To prevent stone accidents, several modifications have been made to a conventional bush cutter head. One of the modification is to mount a shear bar with counter edges over the conventional blade (counter edge cutting type).
Another modification is to put two notched blades, one over the other, and to reciprocally reverse the blade (relative cutting type).
Tests were conducted in relation to stone scattering, operation efficiency and energy required to cut stems of weed, and result were compared with impact cutting type bush cutter without counter edges.
1) Because the counter edges obstructed stone scattering, the percentage of stones scattered toward the operator by the counter edge cutting type bush cutter was half of that of the impact cutting type.
2) The percentage of stones scattered by the counter edge type decreased with the decrease of the blade rotating speed, and the direction of stone scattering tends to shift on the left-hand side of the operator, making it safer to use the counter edge type.
3) The work efficiency for the impact cutting type rapidly decreased as the rotating speed of blade decreases to 5, 000rpm or less, where that of the counter edge type decreased a little with the slow rotating speed.
4) For the counter edge cutter type, the energy to cut single stems of Golden-rod decreased with the decrease in the blade rotating speed, and with the increase in the blade traveling speed. Impact cutting has been shown to impart energy to the stem due to stem deflection and also to suffer energy loss from stem due to blade friction, Hence, impact cutting type would be expected to require more energy than counter edge type.
5) For cutting of young rice plants, the effect of increasing clearance between the blade and counter edge was small over a range of clearance in practice. The young rice plants shearing abilities of the counter edge and relative cutting type were superior to that of the impact cutting type. More than 90% of rice plants were sheared by relative cutting type even at the low level of peripheral speed, 5-15m/s.
Since these cutter heads has a complicated structure, it is evident that more work using different approaches is necessary.

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The working efficiency of a tractor decreases when operated on a field where there are obstacles. In this study, a telephone wire pole was used as an obstacle.
When a tractor approaches an obstacle, the operator has to change its direction of motion to avoid it. As a result, some of the field area around the obstacle is inaccessible by machinery. Therefore, a labor force is required as in the case of traditional methods where a farmer works manually for cultivation and harvesting.
In order to utilize the remaining area of land around the obstacle, a tractor maneuvering method is essential.
To solve these problems, a one seventh scale model of the tractor (Mitsubishi R-4300) was designed and constructed. The motion path of the turning curve was measured at the test field, and both the Mitsubishi R-4300 type tractor and the model tractor showed an improved locus. It has been used continuously for simulation testing to realize the benefit of rational planning for the motion path of the tractor around obstacles.

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We investigated the physical and chemical properties of soil, and the patterns of crop root growth from a serial experiments on successive no-tillage farming for seven years in this paper.
1) The soil hardness of no-tillage plot (NT) was higher than that of conventional tillage plot (CT) in 5-20cm layer, the hardness of NT was almost equivalent to that of CT in 25-35cm layer and the hardness of NT was lower than that of CT in layer below 35cm. The soil hardening has already progressed since the second year of no-tillage farming.
2) There was no difference between CT and NT in three phase of soil. The significant differences in both water content and bulk density for soil layers were observed in common with the two plots.
3) The pH of NT was slightly lower than that of CT.
4) In the analysis on various chemical properties of soil after six years of no-tillage farming, no clear difference between CT and NT was observed except for a few chemical components.
5) Most of the crop root in NT concentrated on 0-10cm soil layer.

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1) The effect of the side-dressing application toward the crop growth and yield was discussed when side-dressing to direct sown chinese cabbage was applied by accurately controlling amount of fertilizer distribution according to the individual crop growth condition at the course of growth.
2) In case of spring-sown cropping, the more difference among the applied amount of fertilizer distribution there was, the less difference among the yield (total fresh crop weight and eatable fresh crop weight) there was when giving the larger canopy crop less fertilizer and the smaller canopy crop much fertilizer. The uniform product possibility would be able to resulted by the fertilizer correction treatment. However, the existance of limitation that the yield difference among the each crop fertilizer distribution was estimated.
3) In automn-sown cropping, the effect of side-dressing to the crop growth was not clear on the stage of 20 days passed after fertilizer application. Moreover, the response of the total fresh crop weight at the harvest time is quicker than that of the eatable fresh crop weight in case of spring-sown cropping. It will be effective for increasing the crop yield to apply the immediate response fertilizer at the course of growth.
4) New model substituted by a cubic expression is proposed to express fertilizing function of fertilizer correction treatment.

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To enrich energy data in the hay making systems with solar energy, we measured fuel consumption and working time of tractor and dryer for a serial processes on a field from Mowing to Re-baling.
1) Working time of the heated air drying process was 63% of the total time, and fuel consumption of this process was 97% of the total fuel, so this process which consumed a lot of petroleum had a serious problem.
2) The total fuel consumption in the several working processes on a field was less than that in the heated air drying process. Fuel consumption per unit area in Harvesting, Conditioning and Raking were larger than those of other working processes.
3) η1 (the part of solar drying) was about 400 times as large as η3 (the part of heated air drying) from the calculation except for the contribution of solar energy.

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