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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 0.1m 3 /h and the structure assembling production rate,
using PLSP, was 2.9m 3 /h. The skidding production rate, using PSP, was 3.5m 3 /h and the
production rate, using PLSP, was 11.9m 3 /h. Loading productivity improved from
4.97m 3 /h, using PSP, to 7.27m 3 /h, using PLSP. Productivity of sawing work element
improved from 0.055m 3 /h, using PSP, to 0.057m 3 /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/m 3 , using PSP and TAS165 350/m 3 , 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. |
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