Even it is to be preferable that no soil adhesion may happen to the rotary tiller, difficulties on ways for getting perfect stoppage on the soil adhesion are existed, nowadays. Therefore, studies on how to remove the soil adhesion on the rotary tiller and structural development for decreasing the soil adhesion are necessary.
The authors examined and discussed on the amount of soil adhesion to every parts of the machines in this study, using the up-cut type rotary that is possible to make various combinations, as steel covers, gum covers, commercial tines, inverted tines (making blade on back ward) and high-polyethylene tines (sticking of high-polyethylene sheet) and etc. In addition, on factors influencing to the adhered soil onto the rotary tillers, the statistical analysis was done by the quantification I. The results were as follows.
(1) By the comparative examinations between the steel cover and the gum cover, it was proved that the separation of the adhered soil appeared in a case of the gum cover. This indicated the effect for a counter measure of soil adhesion by giving vibration of contacted tillage tines onto the gum cover.
(2) Small differences on the comparative soil adhesion of various parts between combinations of the converted tines and the commercial tines were recognized, and the same effects was taken at two examination (Fig. 5, Fig. 8). But the soil adhesion of gum cover side was less than the commercial tines side in three measure point on some examination (Fig. 8).
(3) When comparisons were made on high-polyethylene tines and commercial tines with low moisture contents (37.9-49.8%) of soils, the soil adhesion to the high-polyethylene tines showed in low values compared with commercial tines in every measured places. But the falling off polyethylene sheets sticked on high-polyethylene tines was recognized at about 110m of the tillage, when moisture contents of soils was fairly high (57.8-62.8%). Therefore, the further and perfect methods on the sticking of the polyethylene sheet to tines is needed, in the future.
(4) By results on the statistical analysis of moisture contents of soils, organic matter contents of soils, distance of tillage, kinds of covers and kinds of tines by quantification I, big influences in factors to the soil adhesion by organic matter contents of soils and conditions of operations were observed and also the strongest influence was found by the cover of the rotary tiller in the machines and following these, the tillage tines had a role.
(5) When results of this experiment was summarized, the best way is presumed that operations with both the gum cover and high-polyethylene tines as a counter measure of the stoppage of the soil adhesion to the tillage is made, after the settlement of problems on the falling-off sticked polyethylene sheet from high-polyethylene tines.

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The mechanization of the competing works for both of the crops, which had previously been manual, significantly saved the labor of the works themselves and eased the works, too, while contributing to remedy the working position of workers and to mitigate their fatigue.
1) The use of the development-type hoe eased the digging works of Colocasia esculenta, thus decreasing the damage of the tubers.
2) The introduction of the tuber-harvesting machine for C. esculenta improved the low efficiency and the subjective symptoms of fatigue which accompanied the conventional working system, and produced a labor-saving effect.
3) In the conventional working system for green soybeans, the working time had been 86 hours per 10a., but it was largely shortened to 38 hours 13 minutes in the improved system due to the labor-saving effect.
4) In the conventional working systems for C. esculenta and green soybeans, there had been many cases of subjective symptoms of fatigue due to the squatting position. In the improved system, however, the subjective symptoms decreased because of the outstanding improvement of the working position.

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A riding sprayer in rice field has been developed for large scale paddy fields. It is inevitable that the sprayer damages the rice plant when the sprayer is driven into the paddy field. This study was conducted to determine the practical use of the sprayer in paddy field and how to drive the sprayer without the injury of rice plant.
When the sprayer moved in a straight line, the proportion of injured rice plant was negligible. The proportion of injured rice plant was 3.46% in turning area (6.3m×10.8m) estimated per one time. The proportion of injured rice plant was smaller in turning area where rice plant raw run paralled to sprayer's movement compared to the run vertical to the raw. The yield of the rice plants grown near the trace of the sprayer or under the sprayer was not significantly different from other rice plants.

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A germination model that simulates the relationship between the germination of volunteer wheat and the tillage system in winter wheat-summer crops-barley rotation, were constructed using equations. Simulations were carried out to predict the number of volunteer wheat plants (VWP) appearing in a barley field following several tillage treatments. To evaluate the suit-ability of the growth model, simulated results were compared with observed ones in different experiments. Observed and simulated results generally gave a good fit.
Simulated results indicated that the number of VWP increased in proportion to the amount of failing wheat grain when harvested with a combine and a great number of VWP persisted where rotary-till immediately after the wheat harvest followed rotaty-till in October.
According to the simulation, few VWP appeared where plow-till immediately after the wheat harvest followed rotary-till in October. Few VWP was also appeared where rotary-till in late July followed rotary-till in December. Thus, these tillage treatments effectively prevented contamination of barley grain by volunteer wheat grain.

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In no-tillage farming on clay loam, humid-temperate zone, tendencies of uneven distribution of soil fertility, surface gathered plant root growth and declining of soil percolation and decreasing of yield after continuous cropping can be seen.
In this study, we introduced a fertilizer-injector to no-tillage to the cultivation of dentcorn in order to resolve these problems. This implement can do subsoil breaking and deep-layer fertilizing simultaneously.
The experimental design consists of two main-plots and three sub-plots. Main-plots are no-tillage and rotary tillage (tillage depth: 12cm). Sub-plots are as follows: (1) subsoil breaking and deep-layer fertilizing; (2) subsoil breaking and broadcast fertilizing; (3) broadcast fertilizing.
As a result, subsoil breaking treatment had improved soil hardness, increased air % in the soil three phase, developed root growing especially in the no-tillage plots. But the yield of rotary tillage had declined by the lack of soil moisture. We consider this to be the result of subsoil breaking at dry season. The differences among the no-tillage plots were not significant to the yield.
However, the yields of all no-tillage plots were higher than any rotary tillage plots. It might be possible to get a better result by subsoil breaking when moisture condition is appropriate.
The differences of fertilizer placement did not have any effect on the yield.
For future studies, it is necessary to investigate the optimum season of subsoil breaking and it's remaining effects on the soil.

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