Switchgrass can be established with conventional planting techniques— broadcasting or drilling into a well-till seedbed—or with no-till planters that can drill seed into un-worked bare soil, killed sod or crop stubble. Aside from environmental considerations associated with tillage, perhaps the biggest issue with planting method is the ability to achieve proper planting depth. As noted above, seed depth is critical for successful establishment, and poor seed placement has been a common cause of stand failure with both conventional drilling or broadcast and no-till seeding methods.

Broadcast seeding is the least preferred of planting methods and typically only successful when the seedbed is rolled or compacted after the seed are broadcast (Evers and Butler 2000; Monti et al. 2001). Rolling or packing likely pushes some seed to the appropriate depth, allowing for establishment and survival.

Comparisons of switchgrass establishment by drilling into tilled or non-tilled seedbeds are often confounded and inconsistent (Parrish and Fike

2005) with outcomes dependent on year, location and presence of residues (e. g., see King et al. 1989). Success with no-till seeding methods have been possible for some time (e. g., see Wolf et al. 1989) and Rehm (1990) reported no yield differences between the two planting methods. Some studies have reported greater seedling numbers with no-till planting methods (Harper et al. 2004) but seedling numbers may or may not have long-term effects on stand productivity (see section on row spacing below).

Row Spacing

Although less critical than planting depth and timing, appropriate row spacing allows plants to optimize resource capture with decreased seeding rates. Reducing competition can allow more efficient resource use and support increased yields. Results in Texas from row spacing experiments during establishment years indicate that switchgrass produces more robust plants with greater tiller density and mass as row spacing increases (Muir et al. 2001). Increasing row spacing from 20 to 80 cm also increased yields in Alabama without N fertility (Ma et al. 2001). Similar data are reported by Foster et al. (2012) who found that switchgrass planted at row spacings of 17.8 to 88.9 cm had similar DM yield. These data indicate row spacing may not be a major consideration to successful establishment of switchgrass as a biomass energy crop at low latitude locations. Although there is little information to guide such planting decisions at greater latitudes, we would predict similar outcomes. Potential for success with various row widths offers greater flexibility for farmers with different types of drills and who might apply mechanical tools for weed control.