Development of wet-seeded rice cultivation technique for furrow seeding, 1: Development of direct sowing machine for furrow seeding

The direct sowing machine for furrow seeding was developed in order to obtain stable seeding emergence and to prevent lodging in the paddy field incorporating barley stubble. 1) The direct sowing machine which is attached with the riding type transplanter is consisted of the furrow openers and the seeders. The furrow openers are rolling cylinder round with the 4 rubber type rings. Rolling the cylinder on the surface of puddled soil makes the furrow of about 4 cm width and of about 4 cm depth. Pre-germinated rice seeds coated with CaO2, an oxygen supplier, were drilled into that furrow. Unlike the direct seeding in the submerged paddy field, this methods do not make them covered in soil. Seeding is done on conditions of non submerged. After seeding the field is flooded at 4 to 5 cm water depth. By doing so the merit of this method can be obtained by higher germination ratio. 2) The optimum sowing conditions for this method are 3 to 4 days after puddling, above 50 gf/cm-square of surface soil hardness. The cage type cylinder of the furrow opener is suitable than that made of plastic pipe, especially for stubble incorporating field. Attaching the vane wheels on the both sides of the cylinder smooths ploughing the furrows. Cutting off the rubber ring partly makes intermittent furrow and prevent seeds from floating. 3) Percentage establishment of seedling by this method was 63 to 73%, and was 10% higher than that of the direct seeding in the submerged paddy field. Percentage of fall down or floating seedling by this method was less than the direct seeding in the submerged paddy field. 4) The furrow was gradually filled up with the surface mud. Underground stem depth became 1.5 to 3 cm finally, effective for improved lodging resistance of plant. 5) In the overwrapped traveling area, the following traveling roller buried the previous planted seed into the soil, and that prevented the seedling density from overpopulation