Abstract
In order to reduce the production cost of rice, a work system for the dry seeded rice culture on clay ill-drained paddy field of large lot was studied.
One of the problems to be solved on the dry seeded rice culture is that the seeding is difficult for a couple of days after rain. This is a serious problem, especially in the Hokuriku district.
Therefore, to reduce the rain damage for seeding practice, the effect of soil packing after tillage was investigated under the conditions of natural rain and artificial rain.
The results are as follows:
1. Packing after tillage increased density in the soil layer at the depth of 15cm. The corn index was between 0.39-0.59MPa (4-6kgf/cm2). So, after 15mm/day natural rain and 20mm/day of artificial rain, the sinkage of a tractor with seeding machine at a day after the rain stabilized between 3-4cm.
2. The soil layer in the packed field was tilled to a depth of 9-11cm by a rotary harrow. Soil packing increased the solid ratio of soil and lowered the water content-by weight.
As a result of it, the higher rate of soil pulverization, the lower rate of uncovered seeds and the stable seeding depth were obtained.
3. In the packed field, the rate of emergence showed more than 70% when rice grains were seeded at day after the rain, which is 15mm/day of natural rain or 20mm/day of artificial rain.
4. By soil packing after tillage, it may be possible to seed as scheduled even next day of 15-20mm/day rain. So we can expect that the soil packing expand the number of days for seeding.
