Abstract
We investigated the effects of plowing on growth and grain yield of maize (Zea mays L.) in an upland field converted from an andosol paddy field. A 2-year (2014 and 2015) field study with two hybrids and two tillage systems (rotary tilling and plowing) was conducted. Plowing reduced the time to silking by 1 or 2 days, whereas plant height, leaf color, and leaf area index were not significantly affected by the tillage system. Similarly, the tillage system did not significantly affect root length density; however, plowing of the fields increased root length density from the tassel formation stage to the milky stage. Additionally, plowing tended to increase dry weight at the milky and dough stages in 2014. In 2014, grain yield of the plants grown in plowed fields was higher than that of the plants grown in fields prepared by rotary tilling, while in 2015, there was no significant difference in grain yield between the two tillage systems. Since neither growth depression nor yield decline was observed in maize cultivated in plowed fields, it can be concluded that plowing is useful for maize production in upland field converted from andosol paddy fields.
