In this study, a total of 804 labels on agricultural machinery were investigated. Some labels were difficult to read because of a combination of small print and low contrast between the characters and their background. The legibility of the label characters due to color combination, illuminance level, and user’s age was investigated. 58 samples of labels were used. The illuminance level was set at 3 stages. The subjects were 42 people aged 20 to 80. Minimum legible character size was 6 to 11 point at the “medium” and “high” illuminance level, and 11 to 19 point at the “low”. Minimum legible size for people under 60 was 6 to 16 point, and over 60 was 6 to 23 point.

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From the perspectives of work efficiency and cost-effectiveness, we developed a compaction roller, consisting of a steel drum linked to a roller by a three-point hitch (total load: 960 kg, working width: 2 m), to prevent leakage on a direct-seeded dry paddy field in the North Kyushu region of Japan. In an evaluation of the roller’s performance in a field of gray-lowland-soil that tilled by a rotary tiller, we confirmed that there was a decrease in soil porosity and an increase in soil penetration resistance in the plow layer, as a consequence of an increased number of compactions. Moreover, there was a significant negative correlation between water permeation (basic intake rate: I_B) and plow layer penetration resistance (average value of soil penetration resistance in the plow layer), indicating that roller compaction of the plow layer can contribute to permeability control.

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