Abstract
Direct-seeding culture without tillage and covering soil using the Y-shaped seeding furrow was examined in 1997 and 1998 at a poorly drained paddy field in Hachirogata(Akita Pref., Japan). The percentage of seedling establishment in the plots of polyolefin coated urea(CU)and sigmoid type of CU(SCU)were 50.3% and 44.7%, respectively, in 1997, and 35.7% and 35.3%, respectively, in 1998. The cumulative effective temperature from seeding to the establishment time was 147.6°C and l24.0°C in 1997 and 1998, respectively. The number of established seedling per m2 in the CU and SCU plots was 167 and 149, respectively, in 1997, and 119 and 118, respectively, in 1998. The brown grain yield per m2 in CU and SCU plots was 645 g and 621 g in 1997, and were 501 g and 472 g, respectively, in 1998. These results suggested that the direct seeding of rice on Y-shaped furrow without tillage and covering soil is highly feasible to keep the same level of the yield in the transplanted cultivation of rice in cool and clayey paddy fields in the Tohoku District.
