Fatemeh Afsharnia; Mohammad Asoodar; Abbas Abdeshahi
Volume 1.32, مجموعه مقالات منتشر شده در حوزه مهندسی زراعی قبل از تفکیک مجله علمی کشاورزی در سالهای 1354 تا 1388 , February 1976, , Pages 49-58
Abstract
Effective operation of a system is related to acceptable programming of repair and service activities. Efficient managerial programming is associated with accurate estimation of maintenance system parameters. In this study, four tractors failure rate was investigated by completing 300 questionnaires ...
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Effective operation of a system is related to acceptable programming of repair and service activities. Efficient managerial programming is associated with accurate estimation of maintenance system parameters. In this study, four tractors failure rate was investigated by completing 300 questionnaires from tractor operators in Khuzestan Province. The operators were interviewed in four regions of the province. Under study variables included driver experience, level of education, driving license, skill training course, work location (region and city), type of service and maintenance, storage conditions, distance to first workshop, distance from shelter to farm, machine age, annual use hours and number of failure. Regression analysis by estimating an exponential function showed that the variables such as age of tractor, annual hours used and type of service and maintenance affected the failure rate of each four type tractors. For one percent increase in age of tractor and annual use hours, failure rate increased about 0.6% and 0.24%, respectively. Also, failure rate in MF285, MF399 and U650 tractors was about 0.383, 0.453 and 0.143 percent more than JD3140 tractor, respectively. The preventive maintenance causes 0.252 percent decrease in failure rate.
M. Khorramian; S. Salimpour
Abstract
IntroductionThe area cultivated for wheat is about 550000 ha in Khuzestan province. Limited rainfall conditions and incompatibility of rainfall patterns with wheat crop requirements leads to decreasing of soil moisture and drought stress. Studies have shown that water supply affects the uptake of nutrients ...
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IntroductionThe area cultivated for wheat is about 550000 ha in Khuzestan province. Limited rainfall conditions and incompatibility of rainfall patterns with wheat crop requirements leads to decreasing of soil moisture and drought stress. Studies have shown that water supply affects the uptake of nutrients and nutrient use effeciency. On the other hand, the benefical effect of the application of zinc and potash nutrients under different water stress in Khouzestan is not convenient for farmers. Therefore, this study aimed to determine the effect of drought stress and zinc and potash in silty clay loam soil on yield and water use efficiency (WUE) of wheat. Materials and Methods The experiment was carried out in Safiabad Agricultural Research Center (SARC) of Dezful, Khuzestan during the years of 2008-09 and 2009-10. Before the experiment, initial composite soil samples (0-30 cm & 30-60cm depth) were collected from the experimental plots and were analyzed. The soil was silty clay loam with low organic matter content (OC=0.5-0.75%) and well drained without salinity (ECe=0.27-1.3 ds m-1). On the other hand, micronutrient content of the soil (Fe, Mn and Cu) was higher than the threshold limit. The design was a split plot on a completely randomized block design with three replications. The main plot consisted of three different levels irrigation after 50 (I50), 75 (I75), and 100 mm (I100) evaporation from evaporation pan and sub plots included three levels of fertilizers, without micronutrient (F0), fertilizing based on soil analysis value (F1), and fertilizing basesd on 1.5 times more than the recommended level (F2). Every subplot size was 3.6 m x 10m. The studied cultivar was Chamran and the sowing date was on November with a density of 400 seeds per m-2 and harvested during May in both growing seasons. Soil moisture content was measured before every irrigation in root zone depth using the weighning method. Applied water was measured using flow meter for every treatment. After seed ripening, grain yield per hectare and component yield were measured from the total area of each treatment. Statistical analysis was performed using MSTATC software packages and mean comparison was also performed using Duncan’s Multiple Range Test (DMRT). Results and Discussion The rainfall during plant growth for first and second years was 68 and 221 mm respectively. The mean temperature of Mars and April in the seconed year was 26.1 and 34°C increasing by about 1.4 and 1.9°C compared to the first year. The higher temperature in the second year increased heat stress which led to yield decrease. Irrigation water consumptions in first year for I50, I75, and I100 treatment were 960.6, 804.1 and 682.2 mm and in the second year 182,115 and 95 mm respectively. Higher rainfall in the second year in comparison with the first year led to decrease in number of irrigation events. All the studied parameters except for 1000-grains weight and number of grains per spike were significantly influenced by different levels of fertilizer treatments.The highest yield belonged to fertilizing based on soil test results (F1), (40 kg K per ha, Zinc Sulfat with 200 kg per ha potash) while the lowest yield was found in the control treatment(F0). Cakmak et al. (1996) and Yilmaz et al.(1997) also observed similar responses. A similar trend was observed in the biological yield, number of spike and 1000-grains weight. Increasing rates of K and zinc(up to 40 kg.ha-1) increased the values of crop parameters such as biological yield, number of spike , 1000-grains weight and water use efficiency and thereafter higher levels of K and zinc fertilizer (F2 treatment) led to their decline. Analysis of variance on yield showed that irrigation regime, potash and zinc fertilizer levels were significantly different (p<5%), so that the highest and the lowest yield belonged to I50F2 with 673.5 gr m-2 and I100F0 with 450.3 gr m-2 respectively. Although there was no significant difference between F1 and F2 treatments, increasing the applied fertilizer in I50 treatment increased yield and water use efficiency. On the other hand, applying potash and zinc fertilizer more than recommended levels in soil under moisture stress (I75 and I100), resulted in decreased yield. Conclusion The overall results from this study indicated that it is essential to avoid applying potash and zinc fertilizers over recommended values in soil under moisture stress conditions. Intraction between different irrigation levels in combination with fertilizer showed that I75F1 with yield and WUE, of 6.4 t ha-1 and 1.28 kg m-3 respectively could be recommended.
