| Resumo: |
Wheat is one of the most important food staff in consumption pattern of each country. More than 50% of human energy is supplied from bread in developing countries. Reducing of losses and waists in combine harvesting resulte increasing considerable wheat production in country. Combine loss is less than 2%-3% in developed countries, while that of developing countries is about 15%-20% in different regions and circumstances of harvesting seasons and field conditions. Regarding to research finding that maximum total combine losses are related to combine header loss, so it is necessary to determine precise losses and their causes to improve and modify existing combine's technical characteristics. In this national research project that took place in three provinces of Tehran, Khorasan and Fars, effect of combine type and drum speed to grain losses and waists were investigated. Experimental design was split plot in a completely randomized block design with three replications. Duncan's test was used to statistical analysis of the means. Combine type in four levels of New Holland TC 56, JD 1165, JD 955 and CLASS 68 as a main-plot and drum speed in three levels of 650, 750 and 850 rpm as a sub-plot. Field experiments were carried out in the farmers field with two ha area. Different parameters and factors of each treatment were measured: 1. Pre-harvest loss, 2. Header loss, 3. Drum loss, 4. Cleaning loss, 5. Ground speed & combine field capacity, 6. Drum speed, 7. Linear drum speed, 8. Grain moisture content, 9. Cutting height. The results of Tehran province show that New Holland TC 56 and JD 955 with 1.98% and 2.15% of the total combine losses are the lowest and positioned in class a while JD 1165 and CLASS 68 with 4.29% and 4.12% located in class b. Also New Holland TC 560 has a highest combine capacity of 5187 kg/hr and gets a class of a while JD 1165 while CLASS 68 are in class b and JD 955 is in class c. The results of Fars province show that the highest total combine loss was related to JD 955 and Class 68, 2.72% and 2.84%, respectively, and JD 1165 had the lowest total combine loss (1.61%). The results of Khorasan province show that New Holland TC 56 had a lowest total combine loss (14.3 kg/ha) and got class a and JD 955, JD 1165 and CLASS 68 took class b, c and d, respectively. Also New Holland TC 56 had a highest combine capacity (5,383.58 kg/hr) while CLASS 68, JD 955 and JD 1165 positioned in b, c and d classes, respectively. Therefore, combines improvements and modifications are suggested as 1. Uniform cutting height, 2. compatible reel and ground speed, 3. using effective cutting width, 4. using proper drum speed, 5. choosing proper ground speed regarding crop density.
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