نشریه تحقیقات سامانه ها و مکانیزاسیون کشاورزی
پیاپی 70 (بهار و تابستان 1397)

Design of agricultural machinery and implements for local needs, requires determination of accurate values of physical and mechanical properties of soil, including soil-metal friction coefficient. In this study, the effects of soil moisture content at five levels and sliding speed (at three levels of 0.5, 2.5 and 3.5) on four contact materials namely: steel, cast iron, rubber, and Teflon on the soil- metal external coefficient of friction of of loam, sandy loam and loamy sand soil at 5 levels of soil moisture content was investigated In this context a device was designed and evaluated for accurate determination of soil friction coefficient. Data were analyzed based on 5×4×3 factorial experiment in randomized complete block design using MSTATC software. Due to differences in moisture content at different phases of friction, adhesion and fluid in soils with different textures, statistical analysis was performed separately for each soil texture and nested factorial design was used to study the effects of soil texture. Results showed that in all soil types, three sliding speed levels affected soil-metal friction significantly at the probability level of 1%. Also, with increasing sliding speed, soil-metal friction coefficient had incremental trend. Meanwhile, the results also showed that at the experimental sliding speeds of 0.5, 2.5 and 3.5 cm/s, the trend and pattern of the curves of soil friction coefficient versus soil moisture content were similar. Results of this study and the determined values ​​of parameters of soil-metal friction coefficient and adhesion could be used in the design of agricultural machinery and implements, modeling of the relationship between soil & machine, draft calculation and also in tillage implements performance and their wear and tear investigations.

Several destructive and non-destructive methods are employed to measure the fruits and vegetables quality. Destructive methods are principally expensive and time-consuming. In the current study, some quality attributes of Vitis vinifera CV. Asgari such as soluble solids content (SSC), titratable acidity (TA), pH and total phenolics (TP) measured by near-infrared spectroscopy (NIRS). For this purpose spectroscopy was performed for 110 grape samples in the range of 900-1700 nm chemicals measures were carried out for the quality attributes of samples, and calibrated models were used to establish the correlation between the spectral data and chemical measurements. Results indicated that the best Partial least square (PLS) models had root mean square error of prediction (RMSEP) equivalent to 0.580, brix of 0.02%, 0.125 and 23.441 and correlation coefficients (rp) of 0.927, 0.806, 0.898 and 0.866 for SSC, TA, pH and TP respectively. Comparison between the mean values predicted by the best models and the mean values measured by the reference method for each attribute showed a non-significant difference between the values predicted by the best models and the measured values by reference method at the 5% level for all attributes. It was concluded that NIRs could be a fast and accurate method for non-destructive prediction of some internal quality of Asgari grape< and other attributes which are difficult to measure.

Rice with the cultivation area of more than 565 thousand hectares and production amount of 2.45 million tons is the second most important crop after wheat in Iran. Most of cultivated area is also located in Mazandaran and Guilan province. It is clear that reaching to self-sufficiency in rice production is not possible without assessment of current status of rice mechanization. Therefore present study was conducted to determine current status of rice mechanization and propose needed solutions to improve it. Data were gathered by completing questionnaire and by reviewing the literature and field surveying. In view of information obtaeined; degree of mechanization, level of mechanization, capacity of mechanization, economic efficiency of mechanization, field efficiency of machine, potential ability of machine, working hours and days and productivity coefficient of machine were calculated. The results showed that degree of mechanization of primary tillage and secondary tillage was 99.7 and 99.3%, planting operation with transplanter was 22.69% and harvesting operation with mower and combine was 72.8 %. The lowest degree of mechanization of rice production was obtained for mechanical weeding with the value of 8%. The level of mechanization was calculated 2.63 hp/ha. Mean economic efficiency of mechanization and capacity of mechanization of rice was found to be 1.87 ton/ha and 235 hp.hr/ha, respectively.

Performance of Terradisc stubble cultivator was evaluated in a field experiment during two years in Khuzestan agricultural research center with nine treatments. These treatments were also compared with traditional method. Corn planted in experimental field in summer and wheat cultivated after corn in fall. Terradisc treatments consisted of three levels of forward speed namely: 8, 10, and 12 km/h and three levels of front and rear discs overlaps: 0, 30, and 60 percent. All treatments were replicated three times in this research. The measured and evaluated parameters were fuel consumption, time, effective field capacity, percentage of residue remained on the soil surface, wheat grain yield, and yield components. Two years ANOVA results showed that, tillage method, forward speed, and discs overlap had no significant effect on wheat yield and yield components. Variance analysis of technical parameters showed that effects of forward speed and discs overlap were significant on some of these parameters such as fuel consumption and time requirement. The results showed that amount of residue remained on the soil surface increased significantly, as discs overlap reduced. The highest and lowest remained residue was 88.6 and 64.7 percent in 60 and zero degrees of discs overlap, respectively. Mean weight diameter (MWD) reduced as forward speed increased. MWD calculated 31.6 mm and 33.6 mm in forward speeds of 12 and 8 km/h, respectively. Forward speed of 12 km/h had the minimum fuel consumption (11.8 lit/ha), while the maximum fuel consumption (15.5 lit/ha) belonged to forward speed of 8 km/h. According to obtained results, Terradisc can be recommended as an acceptable option for applying the minimum tillage in corn residue with higher forward speed and lower discs overlap.

A large amount of herbicide is being used for controlling weeds in agricultural, lawns, sport fields on yearly basis. This causes environmental pollution and economic concerns. To reduce the use of herbicides, hand labor may be the best way of removing weeds. It is, however, costly and time consuming. In this paper, two methods of distinguishing weeds from lawns using computer vision techniques are proposed. Due to the fact that the weeds have different colors and identification of them from grass is not possible; therefore, an algorithm was developed based on the assumption that the grass area should contain more edges while the weed area is smoother than the grass area. For identification of weed/grass two methods were used, namely: Bayesian Classifier (BO) and morphology (MO. Results indicated that correct weed identification rates for MO and BO methods were 89.58% and 80.42% respectively. Furthermore, from results obtained it can be concluded that herbicide usage was reduced more than 70%, which from economical point of view as well as reduction of environmental pollution is of great importance.

In this study, a U-shaped reactor with aeration, heating and stirring systems was designed for composting process. The length, width and height of reactor were 110, 66 and 70 cm respectively. The experiment was carried out at different aeration rate (0.2, 0.4 and 0.6 Lit/min.Kg DM) and time (0, 19, 38, 57, 76, 96 hour). The agitation speed and temperature for the purpose of this experiment was; 55 and 1 rpm respectively. In order to adjust the C/N ratio and humidity of compost, two additives namely: zeolites and rice bran was used. The initial moisture content of waste material was between 60 to 65 percent in all operations. Results showed that the changes in the EC, germination index, and C/N ratio were significant. The EC of compost declined and the pH value increased at the end of process for all operations. The average C/N ratio of compost materials changed from 28 to 20.9 after 96 hours in the reactor. In traditional method, the C/N ratio reached to 19.8 after 21 days. Composting process time has a significant effect on germination index. The maximum germination index occurred at the aeration rate of 0.4 Lit/min. Kg DM which was 85 percent. Also the results indicated that the designed reactor with continuous rotating agitator, heating and air pressure was able to convert the food waste to compost within 96 hours. Results indicate that the proposed composting system can create a suitable environment for the growth and performance of micro-organisms in order to accelerate the decomposition of food waste.

Wheat is the most important staple crop in Iran. By reducing losses of wheat at harvest stage, a significant increase of wheat fields production is possible. In view of increasing acceptance and the demand for straw walker combine, especially for harvesting the wheat, under present present investigation, the harvesting losses rate of the conventional combine and the straw walker combine of John Deere 955 and Class 76 were compared. The straw walker and the conventional combines were tested under quite the same field conditions with 14% moisture content. Further losses at different parts of combine such as cutting unit, threshing and separation, tank, MOG and seed germination percentage were also measured. The tested straw walker and the conventional combines were selected from Jandier (Hepko) and class companies. The results showed that the total harvest losses of the straw walker combine and the conventional combine in both Claas and John Deere, had a significant difference. The losses of John Deere straw walker combine mostly occurred at combine wheat storage tank at the value of 4.16%, whereas the losses in straw walker Class combine was mostly occurred at threshing and cleaning units which was about 8.13%. It should be noted that losses of both of tested combine had a significant difference as copared with losses in conventional combine. Finally, it was observed that fuel consumption in case of straw walker Class combine was 55 litres per hectare and 69.44 litres per hectare for straw walker John Deere combine.

In this study agricultural inputs productivity in the wheat cultivation during the year 2015 was analyzed. The considered variables under investigation were social and economic characteristics of farmers, and also different inputs. The research methodology was based on estimation of the average and marginal productivity function of the production and also the elasticity of production. For selection of the appropriate production functions, the likelihood ratio test was used. According to the test results, the translog production function as compared with other functions was more consistent with the observations. Based on obtained results, the maximum and minimum value of the marginal productivity of inputs were for cultivation area and machinery respectively. The final productivity of the machinery in the region represent a declining order of -4.74 kg of wheat, in exchange for additional usage of an hour of the input to the current conditions. Degree of utilization of machinery as an input in areas with no economical production level (third stage) and other inputs were observed to be in the economic production stage (second stage). The simultaneous effect of both acreage and machines on production, indicates that in small and fragmented fields, the possibility of using machineries is not justified and is associated with an increase in the cost of production.

Crop residue management is very important in farmlands. Conservatiion and proper management of residues, improves soil structure, retain moisture and reduces soil erosion. Whereas, crop residue burning converts organic material into ash, increases soil erosion and moisture loss from feild. The aim of present study was to research for accurate, fast and inexpensive methods for monitoring farms where crop residues are burned. keeping this in view, the potential of Landsat 8 sensor local data for monitoring residue burning was evaluated, using three classification methods including; supervised classification, unsupervised classification and detection of changes. Total number of 120 farms with 4 different surface coverage namely: plant residue, soil, green plant and residue ash were considered. Burned field’s location and their area were determined through satellite image with tree methods and their results were compared with field results. The results showed that due to successive changes in surface conditions of experimental farms, between two satellite imagery, such as tillage, seed planting and planted crop emergence, the satellite imagery could not be monitor the burned farms appropriately. Location and estimation of burned farm area by supervised classification was done with high accuracy. Overall classification accuracy of supervised classification method was 96.6, kappa coefficient was 0.93 and R2 was 0.92. Although by the unsupervised classification method some burned farms were separated, but overall classification accuracy and kappa coefficient of this method was low (71.6 and 0.61 respectively). Finally and based on the results it can be suggested that, supervised classification was chosen for farms remote sensing, where crop residues are burned.

It is essential to have integrated information on the energy exchange of forage crops in order to allow comparisons of their energy consumption patterns. Thus the aims of this study are examination of the energy consumption pattern, estimation of the amount of produced CO2eq. and modeling between the yield and energy inputs in three forage crops. These forage crops that are fed to dairy cows were wheat straw, maize silage and alfalfa. The total amount of energy inputs in fields of wheat (and its straw), silage corn and alfalfa were calculated as: 32077.85, 93049.87 and 30208.04 MJ ha-1 respectively. The amount of produced CO2eq. in these three crops were estimated to be 2704.67, 5861.79 and 5538 respectively. The value of energy ratio in two crops of wheat and alfalfa were computed as 2.69 and 2.18 while in the silage crop due to higher amount of output energy rather than input energy was calculated less than one. Also, the adaptive neuro-fuzzy inference system was used for modeling the relation of the yield of these forage crops and the amount of energy inputs. For estimation of the model for wheat straw, the model with three 'gaussmf' memberships function for each input variables was the best among the other models. Also, the best model for maize silage and alfalfa were 'pimf' for tow memberships function and 'trapmf' for three memberships function, respectively.