Ugyen Phuntsho, Kinga Norbu & Pem Lham
Bhutanese agriculture has been at the subsistence level and the adoption of mechanization started only in late 1986 with the establishment of the Agriculture Machinery Centre. One of the most popular farm machines is the power tiller, the use of which is fast replacing the old tradition of land preparation using oxen. However, the adoption of farm machinery for land preparation is limited to the narrow plain areas along the border with India. Most of the country is mountainous where the use of power tillers has become unsafe and less efficient due to high gradients. Further, farmers have been stretching the use of the power tillers for ploughing on the mountain slopes even though it is less labour-efficient and involves risk-taking. In many cases, power tillers are used on land with gradients exceeding 15 degrees with additional labour to prevent the machine from toppling. The experiment was carried out to determine the critical safe angle of the sideways tilt while ploughing, and also to determine the critical angle that is practically possible to increase by using an extension device that was designed and fabricated to increase the wheel tread. This research compares the three treatments, i.e., rubber wheel with normal axle, rubber wheel with the extension device, and paddy wheel for required machine stability. It was observed that the rubber wheel with the normal axle was only feasible up to 9.93 degrees slope, the paddy wheel and rubber wheel with extension device were feasible up to 20 degrees slope. There was a significant (P<0.05) difference between the rubber wheel with normal axle and the rubber wheel with the extension device in terms of stability and no significant difference was observed between the extension device and the paddy wheel. This was achieved by decreasing the centre of gravity in a high slope gradient land and this could help farmers bring more agricultural land with high gradient into meaningful cultivation, thereby, enhancing food production.
Keywords: Gradient; Toppling; Critical angle; Extension Device; Machine stability