The purpose of this research was to develop a chainsaw which is easy to handle, has good working efficiency, and gives less physical stress through the approach of ergonomics. First, we developed a light weight and compact chainsaw for limbing and pruning which displacement is 18.3ml, maximum power 0.65kW and weighs only 2.5kg (with bar and chain). We considered reduction of weight and the parts' layout, and in result we achieved approximately a 500g reduction in weight (with bar and chain), compared to the existing chainsaw which weighs 3.0kg (with bar and chain). The developed chainsaw showed sufficient performance in field monitoring, and cutting performance tests. Thus it was released into the market. After this, we evaluated in more detail its limbing and pruning performance at different heights of operation (100, 150cm). In result of analyzing the surface electromyograms and the volume of oxygen intake per cut, it was found that there was less physical stress in the arms due to the lighter weight, and also that work efficiency was influenced by the lighter weight, operating posture and the engine performance when operating over 150cm position. Thus, the developed chainsaw had an advantage of lighter weight was proven here also.

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In Miyazaki Prefecture, taro is cultivated in wide rows that allow for the use of tractors. We developed a labor-saving method for ridging work using a direct-mount-type hiller. This machine improves upon commercial up-cut rotary tillers in terms of the arrangement of the three rotary blades, the shape of the rotary cover, and the addition of a grass divider. The theoretical field capacity of this machine loaded on a 20-kW tractor is 0.16ha/h with the rotary tiller rotating at 316rpm and the machine running at 0.2m/s. For soil moisture contents of 35-59% and plowing depths of 51-166 mm, the plowing depth (x) and ridging thickness (y) were positively correlated (r=0.95), and the linear regression equation was y=1.03x-15.43. If soil contraction is considered, the required thickness of the ridges immediately after work is 135mm. The equation shows that a 149-mm plowing depth is necessary to obtain a 135-mm thickness. This study confirmed that the machine has sufficient capacity for ridging work for taro cultivation. The effective field capacity for supplemental application and ridging work by the machine was 2.9-3.6 times that of the traditional method. The yield equaled that of cultivation without ridging, and the quality of the product was higher than that of cultivation without ridging.

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A pesticide-drift-preventing curtain composed of a net to prevent drifting of spray droplets, plastic line, iron pipes and spiral stakes was developed. The drift-preventingnet was hung from the plastic line with both ends fixed to a spiral stake. Then, the net was lifted with the props and the lower end of the net was fixed to each prop with clips. Thus, the curtain was set up without using a stepladder.
The amounts of drift deposit on the net and the working hours spent to set up this simple curtain were compared with those for the conventional curtain based on the experience of 6 workers. The cost of the set up was also calculated.
It took 606.5 seconds per 20m to set up the simple curtain. This was significantly shorter than the 938.2 seconds required for the conventional curtain. The dismantling time was also significantly shorter. There was no significant difference in the pulse rate of the workers when setting up and dismantling between the simple and conventional curtains. No significant difference was observed in the drift preventing effect between the two types of curtains. The simple curtain material cost 12,912 yen per 20m and the conventional curtain cost 17,320 yen per 20m. Thus the simple curtain was around 25% cheaper than the conventional one.
When the simple curtain was set up, there were a few problems. The props were not strong enough to support the drift-preventing-net, and it was difficult to roll up the plastic line.

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