by disc harrow twice (nearly 10 cm depth). The two year experiment was conducted based on completely randomized block design in four replicates. 140 kg/ha of wheat (Triticum aestivum L), Chenab cultivar was sown at 50 mm depth for all treatments. The experimental treatments were 20 furrow opener rain drill with 12 cm line space (P), combination of grain drill-furrower (PF60 and PF75) with 60 and 75 cm furrow spaces, also furrower-grain drill (FP60 and FP75 cm) and furrower –grain drill with 3 planted rows on beds (FP3_60 and FP3_75 cm). Soil conductivity of the experimental field (plots) ranged from 1.2 to 3.3 ds mG. The soil texture was silty clay loam with the range of clay content from 34 to36%, and N, P and K contents of the soil were 0.8 to 1, 6.1 to 16.2 and 117 to 192 mg kgG, respectively. Results and discussion Wheat grain yield obtained from all treatments was different; however, harvested grain after FP_75 was the highest compared to others. The highest amount of yield was 5966.7 kg/ha for the first year and 5070 kg/ha for the second year compared to simple planting (P) which was the lowest (4883 and 4271 kg/ha respectively for 2 interval years). Analysis of variance for grain yield indicated that FP-75 had a significant difference (p < 0.01) as compared to others, but grain yield for furrow spaces from 60 to 75 cm was not significantly different. However, the use of furrowers showed significant effects on wheat grain yield. Crop yield and biomass were shown to be different where the furrow was made before sowing. The use of grain drills without furrowers had a great negative effect on crop biomass and grain yield. The results obtained from the second year were similar to the first year. The application of furrow before sowing showed maximum crop yield and biomass, so that the highest and the lowest biomass belonged to FP-75 with 14817 kg ha-1 and P with 11731 kg ha-1, respectively. The harvest index was not significantly different among treatments. Similar results were obtained in wheat plots after harvesting. Conclusion The overall results from this study indicated that the values of crop yield and biomass were maximum where the furrow was made before sowing, as FP-75 treatment had the highest yield. So regarding non-problem of soil salinity in the north of Khuzestan, the use of furrow before sowing can be considered as an appropriate tillage and sowing system for wheat production in the semi-arid region.
Agricultural Machinery
Hamed Ghafarzadeh Zare; Ali Maleki; Mohsen Irani Rahaghi; majid Lashgari
Abstract
Introduction An important process in grain harvesting with the combine harvester is threshing the materials using the thresher unit. An ideal thresher is one that carries out complete threshing with maximum crop input and best grain separation while saves the shape and quality of the grain and minimizes ...
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Introduction An important process in grain harvesting with the combine harvester is threshing the materials using the thresher unit. An ideal thresher is one that carries out complete threshing with maximum crop input and best grain separation while saves the shape and quality of the grain and minimizes grain loss. The vibrations of this unit cause the threshing action to fail and combine harvester loss to increase; therefore, it is highly important to study the vibration produced in the threshing unit. Since measuring the vibration in all working conditions on the farm is expensive, one of the ways to achieve the mentioned objectives is to use a vibration model by the simulation methods in order to examine the effects of vibration on the machine’s and the operator’s performance. Using vibration modeling and dynamic analysis of the structure through a mathematical model, finite element, and modal analysis, the causes and effects of the vibration in different working conditions can be examined with minimum cost. The present study was aimed to carry out the dynamic analysis of combine harvester using operational modal analysis. Therefore, the nonparametric and frequency decomposition methods were used in order to extract values of natural frequencies and damping coefficients, and the information obtained from the modal analysis was utilized to design and update the finite element model of the thresher. Afterward, the vibration of the thresher was adjusted as much as possible by modifying the structure through the weight modification method. Materials and Methods To measure the vibration of the thresher in practical conditions, a piezoelectric accelerometer sensor DYTRAN/MODEL3255A2, an analyzer device, and a signal processing software MEscopeVES were employed. In order to carry out the analysis, the combine harvester was started in its normal conditions and all parts were set in operation. Due to the geometry of the structure, four points were chosen on the bearings of the threshing drum. Afterward, de-noising signals used in MATLAB were utilized to calculate the response power spectral matrix, and singular values decomposition method was applied to it. Finally, by drawing each singular value, resonance peaks of the system were determined with respect to different frequencies, and the system’s damping was estimated. In order to carry out the geometric modeling and the simulation of the thresher by finite element method, ABAQUS finite element software was employed. In order to compare the analytical and the experimental results of NFD value, the predicted and measured natural frequencies were calculated. Modifying the structure as one of the applications of the modal analysis is a technique to consider the effect of physical parameters of a structure on its dynamic properties, i.e. natural frequencies and mode shape in order to improve the structure’s dynamic behavior. In the present study, therefore, modification of the threshing unit was aimed to decrease its vibrations by changing the natural frequency. Due to its complexity, the process of modifying the structure can be carried out by changing the mass and hardness. As presented in the study, modification of the structure was conducted by changing the mass on the finite element model. Results and Discussion The purpose of this study is to determine the vibration characteristics and present a vibration model of the thresher. The vibration responses of the thresher were recorded in working conditions on the bearings of the thresher. Through investigating signal parameters, including root mean square, energy, and entropy in different speeds of the thresher, it was specified that these parameters had significantly higher values in the rotation speed of 1000 rpm compared to other speeds, which proved the disturbance in the rotation speed of 1000 rpm. By examining the range of the natural and excitation frequencies of the threshing unit and also considering the diagram obtained from decomposing the singular values of the power spectral density matrix and Campbell diagram, a resonance frequency was found for the given structure, which is the major cause of vibration in the thresher. Moreover, the speed of 1000 rpm was determined as the critical speed of the thresher. In order to reduce the level of vibrations, the thresher’s excitation frequency should be far enough from the natural frequency; therefore, the process of modifying the structure is carried out by changing the mass applied to the finite element model, and it was observed that the natural frequency of the first mode changed from 16.98 Hz to 12.4 Hz.
