Planting depth effects on overdrilled seedling survival in summer

Abstract

Abstract Planting depth effects on post-emergence development and survival of red clover and ryegrass seedlings were studied by overdrilling seeds with a winged coulter at 0, 13, 26, and 39 mm depths in spring at 3 sites with different soil moisture regimes. Depth had no effect on survival or development of either species where the coulter penetrated below the soil surface (13, 26, and 39 mm). Where the coulter skimmed the surface (0 mm), early root development was restricted. The longest root was either shortened by up to 30 mm where the root penetrated the surface, or, in some red clover seedlings, restricted altogether (no penetration). In the latter instance, seedlings died quickly, adding to the disadvantage of lower emergence where a coulter skims the surface. It is concluded that coulter depth in these soils needs only to be sufficient to produce a moisture-retaining groove (13 mm). Results confirm that seedling density differences created by emergence responses to planting depth can be translated ...