A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering in Agricultural Systems and Engineering, School of Environment, Resources and Development

Thesis (M. Eng.) - Asian Institute of Technology, 2015

Currently, Thailand is the third largest cassava producer of the world and highest in South- East Asia . The annual cassava export value of Thailand has a growth trend of about 100% between 2009 and 2013. There are many processes of cassava production such as land preparation, planting, weed control, fertilization, irrigation and harvesting . However, share of labor and cost in the harvesting process is highest compared to other process. The labor share of cassava harvesting is 61.7% of total cassava pr oduction. Cassava harvesting has been always time and manpower consuming operation. At the moment, the tractor -mounted cassava digger and conveyer is developing in which the famers are involved in cutting, collecting, and stor ing before it is used in the field . During these processes , it requires 50.33 hours (0.02 ha/hr ) per person to finish the land area of one hectare . Therefore, this research highlights the importance of new machine and develops the prototype model called Cassava Stem Chopper that works automatically which do not require any labor meaning reducing the harvesting cost and solve labour shortage problem. This prototype single row cassava stem chopper consists of main frame, a transmission gear unit, a cutting unit, a feeding unit, and a chopping unit. The result found that the average chop ping capacity of this machine was in the range of 171- 819 kg/hr with the traveling speed of 1.44 - 2.42 km/hr. T he re -germination of chopper was 7.5% . In addition to these, it was found that this cassava stem chopper can work 7.5 times faster than traditional method. The break- even point area of the chopper with the capacity of 0.15 ha/hr was equal to 46.2 ha/year at 1.45 km/hr.