Thomas G. Chastain
Our work on grass seed crop residue management suggests that the answer to this question depends on the grass crop species. On-farm trials over 60 site-years and in 6 seed crops species across Oregon were used to compare baling straw with and without flailing of the crop stubble. In several of our grass seed crops including perennial ryegrass, tall fescue, orchardgrass and Chewings fescue, the differences in seed yield for baling and post-bale flail chopping of a field were negligible and were not statistically significant. Thus, there was no requirement for flailing of these crops after baling of the straw in order to harvest good seed yields.
The practice of flailing stubble after baling is commonplace despite this lack of seed yield difference in perennial ryegrass, tall fescue, orchardgrass and Chewings fescue. The stubble is often uneven across the field after the crop has been cut by the swather and sometimes small patches of the field remain uncut for a variety of reasons. Moreover, perennial ryegrass seed fields often will produce new tillers on the tall stubble well above the plant crown (near the soil surface), the normal site for production of tillers. These elevated tillers are known as aerial tillers and while unsightly, they will not adversely impact perennial ryegrass seed yield. Therefore, the primary purpose of a post-bale flail mowing of perennial ryegrass, tall fescue, orchardgrass and Chewings fescue seed crops is to improve the uniformity and appearance of the seed field.
Two of our seed crops have a demonstrated need for flail chopping of the stubble after baling for improvement of seed yield. For strong creeping red fescue, chopping the stubble by flailing after baling increased seed yield by 13% over baling without flailing the stubble. Seed yield was increased by 18% in Kentucky bluegrass when the stubble was flailed after baling. Both of these seed crop species respond with further increases in seed yield when the stubble is cut as close as possible to the plant crowns.