WATER LEAKAGE CONTROL IN A DRY-SEEDED RICE FIELD BY USING VIBRATORY ROLLER

摘要

Dry-seeded rice cultivation is an effective low-cost cultivation method in Japan; however, prevention of water leakage from the cultivated field is a technical problem during this cultivation method, which needs to be addressed. In this study, we assessed the efficiency of using a vibratory roller in a dry-seeded rice field, in preventing water leakage. We measured the acceleration response of the vibrating roller, volume of water leakage from the field, and change in the soil structure by using a MEMS accelerometer, a rapid leakage capacity tester, and a micro-focused X-ray CT scanner, respectively, and the results were assessed to identify any correlation. Period of the main frequency component of the vibration acceleration of the roller paralleled the PTO rotation period, and the amplitude of that was increased significantly with decrease in the volume of water leakage. Water leakage from the field was prevented sufficiently when the water content was beyond the plastic limit before roller compaction. The shape of the soil pore that could efficiently prevent water leakage was flatter than that of the inefficient soil. Furthermore, the total porosity decreased, but the small-sized pore rate increased.