Effects of Previous Crop and Soil Moisture Content on Planting Depth and Stand Establishment of Forage Corn in a No-Tillage System

Abstract

We examined planting depth and stand establishment of forage corn seeded by planter adapted to a no-tillage system as affected by previous tillage systems, (i) no tillage of previous Italian ryegrass harvested at heading stage, (ii) no tillage of previous Italian ryegrass harvested at internode elongation stage, (iii) no tillage of corn harvested in the previous year, and (iv) tillage, combined with two levels of soil moisture content. The system (i) had a larger amount of root residues with higher degree of soil hardness than the others, resulting in shallower planting depth. Sprinkler irrigation increased soil moisture content and soil tended to decrease soil hardness, making it possible to plant corn more deeply. The ratios of stand establishment of no tillage to that of tillage ranged from 87.5% to 104.3% at planting depths of more than 3.0 cm. These results suggest that a no-tillage system would make it possible to ensure deep planting at more than 3.0 cm against large amount of root residues and nearly equivalent stand establishment to the conventional tillage system when the seeding procedure is conducted under high soil moisture conditions, i.e. post-rainfall.