Water leakage control by using vibratory roller on a dry-seeded rice field in southwestern Japan

Dry-seeded rice cultivation is an effective low-cost cultivation method in Japan, but preventing water leakage from cultivated rice fields remains a challenge. Here we assessed the efficiency of using a vibratory roller in a dry-seeded rice field for preventing water leakage. The tests were conducted at two different soil-water contents (WC: 32 and 39%) before roller compaction. We measured the acceleration response of the vibrating roller by using a micro-electro mechanical system (MEMS) accelerometer, and we determined the volume of water leakage from the field by using a rapid leakage capacity tester. We analyzed the changes in the soil structure by using a micro-focused X-ray CT scanner. We analyzed all of the resulting data to identify any correlation. We observed that water leakage from the field was sufficiently prevented when prior to roller compaction, soil moisture content was 39%. The shape of the soil pores that could efficiently prevent water leakage was flatter than that of the inefficiently compacted soil. In addition, the total porosity decreased, but the small-sized pore fraction increased. The vibration acceleration of the roller significantly increased with the decrease in the volume of water leakage. Thus, in addition to assessing the efficiency of vibratory rollers in reducing water leakage, our data suggest that it is to some extent possible to estimate the water leakage prevention effect from the acceleration response of a vibrating roller.