Comparison Of Productivity, Cost And Energy Expenditure When Sawing On Pits awing And Portable Platforms In Agroforestry Farms In Kilimanjaro

ABSTRACT 

Although future increase in timber supply in many countries is expected to come from agroforestry, the problem of on farm timber sawing, physical strain on sawyers caused by “Pitsawing” has to be addressed, to increase timber sawing productivity. This study was aimed at analyzing the productivity and energy expenditure by sawyers when using Traditional Pitsawing Platforms (PSP) and Portable Steel Log Sawing Platforms (PLSP) in agroforestry farms in Kiruweni and Nduweni villages in South Kilimanjaro. Pitsawing productivity data was obtained using time studies of the pitsawing operations on the respective platforms and data on energy expenditure was obtained through heart rate measurements using heart rate monitor. Results indicated that the site preparation production rate, using PSP, was 0.1m3 /h and the structure assembling production rate, using PLSP, was 2.9m3 /h. The skidding production rate, using PSP, was 3.5m3 /h and the production rate, using PLSP, was 11.9m3 /h. Loading productivity improved from 4.97m3 /h, using PSP, to 7.27m3 /h, using PLSP. Productivity of sawing work element improved from 0.055m3 /h, using PSP, to 0.057m3 /h, using PLSP. In sawing, Energy Expenditure (EE) was 12.69kJ/min and 12.4 kJ/min using PSP and PLSP respectively. During pit excavation/structure assembling, EE was 14.05kJ/min, using PSP, and 2.61kJ/min using PLSP. The physical workload was classified as unduly heavy for PSP and light for PLSP. For the skidding work element, the EE decreased from 5.88kJ/min, using PLSP to 4.48kJ/min, using PSP. For the loading work element, the EE was decreased from 5.20kJ/min, using PSP to 3.55kJ/min, using PLSP. The sawing cost was TAS 205 320/m3 , using PSP and TAS165 350/m3 , using PLSP. In conclusion, PLSP is a technically more appropriate technology for reducing EE and sawing costs as well as increasing productivity during timber harvesting in agroforestry farms.