عنوان مقاله [English]
Introduction Weeds are any plant growing at wrong time in the wrong place and also harmful for crops”.Weeds compete with the crop for nutrient and light therefore reduce crop yield. Weed management is a strategy that makes a desired plant population successful in a particular agro-ecosystem using knowledge of the ecology of the undesired plants that is the weed. Recently several ways of controlling weeds are using by farmers, either by using manual, chemical, mechanical or biological means. The earliest and the simplest weed control method is manual weed control. The most effective method of weed management is by making physical contact with the weeds themselves, which are using mechanical weed control machine to reduce the chemical pesticides in mechanized paddy field. This method is among the most important goals in achieving sustainable agriculture development. The present weeding machines have been some demerit which includes of inefficiencies in different farm conditions and the lack of cost-effective purchasing for Sub-ownership land. Therefore to increase of weeding operation quality, the new weeding machine was designed as a single row with rotor propeller by solid work software and manufactured. The weeding unit has been ability to mount on the portable weed cutting machine useable in upland.
Materials and Methods The weeding machine consists of various parts, including of gasoline engine, final drive gearbox, a power transmission shaft and a weeding unit. The weeding unit consisted of chassis, power transfer shaft, propeller, plastic skateboard and protective frame. The diameter of weeding propeller is 22 cm with two blades, which the rotary shaft passes through it. For determination of maximum torque, a total of 9 samples were selected from different areas of paddy field with high weed density and then measured. The maximum propeller torque was determined by torque meter (TQ-8801) through the shaft .The power requirement was calculated about 0.6 hp. So, the gasoline engine with 1.1 kW and 3000rpm was used in designed weeding machine. The gearbox reducer is mounted with a ratio of 1 to 10 after the clutch system was used to provide the rotor rotation at about 200-300 rpm and connected to the engine clutch. The machine field capacity was obtained about 5000 to 7500 m2 per day (10 hours). The actual field operation of weeding machine was evaluated on a 200 m2. The fields was separated into 4 plots and 4 treatments was used in each plots as follow; control (T1), manual weeding (T2), once weeding by machine (T3) and twice weeding at the same time (T4). Data was collected 35 days after transplant (15 days after weeding operation) for each treatment. The height of plant, hill number and efficiency of machine was measured in a completely randomized design with three replications and analyzed by SAS software.
Results and Discussion Based on the requirements of paddy field, the single rotary weeding machine was designed and manufactured. The technical data was obtained based on the computation. The technical results show that the maximum static torque was measured 0.47 N.m. The value of the shaft angle curve designed to be around 0.11 degrees which is very small. Therefore, by consideration of some factors such as; physical ability, fatigue caused by operator's work and unpredicted losses time, the field capacity was obtained about 0.5 to 0.75 ha/day. The results of evaluation experiment showed that there was a significant difference between the treatments at the probability level of 1%. The height of plant was increased in twice weeding treatment (T4) about 19%, manual weeding (T2) about 12%, and once weeding by machine (T3) about 4% in compare of control treatment (T1). The hill numbers was increased in twice weeding treatment about 44%, manual weeding about 40%, and once time weeding by machine about 15% in compared with witness treatment.
Conclusion The product performance is highly correlated with the hill number. There is a meaningful difference between mechanical weeding and manual weeding. In comparison of mechanical weeding methods, the hill number increased about 4% in twice weeding method in compare of once time weeding which shows no meaningful effect. Therefore, once time mechanical weeding (T3) is economically better due to the coexistence of yield with twice weeding (T4). Also, the hill number is increased about 29% in once mechanical weeding in compare of manual weeding. Eventually, once time weeding by machine was recommend.