We examined the workers in the rice processing plants in order to determine the effects of noise pollution. This investigation consisted of a social survey and physical measurements. To summarize our interpretation, we can explain as follows:
1) The predominant noise sources identified were the dryer and the huller in the rice processing plants. The proportion of the plants in which the noise level was higher than 90dB(A) to the worker's ear, is about from 50 to 60 percent.
2) When the plants scale is smaller, the building is located in crowded areas. While the complaints of noise is not heard in sparsely populated areas, in 50 percent of the other plants, the inhabitants in the area lodge complaints.
3) The workers pointed out two detrimental factors in their working enviroments. 70 percent complained of the dust and 21 percent complained of the noise. However a larger proportion of workers in the younger age level in large scale plants were more susceptible to noise than that of higher age levels.
4) The majority of the workers stated the noise in the plants was higher than tractor and combine noise. Therefore, a control of noise in the plants is necessary in rice plants and agricultural machinery.
5) As the predominants noise source in the plants, about half of the workers pointed out the huller and the dryer. The rate agreed very well with the values of physical measurements. As a result, it was clear that the workers accurately recongnized the noise source in the plants and its effects.
6) The effect of the noise in the plants as compared with others such as super express noise and the rate of response to the noise shows lower values. But the effect of the noise in the plants on sleep and conversation are clear and the largest influence is seen in younger age level.
7) The effects of noise in the plants on hearing in conversation begins at a comparatively low level with difficulty in sleeping and mental influence following. And at a high noise level physical influence is seen. Most of the workers reported a feeling that the noise exposure over long period had ill effects on their health.
8) The workers know that there is a standard of the permissible noise exposure but few seem to actually realize the significance.
9) From the results of Fig. 6 and 7, it may be necessary to restrict the permissible noise level in plants to 85dB(A).

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In order to evaluate the effects of mechanical weeding, the index for expression of the effects from time varying tendency of fresh weights of weeds and crops are under inves tigation.
In this report, a new index using “vector indication” was examined.
After applying the new index to the effect of rotary cultivator weeding in chinese cabbage cultivation of fall cropping, it was surmised that the method using “vector indication” was of good utility, because of its brief expression.

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