Abstract
In the Tohoku region, the cultivation of maize in upland fields converted from paddy fields benefits significantly from plowing, and proved to be an effective method for the farmers. This study evaluated seeder settings for achieving a plant density of 7000 plants 10 a-1, yield-related traits, soil pulverization rates, and seedling establishment rates to obtain a combined yield of 800 kg 10 a-1 under plowing conditions in converted paddy fields in central Iwate Prefecture, Japan. A density of 7000 plants 10 a-1 was achieved by increasing the setting of pneumatic seeders by approximately 5% above the target density. The desired combined yield of 800 kg 10 a-1 was obtained only in fields with good drainage. The crop yield per unit area should be set at 900 g m-2, requiring 3161 kernels m-2, a seedling establishment rate of 91%, and a soil pulverization rate of at least 66% to achieve a combined yield of 800 kg 10 a-1 in a well-drained. These results indicate that achievement of a combined yield of 800 kg 10 a-1 with plowing in converted paddy fields depends on sufficient seedling establishment rate and soil pulverization rate, with adequate drainage ensured by appropriate measures. Furthermore, the planting density setting of the seeding machine must exceed the target density to ensure optimal planting density.
